[Federal Register Volume 89, Number 76 (Thursday, April 18, 2024)]
[Rules and Regulations]
[Pages 28218-28485]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-06920]
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Vol. 89
Thursday,
No. 76
April 18, 2024
Part III
Department of Labor
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Mine Safety and Health Administration
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30 CFR Parts 56, 57, 60, et al.
Lowering Miners' Exposure to Respirable Crystalline Silica and
Improving Respiratory Protection; Final Rule
Federal Register / Vol. 89 , No. 76 / Thursday, April 18, 2024 /
Rules and Regulations
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DEPARTMENT OF LABOR
Mine Safety and Health Administration
30 CFR Parts 56, 57, 60, 70, 71, 72, 75, and 90
[Docket No. MSHA-2023-0001]
RIN 1219-AB36
Lowering Miners' Exposure to Respirable Crystalline Silica and
Improving Respiratory Protection
AGENCY: Mine Safety and Health Administration (MSHA), Department of
Labor.
ACTION: Final rule.
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SUMMARY: The Mine Safety and Health Administration (MSHA) is amending
its existing standards to better protect miners against occupational
exposure to respirable crystalline silica, a significant health hazard,
and to improve respiratory protection for miners from exposure to
airborne contaminants. MSHA's final rule also includes other
requirements to protect miner health, such as exposure sampling,
corrective actions to be taken when a miner's exposure exceeds the
permissible exposure limit, and medical surveillance for metal and
nonmetal mines.
DATES:
Effective date: The final rule is effective June 17, 2024, except
for amendments 21, 22, 25, 26, 27, 30, 31, 34, 35, 36, 38, 39, 42, 43,
46, 47, 50, 51, 54, 55, 59, 60, 63, 64, 68, 69, 73, 74, 77, 78, 81, 82,
83, 86, 87, 90, 91, 94, 95, 98, 99, 102, 103, 106, 107, 110, and 111,
which are effective April 14, 2025, and amendments 4, 5, 8, 9, 13, 14,
17, and 18, which are effective April 8, 2026.
Incorporation by reference date: The incorporation by reference of
certain materials listed in the rule is approved by the Director of the
Federal Register beginning June 17, 2024, except for the material in
amendment 60, which is approved beginning April 14, 2025, and the
material in amendments 9 and 18, which is approved beginning April 8,
2026. The incorporation by reference of certain other material listed
in the rule was approved by the Director of the Federal Register as of
July 10, 1995.
Compliance dates: Compliance with this final rule is required April
14, 2025 for coal mine operators and April 8, 2026 for metal and
nonmetal mine operators.
FOR FURTHER INFORMATION CONTACT: S. Aromie Noe, Director, Office of
Standards, Regulations, and Variances, MSHA, at:
[email protected] (email); 202-693-9440 (voice); or 202-693-9441
(facsimile). These are not toll-free numbers.
SUPPLEMENTARY INFORMATION:
The preamble to the final standard follows this outline:
I. Executive Summary
II. Pertinent Legal Authority
III. Regulatory History
IV. Background
V. Health Effects Summary
VI. Final Risk Analysis Summary
VII. Feasibility
VIII. Summary and Explanation of the Final Rule
IX. Summary of Final Regulatory Impact Analysis and Regulatory
Alternatives
X. Final Regulatory Flexibility Analysis
XI. Paperwork Reduction Act
XII. Other Regulatory Considerations
XIII. References
XIV. Appendix
Acronyms and Abbreviations
COPD chronic obstructive pulmonary disease
ESRD end-stage renal disease
FEV forced expiratory volume
FRA final risk analysis
FRIA final regulatory impact analysis
FVC forced vital capacity
L/min liters per minute
mg milligram
mg/m\3\ milligrams per cubic meter
mL milliliter
[micro]g/m\3\ micrograms per cubic meter
MNM metal and nonmetal
MRE Mining Research Establishment
NMRD nonmalignant respiratory disease
PEL permissible exposure limit
PMF progressive massive fibrosis
PRA preliminary risk analysis
RCMD respirable coal mine dust
REL recommended exposure limit
SiO2 silica
TB tuberculosis
TLV[supreg] Threshold Limit Value
TWA time-weighted average
I. Executive Summary
A. Purpose of the Regulatory Action
The purpose of this final rule is to reduce occupational disease in
miners and to improve respiratory protection against airborne
contaminants. The rule sets the permissible exposure limit (PEL) of
respirable crystalline silica at 50 micrograms per cubic meter of air
([micro]g/m\3\) for a full-shift exposure, calculated as an 8-hour time
weighted average (TWA) for all mines. This rule also establishes an
action level for respirable crystalline silica of 25 [micro]g/m\3\ for
a full-shift exposure, calculated as an 8-hour TWA for all mines. In
addition to the PEL and action level, the rule includes provisions for
methods of compliance, exposure monitoring, corrective actions,
respiratory protection, medical surveillance for metal and nonmetal
(MNM) mines, and recordkeeping.
The statutory authority for this rule is provided by the Mine Act
under sections 101(a), 103(h), and 508. 30 U.S.C. 811(a), 813(h), and
957. A full discussion of Mine Act legal requirements can be found in
Section II. Pertinent Legal Authority. MSHA implements and administers
the provisions of the Mine Act to prevent death, illness, and injury
from mining and promote safe and healthful workplaces for miners.
Respirable crystalline silica is classified by the International
Agency for Research on Cancer (IARC) as a human carcinogen.
Occupational exposure to respirable crystalline silica results in
adverse health effects and increases risk of death. The adverse health
effects include silicosis (i.e., acute silicosis, accelerated
silicosis, chronic silicosis, and progressive massive fibrosis),
nonmalignant respiratory diseases (e.g., emphysema and chronic
bronchitis), lung cancer, and kidney disease. Each of these effects is
chronic, irreversible, and potentially disabling or fatal. Occupational
exposure to respirable crystalline silica at mines occurs most commonly
from respirable dust generated during mining activities, such as
cutting, sanding, drilling, crushing, grinding, sawing, scraping,
jackhammering, excavating, and hauling of materials that contain
silica.
Existing standards pertaining to respirable crystalline silica for
both MNM and coal mines have been in place since the early 1970s. For
MNM mines, the existing standards, established by the Department of
Interior, Bureau of Mines, in 1974, helped protect miners from the most
dangerous levels of exposure to respirable crystalline silica. The
existing MNM PELs for the three polymorphs of respirable crystalline
silica are: 0.1 mg/m\3\ or 100 micrograms per cubic meter of air
([micro]g/m\3\) for quartz; 0.05 mg/m\3\ or 50 [micro]g/m\3\ for
cristobalite; and 0.05 mg/m\3\ or 50 [micro]g/m\3\ for tridymite.
Existing standards for coal mines, first established by the Federal
Coal Mine Health and Safety Act of 1969 as interim standards in 1970,
control miners' exposures to respirable crystalline silica indirectly
by reducing the respirable coal mine dust standard when quartz is
present. The exposure limit for respirable crystalline silica during a
coal miner's shift is 100 [micro]g/m\3\, reported as an equivalent
concentration as measured by the Mining Research Establishment (MRE)
instrument.
However, since the promulgation of these existing standards, the
National Institute for Occupational Safety and Health (NIOSH) has
recommended a
[[Page 28219]]
lower respirable crystalline silica exposure level of 50 [micro]g/m\3\
for all workers, including miners. In 2016, the Occupational Safety and
Health Administration (OSHA) established a PEL of 50 and an action
level of 25 [micro]g/m\3\ as an 8-hour TWA in the general and
construction industries and maritime sector that it regulates. In the
mining industry, however, the higher PELs have remained in place for
miners in both the MNM sector and the coal sector.
To better protect miners' health, therefore, with this final rule
MSHA is lowering its existing exposure limits for quartz or respirable
crystalline silica to 50 [micro]g/m\3\ and setting an action level of
25 [mu]g/m\3\ for all miners. As discussed in Section V. Health Effects
Summary and Section VI. Final Risk Analysis Summary, lowering the PEL
will substantially reduce health risks to miners. This final rule also
provides a uniform, streamlined regulatory framework to ensure
consistent protection across mining sectors and make compliance more
straightforward. As discussed in Section VII. Feasibility and Section
IX. Summary of Final Regulatory Impact Analysis and Regulatory
Alternatives, compliance with the final rule is technologically and
economically feasible, and the final rule has quantified benefits in
terms of avoided deaths and illnesses that greatly outweigh the costs,
as well as other important unquantified benefits.
B. Summary of Major Provisions
MSHA amends its existing standards on respirable crystalline silica
or quartz, after considering all the testimonies and written comments
the Agency received from a variety of stakeholders, including miners,
mine operators, labor unions, industry trade associations, government
officials, and public health professionals, in response to its notice
of proposed rulemaking. Below is a summary of major provisions in the
final rule. Section VIII. Summary and Explanation of the Final Rule
discusses each provision in the final rule.
This final rule:
1. Establishes a uniform permissible exposure limit (PEL) and
action level for all mines. The rule sets a PEL for respirable
crystalline silica at 50 micrograms per cubic meter of air ([micro]g/
m\3\) over a full shift, calculated as an 8-hour TWA and an action
level at 25 [micro]g/m\3\ over a full shift, calculated as an 8-hour
TWA for all mines.
2. Requires exposure monitoring for respirable crystalline silica.
Mine operators are required to conduct sampling to assess miners'
exposures to respirable crystalline silica. Mine operators are also
required to evaluate the impact of mining production, processes,
equipment, engineering controls, and geological condition changes on
respirable crystalline silica exposures.
3. Updates the standard for respirable crystalline silica sampling.
ISO 7708:1995(E), Air quality--Particle size fraction definitions for
health-related sampling, First Edition, 1995-04-01 (ISO 7708:1995), is
incorporated by reference. The final rule requires mine operators to
conduct sampling for respirable crystalline silica using respirable
particle size-selective samplers that conform to ISO 7708:1995, which
is the international consensus standard that defines sampling
conventions for particle size fractions used in assessing possible
health effects of airborne particles in the workplace and ambient
environment.
4. Requires immediate reporting and corrective action to remedy
overexposures. Whenever an overexposure is identified, mine operators
must immediately report to MSHA and take corrective action to lower the
concentration of respirable crystalline silica to at or below the PEL,
resample to determine the efficacy of the corrective action taken, and
make a record of all sampling and corrective actions that were taken.
5. Specifies methods of controlling respirable crystalline silica.
All mines are required to install, use, and maintain feasible
engineering controls as the primary means of controlling respirable
crystalline silica; administrative controls may be used, when
necessary, as a supplementary control.
6. Requires temporary use of respirators at metal and nonmetal
mines when miners must work in concentrations above the PEL. When MNM
miners must work in concentrations of respirable crystalline silica
above the PEL while engineering controls are being developed and
implemented or it is necessary by nature of the work involved, the mine
operator shall use respiratory protection as a temporary measure.
7. Updates the respiratory protection standard. ASTM F3387-19,
Standard Practice for Respiratory Protection, approved August 1, 2019
(ASTM F3387-19), is incorporated by reference. When approved
respirators are used, the mine operator must have a written respiratory
protection program to protect miners from airborne contaminants,
including respirable crystalline silica, in accordance with ASTM
requirements.
8. Requires medical surveillance at MNM mines. Metal and nonmetal
mine operators are required to provide to all miners, including those
who are new to the mining industry, periodic medical examinations
performed by a physician or other licensed health care professional
(PLHCP) or specialist, at no cost to the miner. Like coal miners, MNM
miners will be able to monitor their health and detect early signs of
respiratory illness.
The requirements in the new part 60 will take effect on June 17,
2024. For coal mine operators, compliance with part 60 is required by
12 months after the publication date; for MNM operators, compliance is
required by 24 months after the publication date. The delayed
compliance is to strike a balance between meeting the urgent need to
protect miners from this health hazard and giving mining operators
adequate preparation time to allow them to comply effectively with the
new requirements.
In addition, conforming amendments to parts 56, 57, 70, 71, 72, 75,
and 90 will take effect on June 17, 2024. Compliance with conforming
amendments to parts 56 and 57 is required by 24 months after the
publication date; and compliance with conforming amendments to parts
70, 71, 72, 75, and 90 is required by 12 months after the publication
date.
C. Summary of Final Regulatory Impact Analysis
MSHA's economic analysis estimates that the final rule would cost
approximately an average of $89 million per year in 2022 dollars at an
undiscounted rate, $90 million at a 3 percent discount rate, and $92
million at a 7 percent discount rate. Based on the results of the Final
Regulatory Impact Analysis (FRIA), MSHA estimates that this final
rule's monetized benefits would exceed its costs, with or without
discount rates. Monetized benefits are estimated from avoidance of 531
deaths related to NMRD, silicosis, ESRD, and lung cancer and 1,836
cases of silicosis associated with silica exposure over the first 60-
year period after the promulgation of the final rule. The estimated
annualized net benefit is approximately $294 million at an undiscounted
rate, $157 million at a 3 percent discount rate, and $40 million at a 7
percent discount rate.
A rule is significant under Executive Order 12866 Section 3(f)(1),
as amended by E.O. 14094, if it is likely to result in ``an annual
effect on the economy of $200 million or more.'' The Office of
Management and Budget has determined that the final rule is significant
under E.O. 12866 Section 3(f)(1).
[[Page 28220]]
In summary, this final rule will strengthen MSHA's existing
regulatory framework and improve health protections for the nation's
miners. It establishes a uniform PEL that aligns respirable crystalline
silica exposure limits for MNM and coal miners with workers in other
industries. Moreover, the final rule updates the existing respiratory
protection standard to require mine operators to provide miners with
NIOSH-approved respiratory equipment that has been fitted, selected,
maintained, and used in accordance with recent consensus standards. It
also requires all MNM operators to provide medical surveillance in the
form of a medical examination regime similar to the one that already
covers coal miners. Cumulatively, the final rule will lower miners'
risks of developing chronic, irreversible, disabling, and potentially
fatal health conditions, consistent with MSHA's mission and statutory
mandate to prevent occupational diseases and protect U.S. miners from
suffering material health impairments.
II. Pertinent Legal Authority
The statutory authority for this final rule is provided by the Mine
Act under sections 101(a), 103(h), and 508. 30 U.S.C. 811(a), 813(h),
and 957. MSHA implements the provisions of the Mine Act to prevent
death, illness, and injury from mining and promote safe and healthful
workplaces for miners. The Mine Act requires the Secretary of Labor
(Secretary) to develop and promulgate improved mandatory health or
safety standards to prevent hazardous and unhealthy conditions and
protect the health and safety of the nation's miners. 30 U.S.C. 811(a).
Congress passed the Mine Act to address these dangers, finding ``an
urgent need to provide more effective means and measures for improving
the working conditions and practices in the Nation's coal or other
mines in order to prevent death and serious physical harm, and in order
to prevent occupational diseases originating in such mines.'' 30 U.S.C.
801(c). Congress concluded that ``the existence of unsafe and
unhealthful conditions and practices in the Nation's coal or other
mines is a serious impediment to the future growth of the coal or other
mining industry and cannot be tolerated.'' 30 U.S.C. 801(d).
Accordingly, ``the Mine Act evinces a clear bias in favor of miner
health and safety.'' Nat'l Mining Ass'n v. Sec'y, U.S. Dep't of Lab.,
812 F.3d 843, 866 (11th Cir. 2016).
Section 101(a) of the Mine Act gives the Secretary the authority to
develop, promulgate, and revise mandatory health standards to address
toxic materials or harmful physical agents. Under Section 101(a), a
standard must protect lives and prevent injuries in mines and be
``improved'' over any standard that it replaces or revises.
The Secretary must set standards to assure, based on the best
available evidence, that no miner will suffer material impairment of
health or functional capacity from exposure to toxic materials or
harmful physical agents over their working lives. 30 U.S.C.
811(a)(6)(A). In developing standards that attain the ``highest degree
of health and safety protection for the miner,'' the Mine Act requires
that the Secretary consider the latest available scientific data in the
field, the feasibility of the standards, and experience gained under
the Mine Act and other health and safety laws. Id. As a result, courts
have found it ``appropriate to `give an extreme degree of deference' ''
to MSHA `` `when it is evaluating scientific data within its technical
expertise.' '' Nat'l Mining Ass'n, 812 F.3d at 866 (quoting Kennecott
Greens Creek Mining Co. v. MSHA, 476 F.3d 946, 954 (D.C. Cir. 2007)).
Consequently, MSHA's ``duty to use the best evidence and to consider
feasibility . . . cannot be wielded as counterweight to MSHA's
overarching role to protect the life and health of workers in the
mining industry.'' Nat'l Mining Ass'n, 812 F.3d at 866. Thus, ``when
MSHA itself weighs the evidence before it, it does so in light of its
congressional mandate'' in favor of protecting miners' health. Id.
Moreover, ``the Mine Act does not contain the `significant risk'
threshold requirement'' from the OSH Act. Nat'l Mining Ass'n v. United
Steel Workers, 985 F.3d 1309, 1319 (11th Cir. 2021); see also Nat'l
Min. Ass'n v. Mine Safety & Health Admin., 116 F.3d 520, 527-28 (D.C.
Cir. 1997) (contrasting the Mine Act at 30 U.S.C. 811(a) with the OSH
Act at 29 U.S.C. 652 and noting that ``[a]rguably, this language does
not mandate the same risk-finding requirement as OSHA'' and holding
that ``[a]t most, . . . [MSHA] was required to identify a significant
risk associated with having no oxygen standard at all'').
Section 103(h) of the Mine Act gives the Secretary the authority to
promulgate standards involving recordkeeping and reporting. 30 U.S.C.
813(h). Additionally, section 103(h) requires that every mine operator
establish and maintain records, make reports, and provide this
information as required by the Secretary. Id. Section 508 of the Mine
Act gives the Secretary the authority to issue regulations to carry out
any provision of the Mine Act. 30 U.S.C. 957.
MSHA's final rule to lower the exposure limits for respirable
crystalline silica adopts an integrated monitoring approach across all
mining sectors and updates the existing respiratory protection
requirements. The final rule fulfills Congress' direction to protect
miners from material impairments of health or functional capacity
caused by exposure to respirable crystalline silica and other airborne
contaminants.
III. Regulatory History
On August 29, 2019, MSHA published a Request for Information (RFI)
in the Federal Register to solicit information and data on a variety of
topics concerning silica (quartz) in respirable dust (84 FR 45452). In
the RFI, MSHA requested data and information on technologically and
economically feasible best practices to protect MNM and coal miners'
health from exposure to quartz, including a lowered permissible
exposure limit (PEL), new or developing protective technologies, and/or
effective technical and educational assistance (84 FR 45456).
Specifically, MSHA requested input from industry, labor, and other
interested parties on the following four topics: (1) new or developing
technologies and best practices that can be used to protect miners from
exposure to quartz dust; (2) how engineering controls, administrative
controls, and personal protective equipment can be used, either alone
or concurrently, to protect miners from exposure to quartz dust; (3)
additional feasible dust-control methods that could be used by mining
operations to reduce miners' exposures to respirable quartz during
high-silica cutting situations, such as on development sections, shaft
and slope work, and cutting overcasts; and (4) any other experience,
data, or information that may be useful to MSHA in evaluating miners'
exposures to quartz (84 FR 45456).
The Agency received 57 comments from citizens, labor, industry, and
public health stakeholders in response to the RFI. Stakeholders
expressed various and differing opinions on how and to what extent MSHA
should address the protection of miners' health from exposure to
silica. Many of these stakeholders also commented on MSHA's proposed
rulemaking, summarized below.
On June 30, 2023, MSHA made an informal copy of the proposed rule
available on the Agency's website, prior to publication in the Federal
Register, so the public and stakeholders could
[[Page 28221]]
review it in advance of the comment period.
On July 13, 2023, MSHA published the proposed rule, Lowering
Miners' Exposure to Respirable Crystalline Silica and Improving
Respiratory Protection, in the Federal Register (88 FR 44852). The
standalone documents ``Health Effects of Respirable Crystalline
Silica,'' ``Preliminary Risk Analysis,'' and ``Preliminary Regulatory
Impact Analysis'' were also made publicly available at that time. MSHA
proposed to set the PEL of respirable crystalline silica at 50
micrograms \1\ per cubic meter of air ([micro]g/m\3\) for a full-shift
exposure, calculated as an 8-hour time-weighted average. MSHA's
proposal included other requirements for sampling, qualitative
evaluations, corrective actions, and medical surveillance for MNM
mines. Finally, the proposal included requirements for respiratory
protection, including the incorporation by reference of ASTM F3387-19
Standard Practice for Respiratory Protection.
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\1\ One microgram is equal to one-thousandth of a milligram (1
milligram = 1000 micrograms).
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On July 26, 2023, MSHA published a notice in the Federal Register
scheduling three public hearings on the proposed rule (88 FR 48146).
Hearings were held on: (1) August 3, 2023, in Arlington, Virginia; (2)
August 10, 2023, in Beckley, West Virginia; and (3) August 21, 2023, in
Denver, Colorado. Speakers and attendees could participate in-person or
online. There were 14 speakers and over 150 attendees at the Arlington
hearing; 24 speakers and over 200 attendees at the Beckley hearing; and
10 speakers and over 175 attendees at the Denver hearing. Speakers
included active and retired miners and representatives from the mining
industry, unions, the health care profession, advocacy groups, industry
groups, trade associations, and law firms. Transcripts from the public
hearings are available at www.regulations.gov and on the MSHA website.
On August 14, 2023, in response to requests from the public, MSHA
published a notice in the Federal Register extending the comment period
by changing the closing date from August 28, 2023, to September 11,
2023 (88 FR 54961).
During the comment period, MSHA received 157 written comments on
the proposed rule from miners, mine operators, individuals, government
officials, labor organizations, advocacy groups, industry groups, trade
associations, and health organizations. Some commenters supported
various aspects of the proposal. Other commenters opposed aspects of
the proposal and offered recommendations for suggested changes to the
proposed rule. All public comments and supporting documentation are
available at www.regulations.gov and on the MSHA website. MSHA
carefully reviewed and considered the written comments on the proposed
rule and the speakers' testimonies from the hearings and addresses them
in the relevant sections below.
IV. Background
A. Respirable Crystalline Silica Hazard and Mining
Silica is a common component of rock composed of silicon and oxygen
(chemical formula SiO2), existing in amorphous and
crystalline states. Silica in the crystalline state is the focus of
this rulemaking. Respirable crystalline silica consists of small
particles of crystalline silica that can be inhaled and reach the
alveolar region of the lungs, where they can accumulate and cause
disease. In crystalline silica, the silicon and oxygen atoms are
arranged in a three-dimensional repeating pattern. The crystallization
pattern varies depending on the circumstances of crystallization,
resulting in a polymorphic state, meaning several different structures
with the same chemical composition. The most common form of crystalline
silica found in nature is quartz, but cristobalite and tridymite also
occur in limited circumstances. Quartz accounts for the overwhelming
majority of naturally occurring crystalline silica. In fact, quartz
accounts for almost 12 percent of the earth's crust by volume. All
soils contain at least trace amounts of quartz, and it is present in
varying amounts in almost every type of mineral. Quartz is also
abundant in most rock types, including granites, sandstones, and shale.
Moreover, quartz bands and veins are commonly found in limestone
formations, although limestone itself does not contain quartz. Because
of its abundance, crystalline silica in the form of quartz is present
in nearly all mining operations.
Cristobalite and tridymite are formed at very high temperatures and
are associated with volcanic activity. Naturally occurring cristobalite
and tridymite are rare, but they can be found in volcanic ash and in a
relatively small number of rock types limited to specific geographic
regions. Although rare, exposure to cristobalite can occur when
volcanic deposits are mined. In addition, when other materials are
mined, miners can potentially be exposed to cristobalite during certain
processing steps (e.g., heating silica-containing materials) and
contact with refractory materials (e.g., replacing fire bricks in mine
processing facility furnaces). Tridymite is rarely found in nature and
miner exposure to tridymite is much more infrequent.
Most mining activities generate silica dust because silica is often
contained in the ore being mined or in the overburden (i.e., the soil
and surface material surrounding the commodity being mined). Such
activities include, but are not limited to, cutting, sanding, drilling,
crushing, grinding, sawing, scraping, jackhammering, excavating, and
hauling materials that contain silica. These activities can generate
respirable crystalline silica and therefore may lead to miner exposure.
Inhaled small particles of silica dust can be deposited throughout
the lungs. Because of their small size, many of these particles can
reach and remain in the deep lung (i.e., alveolar region), although
some can be cleared from the lungs. Because respirable crystalline
silica particles are not water-soluble and do not undergo metabolism
into less toxic compounds, those particles remaining in the lungs
result in a variety of cellular responses that may lead to pulmonary
diseases, such as silicosis and lung cancer. The respirable crystalline
silica particles that are cleared from the lungs can be distributed to
lymph nodes, blood, liver, spleen, and kidneys, potentially
accumulating in those other organ systems and causing renal disease and
other adverse health effects.
In the U.S. in 2021, a total of 12,162 mines produced a variety of
commodities. As shown in Table IV-1, of those 12,162 total mines,
11,231 mines were MNM mines and 931 mines were coal mines. MNM mines
can be broadly divided into five commodity groups: metal, nonmetal,
stone, crushed limestone, and sand and gravel. These broad categories
encompass approximately 98 different commodities.\2\ Table IV-1 shows
that a majority of MNM mines produce sand and gravel, while the largest
number of MNM miners work at metal mines, not including MNM contract
workers (i.e.,
[[Page 28222]]
independent contractors and employees of independent contractors who
are engaged in mining operations).
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\2\ Commodities such as sand, gravel, silica, and/or stone are
used in road building, concrete construction, the manufacture of
glass and ceramics, molds for metal castings in foundries, abrasive
blasting operations, plastics, rubber, paint, soaps, scouring
cleansers, filters, hydraulic fracturing, and various architectural
applications. Some commodities naturally contain high levels of
crystalline silica, such as high-quartz industrial and construction
sands and granite dimension stone and gravel (both produced for the
construction industry).
[GRAPHIC] [TIFF OMITTED] TR18AP24.131
The 931 coal mines--underground and surface--produce bituminous,
subbituminous, anthracite, and lignite coal. Coal mining activities
generate mixed coal mine dust that contains respirable silicates such
as kaolinite, oxides such as quartz, and other components (IARC, 1997).
These activities include the general mining activities previously
mentioned (e.g., cutting, sanding, drilling, crushing, hauling, etc.),
as well as roof bolter operations, continuous mining machine
operations, longwall mining, and other activities. Table IV-1 shows
that there are more surface coal mines than underground coal mines, but
more miners are working in underground coal mines than surface coal
mines (not including coal contract workers).
B. Existing Standards
Since the early 1970s, MSHA has maintained health standards to
protect MNM and coal miners from excessive exposure to airborne
contaminants, including respirable crystalline silica. These standards
require mine operators to use engineering controls as the primary means
of suppressing, diluting, or diverting dust generated by mining
activities. They also require mine operators to provide miners with
respiratory protection in limited situations for a short period. The
existing standards for MNM and coal mines differ in some respects,
including exposure limits and monitoring requirements. This section
describes MSHA's existing standards for respirable crystalline silica
and presents respirable crystalline silica sampling data to show how
MNM and coal mine operators have complied with the standards in recent
years.
1. Existing Standards--Metal and Nonmetal Mines
MSHA's existing standards for exposure to airborne contaminants in
MNM mines, including respirable crystalline silica, are found in 30 CFR
56 subpart D (Air Quality and Physical Agents) and 30 CFR 57 subpart D
(Air Quality, Radiation, Physical Agents, and Diesel Particulate
Matter). These standards include PELs for airborne contaminants
(Sec. Sec. 56.5001 and 57.5001), exposure monitoring (Sec. Sec.
56.5002 and 57.5002), and control of exposure to airborne contaminants
(Sec. Sec. 56.5005 and 57.5005).
Permissible Exposure Limits. The existing PELs for the three
polymorphs of respirable crystalline silica are based on the
TLVs[supreg] Threshold Limit Values for Chemical Substances in Workroom
Air Adopted by the American Conference of Governmental Industrial
Hygienists (ACGIH) for 1973, incorporated by reference in 30 CFR
56.5001 and 57.5001 (ACGIH, 1974). The 1973 TLV[supreg] establishes
limits for respirable dust containing 1 percent quartz or greater and
is calculated in milligrams per cubic meter of air (mg/m\3\) for each
respirable dust sample. The resulting TLVs[supreg] for respirable dust
containing 1 percent respirable crystalline silica or greater are
designed to limit exposures to less than 0.1 mg/m\3\ or 100 micrograms
per cubic meter of air ([micro]g/m\3\) for quartz, to less than 0.05
mg/m\3\ or 50 [micro]g/m\3\ for cristobalite, and to less than 0.05 mg/
m\3\ or 50 [micro]g/m\3\ for tridymite. Throughout the remainder of
this preamble, the concentrations of respirable dust and respirable
crystalline silica are expressed in [micro]g/m\3\.
Exposure Monitoring. Under 30 CFR 56.5002 and 57.5002, MNM mine
operators must conduct respirable dust ``surveys . . . as frequently as
necessary to determine the adequacy of control measures.'' Mine
operators can satisfy the survey requirement through various
activities, such as respirable dust sampling and analysis, walk-through
inspections, wipe sampling, examination of dust control system and
ventilation system maintenance, and
[[Page 28223]]
review of information obtained from injury, illness, and accident
reports.
MSHA encourages MNM mine operators to conduct sampling for airborne
contaminants to ensure a healthy and safe work environment for miners,
because sampling provides more accurate information about miners'
exposures and the effectiveness of existing controls in reducing
exposures. When a mine operator's respirable dust survey indicates that
miners have been overexposed to any airborne contaminant, including
respirable crystalline silica, the operator is expected to adjust its
control measures (e.g., exhaust ventilation) to reduce or eliminate the
identified hazard. After doing so, the mine operator is expected to
conduct additional surveys to determine whether its adjustments to
control measures were successful. Re-surveying should be done as
frequently as necessary to ensure that the sampling results comply with
the PEL and the implemented control measures remain adequate.
Exposure Controls. MSHA's existing standards for controlling a
miner's exposure to harmful airborne contaminants in Sec. Sec. 56.5005
and 57.5005 require, if feasible, prevention of contamination, removal
by exhaust ventilation, or dilution with uncontaminated air. These
requirements to use feasible engineering controls, supplemented by
administrative controls, are consistent with widely accepted industrial
hygiene principles and NIOSH's recommendations (NIOSH, 1974).
Engineering controls designed to remove or reduce the hazard at the
source are the most effective. Although administrative controls are
considered a supplementary or secondary measure to engineering
controls, mine operators may use administrative controls to further
reduce miners' exposures to respirable crystalline silica and other
airborne contaminants.
The use of respiratory protective equipment is also allowed under
specified circumstances, such as where engineering controls are not yet
developed or when it is necessary due to the nature of the work--for
example, while establishing controls or during occasional entry into
hazardous atmospheres to perform maintenance or investigation.
Respirators approved by NIOSH and suitable for their intended purpose
must be provided by mine operators at no cost to the miner and must be
used by miners to protect themselves against the health and safety
hazards of respirable crystalline silica and other airborne
contaminants. When respiratory protective equipment is used, MNM mine
operators must implement a respiratory protection program consistent
with the requirements of American National Standards Practices for
Respiratory Protection ANSI Z88.2-1969 (ANSI Z88.2-1969).
2. Existing Standards--Coal Mines
Under the existing coal mine standards, there is no separate
standard for respirable crystalline silica. MSHA's existing standards
for exposure to respirable quartz in coal mines, found in 30 CFR 70.101
and 71.101, establish a respirable dust standard when quartz is present
for underground and surface coal mines, respectively. Under 30 CFR part
90 (Mandatory Health Standards--Coal Miners Who Have Evidence of the
Development of Pneumoconiosis), Sec. 90.101 also sets the respirable
dust standard when quartz is present for Part 90 miners.\3\ Coal
miners' exposures to respirable quartz are indirectly regulated through
reductions in the overall respirable dust standards.
---------------------------------------------------------------------------
\3\ A ``Part 90 miner'' is defined in 30 CFR 90.3 as a miner
employed at a coal mine who shows evidence of having contracted
pneumoconiosis based on a chest X-ray or based on other medical
examinations, and who is afforded the option to work in an area of a
mine where the average concentration of respirable dust in the mine
atmosphere during each shift to which that miner is exposed is
continuously maintained at or below the applicable standard.
---------------------------------------------------------------------------
Under its existing respirable coal mine dust standards, MSHA
defines quartz as crystalline silicon dioxide (SiO2), which
includes not only quartz but also two other polymorphs, cristobalite
and tridymite.\4\ Therefore, the terms quartz and respirable
crystalline silica are used interchangeably in the discussions of
MSHA's existing standards for controlling exposures to respirable
crystalline silica in coal mines.
---------------------------------------------------------------------------
\4\ Quartz is defined in 30 CFR 70.2, 71.2, and 90.2 as
crystalline silicon dioxide (SiO2) not chemically
combined with other substances and having a distinctive physical
structure. Crystalline silicon dioxide is most commonly found in
nature as quartz but sometimes occurs as cristobalite or, rarely, as
tridymite. Quartz accounts for the overwhelming majority of
naturally occurring crystalline silica and is present in varying
amounts in almost every type of mineral.
---------------------------------------------------------------------------
Exposure Limits. The exposure limit for respirable crystalline
silica during a coal miner's shift is 100 [micro]g/m\3\, reported as an
equivalent concentration as measured by the Mining Research
Establishment (MRE) instrument.\5\ The equivalent concentration of
respirable crystalline silica must not be exceeded during the miner's
entire shift, regardless of duration. When the equivalent concentration
of respirable quartz exceeds 100 [micro]g/m\3\, under Sec. Sec.
70.101, 71.101, and 90.101, MSHA imposes a reduced respirable dust
standard designed to ensure that respirable quartz will not exceed 100
[micro]g/m\3\. Various sections within a mine may have different
reduced respirable coal mine dust (RCMD) exposure limits. Therefore,
when a respirable dust sample collected by MSHA indicates that the
average concentration of respirable quartz dust exceeds the exposure
limit, the mine operator is required to comply with the applicable dust
standard. Because respirable crystalline silica is a percentage of
RCMD, by reducing the amount of respirable dust to which miners are
exposed during their shifts, the miners' exposures to respirable
crystalline silica are reduced to a level at or below the exposure
limit of 100 [micro]g/m\3\.
---------------------------------------------------------------------------
\5\ As defined in 30 CFR 70.2, an MRE instrument is a
gravimetric dust sampler with a four channel horizontal elutriator
developed by the Mining Research Establishment of the National Coal
Board, London, England. MSHA inspectors use Dorr-Oliver 10-mm nylon
cyclones operated at a 2.0 L/min flow rate (reported as MRE-
equivalent concentrations) for coal mine sampling.
---------------------------------------------------------------------------
Exposure Monitoring. Under Sec. Sec. 70.208, 70.209, 71.206, and
90.207, coal mine operators are required to sample for respirable dust
on a quarterly basis for specified occupations and work areas. The
occupations and work areas specified in the existing coal dust
standards are the occupations and work areas at a coal mine that are
expected to have the highest concentrations of respirable dust--
typically in locations where respirable dust is generated. Respirable
dust sampling must be representative of respirable dust exposures
during a normal production shift and must occur while miners are
performing routine, day-to-day activities. Part 90 miners must be
sampled for the air they breathe while performing their normal work
duties, in their normal work locations, from the start of their work
day to the end of their work day.
Exposure Controls. Under Sec. Sec. 70.208, 70.209, 71.206, and
90.207, coal mine operators are required to use engineering or
environmental controls as the primary means of complying with the
respirable dust standards. For many underground coal mines, providing
adequate ventilation is the primary engineering control for respirable
dust, ensuring that dust concentrations are continuously diluted with
fresh air and exhausted away from miners.
When a respirable dust sample exceeds the exposure limit of 100
[micro]g/m\3\ for respirable quartz, the operator must reduce the
average concentration of RCMD to a level designed to maintain the
quartz level at or below 100 [micro]g/m\3\. If operators exceed the
RCMD standard, they are required to take corrective
[[Page 28224]]
action to reduce exposure and comply with the reduced standard.
Corrective actions that lower respirable coal mine dust, thus lowering
respirable quartz exposures, are selected after evaluating the cause or
causes of the overexposure.
When taking corrective actions to reduce the exposure to respirable
dust, coal mine operators must make approved respiratory equipment
available to miners under Sec. Sec. 70.208, 70.209, and 71.206.
Whenever respiratory protection is used, Sec. 72.700 requires coal
mine operators to comply with requirements specified in ANSI Z88.2-
1969.
C. MSHA Inspection and Respirable Dust Sampling
Under the existing standards, MSHA collects respirable dust samples
at mines and analyzes them for respirable crystalline silica to
determine whether the respirable crystalline silica exposure limits are
exceeded and whether exposure controls are adequate. MSHA's inspection
and respirable dust sampling were discussed in detail in the proposal
(88 FR 44862). This section, for ease of reference, briefly summarizes
the process for MSHA's inspection and respirable dust sampling.
1. Respirable Dust Sample Collection
Under the existing standards, MSHA inspectors arrive at mines,
determine which miners and which areas of the mine to select for
respirable dust sampling, and place gravimetric samplers on the
selected miners and at the selected locations. The gravimetric samplers
capture air from the breathing zone of each selected miner and from
each selected work area for the entire duration of the work shift.
Full-shift sampling is used to minimize errors associated with
fluctuations in airborne contaminant concentrations during the miners'
work shifts and to avoid any speculation about the miners' exposures
during unsampled periods of the work shift. Once sampling is completed,
MSHA inspectors send cassettes containing the full-shift respirable
dust samples to the MSHA Laboratory for analysis.
2. Respirable Dust Sample Analysis
The MSHA Laboratory analyzes respirable dust samples following the
standard operating procedures summarized below.\6\ Any samples that are
broken, torn, or visibly wet are voided and removed before analysis.
Samples are weighed and then examined for validity based on mass gain.
All valid samples that meet the minimum mass gain criteria per the
associated MSHA analytical method are then analyzed for respirable
crystalline silica and for the compliance determination.\7\
---------------------------------------------------------------------------
\6\ The MSHA Laboratory has fulfilled the requirements of the
AIHA Laboratory Accreditation Programs (AIHA-LAP), LLC accreditation
to the ISO/IEC 17025:2017 international standard for industrial
hygiene.
\7\ The minimum mass gain criteria used by the MSHA Laboratory
for the different samples are:
MNM mine respirable dust samples: greater than or equal
to 0.100 mg;
Underground coal mine respirable dust samples: greater
than or equal to 0.100 mg; and
Surface coal mine respirable dust samples: greater than
or equal to 0.200 mg.
Exception: For six surface occupations that have been deemed
``high risk,'' the laboratory uses a minimum mass gain criterion of
greater than or equal to 0.100 mg.
If cristobalite analysis is requested for MNM mine respirable
dust samples, filters having a mass gain of 0.05 mg or more are
analyzed. In the rare instance when tridymite analysis is requested,
a qualitative analysis for the presence of the polymorph is
conducted concurrently with the cristobalite analysis.
---------------------------------------------------------------------------
The MSHA Laboratory uses two analytical methods to determine the
concentration of quartz (and cristobalite and tridymite, if requested)
in respirable dust samples: X-ray diffraction (XRD) for samples from
MNM mines and Fourier transform infrared spectroscopy (FTIR) for
samples from coal mines.\8\ The percentage of silica in the MNM mine
dust sample is calculated using the mass of quartz or cristobalite
determined from the XRD analysis and the measured mass of respirable
dust. Similarly, in the respirable coal mine dust sample, the
percentage of quartz is calculated using the quartz mass determined
from the FTIR analysis and the sample's mass of dust. Current FTIR
methods, however, cannot quantify quartz and cristobalite, and/or
tridymite, in the same sample.
---------------------------------------------------------------------------
\8\ Details on MSHA's analytical procedures for respirable
crystalline silica analysis can be found in ``MSHA P-2: X-Ray
Diffraction Determination of Quartz and Cristobalite in Respirable
Metal/Nonmetal Mine Dust'' and ``MSHA P-7: Determination of Quartz
in Respirable Coal Mine Dust by Fourier Transform Infrared
Spectroscopy.''
Department of Labor, Mine Safety and Health Administration,
Pittsburgh Safety and Health Technology Center, X-Ray Diffraction
Determination of Quartz and Cristobalite in Respirable Metal/
Nonmetal Mine Dust. https://arlweb.msha.gov/Techsupp/pshtcweb/MSHA%20P2.pdf (last accessed Jan. 10, 2024). Department of Labor,
Mine Safety and Health Administration, Pittsburgh Safety and Health
Technology Center, MSHA P-7: Determination of Quartz in Respirable
Coal Mine Dust By Fourier Transform Infrared Spectroscopy. https://arlweb.msha.gov/Techsupp/pshtcweb/MSHA%20P7.pdf (last accessed Jan.
10, 2024).
---------------------------------------------------------------------------
MSHA calculates full-shift exposures to respirable crystalline
silica (and other airborne contaminants) in the same way for MNM and
coal miners when the miner works an 8-hour shift, but the calculated
exposures differ for longer shifts. For work shifts that last longer
than 8 hours, a coal miner's full-shift exposure is calculated using
the entire duration of the coal miner's shift. For the MNM miner, by
contrast, MSHA calculates extended full-shift exposure for respirable
dust samples using 480 minutes (8 hours) as the sampling time, meaning
that contaminants collected over extended shifts (e.g., 600-720
minutes) are calculated as if they had been collected over 480 minutes.
D. Respirable Crystalline Silica Sampling Results--Metal and Nonmetal
Mines
MSHA's respirable crystalline silica sampling results for MNM mines
were discussed in detail in the proposal (88 FR 44863). This section,
for ease of reference, summarizes the results of respirable dust
samples that were collected by MSHA inspectors at MNM mines from 2005
to 2019. From January 1, 2005, to December 31, 2019, a total of 104,354
valid samples were collected. Of this total, 57,769 samples met the
minimum mass gain criteria and were analyzed for respirable crystalline
silica. The vast majority of the 46,585 valid samples that were
excluded from the analysis did not meet the mass gain criteria. Further
information on the valid respirable dust samples that were excluded
from the analysis can be found in Appendix A of the preamble.
1. Annual Results of MNM Respirable Crystalline Silica Samples
Table IV-2 below shows the variation between 2005 and 2019 in: (1)
the number of MNM respirable dust samples analyzed for respirable
crystalline silica; and (2) the number and percentage of samples that
had concentrations of respirable crystalline silica greater than 100
[micro]g/m\3\. Of the 57,769 MNM respirable dust samples analyzed for
respirable crystalline silica over the 15-year period, about 6 percent
(3,539 samples) had respirable crystalline silica concentrations
exceeding the existing PEL of 100 [micro]g/m\3\. The average annual
rates of overexposure ranged from a maximum of approximately 10 percent
in 2006 (the second year) to a minimum of approximately 4 percent in
2019 (the last year of the time series). Compared with the rates in
2005-2008, overexposure rates were substantially lower in 2009-2017,
with a further drop in 2018-19.
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[[Page 28225]]
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BILLING CODE 4520-43-C
2. Analysis of MNM Respirable Crystalline Silica Samples by Commodity
Because the MNM mining industry produces commodities that contain
varying degrees of respirable crystalline silica, it is important to
examine each commodity separately. MNM mines can be grouped by five
commodities: metal, sand and gravel, stone, crushed limestone, and
nonmetal (where nonmetal includes all other materials that are not
metals, besides sand, gravel, stone, and limestone). This grouping is
based on the mine operator-reported mining products and the North
American Industry Classification System (NAICS) codes. (Appendix B of
the preamble provides a list of the NAICS codes relevant for MNM mining
and how each code is assigned to one of the five commodities.)
Table IV-3 shows the distribution of the respirable dust samples
analyzed for respirable crystalline silica by mine commodity. The
percentage of samples with respirable crystalline silica concentrations
greater than the existing exposure limit of 100 [micro]g/m\3\ varies
across the different commodities. It is highest for the metal, sand and
gravel, and stone commodities (at approximately 11, 7, and 7 percent,
respectively), and lowest for the nonmetal and crushed limestone
commodities (at approximately 4 and 3 percent, respectively).
[[Page 28226]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.133
3. Analysis of MNM Respirable Crystalline Silica Samples by Occupation
To examine how miners who perform different tasks differ in
occupational exposure to respirable crystalline silica, MSHA grouped
MNM mining jobs into 11 occupational categories. These categories
include jobs that are similar in terms of tasks performed, equipment
used, and engineering or administrative controls used to control
miners' exposure. For example, backhoe operators, bulldozer operators,
and tractor operators were grouped into ``operators of large powered
haulage equipment,'' whereas belt crew, belt cleaners, and belt
vulcanizers were grouped into ``conveyer operators.'' The 121 MNM job
codes used by MSHA inspectors were grouped into the following
occupational categories: \9\
---------------------------------------------------------------------------
\9\ For a full crosswalk of job codes included in each of these
11 Occupational Categories, please see Appendix C of the preamble.
Also, note that the order of the presentation of the 11 Occupational
Categories here follows the general sequence of mining activities:
first development and production, then ore/mineral processing, then
loading, hauling, and dumping, and finally all others.
---------------------------------------------------------------------------
(1) Drillers (e.g., Diamond Drill Operator, Wagon Drill Operator,
and Drill Helper),
(2) Stone Cutting Operators (e.g., Jackhammer Operator, Cutting
Machine Operator, and Cutting Machine Helper),
(3) Kiln, Mill, and Concentrator Workers (e.g., Ball Mill Operator,
Leaching Operator, and Pelletizer Operator),
(4) Crushing Equipment and Plant Operators (e.g., Crusher Operator/
Worker, Scalper Screen Operator, and Dry Screen Plant Operator),
(5) Packaging Equipment Operators (e.g., Bagging Operator and
Packaging Operations Worker),
(6) Conveyor Operators (e.g., Belt Cleaner, Belt Crew, and Belt
Vulcanizer),
(7) Truck Loading Station Tenders (e.g., Dump Operator and Truck
Loader),
(8) Operators of Large Powered Haulage Equipment (e.g., Tractor
Operators, Bulldozer Operator, and Backhoe Operators),
(9) Operators of Small Powered Haulage Equipment (e.g., Bobcat
Operator, Scoop-Tram Operator, and Forklift Operator),
(10) Mobile Workers (e.g., Laborers, Electricians, Mechanics, and
Supervisors), and
(11) Miners in Other Occupations (e.g., Welder, Dragline Operator,
Ventilation Crew and Dredge/Barge Operator).
Table IV-4 shows sample numbers and overexposure rates by MNM
occupation. Operators of large powered haulage equipment accounted for
the largest number of samples analyzed for silica (17,016 samples),
whereas conveyor operators accounted for the fewest (215 samples).
Table IV-4 also shows the number and percentage of the samples
exceeding the existing respirable crystalline silica PEL of 100
[micro]g/m\3\. In every occupational category, some MNM miners were
exposed to respirable crystalline silica levels above the existing PEL.
In 9 out of the 11 occupational categories, the percentage of samples
exceeding the existing PEL is less than 10 percent, although two have
higher rates, ranging up to more than 19 percent (in the case of stone
cutting operators).
BILLING CODE 4520-43-P
[[Page 28227]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.134
BILLING CODE 4520-43-C
4. Conclusion
This analysis of MSHA inspector sampling data shows that MNM
operators have generally met the existing standard. Of the 57,769
respirable dust samples from MNM mines, approximately 6 percent
exceeded the existing respirable crystalline silica PEL of 100
[micro]g/m\3\, although there are several outliers with much higher
overexposures. For 9 of the 11 occupational categories, less than 10
percent of the respirable dust samples had concentrations over the
existing PEL of 100 [micro]g/m\3\ for respirable crystalline silica.
While stone-cutting operators have historically had high exposures to
respirable dust and respirable crystalline silica \10\ and continue to
experience the highest overexposures of any MNM occupation, about 80
percent of samples taken from stone cutting operators did not exceed
the existing PEL. For the categories of drillers, miners in other
occupations, and operators of large powered haulage equipment,
approximately 5 percent or less of the respirable dust samples showed
concentrations over the existing exposure limit.
---------------------------------------------------------------------------
\10\ Analysis of MSHA respirable dust samples from 2005 to 2010
showed that stone and rock saw operators had approximately 20
percent of the sampled exposures exceeding the PEL. Watts et al.
(2012).
---------------------------------------------------------------------------
In summary, the analysis of MSHA inspector sampling data indicates
that the controls that MNM mine operators are using, together with
MSHA's enforcement, have generally been effective in keeping miners'
exposures at or below the existing limit of 100 [micro]g/m\3\.
E. Respirable Crystalline Silica Sampling Results--Coal Mines
MSHA's respirable crystalline silica sampling results for coal
mines were discussed in detail in the proposal (88 FR 44866). This
section, for ease of reference, summarizes the results of RCMD samples
collected by MSHA inspectors from 2016 to 2021. (The data analyses for
this rulemaking do not include any respirable dust samples collected by
coal mine operators.) The analysis below is based on the samples
collected by MSHA inspectors starting on August 1, 2016, when Phase III
of MSHA's 2014 Lowering Miners' Exposure to Respirable Coal Mine Dust,
Including Continuous Personal Dust Monitors (referred to throughout the
preamble as the 2014 RCMD Standard) (79 FR 24813) went into effect. At
that time, the exposure limits for RCMD were lowered from 2.0 mg/m\3\
to 1.5 mg/m\3\ (MRE equivalent) at underground and surface coal mines,
and from 1.0 mg/m\3\ to 0.5 mg/m\3\ (MRE equivalent) for intake air at
underground coal mines and for Part 90 miners. From August 1, 2016, to
July 31, 2021, MSHA inspectors collected a total of 113,607 valid RCMD
samples. Of the valid samples, only those collected from the breathing
zones of miners were used in the analysis for this rulemaking; no
environmental dust
[[Page 28228]]
samples were included.\11\ Of the valid breathing zone samples, there
were 63,127 samples that met the minimum mass gain criteria and were
analyzed for respirable quartz. The majority of the non-environmental
valid samples excluded from this rulemaking analysis were excluded due
to insufficient mass. Further information on the valid respirable dust
samples that are not included in the rulemaking analysis can be found
in Appendix A of the preamble.
---------------------------------------------------------------------------
\11\ Environmental samples were not included in the analysis to
be consistent with the proposed sampling requirements to determine
individual miner exposure.
---------------------------------------------------------------------------
Of the 63,127 valid samples analyzed for respirable crystalline
silica and used for this analysis, about 1 percent (777 samples) were
over the existing quartz exposure limit of 100 [micro]g/m\3\ (MRE
equivalent) for a full shift, calculated as a TWA.\12\ Overexposure
rates decreased by nearly a quarter between the first half and the
second half of the 2016-2021 period. As in MNM mines, different miner
occupations had different overexposure rates. Using broader groupings,
surface mines experienced higher rates of overexposure than underground
mines (2.4 percent versus 1.0 percent, respectively).
---------------------------------------------------------------------------
\12\ The conversion between ISO values and MRE values uses the
NIOSH conversion factor of 0.857. In the 1995b Criteria Document,
NIOSH presented an empirically derived conversion factor of 0.857
for comparing current (MRE) and recommended (ISO) respirable dust
sampling criteria using the 10 mm Dorr-Oliver nylon cyclone operated
at 2.0 and 1.7 L/min, respectively (i.e., 1.5 mg/m\3\ BMRC-MRE =
1.29 mg/m\3\ ISO).
---------------------------------------------------------------------------
1. Annual Results of Coal Respirable Crystalline Silica Samples
In examining trends from one year to the next, the discussion below
focuses on the samples collected in the 6 calendar years from 2016 to
2021. The number of samples per year was stable from 2017 to 2019
before decreasing in 2020.\13\ The overexposure rate decreased across
the entire 2016 to 2021 period, from 1.41 percent in 2016 to 0.95
percent in 2021. As shown in Table IV-5, a review of the 6 calendar
years reveals that the overexposure rate decreased by nearly a quarter
from 2016-2018 (1.38 percent) to 2019-2021 (1.07 percent).
---------------------------------------------------------------------------
\13\ The coal samples for 2016 begin in August of that year and
the coal samples for 2021 end in July of that year.
[GRAPHIC] [TIFF OMITTED] TR18AP24.135
2. Analysis of Coal Respirable Crystalline Silica Samples by Location
Coal mining activities differ depending on the characteristics and
locations of coal seams. When coal seams are several hundred feet below
the surface, miners tunnel into the earth and use underground mining
equipment to extract coal, whereas miners at surface coal mines remove
topsoil and layers of rock to expose coal seams. Due to these
differences, it is important to examine the respirable crystalline
silica data by location to determine how underground and surface coal
miners differ in occupational exposure to respirable crystalline
silica.
Table IV-6, which presents the overexposure rate by type of mine
where respirable coal mine dust samples were collected, shows that
samples from surface coal mines reflected higher rates of overexposure
than samples from underground mines. Out of the 53,095 respirable coal
mine dust samples from underground mines, 1 percent (537 samples) were
over the existing exposure limit. By contrast, there were 10,032
samples from surface coal mines, and approximately 2.4 percent (240
samples) of those samples were over the existing exposure limit.
[[Page 28229]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.136
3. Analysis of Coal Respirable Crystalline Silica Samples by Occupation
To assess the exposure to respirable crystalline silica of miners
in different occupations, MSHA has consolidated the 220 job codes for
coal mines into 9 occupational categories (using a similar process to
the one it used for the MNM mines, but with different job codes and
categories). For the coal mine occupational categories,\14\ a
distinction is made between occupations based on whether the job tasks
are being performed at the surface of a mine or underground. For
example, bulldozer operators are assigned to the job category of
operators of large powered haulage equipment grouping and then sorted
into separate occupational categories based on whether they are working
at the surface of a mine or underground.
---------------------------------------------------------------------------
\14\ For a full crosswalk of which job codes were included in
each of these nine Occupational Categories, please see Appendix C of
the preamble.
---------------------------------------------------------------------------
Of the nine occupational categories used for coal miners, the five
underground categories are:
(1) Continuous Mining Machine Operators (e.g., Coal Drill Helper
and Coal Drill Operator),
(2) Longwall Workers (e.g., Headgate Operator and Jack Setter
(Longwall)),
(3) Roof Bolters (e.g., Roof Bolter and Roof Bolter Helper),
(4) Operators of Large Powered Haulage Equipment (e.g., Shuttle Car
Operator, Tractor Operator/Motorman, Scoop Car Operator), and
(5) All Other Underground Miners (e.g., Electrician, Mechanic, Belt
Cleaner and Laborer, etc.).
The four surface occupational categories are:
(1) Drillers (e.g., Coal Drill Operator, Coal Drill Helper, and
Auger Operator),
(2) Crusher Operators (e.g., Crusher Attendant, Washer Operator,
and Scalper-Screen Operator),
(3) Operators of Large Powered Haulage Equipment (e.g., Backhoe
Operator, Forklift Operator, and Bulldozer Operator), and
(4) Mobile Workers (e.g., Electrician, Mechanic, Blaster, Laborer,
etc.).
The most sampled occupational category was operators of large
powered haulage equipment (underground), representing approximately 34
percent of the samples taken. The least sampled occupational category
was crusher operators (surface), consisting of 1 percent of the samples
taken. Table IV-7 displays the number and percent of respirable coal
mine dust samples with quartz greater than the existing exposure limit
for each occupational category.
[[Page 28230]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.137
Looking at trends, every occupational category shows a decrease in
overexposure rates over time. See Figure IV-1. Most of the nine
categories had lower rates of overexposure in the 2019-2021 period than
in the 2016-2018 period.
Figure IV-1: Percent of RCMD Samples With Respirable Crystalline Silica
Concentration Greater Than 100 MRE [micro]g/m\3\ (MRE) by Occupational
Category *
[[Page 28231]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.076
* For Crusher Operators (Surface), only one sample with a quartz
concentration greater than 100 [micro]g/m\3\ MRE occurred (in 2018);
and for Mobile Workers (Surface), only nine samples with a quartz
concentration greater than 100 [micro]g/m\3\ MRE occurred (three in
2017, five in 2018 and one in 2021). Source: MSHA MSIS respirable
crystalline silica data for the Coal Industry, August 1, 2016,
through July 31, 2021 (version 20220617).
In all occupational categories, coal miners were sometimes exposed
to respirable crystalline silica levels above the existing exposure
limit. But the sampling data showed that coal mine operators can
generally comply with the existing exposure limit. For example,
although mining tasks performed by the occupational category of roof
bolters (underground) historically resulted in high levels of
overexposure to quartz, the low levels of overexposure for that
occupation in 2016-2021 (i.e., 1 percent) suggest that roof bolters now
benefit from the improved respirable dust standard, improved
technology, and better training.\15\ Over the 2016-2021 period, coal
miners in the occupational category drillers (surface) were the most
frequently overexposed, with approximately 6 percent of samples over
the existing quartz limit; they were followed by longwall workers
(underground) (about 4 percent), operators of large powered haulage
equipment (surface) (about 3 percent), and continuous mining machine
operators (underground) (about 2 percent). For all other occupational
categories, the overexposure rate was less than 1 percent.
---------------------------------------------------------------------------
\15\ The drilling operation in the roof bolting process,
especially in hard rock, generates excessive respirable coal and
quartz dusts, which could expose the roof bolting operator to
continued health risks (Jiang and Luo, 2021).
---------------------------------------------------------------------------
4. Conclusion
This analysis of MSHA inspector sampling data shows that coal mine
operators generally comply with the existing standards related to
quartz. Of the 63,127 valid respirable dust samples from coal mines
over the most recent 5-year period, 1.2 percent had respirable quartz
over the existing exposure limit of 100 [micro]g/m\3\ (MRE equivalent)
for a full-shift exposure, calculated as a TWA. Seven of the nine
occupational categories had overexposure rates of 2.5 percent or less.
Roof bolters (underground), which historically have had high exposures
to respirable dust and respirable crystalline silica, had overexposure
rates of 1 percent over this recent period. The data demonstrates that
the controls that coal mine operators are using, together with MSHA's
enforcement, have generally been effective in keeping miners' exposure
to respirable crystalline silica at or below the existing exposure
limit.
V. Health Effects Summary
This section summarizes the health effects from occupational
exposure to respirable crystalline silica. MSHA's full analysis of the
health effects literature is contained in the standalone document,
entitled ``Effects of Occupational Exposure to Respirable Crystalline
Silica on the Health of Miners'' (referred to as the standalone Health
Effects document throughout the preamble), which is placed in the
rulemaking docket for the MSHA silica rulemaking (RIN 1219-AB36, Docket
No. MSHA-2023-0001). MSHA reviewed a wide range of health effects
literature that included more than 600 studies exploring the
relationship between respirable crystalline silica exposure and
resultant health effects in miners and other workers across various
industries. The purpose of this summary is to briefly present MSHA's
findings on the nature of the hazards of exposure to respirable
crystalline silica. Based on its review of the health effects
literature and the weight-of-evidence approach, MSHA makes the
following conclusions:
1. Miners in MNM and coal mines exposed to respirable crystalline
silica at MSHA's existing exposure limits are subject to material
impairment of health or functional capacity. The illnesses associated
with exposure to respirable crystalline silica develop independent of
other exposures.
2. Occupational exposure to respirable crystalline silica (as
quartz and/or cristobalite) causes silicosis,
[[Page 28232]]
nonmalignant respiratory disease (NMRD) (e.g., emphysema and chronic
bronchitis), lung cancer, and renal disease. Each of these health
effects outcomes is exposure-dependent, potentially chronic,
irreversible, potentially disabling, and can be fatal.
3. Exposure to respirable crystalline silica contributes to the
development of autoimmune disorders through inflammatory pathways.
4. The development of silicosis, NMRD, lung cancer, renal disease,
and autoimmune disorders is largely dependent upon cumulative
respirable crystalline silica exposure.
These conclusions are the basis of MSHA's Final Risk Analysis (FRA)
on miners' exposure to respirable crystalline silica. In the FRA, MSHA
quantifies risks associated with the five specific health outcomes
mentioned above. The FRA summary is presented in Section VI. Final Risk
Analysis Summary and a standalone document, entitled ``Final Risk
Analysis'' (referred to as the standalone FRA document throughout the
preamble), has been placed in the rulemaking docket for the MSHA silica
rulemaking (RIN 1219-AB36, Docket No. MSHA-2023-0001).
From its health effects literature review and FRA, MSHA determines
that miners exposed to respirable crystalline silica continue to face a
risk of material impairment of health or functional capacity under
MSHA's existing exposure limits. Thus, MSHA also makes the following
conclusions:
(1) The rate of silicosis and other diseases caused by respirable
crystalline silica exposure would decrease with reduction in
occupational exposures, which is the most effective way to prevent
these types of diseases.
(2) Regulatory action is necessary to reduce these occupational
exposures and protect miners' health. Section 101(a)(6)(A) of the
Federal Mine Safety and Health Act of 1977, as amended (Mine Act),
requires MSHA to ``set standards which most adequately assure on the
basis of the best available evidence that no miner will suffer material
impairment of health or functional capacity even if such miner has
regular exposure to the hazards dealt with by such standard for the
period of his working life.'' 30 U.S.C. 811(a)(6)(A).
Regulatory action to protect miners' health is required by section
101(a)(6)(A) of the Mine Act, and MSHA's statutory authority and
mission has been recognized and upheld by reviewing courts. ``[T]he
Mine Act evinces a clear bias in favor of miner health and safety.''
Nat'l Min. Ass'n v. Sec'y, U.S. Dep't of Lab., 812 F.3d 843, 866 (11th
Cir. 2016). Courts interpret MSHA's obligation to promulgate standards
to protect the health of the nation's miners to include ``
`prevent[ing],' not merely reduc[ing] the incidence of, `occupational
diseases originating in . . . mines.' '' Id. at 883 (quoting 30 U.S.C.
801(c)). Where occupational disease ``incidence has not been reduced to
zero . . . MSHA has not completely fulfilled its mission to `protect
the health . . . of the Nation's coal or other miners.' '' Id. (quoting
30 U.S.C. 801(g)). Case law instructs that MSHA must demonstrate risk
before regulating: ``[B]efore promulgating a health or safety standard
under the Mine Act, MSHA must show that the substance being regulated
presents a risk of `material impairment of health or functional
capacity' for miners who are regularly exposed to the substance.''
Kennecott Greens Creek Min. Co. v. Mine Safety & Health Admin., 476
F.3d 946, 952 (D.C. Cir. 2007) (quoting 30 U.S.C. 811(a)(6)(A)).
Although the Mine Act requires MSHA to consider the best available
evidence, the ``duty to use the best available evidence . . . cannot be
wielded as a counterweight to MSHA's overarching role to protect the
life and health of workers in the mining industry.'' Nat'l Min. Ass'n,
812 F.3d at 866. With this regulatory action, MSHA is addressing this
urgent need. See 30 U.S.C. 801(c).
On July 13, 2023, MSHA published a notice of proposed rulemaking,
entitled ``Lowering Miners' Exposure to Respirable Crystalline Silica
and Improving Respiratory Protection'', along with supplemental
documents. The Agency specifically sought comments on its preliminary
determination from the literature review that miners' exposure to
respirable crystalline silica presents a risk of material health
impairment or functional capacity. MSHA also requested input on any
additional adverse health effects that should be included or more
recent literature that offers a different perspective. MSHA received
numerous comments in response to this request and considered them in
preparing the final standalone Health Effects document and the final
rule.
This section will describe how MSHA conducted its review of the
health effects literature on respirable crystalline silica and what the
Agency has found about the toxicity of respirable crystalline silica.
This section will also present the findings on the following health
effects: (1) Silicosis; (2) Non-malignant respiratory disease (NMRD),
excluding silicosis; (3) Lung cancer and cancer at other sites; (4)
Renal disease; and (5) Autoimmune diseases. Public comments received
are reflected throughout this section.
A. General Approach to Health Effects Literature Review
MSHA reviewed a wide range of health effects literature totaling
over 600 studies that explore the relationship between respirable
crystalline silica exposure and resultant adverse health effects in
miners and other workers across various industries. The health effects
literature reviewed by MSHA included both studies reviewed by OSHA for
its 2016 respirable crystalline silica standard and many other newer
studies and studies that focused specifically on the mining industry.
OSHA's ``Health Effects Analysis and Preliminary Quantitative Risk
Assessment'' (2013b) included studies that were identified from
previously published scientific reviews, such as the IARC (1997) and
NIOSH (2002), and from newer evaluations of scientific literature,
literature searches, and contact with experts and stakeholders. That
document underwent extensive peer review by a panel of nationally
recognized experts in occupational epidemiology, biostatistics and risk
assessment, animal and cellular toxicology, and occupational medicine
who had no conflict of interest (COI) or apparent bias in performing
the review. These experts were asked to consider the strengths,
weaknesses, interpretations, and inclusion of studies used to support
the findings, and OSHA revised the document based on their feedback.
To ensure that its literature review was thorough and up to date,
MSHA reviewed a large body of additional evidence beyond the studies
considered by OSHA. It added many studies focused on miners' exposures
to respirable crystalline silica, as well as newer studies published
over the past decade. MSHA drew upon numerous studies conducted by
NIOSH, the International Agency for Research on Cancer (IARC), the
National Toxicology Program (NTP), and other researchers. These studies
provided epidemiological data, analyses of morbidity (having a disease
or a symptom of disease) and mortality (disease resulting in death),
progression and pathology evaluations, death certificate and autopsy
reviews, medical surveillance data, health hazard assessments, in vivo
(animal) and in vitro (cell-based) toxicity data, and other
toxicological reviews. These studies are cited throughout this summary
and are listed in the References section of MSHA's standalone Health
Effects
[[Page 28233]]
document. Additionally, these studies appear in the rulemaking docket.
MSHA received some comments from industry stakeholders who
disagreed with MSHA's selection of studies for its literature review
and therefore with its findings. The Nevada Mining Association (NVMA)
and the Sorptive Minerals Institute (SMI) stated that not all relevant
studies were discussed in the Health Effects literature review
(Document ID 1441; 1446). NVMA also stated that the studies referenced
are outdated. The National Stone, Sand, & Gravel Association (NSSGA)
stated that MSHA's review is overly reliant on OSHA's review (2013b)
(Document ID 1448, Attachment 3). The state mining association stated
that the studies MSHA considered do not recognize that the likelihood
of prolonged exposure to respirable crystalline silica has been
dramatically reduced over the years, noting improvements to
respirators, equipment, and engineering controls (Document ID 1441).
However, commenters from health and labor organizations stated that
MSHA's review was thorough, was consistent with the scientific
consensus, and addressed the primary health effects of concern. These
commenters agreed with MSHA's findings and conclusions related to
health risks from exposure to respirable crystalline silica (Document
ID 1398; 1405; 1410; 1416). The American Public Health Association
(APHA) also noted the inclusion of several recent peer-reviewed
publications included in MSHA's review (Document ID 1416). The American
College of Occupational and Environmental Medicine (ACOEM) commented
that there has been an explosion of new information about the molecular
basis for silica's adverse effects since OSHA's comprehensive summary
of the medical literature in its preamble to the 2016 revisions to the
silica standard (Document ID 1405). This commenter stressed that this
new information only adds to the urgency of establishing and enforcing
MSHA's proposed standard and applauded the Agency's review of the
medical and epidemiologic literature on the health effects of silica
exposure.
MSHA has taken several steps to ensure that its review of health
effects literature represents the current understanding of health risks
related to exposures to respirable crystalline silica. In its initial
standalone Health Effects document, which was published alongside the
proposed rule, MSHA included several recent publications (published as
late as 2022), and since then, it has added more recent publications
(through 2023) in its final standalone Health Effects document.
Examples of recent literature included in the standalone Health Effects
document are: Carrington and Hershberger (2022), Cohen et al. (2022),
Descatha et al. (2022), Hall et al. (2022), and Keles et al. (2022).
Furthermore, many of the more recent studies included miners regulated
under the existing MSHA PEL of 100 [micro]g/m\3\ (e.g., Almberg et al.,
2017, 2018a; Graber et al., 2017; Blackley et al., 2018a; Cohen et al.,
2022). In response to the comment that the initial standalone Health
Effects document did not take into account improved mining conditions
or contemporary engineering controls, the Agency notes that it
considered several studies featuring miners in a larger range of
exposure groups, including some that had lower exposure levels (e.g.,
Mannetje et al., 2002b; Park et al., 2002; Buchanan et al., 2003;
Attfield and Costello, 2004; Chen et al., 2012).
Two commenters (an industry trade association and a training
consulting company) stated that MSHA presented a significant amount of
data showing the consequences of the various chronic health effects
that silica can and does have on the human body but no viable data on
mortality and morbidity among MNM miners (Document ID 1442; 1392).
As discussed elsewhere, MSHA is not required to prove a risk of
death due to silica exposure to justify regulating to reduce a silica
health risk. But the evidence shows that respirable silica exposure
causes death as well as chronic disease. MSHA reviewed and discussed
multiple studies that reported an increase in mortality rates
throughout the standalone Health Effects document (e.g., Bang et al.,
2005; Mazurek and Wood, 2008a; Liu et al., 2017a; Wang et al., 2020a).
Examples of MNM morbidity studies included are Mamuya et al. (2007),
Tse et al. (2007a), Rego et al. (2008), Reynolds et al. (2016), and
Wang et al. (2020b); while MNM specific mortality studies include
Attfield and Costello (2004), Chen et al. (2005, 2012), Schubauer-
Berigan et al. (2009), and Vacek et al. (2011), among others. MSHA
considered the best available evidence for MNM and concludes that MNM
miners have an increased mortality and morbidity due to exposure to
respirable crystalline silica.
Commenters from health and labor organizations suggested additional
studies for MSHA to include in the final standalone Health Effects
document (Document ID 1405; 1373; 1449). These studies included topics
such as new information regarding the molecular basis for silica's
adverse health effects or related to engineered stone workers. One
commenter stated that MSHA should include studies from outside of the
mining industry (Document ID 1448, Attachment 3).
MSHA thoroughly reviewed these studies and did not find sufficient
evidence to alter MSHA's overall conclusions of health risk, as
discussed in detail in the sections that follow. However, MSHA did add
many of the recommended studies to its final standalone Health Effects
document (e.g., Chilosi et al., 2003; Chen et al., 2018; Cao et al.,
2020). MSHA also reviewed other suggested literature, including
promising animal studies exploring novel drug treatments for diseases
caused by exposure to respirable crystalline silica; however, it
determined that these studies are not sufficiently developed for
inclusion at this time (e.g., Guo et al., 2019; Huang et al., 2019; Jia
et al., 2022). MSHA has already included several studies related to
non-mining occupations throughout its standalone Health Effects
document. Examples of other occupational studies include studies of
health effects on granite workers (e.g., Davis et al., 1983; Attfield
and Costello, 2004), brick workers (e.g., Merlo et al., 1991), agate
stone grinders (Rastogi et al., 1991), pottery workers (e.g., McDonald
et al., 1995; Cherry et al., 1998), industrial sand workers (e.g.,
McDonald et al., 2001; Rando et al., 2001), concrete workers (e.g.,
Meijers et al., 2001), ceramic workers (e.g., Forastiere et al., 2002),
and foundry workers (e.g., Hertzberg et al., 2002; Vihlborg et al.,
2017), among others. Occupations such as granite, industrial sand, or
concrete workers, represent similar job tasks and exposures which may
overlap with mining occupations. Others such as brick, pottery, and
ceramic workers involve processing of mined materials into a commercial
product.
To analyze the extensive literature that it considered, MSHA used
the widely accepted weight-of-evidence (WoE) approach. Under this
approach, studies with varied methodologies and conclusions are
evaluated for their overall quality. Causal inferences are drawn based
on a determination of whether there is substantial evidence that
exposure increases the risk of a particular adverse health effect. This
approach is a well-accepted method of conducting health hazard
assessments (NRC, 2009; NIOSH, 2019a). Additionally, it was used by
OSHA in its review of health effects literature (2013b) for its 2016
respirable crystalline silica standard. Factors that MSHA considered in
its WoE analysis include: (1) size of the cohort studied and power of
the study to detect a
[[Page 28234]]
sufficiently low level of disease risk; (2) duration of follow-up of
the study population; (3) potential for study bias, such as selection
bias or healthy worker effects, and (4) adequacy of underlying exposure
information for examining exposure-response relationships. Of the
studies examined in the standalone Health Effects document, studies
were deemed suitable for inclusion in the FRA if they provided adequate
quantitative information on exposure and disease risks and were judged
to be of sufficiently high quality according to the above criteria.
MSHA's literature review expanded upon OSHA's (2013b) review of the
health effects literature to support its final respirable crystalline
silica rule (81 FR 16286), reviewing pertinent new research. MSHA's
assessment of the literature is consistent with OSHA's conclusion from
its silica literature review.
MSHA received one comment from the NSSGA challenging the validity
of MSHA's literature review methodology (Document ID 1448, Attachment
3). This commenter submitted a report analyzing MSHA's health effects
literature review, arguing that MSHA's review cannot be replicated or
fully evaluated for its scientific validity and claiming that it is
unclear whether MSHA's interpretations are sufficiently reliable as a
basis for decision-making. The commenter asserted the need for
literature reviews to be done pursuant to Lynch et al.'s (2022)
framework of a ``systematic review,'' a review method that seeks to
eliminate bias by adhering to a transparent, a priori protocol. The
commenter also expressed concerns that MSHA's methodology is
inadequately explained and possibly dated. The commenter suggested
further studies to be included in MSHA's review and provided specific
responses to some of MSHA's statements in its literature review.
On the other hand, the APHA provided a different perspective on the
methodology (Document ID 1416). This commenter stated that MSHA
thoroughly describes the health risks, which include developing chronic
silicosis, accelerated silicosis, progressive massive fibrosis, chronic
obstructive pulmonary disease, lung cancer and kidney disease. Further,
the commenter noted that MSHA's review of the health effects literature
included more than three dozen peer-reviewed papers published in just
the last few years. This commenter concurred with MSHA's determination
that miners' exposure to respirable crystalline silica presents a risk
of material impairment of health or functional capacity.
MSHA disagrees with the comment challenging MSHA's methodology.
Although the ``systematic review'' framework outlined in Lynch et al.
(2022) is increasingly used in review publications, it is not the only
valid method of conducting a literature review of the current science.
As explained in the standalone Health Effects document, MSHA's review
of the scientific literature on respirable crystalline silica used a
widely accepted WoE approach.
The term, ``weight-of-evidence'' was coined as early as 40 years
ago by the NRC (1983) in their seminal publication ``Risk Assessment in
the Federal Government: Managing the Process''. It has become a
fundamental element of the risk assessment process (NRC, 2009; EPA,
1986; Martin et al., 2018; Lee et al., 2023). MSHA selected this
approach for use in its respirable crystalline silica risk analysis for
a variety of reasons. First, it has withstood the scrutiny of
scientists throughout the world (Suter et al., 2020). Second, it has
been used successfully throughout the world for conducting a wide
variety of risk assessments and analyses involving a wide range of
exposures in both occupational and environmental settings (e.g., drugs,
pesticides, industrial chemicals) (EPA, 1986, 2016; National Research
Council (NRC), 2009; Suter et al., 2020; Government of Canada, 2022).
Third, it continues to be a solid and accepted approach that is still
used today (EPA, 1986, 2016; National Research Council (NRC), 2009;
Martin et al., 2018; Suter et al., 2020; Government of Canada, 2022;
Lee et al., 2023). Current searches of the scientific literature (e.g.,
using search engines such as PubMed or Google Scholar) continue to
identify studies in which the WoE approach has been employed. Finally,
numerous courts have approved of federal agencies relying on this
methodology in rulemaking for over 40 years. See Mississippi v. E.P.A.,
744 F.3d 1334, 1344-45 (D.C. Cir. 2013) (upholding the ``weight of
evidence approach'' because ``one type of study might be useful for
interpreting ambivalent results from another type . . . and though a
new study does little besides confirm or quantify a previous finding,
such incremental (and arguably duplicative) studies are valuable
precisely because they confirm or quantify previous findings or
otherwise decrease uncertainty'') (citing Ethyl Corp. v. EPA, 541 F.2d
1, 26 (D.C. Cir. 1976) (en banc)); N. Am.'s Bldg. Trades Unions v.
OSHA, 878 F.3d 271, 284 (D.C. Cir. 2017) (rejecting challenges to
OSHA's ``weight of evidence'' approach supporting its silica
rulemaking). Thus, MSHA finds that the WoE approach is appropriate for
use in its respirable crystalline silica rulemaking.
In summary, MSHA's weight-of-evidence analysis is based on OSHA's
extensive literature review and peer review process; includes a
substantial number of studies and data published after the OSHA
rulemaking; and has received support from NIOSH experts.\16\
---------------------------------------------------------------------------
\16\ MSHA's review benefitted from feedback and review from
experts at NIOSH, both informally and through the interagency review
process organized by OMB, during the literature review process and
preparation of the standalone Health Effects document.
---------------------------------------------------------------------------
As described in greater detail in MSHA's standalone Health Effects
document, the scientific understanding of how respirable crystalline
silica causes adverse health effects has evolved greatly in the more
than 45 years since the Mine Act was passed in 1977. MSHA's review of
the literature indicates that under the existing standards found in 30
CFR parts 56, 57, 70, 71, and 90, miners are still developing
preventable diseases that are material impairments of health or
functional capacity. Regulatory action to reduce occupational exposures
that cause these diseases is necessary to ensure no miner suffers
material impairment of health or functional capacity, as required by
section 101(a)(6)(A) of the Mine Act.
Based on an extensive review of health effects literature, MSHA
determines that occupational exposure to respirable crystalline silica
causes silicosis (acute silicosis, accelerated silicosis, chronic
silicosis, and progressive massive fibrosis (PMF)), NMRD (including
COPD), lung cancer, and end-stage renal disease (ESRD). Each of these
effects is exposure-dependent, potentially chronic, irreversible,
potentially disabling, and can be fatal. In addition, MSHA's review of
the health effects literature has shown that respirable crystalline
silica exposure is causally related to the development of some
autoimmune disorders through inflammatory pathways. Current health
information cited in the final standalone Health Effects document
indicates that miners are suffering material impairment of health or
functional capacity due to their occupational exposures to respirable
crystalline silica. MSHA's review of respirable crystalline silica
health effects concludes that the final rule, which lowers the exposure
limits in MNM and coal mining to 50 [micro]g/m\3\ and establishes an
action level of 25 [micro]g/m\3\ for a full-shift exposure, calculated
as an 8-hour TWA, will reduce the risk
[[Page 28235]]
of miners developing silicosis, NMRD, lung cancer, and renal disease.
B. Toxicity of Respirable Crystalline Silica
Respirable crystalline silica is released into the environment
during mining or milling processes, thus creating an airborne hazard.
The particles may be freshly generated or re-suspended from surfaces on
which they are deposited in mines or mills. Respirable crystalline
silica particles may be irregularly shaped and variable in size. These
particles may be inhaled by miners and can be deposited throughout the
lungs. Some pulmonary clearance of particles deposited in the alveolar
region (deep lung) may occur, but many particles can be retained and
initiate or advance the disease process. The toxicity of these retained
particles is amplified because the particles are not water-soluble and
are not metabolized into less toxic compounds. This is important
because insoluble dusts may remain in the lungs for prolonged periods,
resulting in a variety of cellular responses that can lead to pulmonary
disease (ATSDR, 2019). Respirable crystalline silica particles that are
cleared from the lungs by the lymphatic system are distributed to the
lymph nodes, blood, liver, spleen, and kidneys, potentially
accumulating in these other organ systems and causing renal disease and
other adverse health effects (ATSDR, 2019).
Physical characteristics relevant to the toxicity of respirable
crystalline silica primarily relate to its size and surface
characteristics, both of which play important roles in how respirable
crystalline silica causes tissue damage. Any factor that influences or
modifies these physical characteristics may alter the toxicity of
respirable crystalline silica by affecting the mechanistic processes
(ATSDR, 2019).
Inflammatory pathways affect disease development in various systems
and tissues in the human body. For instance, it has been proposed that
lung fibrosis caused by exposure to respirable crystalline silica
results from a cycle of cell damage, oxidant generation, inflammation,
scarring, and ultimately fibrosis. This has been reported by: Nolan et
al. (1981), Shi et al. (1989, 1998), Lapp and Castranova (1993), Brown
and Donaldson (1996), Parker and Banks (1998), Castranova and
Vallyathan (2000), Castranova (2004), Fubini et al. (2004), Hu et al.
(2017), Benmerzoug et al. (2018), and Yu et al. (2020).
Respirable crystalline silica entering the lungs could cause damage
by a variety of mechanisms, including direct damage to lung cells. In
addition, activation or stimulation by respirable crystalline silica of
alveolar macrophages (after phagocytosis) and/or alveolar epithelial
cells may lead to: (1) release of cytotoxic enzymes, reactive oxygen
species (ROS), reactive nitrogen species (RNS), inflammatory cytokines
and chemokines; (2) eventual cell death with the release of respirable
crystalline silica; and (3) recruitment and activation of
polymorphonuclear leukocytes (PMNs) and additional alveolar macrophages
(Castranova and Vallyathan, 2000; Castranova, 2004; Hamilton et al.,
2008). The elevated production of ROS/RNS could result in oxidative
stress and lung injury that stimulate alveolar macrophages, ultimately
resulting in fibroblast activation and pulmonary fibrosis (Li et al.,
2018; Feng et al., 2020). The prolonged recruitment of macrophages and
PMN causes persistent inflammation, regarded as a primary step in the
development of silicosis.
The strong immune response in the lung following exposure to
respirable crystalline silica may also be linked to a variety of extra-
pulmonary adverse effects such as hypergammaglobulinemia
(overproduction of more than one class of immunoglobulins by plasma
cells), production of rheumatoid factor, anti-nuclear antibodies, and
release of other immune complexes (Haustein and Anderegg, 1998; Green
and Vallyathan, 1996; Parks et al., 1999). Respirable crystalline
silica exposure has also been associated with ESRD through the
initiation of immunological injury to the glomerulus of the kidney
(Calvert et al., 1997).
Proposed mechanisms involved in respirable crystalline silica-
induced carcinogenesis have included: direct DNA damage, inhibition of
the p53 tumor suppressor gene, loss of cell cycle regulation;
stimulation of growth factors, and production on oncogenes (Nolan et
al., 1981; Shi et al., 1989, 1998; Brown and Donaldson, 1996;
Castranova, 2004; Fubini et al., 2004).
Three commenters expressed concerns about the findings of the
health effects literature review and their relevance to the sorptive
minerals industry (Document ID 1446, Attachment 1; 1442; 1419). The SMI
and Essential Minerals Association (EMA) stated that MSHA has an
incomplete understanding of the latest available scientific research
(Document ID 1446, Attachment 1; 1442). Asserting that occluded quartz
in sorptive clays is not fractured (either in the clay formation in
which it exists or during the mining and processing of the material to
form sorptive mineral-based products), the SMI concluded that occluded
quartz in sorptive clays does not pose the health risk posed by
fractured quartz (Document ID 1446, Attachment 1). Discussing at length
studies it recommended MSHA include in its health effects literature
review, SMI and EMA said that much of this research was previously
considered by OSHA (2013b) and that it had led to OSHA's decision to
exempt sorptive clays from coverage under OSHA's silica standard. SMI
also noted that additional research since OSHA's revised silica
standard was promulgated has advanced the question of how quartz causes
disease and the difference in risk potential between fractured and
unfractured and occluded quartz. Asserting that, without consideration
of the additional research provided, the proposed standard would not be
based on the best available evidence and would not reflect the latest
available scientific data in the field, this commenter discussed Mine
Act statutory provisions and case law that it asserted demonstrate the
high level of scientific evidence and scrutiny required of MSHA when
setting health and safety standards.
A more detailed response to SMI's overall comment can be found in
Section VIII.A. General Issues of this preamble. In response to the
suggestion to consider additional studies, MSHA reviewed the suggested
references and added some to the final standalone Health Effects
document (Creutzenberg et al., 2008; Borm et al., 2018; Pavan et al.,
2019). MSHA also notes that some of these studies were already cited in
the version of the standalone Health Effects document published
alongside the proposed rule (e.g., Donaldson and Borm, 1998; Fubini,
1998; Bruch et al., 2004; Fubini et al., 2004). Overall, many of the
studies suggested by the commenter have argued that occluded or aged
quartz is less toxic but have not suggested that occluded or aged
quartz is not toxic or carries no risk of disease. MSHA agrees that
there is some evidence to suggest that occluded silica is less toxic
than unoccluded silica (Wallace et al., 1996), but there is no evidence
that occlusion and the initial reduced toxicity persist following
deposition and retention of the crystalline silica particles in the
lungs. Similarly, animal studies involving respirable crystalline
silica suggest that the aged form has lower toxicity than the freshly
fractured form; however, the aged form still retains toxicity
(Shoemaker et al., 1995; Vallyathan et al., 1995; Porter et al.,
2002c). From these studies, MSHA concludes that
[[Page 28236]]
exposure to the crystalline silica present in sorptive minerals poses a
risk of material impairment of health or functional capacity to miners.
Others appeared to be irrelevant to the scope of the rule, such as
those focused on amorphous silica, microscopy techniques, or workshop
discussions (e.g., Mercer et al., 2018; Weber et al., 2018; Driscoll
and Borm, 2020). MSHA notes that none of the suggested animal studies
included acute or chronic inhalation exposures to aged or occluded
respirable crystalline silica. One suggested review, Poland et al.
(2023) described a 2020 animal inhalation study (nose-only) which did
not include exposures to aged or occluded respirable crystalline
silica; the 2020 study was conducted using amorphous silica and the
data were compared to a 1988 animal study that included whole-body (as
opposed to nose-only) exposures to respirable crystalline silica.\17\
Since this 2020 surface area comparison study described by Poland et
al. (2023) focused on amorphous silica, which is not a part of this
rulemaking, it was deemed unsuitable for inclusion in MSHA's final
standalone Health Effects document. Other animal studies discussing
aged or occluded respirable crystalline silica suggested used either
intratracheal instillation or oropharyngeal aspiration, which do not
reflect the behavior of particles that enter the lungs via inhalation,
including lung clearance (Foster et al., 2001; Wong, 2007; Driscoll and
Borm, 2020). Section VIII.A. General Issues of this preamble responds
more fully to these comments. In its response, MSHA notes that several
studies of occluded or fractured quartz discussed their methods,
including careful handling of occluded samples, but did not include
analysis of occluded quartz that was analyzed with less than careful
handling. This is not applicable to real-world conditions; MSHA's
experience with mining and processing of sorptive minerals includes the
use of grinding and milling processes.
---------------------------------------------------------------------------
\17\ These two studies (1988 and 2020) described by Poland et
al. (2023) had limited comparability for a variety of reasons; they
differ in: (1) rat strains (types of rats), (2) exposure durations,
(3) recovery periods, as well as (4) types of inhalation exposure,
among others.
---------------------------------------------------------------------------
After reviewing the available literature, MSHA concludes that
miners working in the sorptive minerals industry are exposed to
respirable crystalline silica. OSHA (2013b) concluded that while there
was considerable evidence that several environmental influences can
modify surface activity to either enhance or diminish the toxicity of
silica, the available information was insufficient to determine in any
quantitative way how these influences may affect disease risk to
workers in any particular workplace setting (81 FR at 16311). MSHA
agrees with OSHA (2013b) that there is evidence to support that surface
activity of respirable crystalline silica may play a role in producing
disease. However, mining is significantly different from other
industries regulated by OSHA, for instance, in that it involves
milling, grinding and removal of overburden. While the available
information is insufficient to determine how these influences may
affect disease risk to miners in any quantitative way and in any mining
sector. MSHA is permitted `` `to err on the side of overprotection by
setting a fully adequate margin of safety.' '' Kennecott Greens Creek
Min. Co. v. Mine Safety & Health Admin., 476 F.3d 946, 952 (D.C. Cir.
2007) (quoting Nat'l Min. Ass'n v. Mine Safety & Health Admin., 116
F.3d 520, 528 (D.C. Cir. 1997)).
C. Diseases
1. Silicosis
Silicosis is a material impairment of health or functional
capacity, as defined by the Mine Act, and refers to a group of lung
diseases caused by the inhalation of respirable crystalline silica. See
30 U.S.C. 811(a)(6)(A). Silicosis is a progressive, occupational
disease, in which accumulation of respirable crystalline silica
particles causes an inflammatory reaction in the lung. This reaction
leads to lung damage and scarring and, in some cases, progresses to
disability and death. Respirable crystalline silica has long been
identified as a cause of lung diseases in miners, and adverse health
effects were noted and described as early as 1550 by Georgius Agricola
(Agricola, as translated by Banner in 1950). Based on the review of the
literature, MSHA has determined that exposure to respirable crystalline
silica causes silicosis in MNM and coal miners and that it is a
significant cause of premature morbidity and mortality (Mazurek and
Attfield, 2008; Mazurek and Wood, 2008a,b; Mazurek et al., 2015, 2018).
When respirable crystalline silica accumulates in the lungs, it
causes an inflammatory reaction, leading to lung damage and scarring.
Silicosis can continue to develop even after silica exposure has ceased
(Hughes et al., 1982; Ng et al., 1987a; Hessel et al., 1988; Kreiss and
Zhen, 1996; Miller et al., 1998; Yang et al., 2006). It is not
reversible, and there is only symptomatic treatment, including
bronchodilators to maintain open airways, oxygen therapy, and lung
transplants in the most severe cases (Cochrane et al., 1956; Ng et al.,
1987a; Lee et al., 2001; Mohebbi and Zubeyri, 2007; Kimura et al.,
2010; Laney et al., 2017; Almberg et al., 2020; Hall et al., 2022).
Respirable crystalline silica exposure in miners can lead to all three
forms of silicosis (acute, accelerated, and chronic). These forms
differ in the rate of exposure, pathology (structural and functional
changes produced by the disease), and latency period from exposure to
disease onset.
Acute silicosis is an aggressive inflammatory process following
intense exposure to respirable crystalline silica for ``periods
measured in months rather than years'' (Cowie and Becklake, 2016). It
causes alveolar proteinosis, an accumulation of lipoproteins in the
alveoli of the lungs. This restructuring of the lungs leads to symptoms
such as coughing and difficult or labored breathing, and often
progresses to profound disability and death due to respiratory failure
or infectious complications. In addition, symptoms often advance even
after exposure has stopped, primarily due to the massive amount of
protein debris and fluid that collects in the alveoli, which leads to
the impairment of gas exchange (oxygen) in the lungs and respiratory
distress of the patient. The X-ray appearance and results of
microscopic examination of acute silicosis are like those of idiopathic
(having an unknown cause) pulmonary alveolar proteinosis.
Accelerated silicosis includes both inflammation and fibrosis and
is associated with intense respirable crystalline silica exposure.
Accelerated silicosis usually manifests over a period of three to ten
years (Cowie and Becklake, 2016), but it can develop in as little as
two to five years if exposure is sufficiently intense (Davis, 1996).
Accelerated silicosis may have features of both chronic and acute
silicosis, with alveolar proteinosis in addition to X-ray evidence of
fibrosis, seen as small opacities or the large opacities of PMF.
Although the symptoms are like those of chronic silicosis, the clinical
and radiographic progression of accelerated silicosis evolves more
rapidly, and often leads to PMF, severe respiratory impairment, and
respiratory failure. Accelerated silicosis can progress with associated
morbidity and mortality, even if exposure ceases. Accelerated silicosis
is frequently fatal.
Chronic silicosis is the most frequently observed form of silicosis
in the United States today (Banks, 2005; OSHA, 2013b; Cowie and
Becklake,
[[Page 28237]]
2016). It is also the most common form of silicosis diagnosed in
miners. Chronic silicosis is a fibrotic process that typically follows
less intense respirable crystalline silica exposure of ten or more
years (Becklake, 1994; Balaan and Banks, 1998; NIOSH, 2002b;
Kambouchner and Bernaudin, 2015; Cowie and Becklake, 2016; Rosental,
2017; ATSDR, 2019; Barnes et al., 2019; Hoy and Chambers, 2020). It is
identified histopathologically by the presence of the silicotic islet
or nodule that is an agent-specific fibrotic lesion and is recognized
by its pathology (Balaan and Banks, 1998). Chronic silicosis develops
slowly and creates rounded whorls of scar tissue that progressively
destroy the normal structure and function of the lungs. In addition,
the scar tissue opacities become visible by chest X-ray or computerized
tomography (CT) only after the disease is well-established and the
lesions become large enough to view. As a result, surveys based on
identification of small and large opacity disease on chest X-ray films
usually underestimate the true prevalence of silicosis (Craighead and
Vallyathan, 1980; Hnizdo et al., 1993; Rosenman et al., 1997; Cohen and
Velho, 2002). The lesions eventually advance and result in lung
restriction, reduced lung volumes, decreased pulmonary compliance, and
reduction in the gas exchange capabilities of the lungs (Balaan and
Banks, 1998). As the disease progresses, affected miners may have
chronic cough, sputum production, shortness of breath, and reduced
pulmonary function.
Among coal miners, silicosis is usually found in conjunction with
simple coal workers' pneumoconiosis (CWP) because of the miners'
exposures to RCMD that also contains respirable crystalline silica
(Castranova and Vallyathan, 2000). Coal miners also face an added risk
of developing mixed-dust pneumoconiosis (MDP) (includes the presence of
coal dust macules), mixed-dust fibrosis (MDF), and/or silicotic nodules
(Honma et al., 2004; Green, 2019). The autopsy studies on coal miners
that MSHA reviewed support a pathological relationship between mixed-
RCMD or respirable crystalline silica exposures and PMF, silicosis, and
CWP (Davis et al., 1979; Ruckley et al., 1981, 1984; Douglas et al.,
1986; Fernie and Ruckley, 1987; Green et al., 1989, 1998b; Attfield et
al., 1994; Vallyathan et al., 2011; Cohen et al., 2016, 2019, 2022).
Autopsy studies in British coal miners indicated that the more advanced
the disease, the more mixed-RCMD components were retained in the lung
tissue (Ruckley et al., 1984; Douglas et al., 1986). Green et al.
(1998b) determined that of 4,115 coal miners with pneumoconiosis
autopsied as part of the National Coal Workers' Autopsy Study (NCWAS),
39 percent had mixed dust nodules and 23 percent had silicotic nodules.
PMF or ``complicated silicosis'' has been diagnosed in both coal
and MNM miners exposed to dusts containing respirable crystalline
silica. Recent literature on the pathophysiology of PMF supports the
importance of crystalline silica as a cause of PMF in silica-exposed
workers such as coal miners (Cohen et al., 2016, 2022), sandblasters
(Hughes et al., 1982; Abraham and Wiesenfeld, 1997), industrial sand
workers (Vacek et al., 2019), hard rock miners (Verma et al., 1982,
2008), and gold miners (Carneiro et al., 2006a; Tse et al., 2007b).
a. Classifying Radiographic Findings of Silicosis
The studies reviewed by MSHA used one of two established methods
for identifying findings of pneumoconiosis: the International Labour
Office (ILO) Classification System or the Chinese categorization
system, each of which is described below. In addition, the NIOSH case
definition of silicosis used in surveillance systems relies on the ILO
system.
The ILO developed a standardized system to classify the
radiographic appearances of pneumoconiosis identified in chest X-rays
films or digital chest radiographic images (ILO, 1980, 2002, 2011,
2022). One aspect of the ILO system involves grading the size, shape,
and profusion (density) of opacities in the lungs. The density of
opacities is classified on a four-point major category scale (category
0, 1, 2, or 3), with each major category divided into three
subcategories, giving a 12-point scale between 0/- and 3/+. Differences
between ILO categories are subtle. For each subcategory, the top number
indicates the major category that the profusion most closely resembles,
and the bottom number indicates the major category that was given
secondary consideration. For example, film readers may assign
classifications such as 1/0, which means the reader classified it as
category 1, but category 0 (normal) was also considered (ILO, 2022).
Major category 0 indicates the absence of visible opacities consistent
with pneumoconiosis and categories 1 to 3 reflect increasing profusion
of opacities and a concomitant increase in severity of disease.
However, some studies in MSHA's literature review used the Chinese
system of X-ray classification based on the ``Radiological Diagnostic
Criteria of Pneumoconiosis and Principles for Management of
Pneumoconiosis'' (GB5906-86). This includes four categories of
pneumoconiosis findings: a suspected case (0+), stage I, stage II, or
stage III. Under this scheme, a panel of three radiologists determines
the presence and severity of radiographic changes consistent with
pneumoconiosis. The four categories correspond to ILO profusion
category 0/1, category 1, category 2, and category 3, respectively. A
suspected case of silicosis (0+) in a dust-exposed worker refers to a
dust response in the lung and its corresponding lymph nodes, or a scale
and severity of small opacities that fall short of the level observed
in a stage I case of silicosis (Chen et al., 2001; Yang et al., 2006).
MSHA's analysis of silicosis studies uses NIOSH's surveillance case
definition to determine the presence of silicosis. As described further
in the final standalone Health Effects document, NIOSH defines the
presence of silicosis in terms of the ILO system and considers a small
opacity profusion score of 1/0 or greater to indicate pneumoconiosis
(NIOSH, 2014b). This definition originated from testimony before
Congress regarding the 1969 Coal Act in which the Public Health Service
recommended that miners be removed from dusty environments as soon as
they showed ``minimal effects'' of dust exposure on a chest X-ray
(i.e., pinpoint, dispersed micro-nodular lesions). MSHA interprets
``minimal effects'' to mean an X-ray ILO profusion score of category 1/
0 or greater. This is also consistent with Hnizdo et al. (1993), which
recommended that, due to the low sensitivity of chest x-rays for
detecting silicosis, radiographs consistent with an ILO category of 0/1
or greater be considered indictive of silicosis among workers exposed
to a high concentration of silica-containing dust.
b. Progression and Associated Impairment
MSHA reviewed studies referenced by OSHA (2013b) that examined the
relationship between exposure and progression, as well as between X-ray
findings and pulmonary function. Additionally, MSHA considered
literature not previously reviewed by OSHA (2013b) (Mohebbi and
Zubeyri, 2007; Wade et al., 2011; Dumavibhat et al., 2013).
Progression of silicosis is recognized when there are changes or
worsening of the opacities in the lungs, and sequential chest
radiographs are
[[Page 28238]]
classified higher by one or more subcategories (e.g., from 1/0 to 1/1)
because of changes in the location, thickness, or extent of lung
abnormalities and/or the presence of calcifications. The higher the
category number, the more severe the disease. Due to the variability in
film technique and classification of films, some investigators count
progression as advancing two or more subcategories, such as 1/0 to 1/2.
Overall, the studies indicate that progression is more likely with
continued exposure, especially high average levels of exposure.
Progression is also more likely for miners with higher ILO profusion
classifications. As discussed previously, progression of disease may
continue after miners are no longer exposed to respirable crystalline
silica (Cochrane et al., 1956; Maclaren and Soutar, 1985; Hurley et
al., 1987; Kimura et al., 2010; Almberg et al., 2020; Hall et al.,
2020b). In addition, although lung function impairment is highly
correlated with chest X-ray films indicating silicosis, researchers
caution that respirable crystalline silica exposure could impair lung
function before it is detected by X-ray.
Of the studies in which silicosis progression was documented in
populations of workers, four included quantitative exposure data that
were based on either existing exposure levels or historical
measurements of respirable crystalline silica (Ng et al., 1987a study
of granite miners; Hessel et al., 1988 study of gold miners; Miller et
al., 1998 study of coal miners; Miller and MacCalman, 2010 study of
coal miners). In some studies, episodic exposures to high average
concentrations were documented and considered in the analysis. These
exposures were strong predictors of more rapid progression beyond that
predicted by cumulative exposure alone. Otherwise, the variable most
strongly associated in these studies with progression of silicosis was
cumulative respirable crystalline silica exposure (the product of the
concentration times duration of exposure, which is summed over time)
(Ng et al., 1987a; Hessel et al., 1988; Miller et al., 1998; Miller and
MacCalman, 2010). In the absence of concentration measurements,
duration of employment in specific occupations known to involve
exposure to high levels of respirable dust has been used as a surrogate
for cumulative exposure to respirable crystalline silica. Duration of
employment has also been found to be associated with the progression of
silicosis (Ogawa et al., 2003a).
Miller et al. (1998) examined the impact of high quartz exposures
on silicosis disease progression in 547 British coal miners from 1990
to 1991 and evaluated chest X-ray changes after the mines closed in
1981. The study reviewed chest X-rays taken during health surveys
conducted between 1954 and 1978 and data from extensive exposure
monitoring conducted between 1964 and 1978. For some occupations,
exposure was high because miners had to dig through a sandstone stratum
to reach the coal. For example, quarterly mean respirable crystalline
silica (quartz) concentrations ranged from 1,000 to 3,000 [micro]g/m\3\
and for a brief period, concentrations exceeded 10,000 [micro]g/m\3\
for one job. Some of these high exposures were associated with
accelerated disease progression in these miners.
Buchanan et al. (2003) reviewed the exposure history and chest X-
ray progression of 371 retired miners and found that short-term
exposures (i.e., ``a few months'') to high concentrations of respirable
crystalline silica (e.g., >2,000 [micro]g/m\3\) increased the silicosis
risk by three-fold (compared to the risk of cumulative exposure alone)
(see the standalone FRA document).
The risks of increased rate of progression predicted by Buchanan et
al. (2003) have been seen in coal miners (Miller et al., 1998; Laney et
al., 2010, 2017; Cohen et al., 2016), metal (Hessel et al., 1988;
Hnizdo and Sluis-Cremer, 1993; Nelson, 2013), and nonmetal miners such
as silica plant and ground silica mill workers, whetstone cutters, and
silica flour packers (NIOSH, 2000a,b; Ogawa et al., 2003a; Mohebbi and
Zubeyri, 2007). Accordingly, it is important to limit higher exposures
to respirable crystalline silica to minimize the risk of rapid
progressive pneumoconiosis (RPP) in miners. RPP is the development of
progressive massive fibrosis (PMF) and/or an increase in small opacity
profusion greater than one subcategory over five years or less
(Ant[atilde]o et al., 2005).
The results of many surveillance studies conducted by NIOSH as part
of the Coal Workers' Health Surveillance Program indicate that the
pathology of pneumoconiosis in coal miners has changed over time, in
part due to increased exposure to respirable crystalline silica. The
studies of Cohen et al. (2016, 2022) indicate that RPP develops due to
increased exposure to respirable crystalline silica among contemporary
coal miners as compared to historical coal miners. Through the
examination of pathologic materials from 23 contemporary (born in or
after 1930) and 62 historical coal miners (born between 1910 and 1930)
with severe pneumoconiosis, who were autopsied as part of NCWAS, Cohen
et al. (2022) found a significantly higher proportion of silica-type
PMF among contemporary miners (57 percent vs. 18 percent, p <0.001).
They also found that mineral dust alveolar proteinosis (MDAP) was more
common in the current generation of miners and that the lung tissues of
contemporary coal miners contained a significantly greater percentage
and concentration of silica particles than those of past generations of
miners.
Many studies found an association between pulmonary function
decrements and ILO profusion category 2 or 3. Additionally, the review
of the literature indicated a decreased lung function among workers who
were exposed to respirable crystalline silica. MSHA therefore concludes
that respirable crystalline silica exposure may impair lung function in
some instances before silicosis can be detected by chest X-rays.
c. Occupation-Based Epidemiological Studies
MSHA reviewed the occupation-based epidemiological literature,
which examines health outcomes among workers and their potential
association with conditions in the workplace. In addition, MSHA
reviewed additional occupation-based literature specific to respirable
crystalline silica exposure in MNM and coal miners and concludes that
respirable crystalline silica exposure increases the risk of silicosis
morbidity and early mortality.
One study examined the acute and accelerated silicosis outbreak
that occurred during and after construction of Hawk's Nest Tunnel in
West Virginia from 1930 to 1931. There, an estimated 2,500 men worked
in a tunnel drilling rock consisting of 90 percent silica or more. The
study later estimated that at least 764 of the 2,500 workers (30.6
percent) died from acute or accelerated silicosis (Cherniack, 1986).
There was also high turnover among the tunnel workers, with an average
length of employment underground of only about two months.
MSHA's review included the occupation-based literature cited by
OSHA (2013b) in developing its respirable crystalline silica standard
(OSHA, 2016a). Overall, MSHA found substantial evidence suggesting that
occupational exposure to respirable crystalline silica increases the
risk of silicosis. This conclusion is consistent with OSHA's
conclusion.
In a population of granite quarry workers (mean length of
employment:
[[Page 28239]]
23.4 years) exposed to an average respirable crystalline silica
concentration of 480 [micro]g/m\3\, 45 percent of those diagnosed with
simple silicosis showed radiological progression of disease two to ten
years after diagnosis (Ng et al., 1987a). Among a population of gold
miners, 92 percent showed progression after 14 years (Hessel et al.,
1988). Chinese factory workers and miners who were categorized under
the Chinese system of X-ray classification as ``suspected'' silicosis
cases (analogous to ILO 0/1) had a progression rate to stage I
(analogous to ILO major category 1) of 48.7 percent, with an average
interval of about 5.1 years (Yang et al., 2006).
The risk of silicosis, and particularly its progression, carries
with it an increased risk of reduced lung function. Strong evidence has
shown that lung function deteriorates more rapidly in miners exposed to
respirable crystalline silica, especially in those with silicosis
(Hughes et al., 1982; Ng and Chan, 1992; Malmberg et al., 1993; Cowie,
1998). The rates of decline in lung function are greater where disease
shows evidence of radiologic progression (B[eacute]gin et al., 1987; Ng
et al., 1987a; Ng and Chan, 1992; Cowie, 1998). Additionally, the
average deterioration of lung function exceeds that in smokers (Hughes
et al., 1982).
Blackley et al. (2015) found progressive lung function impairment
across the range of radiographic profusion of simple CWP in a cohort of
8,230 coal miners that participated in the Enhanced Coal Workers'
Health Surveillance Program from 2005 to 2013. There, 269 coal miners
had category 1 or 2 chronic CWP. This study also found that each
increase in profusion score was associated with decreases in various
lung function parameters: 1.5 percent (95 percent CI, 1.0 percent-1.9
percent) in forced expiratory volume in one second (FEV1)
percent predicted, 1.0 percent (95 percent CI, 0.6 percent-1.3 percent)
forced vital capacity (FVC) percent predicted, and 0.6 percent (95
percent CI, 0.4 percent-0.8 FEV1/FVC).
Accordingly, MSHA concludes that respirable crystalline silica
exposure increases the risk of silicosis morbidity and mortality among
miners. This conclusion is consistent with OSHA's conclusion that there
is substantial evidence that occupational exposure to respirable
crystalline silica increases the risk of silicosis.
d. Surveillance Data
In addition to occupation-based epidemiological studies, MSHA
reviewed surveillance studies, including those submitted by commenters,
which provide and interpret data to facilitate the prevention and
control of disease, and ultimately MSHA finds that the prevalence of
silicosis generally increases with duration of exposure (work tenure).
This is evident from the statistically significant proportional
mortality ratios (PMRs) reported in the National Occupational Mortality
System (NORMS) data previously reviewed by OSHA and reported by MSHA in
its standalone Health Effects document. Several small and ad hoc
surveillance reports reported in the standalone Health Effects document
also found a prevalence of silicosis of up to 50 percent among working
and retired miners (Hnizdo and Sluis-Cremer, 1993; Ng and Chan, 1994;
Kreiss and Zhen, 1996; Finkelstein, 2000).
However, the available statistics may underestimate silicosis-
related morbidity and mortality in miners. It has been widely reported
that statistics underestimate silicosis cases due to: (1)
misclassification of causes of death (as TB, chronic bronchitis,
emphysema, or cor pulmonale); (2) errors in recording occupation on
death certificates; and (3) misdiagnosis of disease (Windau et al.,
1991; Goodwin et al., 2003; Rosenman et al., 2003; Blackley et al.,
2017). Furthermore, reliance on chest X-ray findings may lead to missed
silicosis cases when fibrotic changes in the lung are not yet visible
on chest X-rays. In other words, silicosis may be present but not yet
detectable by chest X-ray, or it may be more severe than indicated by
the assigned profusion score (Craighead and Vallyathan, 1980; Hnizdo et
al., 1993; Rosenman et al., 1997).
e. Pulmonary Tuberculosis
In addition to the relationship between silica exposure and
silicosis, studies indicate a relationship between silica exposure,
silicosis, and pulmonary TB. MSHA reviewed these studies and concluded
that silica exposure and silicosis increase the risk of pulmonary TB
(Cowie, 1994; Hnizdo and Murray, 1998; teWaterNaude et al., 2006),
concurring with the conclusion reached by OSHA in its review.
Although early descriptions of dust diseases of the lung did not
distinguish between TB and silicosis and most fatal cases described in
the first half of the 20th century were likely a combination of
silicosis and TB (Castranova et al., 1996), more recent findings have
demonstrated that respirable crystalline silica exposure, even without
silicosis, increases the risk of infectious (active) pulmonary TB
(Sherson and Lander, 1990; Cowie, 1994; Hnizdo and Murray, 1998;
teWaterNaude et al., 2006). These co-morbid conditions hasten the
development of respiratory impairment and increased mortality risk even
beyond the risk in unexposed persons with active TB (Banks, 2005).
Ng and Chan (1991) hypothesized that silicosis and TB ``act
synergistically'' (are more than additive) to increase fibrotic scar
tissue (leading to massive fibrosis) or to enhance susceptibility to
active mycobacterial infection. The authors found that lung fibrosis is
common to both diseases, and that both diseases decrease the ability of
alveolar macrophages to aid in the clearance of dust or infectious
particles.
These findings are also supported by studies published since OSHA's
(2013b) review (Oni and Ehrlich, 2015; Ndlovu et al., 2019). Oni and
Ehrlich (2015) reviewed a case of silico-TB in a former gold miner with
ILO category 2/2 silicosis. Ndlovu et al. (2019) found that in a study
sample of South African gold miners who had died from causes other than
silicosis between 2005 and 2015, 33 percent of men (n=254) and 43
percent of women (n=29) at autopsy were found to have TB, whereas seven
percent of men (n=54) and three percent of women (n=4) were found to
have pulmonary silicosis.
Overall, MSHA finds, consistent with OSHA's conclusion, that silica
exposure increases the risk of pulmonary TB, and that pulmonary TB can
be a complication of chronic silicosis.
2. Nonmalignant Respiratory Disease (Excluding Silicosis)
In addition to causing silicosis, exposure to respirable
crystalline silica causes other NMRD. NMRD is an umbrella term that
includes chronic obstructive pulmonary disease (COPD). Emphysema and
chronic bronchitis are two lung diseases included within COPD. In
patients with COPD, either chronic bronchitis or emphysema may be
present or both conditions may be present together (ATS, 2010a).
Based on its review of the literature, MSHA concludes that exposure
to respirable crystalline silica increases the risk for mortality from
NMRD. The following summarizes MSHA's review of the literature.
a. Emphysema
Emphysema results in the destruction of lung architecture in the
alveolar region, causing airway obstruction and impaired gas exchange.
Based on its health effects literature review, MSHA concludes that
exposure to respirable crystalline silica can increase the risk of
emphysema, regardless of whether silicosis is present. In addition,
MSHA concludes that this is the case for
[[Page 28240]]
smokers and that smoking amplifies the effects of respirable
crystalline silica exposure, increasing the risk of emphysema. MSHA's
conclusions are consistent with those drawn by OSHA (2013b). The
reviewed studies are summarized below.
Becklake et al. (1987) determined that a miner who had worked in a
high dust environment for 20 years had a greater chance of developing
emphysema than a miner who had never worked in a high dust environment.
In a retrospective cohort study, Hnizdo et al. (1991a) used autopsy
lung specimens from 1,553 gold miners to investigate the types of
emphysema caused by respirable crystalline silica and found that the
occurrence of emphysema was related to both smoking and dust exposure.
This study also found a significant association between emphysema, both
panacinar and centriacinar emphysema types, and length of employment
for miners working in high dust occupations. A separate study by Hnizdo
et al. (1994) on lifelong non-smoking South African gold miners found
that the degree of emphysema was significantly associated with the
degree of hilar gland nodules, which the authors suggested might serve
as a surrogate for respirable crystalline silica exposure. While Hnizdo
et al. (2000) conversely found that emphysema prevalence was decreased
in relation to dust exposure, the authors suggested that selection bias
was responsible for this finding.
The findings of several cross-sectional and case-control studies
were more mixed. For example, de Beer et al. (1992) found an increased
risk for emphysema; however, the reported odds ratio (OR) was smaller
than that previously reported by Becklake et al. (1987). A study by
Cowie et al. (1993) found that the presence and grade of emphysema were
statistically significant in Black underground gold miners.
B[eacute]gin et al. (1995) found that respirable crystalline silica-
exposed smokers without silicosis had a higher prevalence of emphysema
than a group of asbestos-exposed workers with a similar smoking
history.
Several of the studies found that emphysema might occur in
respirable crystalline silica-exposed workers who did not have
silicosis and suggested a causal relationship between respirable
crystalline silica exposure and emphysema (Becklake et al., 1987;
Hnizdo et al., 1994; B[eacute]gin et al., 1995). Experimental (animal)
studies found that emphysema occurred at lower respirable crystalline
silica exposure concentrations than fibrosis in the airways or the
appearance of early silicotic nodules (Wright et al., 1988). These
findings tend to support human studies that respirable crystalline
silica-induced emphysema can occur absent signs of silicosis.
OSHA (2013b) and others have concluded that there is a relationship
between respirable crystalline silica exposure and emphysema. Green and
Vallyathan (1996) reviewed several studies of emphysema in workers
exposed to silica and found an association between cumulative dust
exposure and death from emphysema. The IARC (1997) also reviewed
several studies and concluded that exposure to respirable crystalline
silica increases the risk of emphysema. Additionally, NIOSH (2002b)
concluded in its Hazard Review that occupational exposure to respirable
crystalline silica is associated with emphysema; however, it noted some
epidemiological studies that suggested that this effect might be less
frequent or absent in non-smokers.
Overall, MSHA concludes that exposure to respirable crystalline
silica causes emphysema even in the absence of silicosis. Thus, MSHA
concurs with the conclusions previously reached by OSHA (2013b).
b. Chronic Bronchitis
MSHA considered many studies that examined the association between
respirable crystalline silica exposure and chronic bronchitis and
concluded the following: (1) exposure to respirable crystalline silica
causes chronic bronchitis regardless of whether silicosis is present;
(2) an exposure-response relationship may exist; and (3) smokers may be
at an increased risk of chronic bronchitis compared to non-smokers.
Chronic bronchitis is long-term inflammation of the bronchi, increasing
the risk of lung infections. This condition develops slowly by small
increments and ``exists'' when it reaches a certain stage, specifically
the presence of a productive cough with sputum production for at least
three months of the year for at least two consecutive years (ATS,
2010b). MSHA's conclusions are supported by OSHA's review of the
literature.
Miller et al. (1997) reported a 20 percent increased risk of
chronic bronchitis in a British mining cohort compared to the disease
occurrence in the general population. Using British pneumoconiosis
field research data, Hurley et al. (2002) calculated estimates of
mixed-RCMD-related disease in British coal miners at exposure levels
that were common in the late 1980s and related their lung function and
development of chronic bronchitis with their cumulative dust exposure.
The authors estimated that by the age of 58, 5.8 percent of these men
would report breathlessness for every 100 gram-hour/m\3\ dust exposure.
The authors also estimated the prevalence of chronic bronchitis at age
58 would be four percent per 100 gram-hour/m\3\ of dust exposure. These
miners averaged over 35 years of tenure in mining and a cumulative
respirable dust exposure of 132 gram-hour/m\3\ (Hurley et al., 2002).
Cowie and Mabena (1991) found that chronic bronchitis was present
in 742 of 1,197 (62 percent) South African gold miners, and Ng et al.
(1992b) found a higher prevalence of respiratory symptoms, independent
of smoking and age, in Singaporean granite quarry workers exposed to
high levels of dust (rock drilling and crushing) compared to those
exposed to low levels of dust (maintenance and transport workers).
However, Irwig and Rocks (1978) compared symptoms of chronic bronchitis
in silicotic and non-silicotic South African gold miners. They did not
find as clear a relationship as did the above studies and concluded
that the symptoms were not statistically more prevalent in the
silicotic miners, although prevalence was slightly higher.
Sluis-Cremer et al. (1967) found that dust-exposed male smokers had
a higher prevalence of chronic bronchitis than non-dust exposed smokers
in a gold mining town in South Africa. Similarly, Wiles and Faure
(1975) found that the prevalence of chronic bronchitis rose
significantly with increasing dust concentration and cumulative dust
exposure in South African gold miners who were smokers, nonsmokers, and
ex-smokers. Rastogi et al. (1991) found that female grinders of agate
stones in India had a significantly higher prevalence of acute
bronchitis, but they had no increase in the prevalence of chronic
bronchitis compared to controls matched by socioeconomic status, age,
and smoking. However, the study noted that the grinders' respirable
crystalline silica exposure durations were very short, and control
workers may also have been exposed to respirable crystalline silica
(Rastogi et al., 1991).
Studies examining the effect of years of mining on chronic
bronchitis risk were mixed. Samet et al. (1984) found that prevalence
of symptoms of chronic bronchitis was not associated with years of
mining in a population of underground uranium miners, even after
adjusting for smoking. However, Holman et al. (1987) studied gold
miners in West Australia and found that the prevalence of chronic
bronchitis, as indicated by ORs (controlled for age and smoking), was
significantly increased in those who had worked in the mines for
[[Page 28241]]
over one year, compared to lifetime non-miners. In addition, while
other studies found no effect of years of mining on chronic bronchitis
risk, those studies often qualified this result with possible
confounding factors. For example, Kreiss et al. (1989) studied 281
hard-rock (molybdenum) miners and 108 non-miner residents of Leadville,
Colorado. They did not find an association between the prevalence of
chronic bronchitis and work in the mining industry (Kreiss et al.,
1989); however, it is important to note that the mine had been
temporarily closed for five months when the study began, so miners were
not exposed at the time of the study.
Some reviews concluded that respirable crystalline silica exposure
causes the development of bronchitis. The American Thoracic Society
(ATS) (1997) published a review that found chronic bronchitis to be
common among worker groups exposed to dusty environments contaminated
with respirable crystalline silica. NIOSH (2002b) also published a
review demonstrating that occupational exposure to respirable
crystalline silica has been associated with bronchitis; however, some
epidemiological studies suggested this effect might be less frequent or
absent in non-smokers.
Additionally, Hnizdo et al. (1990) re-analyzed data from an earlier
investigation (Wiles and Faure, 1975) and found an independent
exposure-response relationship between respirable crystalline silica
exposure and impaired lung function. For miners with less severe
impairment, the effects of smoking and dust together were additive. The
authors also found that for miners with the most severe impairment, the
effects of smoking and dust were synergistic (more than additive)
(Hnizdo et al., 1990).
Overall, MSHA concludes that exposure to respirable crystalline
silica causes chronic bronchitis, regardless of whether silicosis is
present, and that an exposure-response relationship may exist. This
conclusion is consistent with the findings of OSHA's Health Effects
document (2013b).
c. Pulmonary Function Impairment
Pulmonary function impairment is a common feature of NMRD and may
be assessed via spirometry (lung volumes, flows) and gas diffusion
tests. MSHA has reviewed the studies cited by OSHA and agrees with
their conclusions. Based on its review of the evidence in numerous
longitudinal and cross-sectional studies and reviews, OSHA concluded
that there is an exposure-response relationship between respirable
crystalline silica and the development of impaired lung function. OSHA
also concluded that the effect of tobacco smoking on this relationship
may be additive or synergistic, and workers who were exposed to
respirable crystalline silica, but did not show signs of silicosis, may
also have pulmonary function impairment.
OSHA reviewed several longitudinal studies regarding the
relationship between respirable crystalline silica exposure and
pulmonary function impairment. To evaluate whether exposure to silica
affects pulmonary function in the absence of silicosis, the studies
focused on workers who did not exhibit progressive silicosis.
Among both active and retired Vermont granite workers exposed to an
average quartz dust exposure level of 60 [micro]g/m\3\, researchers
found no exposure-related decreases in pulmonary function (Graham et
al., 1981, 1994). However, Eisen et al. (1995) found significant
pulmonary decrements among a subset of granite workers who left work
(termed ``dropouts'') and consequently did not voluntarily participate
in the last of a series of annual pulmonary function tests. This group
experienced steeper declines in lung function compared to the subset of
workers who remained at work (termed ``survivors'') and participated in
all tests, and these declines were significantly related to dust
exposure. Exposure-related changes in lung function were also reported
in a 12-year study of granite workers (Malmberg et al., 1993), in two
five-year studies of South African miners (Hnizdo, 1992; Cowie, 1998),
and in a study of foundry workers whose lung function was assessed
between 1978 and 1992 (Hertzberg et al., 2002). Similar reductions in
FEV1 (indicating an airway obstruction) were linked to
respirable crystalline silica exposure.
Each of these studies reported its findings in terms of rates of
decline in any of several pulmonary function measures (e.g.,
FEV1, FVC, FEV1/FVC). To put these declines in
perspective, Eisen et al. (1995) reported that the rate of decline in
FEV1 seen among the ``dropout'' subgroup of Vermont granite
workers was 4 ml per 1,000 [micro]g/m\3\-year (4 ml per mg/m\3\-year)
of exposure to respirable granite dust. By comparison, FEV1
declines at a rate of 10 ml/year from smoking one pack of cigarettes
daily. From their study of foundry workers, Hertzberg et al. (2002)
reported a 1.1 ml/year decline in FEV1 and a 1.6 ml/year
decline in FVC for each 1,000 [micro]g/m\3\-year of respirable
crystalline silica exposure after controlling for ethnicity and
smoking. From these rates of decline, they estimated that exposure to
100 [micro]g/m\3\ of respirable crystalline silica for 40 years would
result in a total loss of FEV1 and FVC that was less than,
but still comparable to, smoking a pack of cigarettes daily for 40
years. Hertzberg et al. (2002) also estimated that exposure to the
existing MSHA standards (100 [micro]g/m\3\) for 40 years would increase
the risk of developing abnormal FEV1 or FVC by factors of
1.68 and 1.42, respectively.
OSHA reviewed cross-sectional studies that described relationships
between lung function loss and respirable crystalline silica exposure
(or exposure measurement surrogates such as tenure). The results of
these studies were like those of the longitudinal studies previously
discussed. In several studies, respirable crystalline silica exposure
was found to reduce lung function of:
(1) White South African gold miners (Hnizdo et al., 1990),
(2) Black South African gold miners (Irwig and Rocks, 1978; Cowie
and Mabena, 1991),
(3) Respirable crystalline silica-exposed workers in Quebec
(B[eacute]gin et al., 1995),
(4) Rock drilling and crushing workers in Singapore (Ng et al.,
1992b),
(5) Granite shed workers in Vermont (Theriault et al., 1974a,b),
(6) Aggregate quarry workers and coal miners in Spain (Montes et
al., 2004a,b),
(7) Concrete workers in the Netherlands (Meijers et al., 2001),
(8) Chinese refractory brick manufacturing workers in an iron-steel
plant (Wang et al., 1997),
(9) Chinese gemstone workers (Ng et al., 1987b),
(10) Hard-rock miners in Manitoba, Canada (Manfreda et al., 1982)
and in Colorado (Kreiss et al., 1989),
(11) Pottery workers in France (Neukirch et al., 1994),
(12) Potato sorters in the Netherlands (Jorna et al., 1994),
(13) Slate workers in Norway (Suhr et al., 2003), and
(14) Men in a Norwegian community with years of occupational
exposure to respirable crystalline silica (quartz) (Humerfelt et al.,
1998).
OSHA (2013b) recognized that many of these studies found that
pulmonary function impairment: (1) can occur in respirable crystalline
silica-exposed workers without silicosis, (2) was still observable when
controlling for silicosis in the analysis, and (3) was related to the
magnitude and duration of respirable crystalline silica exposure,
rather than to the presence or severity of silicosis. Many other
studies described by OSHA (2013b) have also
[[Page 28242]]
found a relationship between respirable crystalline silica exposure and
lung function impairment, including IARC (1997), the ATS (1997), and
Hnizdo and Vallyathan (2003).
MSHA reviewed the studies and concludes that there is an exposure-
response relationship between respirable crystalline silica and the
impairment of lung function. MSHA also concludes that that the effect
of tobacco smoking on this relationship may be additive or synergistic,
and that workers who were exposed to respirable crystalline silica, but
did not show signs of silicosis, may also have pulmonary function
impairment. MSHA's conclusions are consistent with OSHA's findings from
its literature review.
3. Lung Cancer
Commenters from United Steelworkers (USW), American Industrial
Hygiene Association (AIHA), and Vanderbilt Minerals, agreed with MSHA's
conclusion that miners exposed to respirable crystalline silica have an
increased risk of lung cancer (Document ID 1447; 1351; 1419). The AIHA
also cited research by the International Agency for Research on Cancer
(IARC) as documenting the health risks from inhalation of respirable
crystalline silica, specifically cancers of the lung, stomach, and
esophagus (Document ID 1351). MSHA agrees with this comment for the
reasons discussed below.
a. Lung Cancer
Lung cancer, an irreversible and usually fatal disease, is a type
of cancer that forms in lung tissue. MSHA has found that the scientific
literature supports that respirable crystalline silica exposure
significantly increases the risk of lung cancer mortality among miners.
This determination is consistent with the conclusions of other
government and public health organizations, including the ATS (1997),
the IARC (1997, 2012), the NTP (2000, 2016), NIOSH (2002b), and the
ACGIH (2010), which have classified respirable crystalline silica as a
``known human carcinogen.'' The Agency's determination also is
supported by epidemiological literature, encompassing more than 85
studies of occupational cohorts from more than a dozen industrial
sectors including: granite/stone quarrying and processing
(Gu[eacute]nel et al., 1989a,b; Costello et al., 1995; Carta et al.,
2001; Attfield and Costello, 2004), industrial sand (Sanderson et al.,
2000; Hughes et al., 2001; McDonald et al., 2001, 2005; Rando et al.,
2001; Steenland and Sanderson, 2001), MNM mining (Hessel et al., 1986,
1990; Hnizdo and Sluis-Cremer, 1991; Meijers et al., 1991; Chen et al.,
1992, 2006, 2012; McLaughlin et al., 1992; Hua et al., 1994; Roscoe et
al., 1995; Steenland and Brown, 1995a; Reid and Sluis-Cremer, 1996;
Hnizdo et al., 1997; deKlerk and Musk, 1998; Finkelstein, 1998; Chen
and Chen, 2002; Schubauer-Berigan et al., 2009; Liu et al., 2017a; Wang
et al., 2020a,b, 2021), coal mining (Meijers et al., 1988; Miyazaki and
Une, 2001; Miller et al., 2007; Miller and MacCalman, 2010; Tomaskova
et al., 2012, 2017, 2020, 2022; Graber et al., 2014a,b; Kurth et al.,
2020), pottery (Winter et al., 1990; McLaughlin et al., 1992; McDonald
et al., 1995), ceramic industries (Starzynski et al., 1996),
diatomaceous earth (Checkoway et al., 1993, 1996, 1997, 1999; Seixas et
al., 1997; Rice et al., 2001), and refractory brick industries
(cristobalite exposures) (Dong et al., 1995).
One commenter stated that the work of Steenland and Sanderson
should not be ``discounted'' and that Miller and MacCalman ``did not
report on occupational exposure monitoring concentrations'' reported by
Steenland and Sanderson (Document ID 1351).
MSHA chose Miller and MacCalman (2010) rather than the Steenland et
al. (2001a) pooled cohort study for its lung cancer mortality risk
model but has not discounted the study of Steenland and Sanderson. MSHA
has cited the Steenland and Sanderson (2001) study at multiple points
in the final standalone Health Effects document and has also cited
other investigations from both researchers. The Miller and MacCalman
(2010) study contained detailed time-exposure measurements of both
respirable crystalline silica (quartz) and total mine dust, detailed
individual work histories, and individual smoking histories. Further
discussion regarding the selection of the risk model of Miller and
MacCalman (2001) is located in the standalone FRA document.
The strongest evidence comes from the worldwide cohort and case-
control studies reporting excess lung cancer mortality among workers
exposed to respirable crystalline silica in various industrial sectors.
This evidence is confirmed by the ten-cohort pooled case-control
analysis by Steenland et al. (2001a); the more recent pooled case-
control analysis of seven European countries by Cassidy et al. (2007);
and two national death certificate registry studies, Calvert et al.
(2003) in the United States and Pukkala et al. (2005) in Finland.
Recent studies examined lung cancer mortality among coal and non-
coal miners (Meijers et al., 1988, 1991; Starzynski et al., 1996;
Miyazaki and Une, 2001; Attfield and Kuempel, 2008; Tomaskova et al.,
2012, 2017, 2020, 2022; Graber et al., 2014a,b; NIOSH, 2019a; Kurth et
al., 2020). These studies also discuss the associations between RCMD
and respirable crystalline silica exposures with lung cancer in coal
mining populations. Furthermore, the findings of these newer studies
are consistent with the conclusion of OSHA's final Quantitative Risk
Assessment (QRA) (2016a) that respirable crystalline silica is a human
carcinogen. MSHA concludes that miners, both MNM and coal miners, are
at risk of developing lung cancer due to their occupational exposure to
respirable crystalline silica.
In addition, based on its review of the health effects literature,
MSHA has determined that radiographic silicosis is a marker for lung
cancer risk. Reducing exposure to levels that lower the silicosis risk
would reduce the lung cancer risk to exposed miners (Finkelstein, 1995,
2000; Brown, 2009). MSHA has also found that, based on the available
epidemiological and animal data, respirable crystalline silica causes
lung cancer (IARC, 2012; RTECS, 2016; ATSDR, 2019). Miners who inhale
respirable crystalline silica over time are at increased risk of
developing silicosis and lung cancer (Greaves, 2000; Erren et al.,
2009; Tomaskova et al., 2017, 2020, 2022).
Other toxicity studies (non-animal) provide additional evidence of
the carcinogenic potential of respirable crystalline silica. Studies
using DNA exposed directly to freshly fractured respirable crystalline
silica demonstrate that respirable crystalline silica directly
increases DNA breakage. Cell culture research has investigated the
processes by which respirable crystalline silica disrupts normal gene
expression and replication. Studies have demonstrated that chronic
inflammatory and fibrotic processes resulting in oxidative and cellular
damage may lead to neoplastic changes in the lung (Goldsmith, 1997). In
addition, the biologically damaging physical characteristics of
respirable crystalline silica and its direct and indirect genotoxicity
support MSHA's determination that respirable crystalline silica is an
occupational carcinogen (Borm and Driscoll, 1996; Schins et al., 2002).
b. Cancers of Other Sites
In addition to examining studies on lung cancer, MSHA has reviewed
studies examining the relationship between respirable crystalline
silica exposure and cancers at other sites. MSHA has reviewed the
studies
[[Page 28243]]
examined by OSHA, together with additional studies focusing on miners'
exposure, and has concluded (as OSHA did) that there is insufficient
evidence to demonstrate a causal relationship between respirable
crystalline silica exposure and other (non-lung) cancer mortality. MSHA
notes that OSHA reviewed mortality studies, on cancer of the larynx and
the digestive system, including the stomach and esophagus, and found
that studies suggesting a dose-response relationship were too limited
in terms of size, study design, or potential for confounding variables,
to be conclusive. In addition, NIOSH (2002b) in their respirable
crystalline silica review concluded that no association has been
established between respirable crystalline silica exposure and excess
mortality from cancer at other sites. The following summarizes the
studies reviewed with inconclusive findings.
(1) Laryngeal Cancer
MSHA reviewed three lung cancer studies also discussed by OSHA
(2013b) which suggested an association between respirable crystalline
silica exposure and increased mortality from laryngeal cancer (Davis et
al., 1983; Checkoway et al., 1997; McDonald et al., 2001). However, a
small number of cases were reported in those studies, and the
researchers were unable to determine a statistically significant
effect. Therefore, MSHA found that there was little evidence of an
association based on these studies. OSHA also reached this conclusion.
(2) Gastric (Stomach) Cancer
MSHA reviewed the literature discussed by OSHA (2013b) to assess a
potential relationship between respirable crystalline silica exposures
and stomach cancers. OSHA concurred with observations made previously
by Cocco et al. (1996) and in the NIOSH (2002b) respirable crystalline
silica hazard review, which found that most epidemiological studies of
respirable crystalline silica and stomach cancer did not sufficiently
adjust for the effects of confounding factors. In addition, some of
these studies were not properly designed to assess a dose-response
relationship (Selikoff, 1978; Stern et al., 2001; Moshammer and
Neuberger, 2004; Finkelstein and Verma, 2005) or did not demonstrate a
statistically significant dose-response relationship (Tsuda et al.,
2001; Calvert et al., 2003). For these reasons, MSHA determined these
studies were inconclusive in the context of this rulemaking.
(3) Esophageal Cancer
MSHA has reviewed studies that focused on miners and concludes that
the literature does not support attributing increased esophageal cancer
mortality with exposure to respirable crystalline silica. The studies
by Meijers et al. (1991) and Swaen et al. (1995) assessed mortality
from esophageal cancer in Dutch underground coal miners. Meijers et al.
(1991) reported an elevated standardized mortality ratio (SMR) of 396,
which was not statistically significant. The SMR was based on two cases
out of 334 confirmed pneumoconiosis cases followed through the end of
1983 (case selection based on health screening between 1956-1960).
Swaen et al. (1995) reported a SMR of 62 (95 percent CI: 25-127) based
on seven cases out of 3,790 underground coal miners who were diagnosed
with pneumoconiosis between 1956 and 1960. This result was not
statistically significant.
MSHA reviewed the studies presented by OSHA (2013b) and agrees with
OSHA's conclusion that the literature does not support attributing
increased esophageal cancer mortality to exposure to respirable
crystalline silica. OSHA considered several studies that examined the
relationship between respirable crystalline silica exposures and
esophageal cancer and found that the studies were limited in terms of
size, study design, or potential for confounding variables. Three
nested case-control studies of Chinese workers demonstrated a dose-
response association between increased risk of esophageal cancer
mortality and respirable crystalline silica exposure (Pan et al., 1999;
Yu et al., 2005; Wernli et al., 2006). Other studies also indicated
elevated rates of esophageal cancer mortality with respirable
crystalline silica exposure (Xu et al., 1996a; Tsuda et al., 2001).
However, OSHA (2013b) identified that in all studies, confounding due
to other occupational exposures was possible. Additionally, two large
national mortality studies in Finland and the United States did not
show a positive association between respirable crystalline silica
exposure and esophageal cancer mortality (Calvert et al., 2003;
Weiderpass et al., 2003).
(4) Other Sites
MSHA's review of additional studies specific to miners further
establishes that respirable crystalline silica exposure increases the
risk of lung cancer, although there is insufficient evidence to
demonstrate a causal relationship between respirable crystalline silica
exposure and other (non-lung) cancer mortalities. Specifically, MSHA
concludes that the epidemiological literature is not sufficient to
conclude that there is an association between respirable crystalline
silica exposures and increased cancer of the larynx, gastric cancer
mortality, or esophageal cancer mortality.
MSHA's conclusion is consistent with OSHA's conclusion. Overall,
OSHA concluded that there was insufficient evidence of an association
between silica exposure and cancer at sites other than the lungs. OSHA
included a health literature review by NIOSH (2002b) that examined
effects potentially associated with respirable crystalline silica
exposure; that review identified only infrequent reports of
statistically significant excesses of deaths for other cancers. Cancer
studies have been reported on the following organs/systems: salivary
gland, liver, bone, pancreas, skin, lymphopoietic or hematopoietic,
brain, and bladder (see NIOSH, 2002b for full bibliographic
references). However, the findings were not observed consistently among
epidemiological studies, and NIOSH (2002b) concluded that no
association has been established between these cancers and respirable
crystalline silica exposure. OSHA concurred with NIOSH that these
isolated reports of excess cancer mortality were insufficient to
determine the role of respirable crystalline silica exposure.
MSHA has reviewed the studies cited by OSHA and agrees with OSHA's
conclusion. MSHA's review of additional studies specific to miners
further establishes that respirable crystalline silica exposure
increases the risk of lung cancer, though there is insufficient
evidence to demonstrate a causal relationship between respirable
crystalline silica exposure and other (non-lung) cancer mortalities.
4. Renal Disease
MSHA received two comments related to MSHA's conclusions related to
renal disease. The AIHA agreed that silica probably causes renal
disease, quoting a paper by Steenland (2005b) (Document ID 1351). In
contrast, the NSSGA stated that it was unclear whether renal disease is
causally related to occupational crystalline silica exposure, citing a
2017 German Federal Institute for Occupational Safety and Health
systematic review that conducted a meta-analysis on respirable
crystalline silica and non-malignant renal disease (M[ouml]hner et al.,
2017) (Document ID 1448).
[[Page 28244]]
MSHA acknowledges that some studies have not found associations
between respirable crystalline silica exposures and renal disease;
however, those studies are generally statistically underpowered,
meaning that their sample sizes are too small to detect even some
substantial health effects. In contrast, as discussed below, studies
with large cohort sizes and well-documented, validated job-exposure
matrices found statistically significant effects on renal disease. MSHA
reviewed the study by M[ouml]hner et al. (2017) and found that it was
not suitable for inclusion in the literature review. The selection
terms used by M[ouml]hner et al. (2017) appear to be overly limiting
and did not appear to capture many of the studies that were included in
MSHA's previous standalone Health Effects document published with its
proposed silica rule (e.g., Gregorini et al., 1993; Hotz et al., 1995;
Fenwick and Main, 2000; Rosenman et al., 2000; Kurth et al., 2020).
MSHA also notes that several studies included in the review by
M[ouml]hner et al. (2017) were already cited in MSHA's previous
standalone Health Effects document published with its proposed silica
rule (e.g., Koskela et al., 1987; Brown et al., 1997; Checkoway et al.,
1997; Calvert et al., 2003; Brown and Rushton, 2005b).
Renal disease is characterized by the loss of kidney function and,
in the case of ESRD, a permanent loss of kidney function leading to the
need for a regular course of long-term dialysis or a kidney transplant
to maintain life. MSHA reviewed a wide variety of longitudinal and
mortality epidemiological studies, including case series, case-control,
and cohort studies, as well as case reports, and concludes that there
is substantial evidence in the literature suggesting that occupational
exposures to respirable crystalline silica exposure increases the risk
of morbidity and mortality related to ESRD. However, MSHA notes that
the available literature on respirable crystalline silica exposures and
renal disease in coal miners is less conclusive than the literature
related to MNM miners.
Epidemiological studies have found statistically significant
associations between occupational exposure to respirable crystalline
silica and chronic renal disease (e.g., Calvert et al., 1997), sub-
clinical renal changes, including proteinuria and elevated serum
creatinine (e.g., Ng et al., 1992a; Hotz et al., 1995; Rosenman et al.,
2000), ESRD morbidity (e.g., Steenland et al., 1990), ESRD mortality
(Steenland et al., 2001b, 2002a), and Wegener's granulomatosis (now
known as granulomatosis with polyangiitis, GPA), which is severe injury
to the glomeruli that, if untreated, rapidly leads to renal failure
(Nuyts et al., 1995). The pooled analysis conducted by Steenland et al.
(2002a) is particularly convincing because it involved a large number
of workers from three combined cohorts and had well-documented,
validated job exposure matrices. Steenland et al. (2002a) found a
positive and monotonic exposure-response trend for both multiple-cause
mortality and underlying cause data. MSHA has determined that the
underlying data from Steenland et al. (2002a) are sufficient to provide
useful estimates of risk.
Possible mechanisms suggested for respirable crystalline silica-
induced renal disease include: (1) a direct toxic effect on the kidney,
(2) a deposition in the kidney of immune complexes (e.g.,
Immunoglobulin A (IgA), an antibody blood protein) in the kidney
following respirable crystalline silica-related pulmonary inflammation,
and (3) an autoimmune mechanism (Gregorini et al., 1993; Calvert et
al., 1997). Steenland et al. (2002a) demonstrated a positive exposure-
response relationship between respirable crystalline silica exposure
and ESRD mortality.
Overall, MSHA determines that respirable crystalline silica
exposure in mining increases the risk of renal disease.
5. Autoimmune Disease
Two commenters--AIHA and National Coalition of Black Lung and
Respiratory Disease Clinics (hereafter referred to as ``Black Lung
Clinics'')--agreed with MSHA's finding that there is evidence of a
relationship between respirable crystalline silica exposure and
autoimmune diseases (Document ID 1351; 1410). The Black Lung Clinics
also qualified that there is insufficient data to model the risk of
disease (Document ID 1410). This is consistent with MSHA's conclusion
that there is a casual association between occupational exposure to
respirable crystalline silica and the development of systematic
autoimmune diseases in miners; however, there are no studies available
to date that can be used to model respirable crystalline silica-
exposure risk of autoimmune diseases in the Agency's risk analysis.
Autoimmune diseases occur when the immune system mistakenly attacks
healthy tissues within the body, causing inflammation, swelling, pain,
and tissue damage. Examples of autoimmune diseases include autoimmune
rheumatic diseases, sarcoidosis and seropositive rheumatoid arthritis
(RA), Crohn's disease (CD), ulcerative colitis (UC), systemic lupus
erythematosus (SLE), scleroderma, and systemic sclerosis (SSc). Some
studies reviewed by MSHA suggest a casual association between
occupational exposure to respirable crystalline silica and the
development of systematic autoimmune diseases, particularly RA.
Wallden et al. (2020) found that respirable crystalline silica
exposure is correlated with an increased risk of developing UC, and
that the risk increases with duration of exposure (work tenure) and the
level of exposure. This effect was especially significant in men.
Schmajuk et al. (2019) found that RA was significantly associated with
coal mining and other non-coal occupations exposed to respirable
crystalline silica. Vihlborg et al. (2017) found a significant
increased risk of seropositive RA with high exposure (>48 [micro]g/
m\3\) to respirable crystalline silica when compared to rates for
individuals with lower or no exposure. They examined detailed exposure-
response relationships across four different groups, each of which was
exposed to a different concentration of respirable crystalline silica
(quartiles): <23 [micro]g/m\3\, 24 to 35 [micro]g/m\3\, 36 to 47
[micro]g/m\3\, and >48 [micro]g/m\3\. However, these researchers did
not report the risk of sarcoidosis (a condition in which groups of
cells in the immune system form granulomas in various organ systems)
and seropositive RA in relation to respirable crystalline silica
exposure using models that could be used in MSHA's risk analysis. In
addition, the meta-analysis of 19 published case-control and cohort
studies on scleroderma by Rubio-Rivas et al. (2017) found statistically
significant risks among individuals exposed to respirable crystalline
silica, solvents, silicone, breast implants, epoxy resins, pesticides,
and welding fumes, but did not provide detailed quantitative exposure
information that could be used in the risk analysis.
Based on its literature review, MSHA concludes that there is a
causal association between occupational exposure to respirable
crystalline silica and the development of systemic autoimmune diseases
in miners, but that no studies are available to date that can be used
to model respirable crystalline silica-exposure risk in a risk
analysis.
D. Conclusion
MSHA concludes that exposure to respirable crystalline silica
causes silicosis (acute, accelerated, chronic, and PMF), NMRD
(including COPD), lung cancer, and renal disease. Each of these effects
is exposure-dependent, potentially chronic, irreversible, potentially
disabling, and can be fatal.
[[Page 28245]]
Respirable crystalline silica exposure is also linked to the
development of some autoimmune disorders through inflammatory pathways.
The health effects literature, including peer-reviewed medical,
toxicological, public health, and other related disciplinary
publications, is robust and compelling. It shows that miners exposed to
the existing respirable crystalline silica exposure limits of 100
[micro]g/m\3\ still have an unacceptable amount of excess risk, for
developing and dying from diseases related to their occupational
respirable crystalline silica exposures.
MSHA is entrusted with ensuring that ``no miner will suffer
material impairment of health or functional capacity even if such miner
has regular exposure to the hazards dealt with by such standard for the
period of his working life'' (30 U.S.C. 811(a)(6)(A)). The Agency
believes that when the final rule is implemented and enforced
effectively, it will reduce the rate of silicosis and other diseases
caused by respirable crystalline silica exposure and will substantially
improve miners' lives.
VI. Final Risk Analysis Summary
MSHA's FRA quantifies risks associated with five specific health
outcomes identified in the standalone Health Effects document:
silicosis morbidity and mortality, and mortality from NMRD, lung
cancer, and ESRD. This section serves as a summary of the standalone
FRA document, which is placed into the rulemaking docket for the MSHA
respirable crystalline silica rulemaking (RIN 1219-AB36, Docket No.
MSHA-2023-0001) and is available at Regulations.gov.
MSHA developed an FRA to support its risk determinations and to
quantify the health risk to miners exposed to respirable crystalline
silica under the existing exposure limits for MNM and coal miners, at
the new PEL of 50 [micro]g/m\3\, and at the action level of 25
[micro]g/m\3\.
This analysis addresses three questions related to the final rule:
(1) whether potential health effects associated with existing
exposure conditions constitute material impairment to any miner's
health or functional capacity;
(2) whether existing exposure conditions place miners at risk of
incurring any material impairment if regularly exposed for the period
of their working life; and
(3) whether the final rule will reduce those risks.
To answer these questions, MSHA relied on the large body of
research on the health effects of respirable crystalline silica and
published, peer-reviewed, quantitative risk assessments that describe
the risk of exposed workers to silicosis mortality and morbidity, NMRD
mortality, lung cancer mortality, and ESRD mortality. These
quantitative risk assessments are based on several studies of
occupational cohorts in a variety of industrial sectors. The underlying
studies are described in the standalone Health Effects document and are
summarized in Section V. Health Effects Summary.
Based on its analysis, MSHA found that, once the current mining
workforce is replaced with new entrants to the mining industry so that
all working miners and retired miners have been exposed only under the
new PEL, the final rule will decrease lifetime excess deaths by at
least 1,067 and will decrease lifetime excess cases of non-fatal
silicosis by at least 3,746 among the working and future retired miner
population. In the FRA, MSHA also increases its estimate of the number
of miners who will benefit from this rule to include future retired
miners. While the Preliminary Risk Analysis (PRA) did consider
reductions in excess risk during years of retirement, the PRA did not
account for the fact that future retired miners are among the
population that will benefit from the rule. Once the entire mining
workforce, including future retired miners, has worked only under the
new PEL (i.e., 60 years after the start of implementation of the rule),
both the retired and working miners will experience fewer deaths and
illnesses. The FRA updates benefit estimates to account for all
lifetime excess cases that will be avoided among all working miners and
future retired miners. It is important to note that the FRA (as well as
the FRIA, discussed below in Section IX) only monetizes benefits to
future retired miners. The FRA methodology does not attribute any
health benefits to individuals who retired before the start of
implementation of the final rule.
This summary highlights the main findings from the FRA, briefly
describes how they were derived, and directs readers interested in more
detailed information to corresponding sections of the standalone FRA
document.
A. Summary of MSHA's Final Risk Analysis Process and Methods
MSHA evaluated the literature and selected an exposure-response
model for each of the five health endpoints--silicosis morbidity,
silicosis mortality, NMRD mortality, lung cancer mortality, and ESRD
mortality. The selected exposure-response models were used to estimate
lifetime excess risks and lifetime excess cases among the current
population of working and the future population of retired MNM and coal
miners based on real exposure conditions, as indicated by the samples
in the compliance sampling datasets.
MSHA's FRA is largely based on the methodology and findings from
OSHA's 2013 preliminary quantitative risk assessment (PQRA), OSHA's
2016 final quantitative risk assessment (QRA), and the associated
analysis of health effects in connection with OSHA's promulgation of a
rule setting PELs for workplace exposure to respirable crystalline
silica. OSHA's PQRA presented quantitative relationships between
respirable crystalline silica exposure and multiple health endpoints.
Following multiple legal challenges, the U.S. Court of Appeals for the
D.C. Circuit rejected challenges to OSHA's risk assessment methodology
and its findings on different health risks. N. Am.'s Bldg. Trades
Unions v. OSHA, 878 F.3d 271, 283-89 (D.C. Cir. 2017).
MSHA's FRA presents detailed quantitative analyses of health risks
over a range of exposure concentrations that have been observed in MNM
and coal mines. MSHA applied exposure-response models to estimate the
respirable crystalline silica-related risk of material impairment of
health or functional capacity of miners exposed to respirable
crystalline silica at three levels--(1) the existing standards, (2) the
new PEL, and (3) the action level. As in past MSHA rulemakings, MSHA
estimated and compared lifetime excess risks associated with exposures
at the existing and new PEL (and at the action level) over a miner's
full working life of 45 years and 15 years of retirement.
MSHA's FRA is also based on a compilation of miner exposure data to
respirable crystalline silica. For the MNM sector, MSHA evaluated
57,769 valid respirable dust samples collected between January 2005 and
December 2019; and for the coal sector, MSHA evaluated 63,127 valid
respirable dust samples collected between August 2016 and July 2021.
The compiled data set characterizes miners' exposures to respirable
crystalline silica in various locations (i.e., underground, surface),
occupations (e.g., drillers, underground miners, equipment operators),
and commodities (e.g., metal, nonmetal, stone, crushed limestone, sand
and gravel, and coal). MSHA enforcement sampling indicates a wide range
of exposure concentrations. These include exposures from below the
action level (25 [micro]g/m\3\) to above the existing standards (100
[micro]g/m\3\ in MNM standards and 100 [micro]g/m\3\ MRE in coal
standards,
[[Page 28246]]
which is approximately 85.7 [micro]g/m\3\ ISO).18 19
\18\ As discussed in the FRA, the existing PEL for coal is 100
[mu]g/m\3\ MRE, measured as a full-shift time-weighted average
(TWA). To calculate risks consistently for both coal and MNM miners,
the FRA converts the MRE full-shift TWA concentrations experienced
by coal miners to ISO 8-hour TWA concentrations. (See Section 4 of
the standalone FRA document for a full explanation.) The equation
used to convert MRE full-shift TWA concentrations into ISO 8-hour
TWA concentrations is:
[GRAPHIC] [TIFF OMITTED] TR18AP24.077
Exposures at TWA 100 [micro]g/m\3\ MRE and SWA 85.7 [micro]g/
m\3\ ISO are only equivalent when the sampling duration is 480
minutes (eight hours). However, for the sake of simplicity and for
comparison purposes, the risk analysis approximates exposures at the
existing coal exposure limit of 100 MRE [micro]g/m\3\ as 85.7
[micro]g/m\3\ ISO. Thus, ISO concentration values (measured as an 8-
hour TWA) were used as the exposure metric when (a) calculating risk
under the assumption of full compliance with the existing standards
and (b) calculating risk under the assumption that no exposure
exceeds the new PEL of 50 [mu]g/m\3\. To simulate compliance among
coal miners at the existing exposure limit, exposures were capped at
85.7 [mu]g/m\3\ measured as an ISO 8-hour TWA.
\19\ A sample-specific exposure limit is calculated for each
sample based on the polymorphs present. For samples with >1% quartz
by mass, the formula is:
[GRAPHIC] [TIFF OMITTED] TR18AP24.078
When quartz is the only respirable crystalline silica polymorph
in the sample, the existing MNM standard limits respirable
crystalline silica exposures to 100 [micro]g/m\3\ or less in MNM
operations. Cristobalite exposures are currently limited to 50
[micro]g/m\3\ or less when cristobalite is the only polymorph
present, and the same is true for tridymite \19\. When more than one
polymorph is present in the same sample, then a Threshold Limit
Value for mixtures is used.
One commenter (a safety compliance consultant) stated that the \20\
2005-2019 MNM respirable dust samples analyzed for respirable
crystalline silica show a downward trend in average annual rates of
overexposure and requested access to data for 2020-2022 (Document ID
1383). In response, MSHA notes that the 2020-2022 data may be skewed by
the reduction in mining during the COVID-19 pandemic and would
therefore bias the analysis. Further, 2019 is recent enough to
adequately capture the current exposure profile of working miners.
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\20\
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In addition, commenters from the United Mine Workers of America
(UMWA), the Black Lung Clinics, and the Appalachian Citizens' Law
Center (ACLC) expressed concern that MSHA used coal mine dust data from
2016-2021, a historically low period for quartz levels in coal mining,
according to the commenters (Document ID 1398; 1410; 1445). The ACLC
asserted that, as a result, the estimate of avoided illnesses and
deaths in MSHA's PRA is low and urged the Agency to include a longer
history of coal dust sampling data when estimating miners' future
exposures (Document ID 1445). As discussed below, MSHA chose this time
period to account for the 2014 RCMD Standard, which came into full
effect in 2016. The ACLC also stated that, because the 2014 RCMD
Standard does not directly regulate respirable crystalline silica,
there is no justification for excluding prior sampling data (Document
ID 1445).
MSHA believes the 2014 RCMD Standard impacted respirable
crystalline silica exposures, in part because (a) the coal dust
exposure limit is based on a formula that reduces the limit when the
respirable crystalline silica content exceeds 100 [micro]g/m\3\, and
(b) measures that coal mine operators may have taken to reduce
exposures to coal dust under that rule would have also reduced
exposures to other respirable hazards including crystalline silica.
Using more recent coal exposure data from 2016-2021 thus avoids
possibly attributing benefits from the 2014 RCMD Standard to this rule.
However, MSHA agrees that if respirable crystalline silica
concentrations were to rise in the future--while remaining within the
limits of the 2014 RCMD Standard and complying with all existing
regulations--there would be additional unquantified benefits from the
final rule.\21\ For example, some researchers have attributed the
increase in pneumoconiosis prevalence among miners since the 1990s to
respirable crystalline silica (Cohen et al., 2022; Hall et al., 2020b).
Cohen et al. (2022) states that respirable crystalline silica has
become more concentrated due to improvements in mining equipment and
processing technology, which allow ``recovery of thin coal seams, which
involves the extraction of large quantities of surrounding rock strata
that can contain crystalline silica.'' The possibility that respirable
crystalline silica exposure could increase in the future in the absence
of this rule underscores the rule's importance.
---------------------------------------------------------------------------
\21\ In the analyzed coal compliance data from 2016 through
2021, only 6 percent of samples are above the new PEL of 50 [mu]g/
m\3\. Currently regulation provides protections to keep samples
below 85.7 [mu]g/m\3\, but it is insufficient to prevent increases
in the proportion of concentrations in the range of 50 to 85.7
[mu]g/m\3\. The possibility of such an increase further necessitates
this rule.
---------------------------------------------------------------------------
The primary results of the FRA are the calculated number of deaths
and illnesses avoided assuming full compliance after implementation of
MSHA's final rule. These calculations were performed for non-fatal
silicosis illnesses (morbidity) and for deaths (mortality) due to
silicosis, lung cancer, NMRD, and ESRD. For each health outcome, the
reduced number of illnesses or deaths is calculated as the difference
between (a) the number of excess illnesses and deaths currently
occurring in the industry, assuming mines fully comply with the
previous standards (100 [micro]g/m\3\ for MNM and 85.7 [micro]g/m\3\
ISO for coal) and (b) the number of excess deaths and illnesses
expected to occur following implementation of the final rule, which
includes a new PEL of 50 [micro]g/m\3\ for a full-shift exposure,
calculated as an 8-hour TWA.
Excess risks and cases were estimated under two scenarios: (a) a
Baseline scenario where all exposures were capped at 100 [mu]g/m\3\ for
MNM miners and at 85.7 [mu]g/m\3\ for coal miners, and (b) a new PEL 50
[mu]g/m\3\ scenario where all risks were capped at the new PEL of 50
[mu]g/m\3\ for both MNM and coal miners. The difference between the two
scenarios yields the estimated reduction in lifetime excess risks and
in lifetime excess cases due to the new PEL.
[[Page 28247]]
To calculate excess risks, MSHA grouped MNM miners into the
following exposure intervals: <=25, >25 to <=50, >50 to <=100, >100 to
<=250, >250 to <=500, and >500 [mu]g/m\3\. MSHA grouped coal miners
into the following exposure intervals: <=25, >25 to <=50, >50 to
<=85.7, >85.7 to <=100, >100 to <=250, >250 to <=500, and >500 [mu]g/
m\3\. MSHA calculated the median of all exposure samples in each
exposure interval and assumed the population of miners is distributed
across the exposure intervals in proportion to the number of exposure
samples from the compliance dataset in each interval. Then, miners were
assumed to encounter constant exposure at the median value of their
assigned exposure interval. MSHA adjusted the annual cumulative
exposure by a full-time equivalency (FTE) factor to account for the
fact that miners may experience more or less than 2,000 hours of
exposure per year. MSHA calculated the FTE adjustment factor as the
weighted average of the miner (excluding contract miner) FTE ratio
(0.99 for MNM and 1.14 for coal) and the contract miner FTE ratio (0.59
for MNM and 0.64 for coal), where the weights are the number of miners
[150,928 for MNM miners (excluding contract miners), 60,275 for MNM
contract miners, 51,573 for coal miners (excluding contract miners),
and 22,003 for coal contract miners]. For example, the weighted average
FTE ratio for MNM is (0.987 x 150,928 + 0.591 x 60,275)/(150,928 +
60,275) = 0.87 and is (1.139 x 51,573 + 0.636 x 22,003)/(51, 573 +
22,003) = 0.99 for coal.
MSHA uses weighted average FTE ratios to account for the fact that
contract miners may experience lower exposures per year from mining.
However, this underestimates the cumulative exposures that miners
(excluding contract miners) experience. The average coal miner
(excluding contract miners), for example, works approximately 2,280
hours per year, which equates to an average shift of over 9.1 hours
when assuming 250 working days per year.\22\ Additionally, the studies
the FRA relied on to model excess risks define a full working year as
1,740 hours, in instances where such a definition is given (Buchanan et
al., 2003; Miller and MacCalman, 2010). Based on these studies'
definition of a year, MNM miners (excluding contract miners) have an
FTE ratio of 1.13 and coal miners (excluding contract miners) have an
FTE ratio of 1.31. Additionally, the contract miner FTE ratios likely
have some negative bias since any individual who works for multiple
contracting companies is counted multiple times in the data, inflating
the denominator in the FTE ratio calculation. MSHA also notes that the
contract miner FTE ratios may underrepresent the true overall
cumulative exposures since contract miners may have other jobs
involving exposure to respirable crystalline silica (e.g., in
construction or the oil and gas industry).
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\22\ The fact that miners work over 8-hour shifts is also
supported by MSHA's compliance data, which show an average shift
duration of approximately 9.2 hours for MNM (MSHA, 2022a) and 9.6
hours for coal (MSHA, 2022b). These values differ from the average
hours per day implied by the FTE ratios because the compliance data
is only a sample of full shifts, whereas the FTE data is based on
comprehensive reporting of all full-time and part-time shifts.
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MSHA calculated excess risk, which refers to the additional risk of
disease and death attributable to exposure to respirable crystalline
silica. For silicosis morbidity, MSHA used an exposure-response model
that directly yields the accumulated or lifetime excess risk of
silicosis morbidity, assuming there is no background rate \23\ of
silicosis in an unexposed (i.e., non-miner) group. For the four
mortality endpoints (silicosis mortality, lung cancer mortality, NMRD
mortality, and ESRD mortality), MSHA used cohort life tables to
calculate excess risks, assuming all miners enter the workforce at the
start of age 21, retire at the end of age 65, and do not live past the
end of age 80. From the life tables, MSHA acquired the lifetime excess
risk of mortality by summing the miner cohort's excess mortality risks
in each year from age 21 through age 80. Life tables were also
constructed for unexposed (i.e., non-miner) groups assumed to die from
a given disease at typical rates for the U.S. male population. MSHA
used 2018 data for all males in the U.S. (published by the National
Center for Health Statistics, 2020b) to estimate (a) the disease-
specific mortality rates among unexposed males and (b) the all-cause
mortality rates among both groups (exposed miners and unexposed non-
miners).
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\23\ Here, the ``background'' risk (or rate) refers to the risk
of disease that the exposed person would have experienced in the
absence of exposure to respirable crystalline silica. These
background morbidity and mortality rates are measured using the
disease-specific rates among the general population, which is not
exposed to respirable crystalline silica.
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For a given scenario (either Baseline or New PEL 50 [mu]g/m\3\),
MSHA constructed life tables in the manner described above, both for a
miner cohort exposed to respirable crystalline silica and for an
unexposed non-miner cohort. MSHA calculated excess risk of disease as
the difference between the two cohorts' disease-specific mortality risk
(due to silicosis, lung cancer, NMRD, or ESRD). MSHA determined the
lifetime excess cases by multiplying the lifetime excess risk by the
number of exposed miner FTEs (including contract miner FTEs). Risks and
cases were calculated separately for each exposure interval listed
above. Then, the lifetime excess cases were aggregated across all
exposure intervals. MSHA calculated the final lifetime excess risks per
1,000 miners in the full population of working and future retired
miners by dividing the total number of lifetime excess cases by the
total number of miners in the population (exposed at any interval).
Finally, to estimate the risk reductions and avoided cases of illness
due to the new PEL, MSHA compared the lifetime excess risks and
lifetime excess cases across the two scenarios (Baseline and New PEL 50
[mu]g/m\3\).
In the PRA, MSHA underestimated the number of miners who will
benefit from the proposed rule. Based on the 2019 Quarterly Employment
Production Industry Profile (MSHA, 2019a) and the 2019 Quarterly
Contractor Employment Production Report (MSHA, 2019b), the current
number of working miner FTEs is estimated to be 184,615 for MNM and
72,768 for coal. In the PRA, MSHA assumed excess cases of disease would
be reduced only among these working miners. However, once the current
mining workforce is replaced with new entrants to the mining industry
so that the entire workforce has worked only under the new PEL for
their 45 years of working life, the future mining workforce will
experience fewer excess deaths and illnesses from exposure to
respirable crystalline silica. The PRA's methodology did not include
the number of future retired miners who will experience lower exposure
for their working lives under the final rule and will continue to
benefit during retirement, and therefore, the PRA underestimated the
number of avoided lifetime excess cases attributable to the rule. In
the FRA, the estimates are updated to account for all excess cases that
will be avoided among not only working miners but also future retired
miners. As discussed in greater detail in the FRA, the number of future
retired miners who are expected to benefit from the rule can be
calculated from the survival rates (which are computed in the life
tables) and from the assumption that the mining workforces in MNM and
coal will remain the same size as they are today.
On the related question raised by the ACLC about whether new
clinical data suggests that the PRA underestimated benefits of the
lower PEL, MSHA
[[Page 28248]]
determines that the approach in the PRA is the appropriate one
(Document ID 1445). The risk models that MSHA uses are exposure-
response models, originally selected through OSHA's peer review process
and silica rulemaking, based on past clinical data on patients whose
exposure history was known. Newer data from Black Lung Clinics can
provide suggestive evidence of the risks, but because it is not yet
incorporated into these peer-reviewed risk models, it cannot be
included in this analysis as this commenter recommends.
B. Overview of Epidemiologic Studies
MSHA reviewed extensive research on the health effects of
respirable crystalline silica and quantitative risk assessments
published in the peer-reviewed scientific literature regarding
occupational exposure risks of illness and death from silicosis, NMRD,
lung cancer, and ESRD. The standalone Health Effects document describes
the specific studies reviewed by MSHA. Of the many studies evaluated,
MSHA believes that the 13 studies used by OSHA (2013b) to estimate
risks provide reliable estimates of the disease risk posed by miners'
exposure to respirable crystalline silica. These studies are summarized
in Table VI-1.
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[[Page 28250]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.139
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Of these 13 studies, OSHA selected one per health endpoint for
final modeling and estimation of lifetime excess risk and cases.
Combining the five selected studies with the observed exposure data
yields estimates of actual lifetime excess risks and lifetime excess
cases among working and future retired miner populations based on real
exposure conditions. Table VI-2 summarizes key characteristics of the
models presented in the 13 studies from OSHA's PQRA, including the
cohort that was investigated, the specific health endpoint (e.g., chest
X-ray of category 2/1+), whether a lag between exposure and excess risk
was included, and key model parameters. MSHA evaluated the evidence of
OSHA's analysis of the 13 studies and the accompanying risks associated
with exposure at 25, 50, 100, 250, and 500 [micro]g/m\3\. Thorough
evaluation has led MSHA to determine that the studies OSHA selected
still provide the best available epidemiological models (with the
exception of lung cancer mortality). However, MSHA utilized the Miller
and MacCalman (2010) study to estimate risks for lung cancer mortality.
This study was included in OSHA's health effects assessment and PQRA
but was published after OSHA completed much of its modeling for the
PQRA. The following lists the studies used by MSHA for each health
endpoint:
Silicosis morbidity: Buchanan et al. (2003);
Silicosis mortality: Mannetje et al. (2002b);
NMRD mortality: Park et al. (2002);
Lung cancer mortality: Miller and MacCalman (2010); and
ESRD mortality: Steenland et al. (2002a).
As explained in detail in the standalone FRA document, MSHA
developed its risk estimates based on recent mortality data and certain
assumptions that differed from those used by OSHA. Examples of these
MSHA assumptions include a lifetime that ends at age 80, updated
background mortality data and all-cause mortality, miner population
sizes, and miner-specific full-time equivalents (FTEs).\24\
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\24\ FTEs were used to adjust the cumulative exposure over a
year based on the average number of hours that miners work.
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[[Page 28251]]
MSHA's modeling has been done using life tables, in a manner
consistent with OSHA's PQRA. In general, the life table is a technique
that allows estimation of excess risk of disease-specific mortality
while factoring in the probability of surviving to a particular age,
assuming no exposure to respirable crystalline silica. This analysis
accounts for competing causes of death, background mortality rates of
disease, and the effect of the accumulation of risk due to elevated
mortality rates in each year of a working life. For each cause of
mortality, the selected study was used in the life table analysis to
compute the increase in miners' disease-specific mortality rates
attributable to respirable crystalline silica exposure.
MSHA uses cumulative exposure (i.e., cumulative dose) to
characterize the total exposure over a 45-year working life. Cumulative
exposure is defined as the product of exposure duration and exposure
intensity (i.e., exposure level). Cumulative exposure is the predictor
variable in the selected exposure-response models.
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Two commenters (SMI and NVMA) expressed concern that not all
relevant studies were considered in MSHA's analysis of the health
effects literature on occupational exposure to respirable crystalline
silica (Document ID 1446; 1441). For example, the NVMA commented that
the studies referenced in the health effects literature review are
[[Page 28255]]
outdated and do not recognize the changing conditions in mines that
reduce the likelihood of prolonged exposure to respirable crystalline
silica, such as the updates made by mines in response to the diesel
particulate matter standard published in the early 2000s (Document ID
1441). Similarly, the Pennsylvania Coal Alliance stated that the
majority of research MSHA relied on did not account for significant
technological advancements in mining and dust control technology
(Document ID 1378). This commenter further asserted that the rule
cannot be justified until the effects of the 2014 RCMD Standard are
better understood (Document ID 1378).
MSHA reviewed the relevant literature, including recent
publications. Additionally, in response to comments on the PRA, MSHA
read and reviewed studies suggested by commenters. MSHA selected the
studies which provide the best available epidemiological models to
develop the estimates of lifetime excess risks and lifetime excess
cases. These models contain information regarding how the cumulative
level of exposure relates to the risk of adverse health outcomes. The
selected studies were based on analyses of miners with a range of
exposure histories. Further, MSHA's modeling of the avoided cases in
the FRA directly accounts for any relevant changes in exposure
conditions because it includes exposure data from as recently as 2019
for MNM miners and 2021 for coal miners. The exposure data captures
actual concentrations of respirable crystalline silica that miners were
exposed to during their shifts. To the extent that changing conditions,
technological advancements, or the 2014 RCMD Standard have impacted
miners' exposures to respirable crystalline silica, these effects are
accounted for in MSHA's models, which use recent exposure data. The
final provisions of the 2014 RCMD Standard went into effect in 2016,
which is the first year of coal exposure data MSHA used when modeling
coal miners' exposures to respirable crystalline silica dust.
For each health endpoint, MSHA generated two sets of risk
estimates--one representing a scenario of full compliance with the
existing standards (herein referred to as the ``Baseline'' scenario)
and another representing a scenario wherein no samples exceed the new
PEL (herein referred to as the ``New PEL 50 [mu]g/m\3\'' scenario). In
the Baseline scenario, MNM miners in the >100-250, >250-500, and >500
[mu]g/m\3\ groups were assigned exposure intensities of 100 [mu]g/m\3\
ISO. Coal miners in the 85.7-100, >100-250, >250-500, and >500 [mu]g/
m\3\ groups were assigned exposure intensities of 85.7 [mu]g/m\3\ ISO,
calculated as an 8-hour TWA. Exposure intensities were not changed for
miners with lower exposure concentrations, because their exposures were
considered compliant with the existing standards. A similar procedure
was used for the New PEL 50 [mu]g/m\3\ scenario, except that each miner
group whose exposure exceeded the new PEL was assigned a new exposure
of 50 [mu]g/m\3\ ISO (for both MNM and coal). This process--of creating
an exposure profile based on actual exposure data and modifying it
based on the existing standards or the new PEL--allowed MSHA to
estimate real exposure conditions that miners would encounter under
each scenario, thereby enabling estimates of the actual excess risks
the current population of miners would experience under each scenario
(Baseline and New PEL 50 [mu]g/m\3\).
For purposes of calculating risk in the FRA, both for MNM and coal
miners, MSHA estimated excess risks by using the concentration of
respirable crystalline silica collected over the full shift and
calculating it as a full-shift, 8-hour TWA expressed in ISO standards.
This metric of exposure intensity--the 8-hour TWA concentration of
respirable crystalline silica in ISO standards--was used consistently
across all sets of estimates (both MNM and coal sectors, and both the
Baseline and New PEL 50 [mu]g/m\3\ scenarios), thereby facilitating
meaningful comparison. MSHA acknowledges that this metric of exposure
intensity does not correspond to the manner in which coal exposure
concentrations are currently calculated for purposes of evaluating
compliance under the existing standard. As discussed in Section 4 of
the standalone FRA document, MSHA believes that a full-shift, 8-hour
TWA concentration properly represents risks to miners and thus is the
most appropriate cumulative exposure metric for computing risk given
that FTEs were used to scale exposure durations relative to the
assumption of 250 8-hour workdays per year.
Commenters, including MSHA Safety Services Inc.; Silica Safety
Coalition (SSC); the NSSGA; Jervois Idaho Cobalt Operations; and the
EMA, suggested that disease data show respirable crystalline silica
exposure and associated adverse health effects are not a problem or
crisis in MNM mining or that there is only negligible exposure to
respirable crystalline silica for certain MNM miners (Document ID 1392;
1432; 1448; 1453; 1442). Similarly, the Portland Cement Association
stated that silicosis is unknown in the cement industry (Document ID
1407). One miner-related business further stated that silicosis cases
are on the rise in coal and are decreasing in MNM and, therefore,
MSHA's standard should focus only on coal mining, specifically
underground coal mining (Document ID 1392). In addition, MNM mine
operators such as K & E Excavating Inc. and K & E Alaska, Inc., also
commented that there is little to no evidence of silicosis or other
similar symptoms in MNM mining, especially in comparison to coal mining
(Document ID 1435; 1436). Finally, the president of N-Compliance Safety
Services expressed concern regarding the origin of the mortality
reduction data included in the FRA and stated that they could not find
deaths reported by MSHA for MNM miners or the associated 7000-1 forms
(Document ID 1383).
On the other hand, several commenters from labor unions and health
organizations agreed with MSHA's finding that MNM miners are at risk of
respirable crystalline silica-related disease from occupational
exposures (Document ID 1447; 1449; 1418; 1373). USW asserted that rock
crushing in iron and other surface mines can release silica-laden dust
and that silica is also a hazard in cement plants (Document ID 1447).
The same commenter stated that silica control in MNM mines is becoming
increasingly important because of new technologies that are likely to
lead to higher dust exposures (Document ID 1447). Further, Miners
Clinic of Colorado commented that its data support the need for better
control of exposure to respirable crystalline silica in MNM mines, and
said that, of the 400 MNM miners the clinic provided medical
surveillance for in the past 20 years, 62 percent reported having spent
over half of their mining tenure in MNM or at least 10 years as a MNM
miner and, of those 62 percent, 26 percent had pneumoconiosis (based on
a positive chest radiograph B reading) (Document ID 1418). This
commenter concluded that MNM miners are at risk for progressive and
potentially disabling work-related lung disease, although information
on silicosis disease rates among MNM miners are less readily available
than those for coal miners (Document ID 1418). Finally, citing several
studies (Kramer et al., 2012; Friedman et al., 2015; Leso et al., 2019;
Rose et al., 2019; Wu et al., 2020; LACDHS, 2022; Fazio et al., 2023),
the Association of Occupational and Environmental Clinics (AOEC) said
that severe silicosis in the engineered stone manufacturing industry
has been reported around the
[[Page 28256]]
world, including in the United States (Document ID 1373).
MSHA disagree with the assertion that silicosis or other diseases
linked to respirable crystalline silica are not risks for MNM miners.
MSHA reviewed a wide range of studies that demonstrated disease risks
amongst miners occupationally exposed to respirable crystalline silica.
These studies were not limited to underground coal miners and show that
respirable crystalline exposure produces excess risk for coal and MNM
miners as well as underground and surface miners. The studies MSHA
evaluated covered occupations relevant to MNM mining such as
sandblasters (Abraham and Wiesenfeld, 1997; Hughes et al., 1982),
industrial sand workers (Vacek et al., 2019), hard rock miners (Verma
et al., 1982, 2008), and gold miners (Carneiro et al., 2006a; Tse et
al., 2007b), metal miners (Hessel et al., 1988; Hnizdo and Sluis-
Cremer, 1993; Nelson, 2013), and nonmetal miners such as silica plant
and ground silica mill workers, whetstone cutters, and silica flour
packers (Mohebbi and Zubeyri, 2007; NIOSH, 2000a,b; Ogawa et al.,
2003a). Of the MNM exposure samples MSHA collected over the 2016-2021
period, 18.2 percent exceed the new PEL of 50 [mu]g/m\3\ and 6.4
percent exceed the existing PEL of 100 [mu]g/m\3\. Based on the
analysis presented in the FRA, MNM miners are exposed to concentrations
of respirable crystalline silica that are associated with elevated
risks of morbidity and mortality from a variety of diseases.
Further, the ACOEM commented that new information about the
molecular basis for silica's adverse health effects since OSHA's 2016
summary of the medical literature highlights the need for establishing
and enforcing the 50 [mu]g/m\3\ PEL (Wang et al., 2018; Chanda et al.,
2019; Feng et al., 2020; Wu et al., 2021) (Document ID 1405). MSHA's
review of the more recent health effects literature also supports a
causal association between respirable crystalline silica exposure and
increased risk of silicosis morbidity and mortality. Thus, MSHA
believes that silicosis and other diseases are a risk to any miner
exposed to high levels of silica dust concentrations, regardless of
mining commodity.
Regarding the comment about reported deaths, selected surveillance
data for both silicosis cases and silicosis deaths are reported in the
standalone Health Effects document. Nonetheless, MSHA's estimated risk
and case reductions are based on samples MSHA collected from MNM mines
and peer-reviewed models of the relationship between exposure to
respirable crystalline silica and related diseases. The FRA does not
rely on reported mortality data. MSHA previously has not required
operators to conduct medical surveillance for MNM miners and becomes
aware of cases only when miners inform their employer of their illness.
Thus, these case data are not complete enough to serve as a basis for
estimating applicable exposure-response models needed for a
comprehensive risk analysis. However, MSHA believes that the final
rule's MNM medical surveillance provisions, which are discussed in
further detail in the FRIA and in the final rule text, will likely help
to improve this gap in the data.
Commenters from the SMI, EMA, and Vanderbilt Minerals, argued that
the aged and occluded crystalline silica (quartz) encountered in
sorptive minerals, does not pose the same health risk of other forms of
crystalline silica (Document ID 1446; 1442; 1419). The SMI commented
that their mining and processing operations do not pose a risk to
miners' health (Document ID 1446). A more comprehensive discussion of
these commenters' concerns is addressed in the preamble under Section
VIII.A.3. Sorptive Minerals.
The Agency notes that, unlike OSHA, MSHA has no requirement to
identify a ``significant risk'' before regulating to protect miners'
health and safety. Nat'l Mining Ass'n v. United Steel Workers, 985 F.3d
1309, 1319 (11th Cir. 2021) (``[T]he Mine Act does not contain the
`significant risk' threshold requirement . . . from the OSH Act.'').
Moreover, unlike OSHA-regulated industries, the mining of sorptive
minerals involves the removal of overburden, which can disturb
sedimentary and other silica-rich rock that could contain unoccluded
respirable crystalline silica. The mining and milling processes
generate and expose miners to hazardous dust surrounding the mined
deposits. Also, during mineral processing, sorptive minerals may be
crushed, heated, dried to remove moisture, re-crushed, and then
screened to produce various grades of finished products. These
processes have the potential to fracture and change the nature of the
surface characteristics of the quartz in the mined commodity. Sorptive
minerals have always been subject to MSHA's previous PEL, without
exemption.
MSHA examined evidence and references from the commenters and
conducted its own review of the scientific literature. MSHA agrees that
there is some evidence to suggest that occluded silica is less toxic
than unoccluded silica (Wallace et al., 1996). Animal studies involving
respirable crystalline silica suggest that the aged form has lower
toxicity than the freshly fractured form; however, the aged form still
retains significant toxicity (Shoemaker et al., 1995; Vallyathan et
al., 1995; Porter et al., 2002c). MSHA finds that ``lower toxicity''
does not imply the absence of adverse health effects. In addition,
there is no evidence that occlusion and the initial reduced toxicity
persist following deposition and retention of the crystalline silica
particles in the lungs.
There have been few epidemiological studies focused on workers
exposed to dust generated from sorptive minerals. Examples include
Phibbs et al. (1971) and Waxweiler et al. (1988). These small cohort
studies did not evaluate exposures to a wide variety of sorptive
minerals and relied on data from outdated exposure assessment methods.
These studies neither disprove the health-based risks associated with
exposure to respirable crystalline silica nor support a conclusion that
sorptive minerals present no risk. Other epidemiological studies of
workers exposed to clay-occluded respirable crystalline silica have
shown that occupational silicosis can occur among exposed workers
(Phibbs et al., 1971; Love et al., 1995, 1999; Chen et al., 2005, 2006,
2012; Harrison et al., 2005). Therefore, MSHA disagrees with these
commenters.
MSHA finds that the limited epidemiological data involving sorptive
minerals do not refute the conclusions drawn from other epidemiological
and toxicological studies included in MSHA's standalone Health Effects
document. MSHA concludes, from the best available evidence, that
exposure to the crystalline silica present in sorptive minerals poses a
risk of material impairment of health or functional capacity to miners.
In the Posthearing Brief to OSHA, NIOSH (2014) concluded that
``currently available information is not adequate to inform
differential quantitative risk management approaches for crystalline
silica that are based on surface property measurements.'' MSHA concurs
with NIOSH's recommendation for a single PEL for respirable crystalline
silica without consideration of surface properties.
C. Summary of Studies Selected for Modeling
After reviewing the available studies that support quantitative
modeling, MSHA selected one exposure-response model from literature for
each of the five health outcomes that are modeled in the FRA. These
selections and the exposure-response models are discussed below.
[[Page 28257]]
1. Silicosis Morbidity
Due to the long latency periods associated with chronic silicosis,
OSHA's respirable crystalline silica standard relied on the subset of
studies that were able to contact and evaluate many workers through
retirement. Studies that included retired workers provides the best
available evidence of lifetime risk of silicosis morbidity.
The health endpoint of interest in these studies was the appearance
of opacities on chest radiographs indicative of pulmonary
pneumoconiosis (a group of lung diseases caused by the lung's reaction
to inhaled dusts). The most reliable estimates of silicosis morbidity,
as detected by chest X-rays, come from the studies that evaluated those
X-rays over time, included radiographic evaluation of workers after
they left employment, and derived cumulative or lifetime estimates of
silicosis disease risk.
To describe the presence and severity of pneumoconiosis, including
silicosis, the International Labour Organization (ILO) developed a
standardized system to classify lung opacities identified on chest
radiographs (X-rays) (ILO, 1980, 2002, 2011, 2022). The ILO system
grades the size, shape, and profusion of opacities. Although silicosis
is defined and categorized based on chest X-ray, the X-ray is an
imprecise tool for detecting pulmonary pneumoconiosis (Craighead and
Vallyathan, 1980; Hnizdo et al., 1993; Rosenman et al., 1997; Cohen and
Velho, 2002). Hnizdo et al. (1993) recommended that an ILO category 0/1
(or greater) should be considered indicative of silicosis among workers
exposed to high respirable crystalline silica concentrations. They
noted that the sensitivity of the chest X-ray as a screening test
increases with disease severity and to maintain high specificity,
category 1/0 (or 1/1) chest X-rays should be considered as a positive
diagnosis of silicosis for miners who work in low dust occupations
(Hnizdo et al., 1993). MSHA, consistent with NIOSH's use of chest X-
rays in their occupational respiratory disease surveillance program
(NIOSH, 2014b), agrees that a small opacity profusion score of 1/0 is
consistent with chronic silicosis stage 1. Most of the studies reviewed
by MSHA considered a finding consistent with an ILO category of 1/1 or
greater to be a positive diagnosis of silicosis, although some also
considered an X-ray classification of 1/0 or 0/1 to be positive. The
low sensitivity of chest radiography to detect minimal silicosis
suggests that risk estimates derived from radiographic evidence likely
underestimate the true risk of this disease (Craighead and Vallyathan,
1980; Hnizdo et al., 1993; Rosenman et al., 1997; Cohen and Velho,
2002; Hoy et al., 2023).
OSHA summarized the Miller et al. (1995, 1998) and Buchanan et al.
(2003) studies in their final respirable crystalline silica standard in
2016 (OSHA 2016a, 81 FR 16286, 16316). These researchers reported on a
1991 follow-up study of 547 survivors of a 1,416-member cohort of
Scottish coal workers from a single mine. These men had all worked in
the mine during the period between early 1971 and mid-1976, during
which time they had experienced ``unusually high concentrations of
freshly cut quartz in mixed coal mine dust.'' The population's
exposures to quartz dust had been measured in unique detail for a
considerable proportion of the men's working lives (OSHA, 2013b, page
333).
The 1,416 men had previous chest X-rays dating from before, during,
or just after this high respirable crystalline silica exposure period.
Of these 1,416 men, 384 were identified as having died by 1990/1991. Of
the 1,032 remaining men, 156 were untraced, and, of the 876 who were
traced and replied, 711 agreed to participate in the study. Of these,
the total number of miners who were surveyed was 551. Four of these
were omitted, two because of a lack of an available chest X-ray. The
547 surviving miners (age range: 29-85 years, average=59 years) were
interviewed and received their follow-up chest X-rays between November
1990 and April 1991. The interviews consisted of questions on current
and past smoking habits and occupational history since leaving the coal
mine, which closed in 1981. They were also asked about respiratory
symptoms and were given a spirometry test (OSHA, 2013b, pages 333-334).
Exposure characterization was based on extensive respirable dust
sampling; samples were analyzed for quartz content by IR spectroscopy.
Between 1969 and 1977, two coal seams were mined. One had produced
quarterly average concentrations of respirable crystalline silica much
less than 1,000 [mu]g/m\3\ (only 10 percent exceeded 300 [mu]g/m\3\).
The other more unusual seam (mined between 1971 and 1976) lay in
sandstone strata and generated respirable crystalline silica levels
such that quarterly average exposures exceeded 1,000 [mu]g/m\3\ (10
percent of the quarterly measurements were over 10,000 [mu]g/m\3\).
Thus, this cohort study allowed evaluation of the effects of both
higher and lower respirable crystalline silica concentrations and
exposure-rate effects on the development of silicosis (OSHA, 2013b,
page 334).
Three physicians read each chest film taken during the current
survey as well as films from the surveys conducted in 1974 and 1978.
Films from an earlier 1970 survey were read only if no films were
available from the subsequent two surveys. Silicosis cases were
identified if the median classification of the three readers indicated
an ILO category of 1/1 or greater (Miller et al., 1995, page 24), plus
a progression from the earlier reading. Of the 547 men, 203 (38
percent) showed progression of at least 1 ILO category from the 1970s'
surveys to the 1990-91 survey; in 128 of these (24 percent), there was
progression of 2 or more ILO categories. In the 1970s' surveys, 504 men
had normal chest X-rays; of these, 120 (24 percent) acquired an
abnormal X-ray consistent with ILO category 1/0 or greater at the
follow-up. Of the 36 men whose X-rays were consistent with ILO category
1/0 or greater in the 1970s' surveys, 27 (75 percent) exhibited further
progression at the 1990/1991 follow-up. Only one subject showed a
regression from any earlier reading, and that was slight, from 1/0 to
0/1. The earlier Miller et al. (1995) report presented results for
cases classified as having X-ray films consistent with either 1/0+ and
2/1+ degree of profusion; the Miller et al. (1998) analysis and the
Buchanan et al. (2003) re-analyses emphasized the results from cases
having X-rays classified as 2/1+ (OSHA, 2013b, page 334).
MSHA modeled the exposure-response relationship by using cumulative
exposure expressed as gram/m\3\-hours, assuming 2,000 work hours per
year and a 45-year working life (after adjusting for full-time
equivalents, including miners (excluding contract miners) and contract
miners). MSHA estimated risk at the existing standard assuming
cumulative exposure to 100 [mu]g/m\3\ ISO for MNM miners and 85.7
[mu]g/m\3\ ISO (100 [mu]g/m\3\ MRE) for coal miners. Respirable
crystalline silica exposures were calculated by commodity, and median
exposure values were used within a variety of exposure intervals. Risks
were computed using a life table methodology which iteratively updated
the survival, risk, and mortality rates each year based on the results
of the preceding year. Covariates in the regression included smoking,
age, amount of coal dust, and percent of quartz in the coal dust during
various previous survey periods.
Both Miller et al. papers (1995, 1998) presented the results of
numerous regression models, and they compared
[[Page 28258]]
the results of the partial regression coefficients using Z statistics
of the coefficient divided by the standard error. Also presented were
the residual deviances of the models and the residual degrees of
freedom. In the introduction to the results section, Miller et al.
(1995) stated that, ``in none of the models fitted was there a
significant effect of smoking habit (current, ex-smoker, and never
smoker), nor was there any evidence of any difference between smoking
groups in their relationship of response with age.'' They therefore
presented the results of the regression analyses without terms for
smoking effects (i.e., without including smoking effects as a variable
in the final regression analysis, because they found that smoking did
not affect the modeling results). The logistic regression models
developed by Miller et al. (1995) included terms for cumulative
exposure and age. In their later publication, Miller et al. (1998)
presented models similar to their 1995 report, but without the age
variable. Their logistic regression model A from Table 7 of their
report (page 56) included only an intercept (-4.32) and the respirable
crystalline silica (quartz) cumulative exposure variable (0.416). They
estimated that respirable crystalline silica exposure at an average
concentration of 100 [mu]g/m\3\ for 15 years (2.6 gram/m\3\-hr assuming
1,750 hours worked per year) would result in an increased risk of
silicosis (ILO>2/1) of 5 percent (OSHA, 2013b, page 334).
OSHA had a high degree of confidence in the estimates of silicosis
morbidity risk from this Scotland coal mine study. This was mainly
because of highly detailed and extensive exposure measurements,
radiographic records, and detailed analyses of high exposure-rate
effects. MSHA has reviewed and agrees with OSHA's conclusion.
Buchanan et al. (2003) provided an analysis and risk estimates only
for cases having X-ray films consistent with ILO category 2/1+ extent
of profusion of opacities, after adjusting for the disproportionately
severe effect of exposure to high respirable crystalline silica
concentrations. Estimating the risk of 1/0+ profusions from the
Buchanan et al. (2003) or the earlier Miller et al. (1995, 1998)
publications can only be roughly approximated because of the summary
information included. Table 4 of Miller et al. (1998, page 55) presents
a cross-tabulation of radiograph progression, using the 12-point ILO
scale, from the last baseline examination to the 1990/1991 follow-up
visit for the 547 men at the Scottish coal mine. From this table, among
miners having both early X-ray films and follow-up films, 44 men had
progressed to 2/1+ by the last follow-up and an additional 105 men had
experienced the onset of silicosis (i.e., X-ray films were classified
as 1/0, 1/1, or 1/2). Thus, by the time of the follow-up, there were
three times more miners with silicosis consistent with ILO category 1
than there were miners with a category 2+ level of severity ((105 +
44)/44 = 3.38). This suggests that the Buchanan et al. (2003) model,
which reflects the risk of progressing to ILO category 2+,
underestimates the risk of acquiring radiological silicosis by about
three-fold in this population (OSHA, 2013b, page 336). This type of
analysis shows that the risk of developing silicosis estimated from the
Buchanan et al. (2003) and Miller et al. (1998) studies is of the same
magnitude as the risks reported by Hnizdo and Sluis-Cremer (1993)
(OSHA, 2013b, page 338).
MSHA estimated silicosis risk by using the Buchanan et al. (2003)
model that predicted the lifetime probability of developing silicosis
at the 2/1+ category based on cumulative respirable crystalline silica
exposures. As discussed previously, MSHA applied the Buchanan et al.
(2003) model, assuming that miners are exposed for 45 years of working
life extending from the start of age 21 through the end of age 65,
using a life table approach. Buchanan et al. provides an exposure-
response model using cumulative exposure in mg/m\3\-hours as the
predictor variable and lifetime risk of silicosis as the outcome
variable. MSHA assumed 45 years of exposure, each such year having a
duration of 2,000 work hours, scaled by a weighted average FTE ratio
that accounts for the average annual hours worked by miners (excluding
contract miners) and contract miners.
2. Accelerated Silicosis and Rapidly Progressive Pneumoconiosis (RPP)
Study
OSHA concluded in their risk assessment, and MSHA agrees, that
there is little evidence of a dose-rate effect at respirable
crystalline silica concentrations in the exposure range of 25 [mu]g/
m\3\ to 500 [mu]g/m\3\ (81 FR 16286, 16396). OSHA noted that the risk
estimates derived from the Buchanan et al. (2003) study were not
appreciably different from those derived from the other studies of
silicosis morbidity (see OSHA 2016a, 81 FR 16286, 16386; Table VI-1.
Summary of Lifetime or Cumulative Risk Estimates for Crystalline
Silica). However, OSHA also concluded that some uncertainty related to
dose-rate effects exists at concentrations far higher than the exposure
range of interest. OSHA stated that it is possible for such a dose-rate
effect to impact the results if not properly addressed in study
populations with high concentration exposures. OSHA used the model from
the Buchanan et al. (2003) study in its silicosis morbidity risk
assessment to account for possible dose-rate effects at high average
concentrations (OSHA 2016a, 81 FR 16286, 16396; OSHA, 2013b, pages 335-
342). MSHA has reviewed and agrees with OSHA's conclusions.
NIOSH stated in its post-hearing brief to OSHA that a ``detailed
examination of dose rate would require extensive and real time exposure
history which does not exist for silica (or almost any other agent)''
(81 FR 16285, 16375). Similarly, Dr. Kenneth Crump, a researcher from
Louisiana Tech University Foundation who served on OSHA's peer review
panel for the Review of Health Effects Literature and Preliminary
Quantitative Risk Assessment, wrote to OSHA that, ``[h]aving noted that
there is evidence for a dose rate effect for silicosis, it may be
difficult to account for it quantitatively. The data are likely to be
limited by uncertainty in exposures at earlier times, which were likely
to be higher'' (OSHA 2016a, 81 FR 16286, 16375). OSHA agreed with the
conclusions of NIOSH and Dr. Crump. OSHA believed that it used the best
available evidence to estimate risks of silicosis morbidity and
sufficiently accounted for any dose rate effect at high silica average
concentrations by using the Buchanan et al. (2003) study as part of
their final Quantitative Risk Analysis (QRA) (OSHA 2016a, 81 FR 16286,
16396). MSHA has reviewed and agrees with OSHA's conclusions.
MSHA is using the Buchanan et al. (2003) study to explain, in part,
the observed cases of progressive lung disease in miners, known as RPP
in coal miners (Laney and Attfield, 2010; Wade et al., 2011; Laney et
al., 2012b, 2017; Blackley et al., 2016b, 2018b; Almberg et al., 2018a;
Reynolds et al., 2018b; Halldin et al., 2019, 2020; Cohen et al., 2022)
and accelerated silicosis in MNM miners (Hessel et al., 1988; Mohebbi
and Zubeyri, 2007; Dumavibhat et al., 2013). This research explains, in
part, the progressive disease observed in shorter-tenured miners. MSHA
believes that the risks estimated by the Buchanan et al. model can be
applied to all mining populations that have similar respirable
crystalline silica exposure exceedances. MSHA data also indicate that a
smaller number of MSHA samples showed respirable crystalline silica
concentrations well above the existing MSHA standard of 100 [mu]g/m\3\.
Over the last 15 years of MNM compliance data,
[[Page 28259]]
188 samples (0.3 percent) were over 500 [mu]g/m\3\; the upper range of
exposure was 4,289 [mu]g/m\3\ ISO (see FRA Table 4 of the FRA
document). Over the last 5 years of coal compliance data, eight samples
(<0.1 percent) were over 500 [mu]g/m\3\; the upper range of exposure
was 791.4 [mu]g/m\3\ MRE (see FRA Table 7 of the standalone FRA
document).
Analysis provided by Buchanan et al. (2003) provides strong
evidence of an exposure-rate effect for silicosis in a British
Pneumoconiosis Field Research (PFR) coal mining cohort exposed to high
levels of respirable crystalline silica over short periods of time
(OSHA, 2013b, page 335). Exposure was categorized as pre- and post-
1964, the latter period being that of generally higher quartz
concentrations used to estimate exposure-rate effects. For the purpose
of this analysis, the results were presented for the 371 men (out of
the original 547) who were between the ages of 50 and 74 at the time of
the 1990/1991 follow-up, ``since they had experienced the widest range
of quartz concentrations and showed the strongest exposure-response
relations.'' Thus, combined with their exposure history, which went
back to pre-1954, many of these men had 30 to 40+ years of highly
detailed occupational exposure histories available for analysis. Of
these 371 miners, there were 35 men (9.4 percent) who had X-ray films
consistent with ILO category 2/1+, with at least 29 of them having
progressed from less severe silicosis since the previous follow-up
during the 1970s (from Miller et al., 1998) (OSHA, 2013b, page 335).
The Buchanan et al. (2003) re-analysis presented logistic
regression models in stages. In the final stage of modeling, using only
the statistically significant post-1964 cumulative exposures, the
authors separated these exposures into, ``two quartz concentration
bands, defined by the cut-point 2.0 mg/m\3\.'' This yielded the final
simplified equation, adapted from Buchanan et al., 2003, page 162:
[GRAPHIC] [TIFF OMITTED] TR18AP24.079
where p2 is the probability of profusion category 2/1 or
higher (2/1+) at follow-up and E is the cumulative exposure.
In this model, both the cumulative exposure concentration variables
were ``highly statistically significant in the presence of the other''
(Buchanan et al., 2003, page 162). Since these variables were in the
same units, mg/m\3\-hr, the authors noted that the coefficient for
exposure concentrations >2,000 [micro]g/m\3\ (>2.0 mg/m\3\) was three
times that for the concentrations <2,000 [micro]g/m\3\ (<2.0 mg/m\3\).
They concluded that their latest analysis showed that ``the risk of
silicosis over a working lifetime can rise dramatically with exposure
to such high concentrations over a timescale of merely a few months''
(Buchanan et al., 2003, page 163; OSHA, 2013b, page 336).
Buchanan et al. (2003) also used these models to estimate the risk
of acquiring a chest X-ray classified as ILO category 2/1+, 15 years
after exposure ends, as a function of low <2,000 [micro]g/m\3\ (<2.0
mg/m\3\) and high >2,000 [micro]g/m\3\ (>2.0 mg/m\3\) quartz
concentrations. OSHA chose to use this model to estimate the risk of
radiological silicosis consistent with an ILO category 2/1+ chest X-ray
for several exposure scenarios. They assumed 45 years of exposure,
2,000 hours/year of exposure, and no exposure above a concentration of
2,000 [micro]g/m\3\ (2.0 mg/m\3\) (OSHA, 2013b, page 336).
Buchanan et al. (2003) used these models to estimate the combined
effect on the predicted risk of low quartz exposures (e.g., 100
[micro]g/m\3\, equal to 0.1 mg/m\3\) and short-term exposures to high
quartz concentrations (e.g., 2,000 [micro]g/m\3\, equal to 2 mg/m\3\).
Predicted risks were estimated for miners who progressed to silicosis
level 2/1+ 15 years after exposure ended. This analysis showed the
increase in predicted risk with relatively short periods of quartz
exceedance exposures, over 4, 8, and 12 months. Buchanan et al.
predicted a risk of 2.5 percent for 15 years quartz exposure to 100
[micro]g/m\3\ (0.1 mg/m\3\). This risk increased to 10.6 percent with
the addition of only 4 months of exposure at the higher concentration.
The risk increased further to 72 percent with 12 months at the higher
exposure of 2,000 [micro]g/m\3\ (2.0 mg/m\3\).
The results indicated miners exposed to exceedances above MSHA's
existing standard could develop progression of silicosis at an
exaggerated rate. The results of Buchanan et al. also indicated that
miners' exposure to exceedances at the new PEL will also suffer
increased risk of developing progressive disease, though at a reduced
rate (see Buchanan et al. (2003), Table 4, page 163).
MSHA used a life table approach to estimate the lifetime excess
silicosis morbidity from age 21 to age 80, assuming exposure from the
start of age 21 through the end of age 65 (45 years of working life)
and an additional 15 years of potential illness progress thereafter.
MSHA used the Buchanan et al. (2003) model to estimate the effect of
respirable crystalline silica exposure exceedances as seen in MSHA's
compliance data on miners' silicosis risk at the existing and new
standard. The model predicted the probability of developing silicosis
at the 2/1+ category based on cumulative respirable crystalline silica
exposures. Age-specific cumulative risk was estimated as 1/(1+EXP(-(-
4.83+0.443*cumulative exposure))). The model determined that even at
17.4 hours on average per year at an exposure of 1,500 [micro]g/m\3\
(1.50 mg/m\3\), miners' risk of developing 2/1+ silicosis increased
from a baseline of 24.8/1,000 to 29.0/1,000 at the existing standard
and 14/1,000 to 16.6/1,000 at the new standard. Of course, the more
hours exposed to these levels of respirable crystalline silica resulted
in even higher increased risk. It is important to note that NIOSH's X-
ray classification of the lowest case of pneumoconiosis is 1/0
profusion of small opacities (NIOSH, 2008c, page A-2). Using a case
definition of level 2/1+, the miners studied by Buchanan et al. (2003)
would be more likely to show clinical signs of disease. MSHA emphasizes
the importance of maintaining miner exposure to respirable crystalline
silica at or below the 50 [mu]g/m\3\ PEL to minimize these health risks
as much as possible.
3. Silicosis and NMRD Mortality
Silicosis mortality was ascertained in the studies included in the
pooled analysis by Mannetje et al. (2002b). These studies included
cohorts of U.S. diatomaceous earth workers (Checkoway et al., 1997),
Finnish granite workers (Koskela et al., 1994), U.S. granite workers
(Costello and Graham, 1988), U.S. industrial sand workers (Steenland
and Sanderson, 2001), U.S. gold miners (Steenland and Brown, 1995b),
and Australian gold miners (de Klerk and Musk, 1998). The researchers
analyzed death certificates across all cohorts for cause of death. OSHA
relied upon the published, peer-reviewed, pooled analysis of six
[[Page 28260]]
epidemiological studies first published by Mannetje et al. (2002b) and
a sensitivity analysis of the data conducted by ToxaChemica
International, Inc. (2004). OSHA used the model described by Mannetje
et al. (2002b) and the rate ratios that were estimated from the
ToxaChemica, International Inc. sensitivity analysis to estimate the
risks of silicosis mortality. This process better controlled for age
and exposure measurement uncertainty (OSHA, 2013b, page 295). MSHA has
reviewed and agrees with OSHA's conclusions. These studies are
summarized below, including detailed discussion and analysis of
uncertainty in the studies and associated risk estimates.
OSHA found that the estimates from Mannetje et al. (2002b) and
ToxaChemica Inc. probably understated the actual risk because silicosis
is underreported as a cause of death since there is no nationwide
system for collecting silicosis morbidity case data (OSHA, 2016a, 81 FR
16286, 16325). To help address this uncertainty, OSHA also included an
exposure-response analysis of diatomaceous earth workers (Park et al.,
2002). This analysis better recognized the totality of respirable
crystalline silica-related respiratory disease than the datasets of
Mannetje et al. (2002b) and ToxaChemica International Inc. (2004).
Information from the Park et al. (2002) study (described in the next
subsection) was used to quantify the relationship between cristobalite
exposure and mortality caused by NMRD, which includes silicosis,
pneumoconiosis, emphysema, and chronic bronchitis. The category of NMRD
captures much of the silicosis misclassification that results in
underestimation of the disease. NMRD also includes risks from other
lung diseases associated with respirable crystalline silica exposures.
OSHA found the risk estimates derived from Park et al. (2002) were
important to include in their range of estimates of the risk of death
from respirable crystalline silica-related respiratory diseases,
including silicosis (OSHA, 2013b, pages 297-298). OSHA concluded that
the ToxaChemica International Inc. (2004) re-analysis of Mannetje et
al.'s (2002b) silicosis mortality data and Park et al.'s (2002) study
of NMRD mortality provided a credible range of estimates of mortality
risk from silicosis and NMRD across many workplaces. The upper end of
this range, based on the Park et al. (2002) study, is less likely to
underestimate risk because of underreporting of silicosis mortality.
However, risk estimates from studies focusing on cohorts of workers
from different industries cannot be directly compared (OSHA 2016a, 81
FR 16286, 16397).
a. Silicosis Mortality: Mannetje et al. (2002b); ToxaChemica,
International, Inc. (2004)
Mannetje et al. (2002b) relied upon the epidemiological studies
contained within the Steenland et al. (2001a) pooled analysis of lung
cancer mortality that also included extensive data on silicosis. The
six cohorts included:
(1) U.S. diatomaceous earth workers (Checkoway et al., 1997),
(2) Finnish granite workers (Koskela et al., 1994),
(3) U.S. granite workers (Costello and Graham, 1988),
(4) U.S. industrial sand workers (Steenland and Sanderson, 2001),
(5) U.S. gold miners (Steenland and Brown, 1995b), and
(6) Australian gold miners (de Klerk and Musk, 1998).
These six cohorts contained 18,364 workers and 170 silicosis
deaths, where silicosis mortality was defined as death from silicosis
(ICD-9 502, n=150) or from unspecified pneumoconiosis (ICD-9 505,
n=20). Table VI-3 provides information on each cohort, including size,
time period studied, overall number of deaths, and number of deaths
identified as silicosis for the pooled analysis conducted by Mannetje
et al. (2002b). The authors stated this definition may have
underestimated the number of silicosis deaths some of which may have
been misclassified as other causes (e.g., tuberculosis or COPD without
mention of pneumoconiosis). Four cohorts were not included in the
silicosis mortality study. The three Chinese studies did not use the
ICD to code cause of death. In the South African gold miner study,
silicosis was not generally recognized as an underlying cause of death.
Thus, it did not appear on death certificates (OSHA, 2013b, page 292).
[[Page 28261]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.143
Mannetje et al. (2002a) described the exposure assessments
developed for the pooled analysis. Exposure information from each of
the 10 cohort studies varied and included dust measurements
representing particle counts, mass of total dust, and respirable dust
mass. Measurement methods also changed over time for each of the cohort
studies. Generally, sampling was performed using impingers in earlier
decades, and gravimetric techniques later. Exposure data based on
analysis for respirable crystalline silica by XRD (the current method
of choice) were available only from the study of U.S. industrial sand
workers. To develop cumulative exposure estimates for all cohort
members and to pool the cohort data, all exposure data were converted
to units of [micro]g/m\3\ (mg/m\3\) respirable crystalline silica.
Cohort-specific conversion factors were generated based on the silica
content of the dust to which workers were exposed. In some instances,
results of side-by-side comparison sampling were available. Within each
cohort, available job- or process-specific information on the silica
composition or nature of the dust was used to reconstruct respirable
crystalline silica exposures. Most of the studies did not have exposure
measurements prior to the 1950s. Exposures occurring prior to that time
were estimated either by assuming such exposures were the same as the
earliest recorded for the cohort or by modeling that accounted for
documented changes in dust control measures.
To evaluate the reasonableness of the exposure assessment for the
lung cancer pooled study, Mannetje et al. (2002a) investigated the
relationship between silicosis mortality and cumulative exposure. They
performed a nested case-control analysis for silicosis or unspecified
pneumoconiosis using conditional logistic regression. Since exposure to
respirable crystalline silica is the sole cause of silicosis, any
finding for which cumulative exposure was unrelated to silicosis
mortality risk would suggest that serious misclassification of the
exposures assigned to cohort members occurred. Cases and controls were
matched for race, sex, age (within 5 years), and 100 controls were
matched to each case. Each cohort was stratified into quartiles by
cumulative exposure. Standardized rate ratios (SRRs) were calculated
using the lowest-exposure quartile as the baseline. Odds ratios (ORs)
were also calculated for the pooled data set overall, which was
stratified into quintiles based on cumulative exposure. For the pooled
data set, the relationship between the ORs for silicosis mortality and
cumulative exposure, along with each of the 95 percent confidence
intervals (95% CI), were as follows:
(1) 4,450 [micro]g/m\3\-years (4.45 mg/m\3\-years), OR=3.1 (95% CI:
2.5-4.0);
(2) 9,080 [micro]g/m\3\-years (9.08 mg/m\3\-years), OR=4.6 (95% CI:
3.6-5.9);
(3) 16,260 [micro]g/m\3\-years (16.26 mg/m\3\-years), OR=4.5 (95%
CI: 3.5-5.8); and
(4) 42,330 [micro]g/m\3\-years (42.33 mg/m\3\-years), OR=4.8 (95%
CI: 3.7-6.2).
In addition, in seven of the cohorts, there was a statistically
significant trend between silicosis mortality and cumulative exposure.
For two of the cohorts (U.S. granite workers and U.S. gold miners), the
trend test was not statistically significant (p=0.10). An analysis
could not be performed on the South African gold miner cohort because
silicosis was never coded as an underlying cause of death, apparently
due to coding practices in that country.
Based on this analysis, Mannetje et al. (2002a) concluded that the
exposure-response relationship for the pooled data set was ``positive
and reasonably monotonic.'' That is, the response increased with
increasing exposure. The results also indicated that the exposure
assessments provided reasonable estimates of cumulative exposures. In
addition, despite some large differences in the range of cumulative
exposures between cohorts, a clear positive exposure-response trend was
evident in seven of the cohorts (OSHA, 2013b, page 271).
Furthermore, in their pooled analysis of silicosis mortality for
six of the cohorts, Mannetje et al. (2002b) found a clear and
consistently positive response with increasing decile of cumulative
exposure, although there was an anomaly in the 9th decile. Overall,
these data supported a monotonic exposure-
[[Page 28262]]
response relationship for silicosis. Although some exposure
misclassification almost certainly existed in the pooled data set, the
authors concluded that exposure estimates did not appear to have been
sufficiently misclassified to obscure an exposure-response relationship
(OSHA, 2013b, page 271).
As part of an uncertainty analysis conducted for OSHA, Drs.
Steenland and Bartell (ToxaChemica International, Inc., 2004) examined
the quality of the original data set and analysis to identify and
correct any data entry, programming, or reporting errors (ToxaChemica
International, Inc., 2004). This quality assurance process revealed a
small number of errors in exposure calculations for the originally
reported results. Primarily, these errors resulted from rounding of job
class exposures when converting the original data file for use with a
different statistical program. Although the corrections affected some
of the exposure-response models for individual cohorts, ToxaChemica
International, Inc. (2004) reported that models based on the pooled
dataset were not impacted by the correction of these errors (OSHA,
2013b, pages 271-272).
Silicosis mortality was evaluated using standard life table
analysis in Mannetje et al. (2002b). Poisson regression, using 10
categories of cumulative exposure and adjusting for age, calendar time,
and cohort, was conducted to derive silicosis mortality rate ratios
using the lowest exposure group of 0-100 [micro]g/m\3\-years (0-0.1 mg/
m\3\-year) as the referent group. More detailed exploration of the
exposure-response relationship using a variety of exposure metrics,
including cumulative exposure, duration of exposure, average exposure
(calculated as cumulative exposure/duration), and the log
transformations of these variables, was conducted via nested case-
control analyses (conditional logistic regression). Each case was
matched to 100 controls selected from among those who had survived to
at least the age of the case, with additional matching on cohort, race,
sex, and date of birth within 5 years. The authors explored lags of 0,
5, 10, 15, and 20 years, noting that there is no a priori reason to
apply an exposure lag, as silicosis can develop within a short period
after exposure. However, a lag could potentially improve the model, as
there is often a considerable delay in the development of silicosis
following exposure. In addition to the parametric conditional logistic
regression models, the authors performed some analyses using a cubic-
spline model, with knots at 5, 25, 50, 75, and 95 percent of the
distribution of exposure. Models with cohort-exposure interaction terms
were fit to assess heterogeneity between cohorts (OSHA, 2013b, page
294).
The categorical analysis found a nearly monotonic increase in
silicosis rates with cumulative exposure, from 4.7 per 100,000 person-
years in the lowest exposure category (0-990 [micro]g/m\3\-years [0-
0.99 mg/m\3\-years]) to 299 per 100,000 person-years in the highest
exposure category (>28,000 [micro]g/m\3\-years [>28 mg/m\3\-years]).
Nested case-control analyses showed a significant association between
silicosis mortality and cumulative exposure, average exposure, and
duration of exposure. The best-fitting conditional logistic regression
model used log-transformed cumulative exposure with no exposure lag,
with a model [chi]\2\ of 73.2 versus [chi]\2\ values ranging from 19.9
to 30.9 for average exposure, duration of exposure, and untransformed
cumulative exposure (1 degree of freedom). No significant heterogeneity
was found between individual cohorts for the model based on log-
cumulative exposure. The cubic-spline model did not improve the model
fit for the parametric logistic regression model using the log-
cumulative exposure (OSHA, 2013b, page 294).
Mannetje et al. (2002b) developed estimates of silicosis mortality
risk through age 65 for two levels of exposure (50 and 100 [micro]g/
m\3\ respirable crystalline silica), assuming a working life of
occupational exposure from age 20 to 65. Risk estimates were calculated
based on the silicosis mortality rate ratios derived from the
categorical analysis described above. The period of time over which
workers' exposures and risks were calculated (age 20 to 65) was divided
into one-year intervals. The mortality rate used to calculate risk in
any given interval was dependent on the worker's cumulative exposure at
that time. The equation used to calculate risk is as follows:
[GRAPHIC] [TIFF OMITTED] TR18AP24.080
Where timei is equal to 1 year for every age i, and ratei is the age-,
calendar time-, and cohort adjusted silicosis mortality rate associated
with the level of cumulative exposure acquired at age i, as presented
in Mannetje et al. (2002b, Table 2, page 725). The calculated absolute
risks equal the excess risks since there is no background rate of
silicosis in the exposed population. Mannetje et al. (2002b) estimated
the lifetime risk of death from silicosis, assuming 45 years of
exposure to 100 [micro]g/m\3\, to be 13 deaths per 1,000 workers; at an
exposure of 50 [micro]g/m\3\, the estimated lifetime risk was 6 per
1,000. Confidence intervals (CIs) were not reported (OSHA, 2013b, page
295).
In summary, OSHA's estimates of silicosis morbidity risks were
based on studies of active and retired workers for which exposure
histories could be constructed and chest X-ray films could be evaluated
for signs of silicosis. MSHA agrees with OSHA's estimate of silicosis
morbidity risks.
There is evidence in the record that chest X-ray films are
relatively insensitive to detecting lung fibrosis (OSHA 2016a, 81 FR
16286, 16397). Hnizdo et al. (1993) found chest X-ray films to have low
sensitivity for detecting lung fibrosis related to initial cases of
silicosis, compared to pathological examination at autopsy. To address
the low sensitivity of chest X-rays for detecting silicosis, Hnizdo et
al. (1993) recommended that radiographs consistent with an ILO category
of 0/1 or greater be considered indicative of silicosis among workers
exposed to a high concentration of respirable crystalline silica-
containing dust. In like manner, to maintain high specificity, chest X-
rays classified as category 1/0 or 1/1 should be considered as a
positive diagnosis of silicosis in miners who work in low dust (0.2 mg/
m\3\) occupations. The studies on which OSHA relied in its risk
assessment typically used an ILO category of 1/0 or greater to identify
cases of silicosis. According to Hnizdo et al. (1993), they were
unlikely to have included many false positives (i.e., assumed diagnosis
of silicosis in a miner without the disease), but may have included
false negatives (i.e., failure to identify cases of silicosis). Thus,
in OSHA's risk assessment, the use of chest X-rays to
[[Page 28263]]
ascertain silicosis cases in the morbidity studies may have
underestimated risk given the X-rays' low sensitivity to detect
disease. MSHA agrees with OSHA's assessment.
To estimate the risk of silicosis mortality at the then existing
and then proposed exposure limits, OSHA used the categorical model
described by Mannetje et al. (2002b) but did not rely upon the Poisson
regression in their study. Instead, OSHA used rate ratios estimated
from a nested case-control design implemented as part of a sensitivity
analysis (ToxaChemica International, Inc., 2004). The case-control
design was selected because it was expected to better control for age.
In addition, the rate ratios derived from the case control study were
derived from a Monte Carlo analysis to reflect exposure measurement
uncertainty (See ToxaChemica International, Inc. (2004), Table 7, page
40). The rate ratio for each interval of cumulative exposure was
multiplied by the annual silicosis rate assumed to be associated with
the lowest exposure interval, 4.7 per 100,000 for exposures of 990
[micro]g/m\3\-years (0.99 mg/m\3\-years), to estimate the silicosis
rate for each interval of exposure. The lifetime silicosis mortality
risk is the sum of the silicosis rate for each year of life through age
85 and assuming exposure from age 20 to 65. From this analysis, OSHA
estimated the silicosis mortality risk for exposure to the then
existing general industry exposure limit (100 [micro]g/m\3\) and then
proposed exposure limit (50 [micro]g/m\3\) to be 11 (95% CI 5-37) and 7
(95% CI 3-21) deaths per 1,000 workers, respectively. For exposure to
250[micro]g/m\3\ (0.25 mg/m\3\) and 500 [micro]g/m\3\ (0.5 mg/m\3\),
the range approximating the then existing construction/shipyard
exposure limit, OSHA estimated the risk to range from 17 (95% CI 5-66)
to 22 (95% CI 6-85) deaths per 1,000 workers (OSHA, 2013b, page 294-
295).
In view of the aforementioned discussion, MSHA agrees with OSHA's
analysis, and MSHA also selected the Mannetje et al. (2002b) study for
estimating silicosis mortality risks and cases. MSHA used a life table
analysis to estimate the lifetime excess silicosis mortality through
age 80. To estimate the age-specific risk of silicosis mortality at the
existing standards, the new PEL, and the action level, MSHA used the
same categorical model that OSHA used in their PQRA (as described above
from Mannetje et al., 2002b; ToxaChemica International, Inc., 2004) to
estimate lifetime risk following cumulative exposure of 45 years. MSHA
used the 2018 all-cause mortality rates (NCHS, Underlying Cause of
Death, 2018 on CDC WONDER Online Database, released in 2020b) as all-
cause mortality rates. As stated previously, the general (unexposed)
population is assumed to have silicosis mortality rates equal to zero.
In response to MSHA's question about the PRA in the proposed rule,
the NVMA cited a 2021 study examining silica exposure in artificial
stone workers, which this commenter asserted found higher prevalence of
silicosis amongst those who did not use personal protective equipment
(PPE) and amongst tobacco users (Requena-Mullor et al., 2021) (Document
ID 1441). This commenter continued that wearing respirators is a
beneficial aid in protecting workers and that other technological
advances in the mining industry have reduced exposures to respirable
crystalline silica. However, this commenter did not elaborate on how
the cited study or the technological advances within the industry
relate to MSHA's risk analysis or whether the commenter believes the
presented information indicate any weaknesses or shortcomings in MSHA's
modeling. Further, the particular study this commenter cited did not
find a statistically significant difference between tobacco users and
non-tobacco users (Requena-Mullor et al., 2021).
MSHA acknowledges that the relationship between exposure to
respirable crystalline silica and silicosis may be confounded by
several variables, including smoking. However, confounders are
discussed in the FRA and were considered by the original authors of the
studies MSHA selected for modeling. Park et al. (2002), which MSHA used
to model NMRD mortality, fit a model that was stratified on smoking
status. Mannetje et al. (2002b) did not account for smoking but noted
that ``no effect of smoking was detected in a study of Colorado
miners.'' Moreover, the Mannetje et al. (2002b) model was used to
determine how many of the NMRD deaths were attributable to silicosis as
opposed to other forms of NMRD. The total estimate for NMRD deaths
including silicosis is based on Park et al. (2002), which did account
for smoking status. Buchanan et al. (2003), which MSHA used to estimate
silicosis morbidity, originally included smoking status as a covariate,
but the authors removed this variable from the final model because it
did not improve the model fit by a statistically significant amount.
Further, regarding the commenter's assertion that technological
advancements in the mining industry may reduce exposure levels, these
reductions are accounted for in the models, which use recent exposure
data.
b. NMRD Mortality: Park et al. (2002)
In addition to causing silicosis, exposure to respirable
crystalline silica causes increased risks of other NMRD. These include
chronic obstructive pulmonary disease (COPD), which includes chronic
bronchitis, emphysema, and combinations of the two, and is a cause of
chronic airways obstruction. COPD is characterized by airflow
limitation that is usually progressive and not fully reversible. OSHA
reviewed several studies of NMRD morbidity and used a study by Park et
al. (2002) to assess NMRD risk. Checkoway et al. (1997) originally
studied a California diatomaceous earth cohort for which Park et al.
(2002) then analyzed the effect of respirable crystalline silica
exposures on the development of NMRD. The authors quantified the
relationship between exposure to cristobalite and mortality from NMRD
(OSHA, 2013b, page 295).
The California diatomaceous earth cohort consisted of 2,570
diatomaceous earth workers employed for 12 months or more from 1942 to
1994. As noted above, Park et al. (2002) was interested in the
relationship between cristobalite exposure and mortality from chronic
lung disease other than cancer (LDOC). LDOC included chronic diseases
such as pneumoconiosis (which included silicosis), chronic bronchitis,
and emphysema, but excluded pneumonia and other infectious diseases.
The researchers selected LDOC as the health endpoint for three reasons.
First, increased mortality from LDOC had been documented among
respirable crystalline silica-exposed workers in several industry
sectors, including gold mining, pottery, granite, and foundry
industries. Second, the authors pointed to the likelihood that
silicosis as a cause of death is often misclassified as emphysema or
chronic bronchitis. Third, the number of deaths from the diatomaceous
earth worker cohort that were attributed to silicosis was too small
(10) for analysis. Industrial hygiene data for the cohort were
available from the employer for total dust, respirable crystalline
silica (mostly cristobalite), and asbestos. Smoking information was
available for about 50 percent of the cohort and for 22 of the 67 LDOC
deaths available for analysis, permitting Park et al. (2002) to
partially adjust for smoking (OSHA, 2013b, pages 295-296).
Park et al. (2002) used the exposure assessment previously reported
by Seixas et al. (1997) and used by Rice et al. (2001) to estimate
cumulative
[[Page 28264]]
respirable crystalline silica exposures for each worker in the cohort
based on detailed work history files. The average respirable
crystalline silica concentration for the cohort was 290 [micro]g/m\3\
(0.29 mg/m\3\) over the period of employment (Seixas et al., 1997). The
total respirable dust concentration in the diatomaceous earth plant was
3,550 [micro]g/m\3\ (3.55 mg/m\3\) before 1949 and declined by more
than 10-fold after 1973, to 290 [micro]g/m\3\ (0.29 mg/m\3\) (Seixas et
al., 1997). The concentration of respirable crystalline silica in the
dust ranged from 1 to 25 percent and was dependent on the location
within the worksite. It was lowest at the mine and greatest in the
plant where the raw ore was calcined into final product. The average
cumulative exposure values for total respirable dust and respirable
crystalline silica were 7,310 [micro]g/m\3\-year (7.31 mg/m\3\-year)
and 2,160 [micro]g/m\3\-year (2.16 mg/m\3\-year), respectively. The
authors also estimated cumulative exposure to asbestos (OSHA, 2013b,
page 296).
Using Poisson regression models and Cox proportional hazards
models, the authors fit the same series of relative rate exposure-
response models that were evaluated by Rice et al. (2001) for lung
cancer (i.e., log-linear, log-square root, log-quadratic, linear
relative rate, a power function, and a shape function). In general
form, the relative rate model was:
Rate = exp(a0) x [fnof](E),
where exp(a0) is the background rate and E is the cumulative
respirable crystalline silica exposure. Park et al. (2002) also
employed an additive excess rate model of the form:
Rate = exp(a0) + exp(aE),
Relative or excess rates were modeled using internal controls and
adjusting for age, calendar time, ethnicity, and time since first entry
into the cohort. In addition, relative rate models were evaluated using
age- and calendar time-adjusted external standardization to U.S.
population mortality rates for 1940 to 1994 (OSHA, 2013b, page 296).
There were no LDOC deaths recorded among workers having cumulative
exposures above 32,000 [micro]g/m\3\-years (32 mg/m\3\-years), causing
the response to level off or decline in the highest exposure range. The
authors believed the most likely explanation for this observation
(which was also observed in their analysis of silicosis morbidity in
this cohort) was some form of survivor selection, possibly smokers or
others with compromised respiratory function leaving work involving
extremely high dust concentrations. These authors suggested several
alternative explanations. First, there may have been a greater
depletion of susceptible populations in high dust areas. Second, there
may have been greater misclassification of exposures in the earlier
years where exposure data were lacking (and when exposures were
presumably the highest) (OSHA, 2013b, pages 296-297).
Therefore, Park et al. (2002) performed exposure-response analyses
that restricted the dataset to observations where cumulative exposures
were below 10,000 [micro]g/m\3\-years (10 mg/m\3\-years). This is a
level more than four times higher than that resulting from 45 years of
exposure to the former OSHA PEL for cristobalite (which was 50
[micro]g/m\3\ (0.05 mg/m\3\) when cristobalite was the only polymorph
present). These researchers also conducted analyses using the full
dataset (OSHA, 2013b, page 297).
Model fit was assessed by evaluating the decrease in deviance
resulting from addition of the exposure term, and cubic-spline models
were used to test for smooth departures from each of the model forms
described. Park et al. (2002) found that both lagged and unlagged
models fit well, but unlagged models provided a better fit. In
addition, they believed that unlagged models were biologically
plausible in that recent exposure could contribute to LDOC mortality.
The Cox proportional hazards models yielded results that were similar
to those from the Poisson analysis. Consequently, only the results from
the Poisson analysis were reported. In general, the use of external
adjustments for age and calendar time yielded considerably improved fit
over models using internal adjustments. The additive excess rate model
also proved to be clearly inferior compared to the relative rate
models. With one exception, the use of cumulative exposure as the
exposure metric consistently provided better fits to the data than did
intensity of exposure (i.e., cumulative exposure divided by duration of
exposure). As to the exception, when the highest-exposure cohort
members were included in the analysis, the log-linear model produced a
significantly improved fit with exposure intensity as the exposure
metric, but a poor fit with cumulative exposure as the metric (OSHA,
2013b, page 297).
Among the models based on the restricted dataset [excluding
observations with cumulative exposures greater than 10,000 [micro]g/
m\3\-years (10 mg/m\3\-years)], the best-fitting model with a single
exposure term was the linear relative rate model using external
adjustment. Most of the other single-term models using external
adjustment fit almost as well. Of the models with more than one
exposure term, the shape model provided no improvement in fit compared
with the linear relative rate model. The log-quadratic model fit
slightly better than the linear relative rate model, but Park et al.
(2002) did not consider the gain in fit sufficient to justify an
additional exposure term in the model (OSHA, 2013b, page 297).
Based on its superior fit to the cohort data, Park et al. (2002)
selected the linear relative rate model with external adjustment and
use of cumulative exposure as the basis for estimating LDOC mortality
risks among exposed workers. Competing mortality was accounted for
using U.S. death rates published by the National Center for Health
Statistics (1996). The authors estimated the lifetime excess risk for
white men exposed to respirable crystalline silica (mainly
cristobalite) for 45 years at 50 [micro]g/m\3\ (0.05 mg/m\3\) to be 54
deaths per 1,000 workers (95% CI: 17-150) using the restricted dataset,
and 50 deaths per 1,000 using the full dataset. For exposure to 100
[micro]g/m\3\ (0.1 mg/m\3\), they estimated 100 deaths per 1,000 using
the restricted dataset, and 86 deaths per 1,000 using the full dataset.
The CIs were not reported (OSHA, 2013b, page 297).
The estimates of Park et al. (2002) were about eight to nine times
higher than those that were calculated for the pooled analysis of
silicosis mortality (Mannetje et al., 2002b). Also, these estimates are
not directly comparable to those from Mannetje et al. (2002b) because
the mortality endpoint for the Park et al. (2002) analysis was death
from all non-cancer lung diseases beyond silicosis (including
pneumoconiosis, emphysema, and chronic bronchitis). In the pooled
analysis by Mannetje et al. (2002b), only deaths coded as silicosis or
other pneumoconiosis were included (OSHA, 2013b, pages 297-298).
Less than 25 percent of the LDOC deaths in the Park et al. (2002)
analysis were coded as silicosis or other pneumoconiosis (15 of 67). As
noted by Park et al. (2002), it is likely that silicosis as a cause of
death is often misclassified as emphysema or chronic bronchitis
(although COPD is part of the spectrum of disease caused by respirable
crystalline silica exposure and can occur in the absence of silicosis).
Thus, the selection of deaths by Mannetje et al. (2002b) may have
underestimated the true risk of silicosis mortality. The analysis by
Park et al. (2002) would have more fairly captured the total
respiratory mortality risk from all non-malignant causes, including
[[Page 28265]]
silicosis and chronic obstructive pulmonary disease. Furthermore, Park
et al. (2002) used untransformed cumulative exposure in a linear model
compared to the log-transformed cumulative exposure metric used by
Mannetje et al. (2002b). This would have caused the exposure-response
relationship to flatten in the higher exposure ranges (OSHA, 2013b,
page 298).
It is also possible that some of the difference between Mannetje et
al.'s (2002b) and Park et al.'s (2002) risk estimates reflected factors
specific to the nature of exposure among diatomaceous earth workers
(e.g., exposure to cristobalite vs. quartz). However, neither the
cancer risk assessments nor assessments of silicosis morbidity
supported the hypothesis that cristobalite is more hazardous than
quartz (OSHA, 2013b, page 298).
Based on the available risk assessments for silicosis mortality,
OSHA believed that the estimates from the pooled study by Mannetje et
al.'s (2002b) likely underestimated mortality risk given that the study
only counted deaths where silicosis was specifically identified on
death certificates, which are prone to misclassification. In contrast,
the risk estimates provided by Park et al. (2002) for the diatomaceous
earth cohort would have captured some of this misclassification and
included risks from other lung diseases (e.g., emphysema, chronic
bronchitis) that have been associated with respirable crystalline
silica exposure. Therefore, OSHA believed that the Park et al. (2002)
study provided a better basis for estimating the respirable crystalline
silica-related risk of NMRD mortality, including that from silicosis.
Based on Park et al.'s (2002) linear relative rate model [RR = 1 +
[beta]x, where [beta] = 0.5469 (no standard error reported) and x =
cumulative exposure], OSHA used a life table analysis to estimate the
lifetime excess NMRD mortality through age 85. For this analysis, OSHA
used all-cause and cause-specific background mortality rates for all
males (National Center for Health Statistics, 2009). Background rates
for NMRD mortality were based on rates for ICD-10 codes J40-J47
(chronic lower respiratory disease) and J60-J66 (pneumoconiosis). OSHA
believed that these corresponded closely to the ICD-9 disease classes
(ICD 490-519) used by the original researchers. According to CDC
(2001), background rates for chronic lower respiratory diseases were
increased by less than five percent because of the reclassification to
ICD-10. From the life table analysis, OSHA estimated that the excess
NMRD risk due to respirable crystalline silica exposure at the former
general industry PEL (100 [micro]g/m\3\) and at OSHA's final PEL (50
[micro]g/m\3\) for 45 years are 83 and 43 deaths per 1,000,
respectively. For exposure at the former construction/shipyard exposure
limit, OSHA estimated that the excess NMRD risk ranged from 188 to 321
deaths per 1,000 (OSHA, 2013b, page 298).
Following its own independent review, MSHA agrees with and has
followed the rationale presented by OSHA in its selection of the Park
et al. (2002) model to estimate NMRD mortality risk in miners.
MSHA used a life table analysis to estimate the lifetime excess
NMRD mortality through age 80. MSHA used the Park et al. (2002) model
to estimate age-specific NMRD mortality risk as 1 + 0.5469 * cumulative
exposure. MSHA used all-cause and cause-specific background mortality
rates for all males for 2018 (National Center for Health Statistics,
Underlying Cause of Death 2018 on CDC WONDER Online Database, released
in 2020b). Background rates for NMRD mortality were based on rates for
ICD-10 codes J40-J47 (chronic lower respiratory disease) and J60-J66
(pneumoconiosis).
A state mining association cited CDC data to state that the largest
decrease in pneumoconiosis deaths over the 1999-2018 time period was in
the coal mining industry, with a decrease of 69.6 percent, and the
largest increase was in the OSHA construction sector (Bell and Mazurek,
2020) (Document ID 1368). This commenter also stated that, beyond the
CDC data, there is little understanding of pneumoconiosis case
attribution, such as what percentage of cases were specifically due to
mining-related employment compared to non-mining activities that might
lead to harmful exposure. The commenter's point that it is difficult to
correctly attribute pneumoconiosis is precisely why MSHA's FRA has
relied on peer-reviewed epidemiological studies, which control for
confounders where necessary and quantify the precise exposure-response
relationship. Regarding pneumoconiosis, the cited article was about
declining pneumoconiosis deaths in particular. Other sources, including
analysis by NIOSH, show that the prevalence of pneumoconiosis illness
has risen substantially among miners since the 1990s (NIOSH, 2021d).
This same trend in pneumoconiosis illness among coal miners was also
mentioned by three other commenters--the ACLC, Appalachian Voices, and
the UMWA (Document ID 1445; 1425; 1398). While it may be true that
prevalence of pneumoconiosis deaths decreased among the entire U.S.
population during this period, trends in pneumoconiosis deaths tend to
lag trends in pneumoconiosis illness because people can live many years
with the disease prior to death. The increasing prevalence of the
illness among miners indicates that pneumoconiosis deaths also are
expected to rise in the future. In addition, trends among the full U.S.
population may not reflect trends among miners in particular, since the
mining workforce has decreased in size since the 1990s. Thus, MSHA does
not believe that pneumoconiosis illnesses or deaths among coal miners
would decline in the future in the absence of this rule and, therefore,
affirms that the final rule is needed to protect the health of all
miners from various respirable crystalline silica-related diseases.
4. Lung Cancer Mortality
Since the publication of OSHA's final rule in 2016, NIOSH has
published two documents concerning occupational carcinogens, Chemical
Carcinogen Policy (2017b) and Practices in Occupational Risk Assessment
(2019a). NIOSH will no longer set recommended exposure levels for
occupational carcinogens. Instead, NIOSH intends to develop risk
management limits for carcinogens (RML-Cas) to acknowledge that, for
most carcinogens, there is no known safe level of exposure. An RML-CA
is a reasonable starting place for controlling exposures. An RML-CA
limit is based on a daily maximum 8-hour TWA concentration of a
carcinogen above which a worker should not be exposed (NIOSH, 2017b,
page vi). RML-Cas for occupational carcinogens are established at the
estimated 95% lower confidence limit on the concentration (e.g., dose)
corresponding to 1 in 10,000 (10-4) lifetime excess risk
(when analytically possible to measure) (NIOSH, 2019a). NIOSH stated
that in order to incrementally move toward a level of exposure to
occupational chemical carcinogens that is closer to background, NIOSH
will begin issuing recommendations for RML-Cas that would advise
employers to take additional action to control chemical carcinogens
when workplace exposures result in excess risks greater than
10-4 (NIOSH, 2017b, page vi).
MSHA used the Miller et al. (2007) and Miller and MacCalman (2010)
studies to estimate lung cancer mortality risk in miners. In British
coal miners, excess lung cancer mortality was studied through the end
of 2005 in a cohort of 17,800 miners (Miller et al., 2007; Miller and
MacCalman, 2010). By that time, the cohort had accumulated
[[Page 28266]]
516,431 person-years of observation (an average of 29 years per miner),
with 10,698 deaths from all causes. Overall lung cancer mortality was
elevated (Standard Mortality Ratio (SMR) = 115.7, 95% CI: 104.8-127.7),
and a positive exposure-response relationship with respirable
crystalline silica exposure was determined from Cox regression after
adjusting for smoking history. Three strengths of this study were: (1)
the detailed time-exposure measurements of quartz and total mine dust,
(2) detailed individual work histories, and (3) individual smoking
histories. For lung cancer, analyses based on Cox regression provided
strong evidence that, for these coal miners, although quartz exposures
were associated with increased lung cancer risk, simultaneous exposures
to coal dust did not cause increased lung cancer risk (OSHA 2016a, 81
FR 16286, 16308).
Miller et al. (2007) and Miller and MacCalman (2010) conducted a
follow-up study of cohort mortality, begun in 1970. Their previous
report on mortality presented a follow-up analysis on 18,166 coal
miners from 10 British coal mines followed through the end of 1992
(Miller et al., 1997). The 2 reports from 2007 and 2010 analyzed the
mortality experience of 17,800 of these miners (18,166 minus 346 men
whose vital status could not be determined) and extended the analysis
through the end of 2005. Causes of deaths that were of particular
interest included pneumoconiosis, other NMRD, lung cancer, stomach
cancer, and tuberculosis. The researchers noted that no additional
exposure measurements were included in the updated analysis, since all
the mines had closed by the mid-1980s. However, some of these men might
have had additional exposure at other mines or facilities not reported
in this study (OSHA, 2013b, page 287).
This cohort mortality study used Cox proportional hazards
regression methods which controlled for a variety of external and
internal factors. The external controls included British administrative
regional age-, time-, and cause-specific mortality rates from which to
calculate SMRs. The internal controls included each miner's age,
smoking status, and detailed dust and respirable crystalline silica
(quartz) time-dependent exposure measurements. Cox regression analyses
were done in stages, with the initial analyses used to establish what
factors were required for baseline adjustment (OSHA, 2013b, page 287).
For the analysis using external mortality rates, the all-cause
mortality SMR from 1959 through 2005 was 100.9 (95% CI: 99.0-102.8),
based on all 10,698 deaths. However, these SMRs were not uniform over
time. For the period from 1990-2005, the SMR was 109.6 (95% CI:106.5-
112.8), while the ratios for previous periods were less than 100. This
pattern of increasing SMRs in the recent past was also seen for cause-
specific deaths from chronic bronchitis, SMR = 330.0 (95% CI:268.1-
406.2); tuberculosis, SMR = 193.4 (95% CI: 86.9-430.5); cardiovascular
disease, SMR = 106.6 (95% CI: 102.0-111.5); all cancers, SMR = 107.1
(95% CI:101.3-113.2); and lung cancer, SMR = 115.7 (95% CI: 104.8-
127.7). The SMR for NMRD was 142.1 (95% CI: 132.9-152.0) in this recent
period and remained highly statistically significant. In their previous
analysis on mortality from lung cancer, reflecting follow-up through
1995, Miller et al. (1997) had not found any increase in the risk of
lung cancer mortality (OSHA, 2013b, page 287).
OSHA reported that Miller and MacCalman (2010) used these analyses
to estimate relative risks for a lifetime exposure of 5 gram-hours/m\3\
(ghm-3) to quartz (OSHA, 2013b, page 288). This is
equivalent to approximately 55 [micro]g/m\3\ (0.055 mg/m\3\) for 45
years, assuming 2,000 hours per year of exposure and/or 100
ghm-3 total dust. The authors estimated relative risks (see
Miller and MacCalman (2010), Table 4, page 9) for various causes of
death including pneumoconiosis, COPD, ischemic heart disease, lung
cancer, and stomach cancer. Their results were based on models with
single exposures to dust or respirable crystalline silica (quartz) or
simultaneous exposures to both, with and without 15-year lag periods.
Generally, the risk estimates were slightly greater using a 15-year lag
period.
For the models using only quartz exposures with a 15-year lag,
pneumoconiosis, RR = 1.21 (95% CI: 1.12-1.31); COPD, RR = 1.11 (95% CI:
1.05-1.16); and lung cancer, RR = 1.07 (95% CI: 1.01-1.13) showed
statistically significant increased risks.
For lung cancer, analyses based on these Cox regression methods
provided strong evidence that, for these coal miners, quartz exposures
were associated with increased lung cancer risk, but simultaneous
exposures to coal dust were not associated with increased lung cancer
risk. The relative risk (RR) estimate for lung cancer deaths using coal
dust with a 15-year lag in the single exposure model was 1.03 (95% CI:
0.96 to 1.10). In the model using both quartz and coal mine dust
exposures, the RR based on coal dust decreased to 0.91, while that for
quartz exposure remained statistically significant, increasing to a RR
= 1.14 (95% CI: 1.04 to 1.25). According to Miller and MacCalman
(2010), other analyses have shown that exposure to radon or diesel
fumes was not associated with an increased cancer risk among British
coal miners (OSHA, 2013b, page 288).
The RRs in the Miller and MacCalman (2010) report were used to
estimate excess lung cancer risk for OSHA's purposes. Life table
analyses were done as in the other studies above. Based on the RR of
1.14 (95% CI: 1.04-1.25) for a cumulative exposure of 5
ghm-3, the regression slope was recalculated as [beta] =
0.0524 per 1,000 [micro]g-years (per mg/m-3-years) and used
in the life table program. Similarly, the 95-percent CI on the slope
was 0.0157-0.08926. From this study, the lifetime (to age 85) risk
estimates for 45 years of exposure to 50 [micro]g/m\3\ (0.05 mg/m\3\)
and 100 [micro]g/m\3\ (0.100 mg/m\3\) respirable crystalline silica
were 6 and 13 excess lung cancer deaths per 1,000 workers,
respectively. These lung cancer risk estimates were less by about two-
to four-fold than those estimated from the other cohort studies
described above.
However, three factors might explain these differences. First,
these estimates were adjusted for individual smoking histories so any
smoking-related lung cancer risk (or smoking-respirable crystalline
silica interaction) that might possibly be attributed to respirable
crystalline silica exposure in the other studies was not reflected in
the risk estimates derived from the study of these coal miners. Second,
these coal miners had significantly increased risks of death from other
lung diseases, which may have decreased the lung cancer-susceptible
population. Of note, for example, were the higher increased SMRs for
NMRD during the years 1959-2005 for this cohort (Miller and MacCalman,
2010, Table 2, Page 7). Third, the difference in risk seen in these
coal miners may have been the result of differences in the toxicity of
quartz present in the coal mines as compared to the work environments
of the other cohorts. One Scottish mine (Miller et al., 1998) in this
10-mine study had been cited as having presented ``unusually high
exposures to [freshly fractured] quartz.'' However, this was also
described as an atypical exposure among miners working in the 10 mines.
Miller and MacCalman (2010) stated that increased quartz-related lung
cancer risk in their cohort was not confined to that Scottish mine
alone. They also stated, ``The general nature of some quartz exposures
in later years . . . may have been different from earlier periods when
coal extraction was
[[Page 28267]]
largely manual . . .'' (OSHA, 2013b, page 288).
All these factors in this mortality analysis for the British coal
miner cohort could have combined to yield an underestimation of lung
cancer risk estimates. However, OSHA believed that these coal miner-
derived estimates were credible because of the quality of several study
factors relating to both study design and conduct. In terms of design,
the cohort was based on union rolls with very good participation rates
and good reporting. The study group also included over 17,000 miners,
with an average of nearly 30 years of follow-up, and about 60 percent
of the cohort had died. Just as important was the high quality and
detail of the exposure measurements, both of total dust and quartz.
However, one exposure factor that may have biased the estimates upward
was the lack of exposure information available for the cohort after the
mines closed in the mid-1980s. Since the mortality ratio for lung
cancer was higher during the last study period, 1990-2005, this period
contributed to the increased lung cancer risk. It is possible that any
quartz exposure experienced by the cohort after the mines had closed
could have accelerated either death or malignant tumor (lung cancer)
growth. By not accounting for this exposure, if there was any, the risk
estimates would have been biased upwards. Although the 15-year lag
period for quartz exposure used in the analyses provided slightly
higher risk estimates than use of no lag period, the better fit seen
with the lag may have been artificial. This may have occurred because
there appeared to have been no exposures during the recent period when
risks were seen to have increased (OSHA, 2013b, page 289).
MSHA believes, as OSHA did, that this study of a large British coal
mining cohort provides convincing evidence of the carcinogenicity of
respirable crystalline silica. This large cohort study, with almost 30
years of follow-up, demonstrated a positive exposure-response after
adjusting for smoking histories. Additionally, the authors state that
there was no evidence that exposure to potential confounders such as
radon and diesel exhaust were associated with excess lung cancer risk
(Miller and MacCalman (2010, page 270). MSHA is relying on the British
studies conducted by Miller et al. (2007) as well as Miller and
MacCalman (2010) to estimate the lung cancer risk in all miners.
MSHA found these two studies suitable for use in the quantitative
characterization of health risks to exposed miners for several reasons.
First, their study populations were of sufficient size to provide
adequate statistical power to detect low levels of risk. Second,
sufficient quantitative exposure data were available over a sufficient
span of time to characterize cumulative respirable crystalline silica
exposures of cohort members. Third, the studies either adjusted for or
otherwise adequately addressed confounders such as smoking and exposure
to other carcinogens. Finally, these researchers developed quantitative
assessments of exposure-response relationships using appropriate
statistical models or otherwise provided sufficient information that
permits MSHA to do so.
MSHA implemented the risk model in its life table analysis so that
the use of background rates of lung cancer and assumptions regarding
length of exposure and lifetime were consistent across models. Thus,
MSHA was able to estimate lung cancer risks associated with exposure to
specific levels of respirable crystalline silica of interest to the
Agency. MSHA used the Miller et al. (2007) and Miller and MacCalman
(2010) model to estimate age-specific cumulative lung cancer mortality
risk as EXP(0.0524 * cumulative exposure), lagged 15 years.
MSHA's FRA uses risk estimates derived from 10 coal mines in the
U.K. (Miller et al., 2007; Miller and MacCalman, 2010). These
researchers developed regression analyses for time-dependent estimates
of individual exposures to respirable dust. Their analyses were based
on the detailed individual exposure estimates of the PFR program. To
estimate mortality risk for lung cancer from the pooled cohort
analysis, MSHA used the same life table approach as OSHA. However, for
this life table analysis, MSHA used 2018 mortality rates for U.S. males
(i.e., all-cause and background lung cancer). The 2018 lung cancer
death rates were based on the ICD-10 classification of diseases codes,
C34.0, C34.2, C34.1, C34.3, C34.8, and C34.9. Lifetime risk estimates
reflected excess risk through age 80. To estimate lung cancer risks,
MSHA used the log-linear relative risk model, exp (0.0524 x cumulative
exposure), lagged 15 years. The coefficient for this model was 0.0524
(OSHA, 2013b, page 290).
MSHA's use of Miller and MacCalman (2010) to estimate lung-cancer
mortality risk is in contrast to OSHA's use of Steenland et al. (2001a)
to estimate lung-cancer mortality risk. There are several reasons for
MSHA's use of Miller and MacCalman (2010). First, it covers coal
mining-specific cohort large enough (with 45,000 miners) to provide
adequate statistical power to detect low levels of risk, and it covers
an extended follow-up period (1959-2006). Second, the study provided
data on cumulative exposure of cohort members and adjusted for or
addressed confounders such as smoking and exposure to other
carcinogens. Finally, it developed quantitative assessments of
exposure-response relationships using appropriate statistical models or
otherwise provided sufficient information that permitted MSHA to do so.
NVMA criticized MSHA's reliance on the Miller and MacCalman (2010)
study because, according to the commenter, it primarily focused on coal
miners, does not consider technological advancements in the mining
sector, and is ``insufficient for justifying the implementation of a
rule of this magnitude on MNM mines'' (Document ID1441). Commenters
from the Black Lung Clinics and UMWA were in support of MSHA's use of
Miller and MacCalman (2010) in assessing lung cancer mortality
(Document ID 1410; 1398).
MSHA does not agree that reliance on Miller and MacCalman (2010)
refutes the risk of material impairment of health to MNM miners. MSHA
considered several other studies on lung cancer mortality, which
covered a variety of populations aside from coal miners, including gold
miners, diatomaceous earth workers, granite workers, industrial sand
employees, pottery workers, tin miners, and tungsten miners. As OSHA
showed in its QRA, the estimates from Miller and MacCalman (2010) were
lower by roughly two- to four-fold than the estimates from other cohort
studies. In selecting Miller and MacCalman (2010), MSHA chose a study
that found smaller risks than the other studies. The Miller and
MacCalman (2010) study has many strengths, including the fact that it
had very high participation rates, with over 17,000 miners and nearly
30 years of follow up. In addition to detailed exposure information,
the study also used individual smoking histories to adjust its
estimates for the effect of smoking. Further, exposure changes owing to
technological advancements are accounted for by MSHA's models which use
recent exposure data.
Urging MSHA to lower the PEL to 25 [micro]g/m\3\, the AIHA
commented that the work by Steenland and Sanderson should not be
discounted (Document ID 1351). The commenter said that a 2001 Steenland
and Sanderson study showed a significant increase in mortality risk
from lung cancer at average exposure levels greater than 65 [micro]g/
m\3\, indicating
[[Page 28268]]
that 50 [micro]g/m\3\ would probably not be protective of workers'
health.
MSHA clarifies that, although it departed from OSHA's risk
assessment by using the exposure-response model from Miller and
MacCalman (2010) to assess lung cancer mortality, Steenland and
Sanderson's work was not discounted. MSHA relied on Steenland and
Sanderson in the standalone Health Effects document and the FRA.
Further, MSHA acknowledges that there remains a risk of material
impairment of health at the revised PEL; however, a further reduction
in the PEL is not achievable at all mines (see MSHA's Technological
Feasibility analysis). MSHA concludes that the final PEL will provide a
substantial reduction in the risk of material impairment of health to
miners.
5. ESRD Mortality
Several epidemiological studies have found statistically
significant associations between occupational exposure to respirable
crystalline silica and renal disease, although others have failed to
find a statistically significant association. These studies are
discussed in the standalone Health Effects document (Section 14).
Possible mechanisms suggested for respirable crystalline silica-induced
renal disease included a direct toxic effect on the kidney, deposition
of immune complexes (IgA) in the kidney following respirable
crystalline silica-related pulmonary inflammation, and an autoimmune
mechanism (Gregorini et al., 1993; Calvert et al., 1997; Parks et al.,
1999; Steenland, 2005b) (OSHA 2016a, 81 FR 16286, 16310).
MSHA, like OSHA, chose the Steenland et al. (2002a) study to
include in the FRA. In a pooled cohort analysis, Steenland et al.
(2002a) combined the industrial sand cohort from Steenland et al.
(2001b), the gold mining cohort from Steenland and Brown (1995a), and
the Vermont granite cohort studies by Costello and Graham (1988). All
three were included in portions of OSHA's PQRA for other health
endpoints: under lung cancer mortality in Steenland et al. (2001a) and
under silicosis mortality in the related work of Mannetje et al.
(2002b). In all, the combined cohort consisted of 13,382 workers with
exposure information available for 12,783. The analysis demonstrated
statistically significant exposure-response trends for acute and
chronic renal disease mortality with quartiles of cumulative respirable
crystalline silica exposure (OSHA 2016a, 81 FR 16286, 16310).
The average duration of exposure, cumulative exposure, and
concentration of respirable crystalline silica for the pooled cohort
were 13.6 years, 1,200 [micro]g/m\3\-years (1.2 mg/m-3-
years), and 70 [micro]g/m\3\ (0.07 mg/m\3\), respectively. Renal
disease risk was most prevalent among workers with cumulative exposures
of 500 [micro]g/m\3\ or more (Steenland et al., 2002a). SMRs (compared
to the U.S. population) for renal disease (acute and chronic
glomerulonephritis, nephrotic syndrome, acute and chronic renal
failure, renal sclerosis, and nephritis/nephropathy) were statistically
significant and elevated based on multiple cause of death data (SMR
1.28, 95% CI: 1.10-1.47, 194 deaths) and underlying cause of death data
(SMR 1.41, 95% CI: 1.05-1.85, 51 observed deaths) (OSHA, 2013b, page
315).
A nested case-control analysis was also performed which allowed for
more detailed examination of exposure-response. This analysis included
95 percent of the cohort for which there were adequate work history and
quartz exposure data. This analysis included 50 cases for underlying
cause mortality and 194 cases for multiple-cause mortality. Each case
was matched by race, sex, and age within 5 years to 100 controls from
the cohort. Exposure-response trends were examined in a categorical
analysis where renal disease mortality of the cohort divided by
exposure quartile was compared to U.S. rates (OSHA, 2013b, page 315).
In this analysis, statistically significant exposure-response
trends for SMRs were observed for multiple-cause (p<0.000001) and
underlying cause (p=0.0007) mortality (Steenland et al., 2002a, Table
1, Page 7).
With the lowest exposure quartile group serving as a referent, the
case-control analysis showed monotonic trends in mortality with
increasing cumulative exposure. Conditional regression models using
log-cumulative exposure fit the data better than cumulative exposure
(with or without a 15-year lag) or average exposure. Odds ratios by
quartile of cumulative exposure were 1.00, 1.24, 1.77, and 2.86
(p=0.0002) for multiple cause analyses and 1.00, 1.99, 1.96, and 3.93
for underlying cause analyses (p=0.03) (Steenland et al., 2002a, Table
2, Page 7). For multiple-cause mortality, the exposure-response trend
was statistically significant for cumulative exposure (p=0.004) and
log-cumulative exposure (p=0.0002), whereas for underlying cause
mortality, the trend was statistically significant only for log-
cumulative exposure (p=0.03). The exposure-response trend was
homogeneous across the three cohorts and interaction terms did not
improve model fit (OSHA, 2013b, pages 216, 315).
Based on the exposure-response coefficient for the model with the
log of cumulative exposure, Steenland (2005b) estimated lifetime excess
risks of death (age 75) over a working life (age 20 to 65). At 100
[micro]g/m\3\ (0.1 mg/m\3\) respirable crystalline silica, this risk
was 5.1 percent (95% CI 3.3-7.3) for ESRD based on 23 cases (Steenland
et al., 2001b). It was 1.8 percent (95% CI 0.8-9.7) for kidney disease
mortality (underlying), based on 51 deaths (Steenland et al., 2002a)
above a background risk of 0.3 percent (OSHA, 2013b, page 216).
MSHA notes that these studies added to the evidence that renal
disease is associated with respirable crystalline silica exposure.
Statistically significant increases in odds ratios and SMRs were seen
primarily for cumulative exposures of >500 [micro]g/m\3\-years (0.5 mg/
m\3\-years). Steenland (2005b) noted that this could have occurred from
working for 5 years at an exposure level of 100 [micro]g/m\3\ (0.1 mg/
m\3\) or 10 years at 50 [micro]g/m\3\ (0.05 mg/m\3\).
OSHA had a large body of evidence, particularly from the three-
cohort pooled analysis (Steenland et al., 2002a), on which to conclude
that respirable crystalline silica exposure increased the risk of renal
disease mortality and morbidity. The pooled analysis by Steenland et
al. (2002a) involved a large number of workers from three cohorts with
well-documented, validated job-exposure matrices. These researchers
found a positive, monotonic increase in renal disease risk with
increasing exposure for underlying and multiple cause data. Thus, the
exposure and work history data were unlikely to have been seriously
misclassified. However, there are considerably less data available for
renal disease than there are for silicosis mortality and lung cancer
mortality. Nevertheless, OSHA concluded that the underlying data were
sufficient to provide useful estimates of risk and included the
Steenland et al. (2002a) analysis in its PQRA (OSHA, 2013b, pages 229,
316).
To estimate renal disease mortality risk from the pooled cohort
analysis, OSHA implemented the same life table approach as was done for
the assessments on lung cancer and NMRD. However, for this life table
analysis, OSHA used 1998 all-cause and background renal mortality rates
for U.S. males, rather than the 2006 rates used for lung cancer and
NMRD. The 1998 rates were based on the ICD-9 classification of
diseases, which was the same as used by Steenland et al. (2002a) to
ascertain the cause of death of workers in their study. However, U.S.
[[Page 28269]]
cause-of-death data from 1999 to present are based on the ICD-10, in
which there were considerable changes in the classification system for
renal diseases. According to CDC (2001), the change in the
classification from ICD-9 to ICD-10 increased death rates for
nephritis, nephritic syndrome, and nephrosis by 23 percent, in large
part due to reclassifying ESRD. The change from ICD-9 to ICD-10 did not
materially affect background rates for those diseases grouped as lung
cancer or NMRD. Consequently, OSHA conducted its analysis of excess
renal disease mortality associated with respirable crystalline silica
exposure using background mortality rates for 1998. As before, lifetime
risk estimates reflected excess risk through age 85. To estimate renal
mortality risks, OSHA used the log-linear model with log-cumulative
exposure that provided the best fit to the pooled cohort data
(Steenland et al., 2002a). The coefficient for this model was 0.269
(SE=0.120) (OSHA, 2013b, page 316). Based on the life table analysis,
OSHA estimated that exposure to the former general industry exposure
limit of 100 [micro]g/m\3\ and to the final exposure limit of 50
[micro]g/m\3\ over a working life would result in a lifetime excess
renal disease risk of 39 (95% CI: 2-200) and 32 (95% CI: 1.7-147)
deaths per 1,000, respectively. OSHA also estimated lifetime risks
associated with the former construction and shipyard exposure limits of
250 and 500 [micro]g/m\3\. These lifetime excess risks ranged from 52
(95% CI 2.2-289) to 63 (95% CI 2.5-368) deaths per 1,000 workers (OSHA,
2013b, page 316).
MSHA acknowledges the uncertainty associated with the divergent
findings in the renal disease literature; however, MSHA concludes that
the evidence supporting causality regarding renal risk outweighs the
evidence casting doubt on that conclusion.
Upon reviewing the PRA, the NSSGA commented that it is unclear
whether renal disease is causally related to occupational respirable
crystalline silica exposure (Document ID 1448, Attachment 3). The
commenter cited a 2017 German Federal Institute for Occupational Safety
and Health systematic review and meta-analysis on respirable
crystalline silica and non-malignant renal disease, which concluded
that ``while the studies of cohorts exposed to silica found elevated
SMRs for renal disease, no clear evidence of a dose-response
relationship emerged.'' As detailed above in Section V. Health Effects
Summary and further discussed in MSHA's standalone Health Effects
document, MSHA reviewed a wide variety of studies which suggest that
occupational exposure to respirable crystalline silica increases the
risk of renal disease, including the risk of non-malignant cases. The
Steenland et al. (2002a) study, which was selected for modeling ESRD
risk in the FRA, found a monotonic increase in renal disease risk with
increasing exposures to respirable crystalline silica. MSHA believes
that the Steenland et al. (2002a) study has several strengths,
including (1) a large cohort with well-documented and validated job-
exposure matrices and (2) low risk of bias from exposure
misclassification. The FRA has selected studies for modeling risks
based on a thorough evaluation of each study's methodology. The fact
that other studies (which MSHA did not use for modeling) may have found
significantly elevated mortality ratios but inconclusive exposure-
response relationships does not render invalid the findings or
methodological strengths of Steenland et al. (2002a). Thus, MSHA
concludes that increasing exposure to respirable crystalline silica
increases a miner's risk of renal disease and reaffirms its decision to
model benefits stemming from reductions in ESRD mortality due to the
final rule in the FRA.
To estimate renal disease mortality risk from the pooled cohort
analysis, MSHA implemented the same life table approach as OSHA.
However, MSHA's life table analysis used 2018 all-cause and 1998
background renal mortality rates for U.S. males. The 1998 renal death
rates were based on the ICD-9 classification of diseases, 580-589. This
is the same classification used by Steenland et al. (2002a) to
ascertain the cause of death of workers in their study. Consequently,
MSHA conducted its analysis of excess ESRD mortality risk associated
with exposure to respirable crystalline silica using background ESRD
mortality rates for 1998. The U.S. cause-of-death data from 2018 were
used as well to estimate the rate of death due to all causes among the
unexposed population. Lifetime excess risk estimates reflect the excess
risk through age 80. To estimate ESRD excess mortality risks, MSHA used
the log-linear model with log-cumulative exposure that provided the
best fit to the pooled cohort data (Steenland et al., 2002a), as
EXP(0.269*ln(cumulative exposure)). The coefficient for this model was
0.269 (SE=0.120) (OSHA, 2013b, page 316). 6. Coal Workers'
Pneumoconiosis (CWP) and Progressive Massive Fibrosis (PMF).
Exposure to respirable coal mine dust causes lung diseases
including CWP, emphysema, silicosis, and chronic bronchitis, known
collectively as ``black lung.'' These diseases are debilitating,
incurable, and can result in disability and premature death. There are
no specific treatments to cure CWP or COPD. These chronic effects may
progress even after miners are no longer exposed to coal dust.
MSHA's 2014 Coal Dust Rule quantified benefits among coal miners
related to reduced cases of CWP due to lower exposure limits for
respirable coal mine dust. In the FRA, MSHA has not quantified the
reduction in morbidity risk associated with CWP among coal miners.
Nonetheless, MSHA believes that the final rule would reduce the excess
risk of morbidity from this disease. Many coal miners work extended
shifts, increasing their potential exposure to respirable crystalline
silica; therefore, calculating exposures based on a full-shift 8-hour
TWA would be more protective. Thus, the final rule is expected to
provide additional reductions in CWP risk beyond those ascribed in the
2014 Coal Dust Rule. However, exposure-response relationships based on
respirable crystalline silica exposure are not available for CWP, so
the reductions in this disease due to reductions in silica exposure
cannot be quantified.
In the FRA, PMF deaths are captured in part by silicosis mortality
as defined by Mannetje et al. (2002b). Those PMF deaths not captured by
the definition in Mannetje et al. are likely captured by the definition
of NMRD mortality adopted from Park et al. (2002). Thus, the FRA fully
characterizes the reduction in lifetime cases of PMF mortality
including mortality due to complicated CWP and complicated silicosis.
However, the FRA likely underestimates reduction in PMF morbidity. This
is because the Buchanan et al. (2003) model, which was used to model
silicosis morbidity, likely undercounts PMF due to exclusion of cases
below the threshold of 2/1+ profusion of opacities on a chest X-ray.
While the FRA quantifies reduction in lifetime mortality cases from CWP
and PMF (which are included under NMRD), there are likely additional
unquantified morbidity benefits from CWP and PMF that are not captured.
Finally, the Appalachian Voices expressed concern that the modeling
conducted for the rule does not incorporate data that medical clinics
in Appalachia have reported since 2010 (Document ID 1425). This
commenter stated that, while not all cases can be attributed directly
to silica exposure, reporting over the last 15 years has led medical
experts to believe that silica is a significant driver of the increased
prevalence of severe black lung disease
[[Page 28270]]
in Central Appalachia, and that any rule designed to reduce silica
exposure should consider data from clinics in Central Appalachia to
ensure a more realistic accounting of current morbidity and set a high
goal for future morbidity. This commenter urged MSHA to review data
from black lung clinics in Central Appalachia.
MSHA notes that comprehensive longitudinal clinical outcome data,
paired with exposure histories, are not available for U.S. miners. MSHA
acknowledges that these data would be useful for the purpose of
estimating risk reductions and acknowledges that the exposure-response
models used in this FRA are not based on current disease incidence
among U.S. miners. While clinic data help document pneumoconiosis as an
important problem, these data alone are not sufficient to estimate the
reduction in excess morbidity and mortality that are specifically
attributable to the new PEL. Calculating future miners' reduction in
excess cases from the current disease incidence reported by clinics
would also require those clinic patients' exposure and work histories,
which are not available. Moreover, the data from medical clinics in
Appalachia represent only a portion of miners whose respirable
crystalline silica exposures may have exceeded the existing standard
and who may have worked during a time when the coal mining industry was
larger. The methodology of the FRA is to use peer-reviewed exposure-
response models to estimate avoided excess deaths and illnesses that
are specifically attributable to reducing respirable crystalline silica
exposure from, at most, the existing standard to the new PEL of 50
[mu]g/m\3\. MSHA has not quantified reductions in simple or complicated
CWP morbidity, as an exposure-response model for respirable crystalline
silica and CWP is not available, and this final rule does not regulate
levels of coal dust. Nonetheless, miners will likely see reductions in
CWP risk, including risk of severe forms of CWP such as PMF, due to the
final rule, since respirable crystalline silica exposure may play a
role in development of CWP, and because concentrations of mixed coal
dust may decrease due to this rule. These benefits associated with
reductions in CWP mortality and morbidity are not quantified in the
FRA.
D. Overview of Results
Table VI-4 summarizes the FRA's main results: once all miners and
retirees have only been exposed under the new PEL, the final rule is
expected to result in at least 1,067 avoided deaths and 3,746 avoided
cases of silicosis morbidity among the working and future retired miner
population. This is a change from the PRA, which predicted at least 799
avoided deaths and 2,809 avoided cases of silicosis morbidity in the
working miner population. The increased avoided deaths and cases in the
FRA are the result of changes to MSHA's risk analysis methodology;
specifically, the inclusion of future retired miners. This
methodological change is discussed in detail in the standalone FRA. The
expected reductions in death and illness in the FRA are based on actual
exposure conditions, peer-reviewed exposure-response models, and the
assumption that miners have 45 years of employment under the new PEL
(from the beginning of age 21 through the end of age 65) and 15 years
of retirement (up through the end of age 80). These estimates of the
avoided lifetime excess mortality and morbidity represent the final
calculations based on the five selected models and the observed
exposure data. The first group of miners that will experience the
avoided lifetime deaths and illnesses shown in Table VI-4 is the
population living 60 years after the start of implementation of the
final rule. In other words, this group will only contain miners
exclusively exposed under the final rule for the duration of their
working lives. To calculate benefits associated with the rulemaking,
the economic analysis monetizes avoided deaths and illnesses while
accounting for the fact that, during the first 60 years following the
start of implementation of the final rule, miners will have fewer
avoided lifetime deaths and illnesses because they will have been
exposed under both the existing standards and the new PEL.
[GRAPHIC] [TIFF OMITTED] TR18AP24.144
Table VI-5 summarizes miners' expected percentage reductions in
lifetime excess risk of developing or dying from certain diseases due
to their reduced respirable crystalline silica exposure expected to
result from implementation of the final rule. The lifetime excess risk
reflects the probability of developing or dying from diseases over a
maximum lifetime of 45 years of exposure during employment and 15 years
of retirement.\25\ The excess
[[Page 28271]]
risk reduction compares (a) miners' excess health risks associated with
respirable crystalline silica exposure at the limits included in MSHA's
existing standards to (b) miners' excess health risks associated with
exposure at this standard's new PEL. MSHA expects full-scale
implementation to reduce lifetime excess mortality risk by 9.5 percent
and to reduce lifetime excess silicosis morbidity risk by 41.9 percent.
Excess mortality risk includes the excess risk of death due to
silicosis, NMRD, lung cancer, and ESRD.
---------------------------------------------------------------------------
\25\ In the model, not every miner lives through age 80, and
deaths occur at the expected rate given the all-cause mortality
rates and given miners' elevated mortality risk due to their
exposure to respirable crystalline silica. Excess risks stop
accruing after death, and the life table methodology accounts for
these deaths. For example, only roughly half of an original cohort
of 21-year-old miners are expected to be alive at the start of age
80.
[GRAPHIC] [TIFF OMITTED] TR18AP24.145
Table VI-6 presents MSHA's estimates of lifetime excess risk per
1,000 miners at exposure levels equal to the existing standards, the
new PEL, and the action level. These estimates are adjusted for FTE
ratios and thus utilize cumulative exposures that more closely reflect
the average hours worked per year.\26\ For an MNM miner who is
presently exposed at the existing PEL of 100 [mu]g/m\3\ (and given the
weighted average FTE ratio of 0.87), implementing the new PEL will
lower the miner's lifetime excess risk of death by 58.8 percent for
silicosis, 45.7 percent for NMRD (not including silicosis), 52.7
percent for lung cancer, and 19.9 percent for ESRD. The MNM miner's
risk of acquiring a non-fatal case of silicosis will decrease by 80.4
percent.
---------------------------------------------------------------------------
\26\ The FTE ratios used in these calculations are a weighted
average of the FTE ratio for production employees and the FTE ratio
for contract miners.
---------------------------------------------------------------------------
For a coal miner who is currently exposed at the existing standard
of 85.7 [mu]g/m\3\ (and given the weighted average FTE ratio of 0.99),
implementing the new PEL will lower the miner's lifetime excess risk of
death by 42.6 percent for silicosis mortality, 40.2 percent for NMRD
mortality (not including silicosis), 43.4 percent for lung cancer
mortality, and 15.8 percent for ESRD mortality. The coal miner's
lifetime excess risk of acquiring non-fatal silicosis will decrease by
73.8 percent. While even greater reductions would be achieved at
exposures equal to the action level (25 [mu]g/m\3\), some residual
risks do remain at exposures of 25 [mu]g/m\3\. Notably, at the action
level, ESRD risk is still 20.7 per 1,000 MNM miners and 21.6 per 1,000
coal miners. At the action level, risk of non-fatal silicosis is 16.3
per 1,000 MNM miners and 16.9 per 1,000 coal miners.
BILLING CODE 4520-43-P
[[Page 28272]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.146
BILLING CODE 4520-43-C
Supporting the need for the proposed rule overall, the National
Black Lung Association (NBLA) cited a 2023 investigation (Berkes and
Hicks, 2023), which the commenter said reported 21,000 excessive
respirable crystalline silica dust exposures from 1986 to 2016
(Document ID 1402). In its above review of exposure data, MSHA also
found exposures that exceeded the new PEL. On the other hand,
questioning the necessity of the proposed rule for the coal industry,
the Pennsylvania Coal Alliance asserted that only 1.2 percent of the
samples MSHA relied on for its analysis showed an exceedance of 100
[mu]g/m\3\ (Document ID 1378).
While coal exposure data since 2016 may indicate a recent trend of
less frequent noncompliance, 6.9 percent of samples for coal miners
showed an exceedance of the new PEL. As Table VI-6 demonstrates,
reducing a coal miner's exposure from 85.7 [mu]g/m\3\ to 50 [mu]g/m\3\
is expected to reduce his total silicosis morbidity risk by 71 percent
(from 189.9 to 54.2 per 1,000), reduce his silicosis mortality risk by
43 percent (from 14.1 to 8.1 per 1,000), reduce his total NMRD
mortality by 41 percent (from 53.2 to 31.5 per 1,000), reduce his lung
cancer mortality risk by 43 percent (from 5.3 to 3.0 per 1,000), and
reduce his ESRD mortality by 16 percent (from 32.3 to 27.2 per 1,000).
Additionally, for a typical coal miner exposed between 50 [mu]g/m\3\
and 85.7 [mu]g/m\3\, the new PEL is expected to reduce his silicosis
morbidity risk by 46 percent (from 79.5 to 54.3 per 1,000), reduce his
lung cancer mortality risks by 22 percent (from 3.6 to 3.0 per 1,000),
reduce his silicosis mortality risk by 15 percent (from 9.4 to 8.1 per
1,000), reduce his NMRD mortality risk by 20 percent (from 37.9 to 31.5
per 1,000), and reduce his ESRD mortality risk by 6 percent (from 28.9
to 27.2 per 1,000). The benefits calculated in the main analysis of the
FRA represent only those benefits of reducing exposures from, at most,
the existing standard to the new PEL of 50 [mu]g/m\3\. Even when
assuming compliance with the existing standard, the results of the FRA
affirm the need for the rule for all mining industries.
E. Healthy Worker Bias
MSHA accounted for ``healthy worker survivor bias'' in estimating
the risks for coal and MNM miners. The healthy worker survivor bias
causes epidemiological studies to underestimate excess risks associated
with occupational exposures. As with most worker populations, miners
are composed of heterogeneous groups that possess varying levels of
background health. Over the course of miners' careers, illness tends to
remove the most at-risk workers from the workforce prematurely, thus
causing the highest cumulative exposures to be experienced by the
healthiest workers who are most resistant to developing disease.
Failing
[[Page 28273]]
to account for this imbalance of cumulative exposure across workers
negatively biases risk estimates, thereby underestimating true risks in
the population. Keil et al. (2018) analyzed a type of healthy worker
bias referred to as the healthy worker survivor bias in the context of
OSHA's 2016 life table estimates for risk associated with respirable
crystalline silica exposure. After analyzing data from 65,999 workers
pooled across multiple countries and industries, Keil et al. found that
the ``healthy worker survivor bias results in a 28% underestimate of
risk for lung cancer and a 50% underestimate for other causes of
death,'' with risk being defined as ``cumulative incidence of mortality
[at age 80].''
Given that MSHA has calculated risks using the same underlying
epidemiological studies OSHA used in 2016, the healthy worker survivor
bias is likely impacting the estimates in Table V-6 of lifetime excess
risk and lifetime excess cases avoided. Accordingly, as part of a
sensitivity analysis, MSHA re-estimated risks for MNM and coal miners
to account for the healthy worker survivor bias. MSHA adjusted for this
effect by increasing the risk estimates of lung cancer risk by 28
percent and increasing the risk of each other disease by 50 percent.
This produced larger estimates of lifetime excess risk reductions and
lifetime excess cases avoided, which are presented in FRA Table 23
through FRA Table 26 of the FRA document. As these tables show, when
adjusting for the healthy worker survivor bias, the new PEL will
decrease lifetime silicosis morbidity risk by 23.9 cases per 1,000 MNM
miners (compared to the unadjusted estimate of 15.9 cases per 1,000 MNM
miners, see FRA Table 15 of the FRA document) and 5.8 cases per 1,000
coal miners (compared to 3.8 cases per 1,000 coal miners, see FRA Table
16 of the FRA document). Still accounting for the healthy worker
survivor bias, the new PEL will decrease total morbidity by 5,131
lifetime cases among MNM miners (compared to 3,421 cases, see FRA Table
17 of the FRA document) and by 487 lifetime cases among coal miners
(compared to 325 cases, see FRA Table 18 of the FRA document). Among
the current MNM and coal mining populations, implementation of the new
PEL during their full lives will have avoided 1,457 deaths and 126
deaths, respectively, over their lifetimes (compared to unadjusted
estimates of 982 deaths and 85 deaths, respectively).
MSHA believes adjusted estimates for the healthy worker survivor
bias are more reliable than unadjusted estimates. However, given that
the literature does not support specific scaling factors for each of
the health endpoints analyzed, these adjustments for the healthy worker
survivor bias have not been incorporated into the final lifetime excess
risk estimates that served as the basis for monetizing benefits.
Because the monetized benefits do not account for the healthy worker
bias, MSHA believes the reductions in lifetime excess risks and
lifetime excess cases, as well as the monetized benefits, likely
underestimate the true reductions and benefits attributable to the
final rule.
The ACLC provided comments that the agency's proposed rule would do
little to alter the status quo (Document ID 1445). Specifically, this
commenter cited the findings of the PRA that thousands of miners would
continue to get sick and die from overexposure to silica dust under the
new proposed rule (Document ID 1445). Recommending that the Agency
should focus on entirely preventing any disability or disease from
inhaling silica dust, the commenter urged MSHA to strengthen the
proposed rule such that the vast majority of miner lives will be saved
over the coming decades (Document ID 1445). MSHA acknowledges that
reducing respirable crystalline silica concentrations to 25 [mu]g/m\3\
would further reduce morbidity and mortality amongst miners. However,
MSHA determined that a PEL of 25 [mu]g/m\3\ would not be achievable for
all mines.
Also, upon reviewing these results, many commenters, including the
ACLC, the American Thoracic Society, the American Lung Association, and
the American College of Chest Physicians (hereafter referred to as
``The American Thoracic Society et al.''), Appalachian Voices, USW, and
the AOEC discussed how silica-related diseases are becoming more
prevalent and/or severe in miners (Document ID 1445; 1421; 1425; 1447;
1373; 1391; 1439; 1372; 1353; 1375). They expressed concern that
recently there has been an increase in cases of black lung disease,
pneumoconiosis, and other related illnesses. The American Thoracic
Society et al. stated that the increase in the number of cases is due
to increasing silica exposures in mining processes, citing studies
supporting this point (Cohen et al., 2016, 2022) (Document ID 1421).
Appalachian Voices added that research has found that black lung
disease is occurring at its highest level in decades, is affecting more
younger miners now than in the past, and is more frequently presenting
in its more severe form, PMF (Document ID 1425). The ACLC echoed this
point, stating that, in the 1990s, the worst forms of black lung
disease (i.e., PMF) had almost been eradicated in the United States
(Document ID 1445). This commenter expressed concern that the
prevalence of black lung disease has grown in the past decade, and
clinics in eastern Kentucky and southwest Virginia have diagnosed
hundreds of cases of PMF. The commenter cited a new analysis of data
from NIOSH and black lung clinics that, according to the commenter,
reveals more than 4,000 cases of the most advanced form of black lung
since 2010, as well as more than 1,500 advanced black lung diagnoses in
just the last 5 years (Document ID 1445). The UMWA described
surveillance findings from the National Academies of Sciences,
Engineering, and Medicine (NASEM) that severe pneumoconiosis where
respirable crystalline silica is likely an important contributor is
presenting in relatively young miners, sometimes in their late 30s and
early 40s (Document ID1398). The ACLC and UMWA expressed concern that
the risk estimates presented in the PRA heavily underestimated the
avoided cases because it severely underestimated current disease
incidence (Document ID 1445; 1398).
There are a number of reasons why current incidence of disease
would be higher than estimates in the FRA:
For all diseases except silicosis, the FRA does not
present the total number of cases that are expected in the future. The
FRA only presents the number of excess cases that miners experience due
to their occupational exposure to respirable crystalline silica. For
example, the FRA presents an estimated 1,794 excess ESRD deaths over
the next 60 years under the baseline scenario among coal miners. This
estimate would rise from 1,794 to 2,407 when including all ESRD deaths
and not just the excess ESRD deaths attributable to respirable
crystalline silica exposure.\22\ For silicosis and PMF, the number of
excess cases equals the number of total cases, since MSHA assumes non-
miners have no background risk of silicosis or PMF.
There is a lag between the time when exposure occurred and
new diagnoses. Many of the new cases of silicosis and PMF that are
currently being diagnosed in coal miners are for individuals who likely
worked during a time when the coal mining industry was substantially
larger than (e.g., roughly double) its current size. The number of
miners who are being diagnosed today belong to larger cohorts than
those currently entering the mining workforce. Consequently, the number
of disease cases and deaths amongst retired miners 60 years in the
future
[[Page 28274]]
would be expected to be lower than that amongst currently retired
miners because the latter group is larger in size.
Additionally, as the FRA explains, the Baseline scenario
involves reducing all noncompliant exposures to the existing standard
(100 [mu]g/m\3\ for MNM or 85.7 [mu]g/m\3\ for coal). This is done to
avoid attributing benefits to this rule which should instead be
attributed to a previous rule. Consistent with this approach, MSHA also
has not estimated the cost to become compliant with existing standards.
Capping noncompliant exposures at 100 [mu]g/m\3\ for MNM or 85.7 [mu]g/
m\3\ for coal increases the discrepancy between the present-day
incidence and expected future cases under the baseline scenario. For
coal miners, estimates of avoided cases assume that, in the absence of
this rule, miners would be exposed to the same levels of respirable
crystalline silica that have been observed in the coal compliance data
from 2016 through 2021. This more recent period was selected to account
for the fact that MSHA's 2014 RCMD Standard likely reduced
concentrations of respirable crystalline silica. Coal miners who are
being diagnosed with silicosis and PMF today likely suffered from
higher exposures than those represented by more recent compliance data,
which would lead to higher incidence of silicosis and PMF than the QRA
projects for future miners.
For PMF morbidity, not all cases of this disease are
quantified in the FRA. The term ``PMF'' is used to refer to complicated
CWP (caused by coal dust exposure) and to refer to complicated
silicosis (caused by respirable crystalline silica exposure). The FRA
only captures silicosis profusion 2/1+ morbidity (which may overlap
partially with some definitions of PMF) but does not quantify benefits
associated with reducing CWP morbidity.
F. Uncertainty Analysis
MSHA conducted extensive uncertainty analyses to assess the impact
on risk estimates of factors including treatment of data in excess of
the new PEL, sampling error, and use of average rather than median
point estimates for risk. The impact of excluding insufficient mass
(weight) samples was also examined. As discussed below, some sources of
uncertainty suggest that miners' risks may be lower than what MSHA
modeled, and other sources suggest that risks may be higher. MSHA's
estimates represent central values, which are based on the most
reliable data and assumptions. Moreover, the overall weight-of-evidence
indicates that increased exposures to respirable crystalline silica
cause increased risk of mortality and morbidity, from which it follows
that reduced exposures would lead to reduced risks.
1. Sampling Error in Exposure Data
To quantify the impact of sampling uncertainty on the risk
estimates, 1,000 bootstrap resamples of the original exposure data were
generated (sampling with replacement). The resamples were stratified by
commodity to preserve the relative sampling frequencies of coal, metal,
non-metal, sand and gravel, crushed limestone, and stone observations
in the original dataset. Risk calculations were repeated on each of the
1,000 bootstrap samples, thereby generating empirical distributions for
all risk estimates. From these empirical distributions, 95 percent
confidence intervals were calculated. These confidence intervals
characterize the uncertainty in the risk estimates arising from
sampling error in the exposure data. All lifetime excess risk estimates
had narrow confidence intervals, indicating that the estimates of
lifetime excess morbidity and mortality risks have a high degree of
precision.
In regard to use of average, rather than median, point estimates of
risk, the estimates acquired from average exposures are similar to the
estimates from median exposures, with 95 percent confidence intervals
having similar widths. However, the 95 percent confidence intervals are
not always overlapping, and average exposures tended to yield higher
estimates of reduced morbidity and mortality. Among MNM miners, MSHA
expects the new PEL to reduce lifetime excess cases of silicosis
morbidity by 3,394-3,703 when using average exposures to model risks
(see FRA Table 41 of the FRA document), compared to 3,271-3,576 fewer
cases when using median exposures to model risks (see FRA Table 37 of
the FRA document). Among coal miners, this reduction in excess cases of
silicosis morbidity is expected to be 328-372 when using average
exposures (see FRA Table 42 of the FRA document), compared to 305-354
when using median exposures (see FRA Table 38 of the FRA document). The
new PEL is estimated to prevent 981-1,056 MNM miner deaths and 87-97
coal miner deaths when using average exposures to model risks (see FRA
Tables 41 and 42 of the FRA document), compared to 945-1,020 fewer MNM
miner deaths and 80-92 fewer coal miner deaths using median exposures
to model risks (see FRA Tables 37 and 38 of the FRA document).
2. Alternate Treatment of Exposure Samples in Excess of the New
Exposure Limit
To estimate excess risks and excess cases under the new PEL, MSHA
assumed that no exposures will exceed the new limit, which effectively
reduced any exposures exceeding 50 [mu]g/m\3\ to 50 [mu]g/m\3\.
However, if mines implement controls with the goal of reducing
exposures to 50 [mu]g/m\3\ on every shift, then some exposure currently
in excess of 50 [mu]g/m\3\ will likely decrease below the new PEL. For
this reason, the estimation method of capping all exposure data at 50
[mu]g/m\3\ represents a ``lowball'' estimate of risk reductions due to
the new PEL. In this section, MSHA presents estimates using an
alternate ``highball'' method wherein exposures exceeding 50 [mu]g/m\3\
are set equal to the median exposure value for the 25-50 [mu]g/m\3\
exposure group. Because this highball method attributes larger
reductions in exposure to the new PEL, it estimates higher lifetime
excess risk reductions and more avoided lifetime excess cases.
As with lifetime excess risks, the highball method also yields
larger reductions in lifetime excess cases. Using the highball method,
MNM miners are expected to experience 4,148 fewer cases of non-fatal
silicosis and coal miners are expected to experience 446 fewer cases of
non-fatal silicosis over their lifetimes. MNM miners would experience
1,519 fewer deaths and coal miners would experience 164 fewer deaths
over their lifetimes. Compared to the lowball method--which estimates
that the new PEL would avoid a total of 3,746 lifetime cases of non-
fatal silicosis and 1,067 lifetime excess deaths (among both MNM and
coal miners)--the highball method estimates totals of 4,594 avoided
lifetime cases of non-fatal silicosis and 1,683 avoided lifetime excess
deaths.
3. Samples With Insufficient Mass
The MSHA Laboratory does not analyze samples for respirable
crystalline silica that do not meet a minimum threshold for total
respirable dust mass. The MNM exposure data gathered by enforcement
from January 1, 2005, through December 31, 2019, contain samples that
were analyzed using the P-2 method. As discussed, the P-2 method
specifies that filters are only analyzed for quartz if they achieve a
net mass (weight) gain of 0.100 mg or more. If cristobalite is
requested, a mass gain of 0.050 mg or more is required for a filter to
be analyzed (MSHA, 2022c). During the 15-year sample period for MNM
exposure data, 40,618 MNM
[[Page 28275]]
samples were not analyzed because the filter failed to meet the P-2
minimum net mass gain requirements.
Similarly, the coal exposure data gathered by enforcement from
August 1, 2016, through July 31, 2021, contains samples that were
analyzed using the P-7 method. For samples taken in underground mines,
the P-7 method requires a minimum sample mass of 0.100 mg \27\ of dust
for the sample to be analyzed for quartz. For samples taken in surface
coal mines, the P-7 method typically requires a minimum sample mass of
0.200 mg of dust for the sample to be analyzed for quartz. During the
five-year sample period for coal exposure data, 32,401 valid full-shift
coal samples were not analyzed because the P-7 method's minimum mass
requirement was not met.
---------------------------------------------------------------------------
\27\ Often the threshold for analyzing Coal samples is >=0.1 mg.
There are, however, some exceptions based on Sample Type and
Occupation Code. For samples with Sample Type 4 or 8, if the
sample's Occupation Code is not 307, 368, 382, 383, 384, or 386,
then the threshold is >=0.2 mg.
---------------------------------------------------------------------------
MNM and Coal samples that did not meet the MSHA Laboratory's
minimum mass criteria were excluded from the risk analysis because
their concentrations of respirable crystalline silica are not known.
The unanalyzed samples all had very low total respirable dust mass,
making it unlikely that many would have exceeded the existing standards
or the new PEL. Nonetheless, excluding these unanalyzed samples from
the exposure datasets may introduce bias, potentially causing the
Agency to overestimate the proportion of high-intensity exposure
values.
As a sensitivity analysis, MSHA used imputation techniques to
estimate the respirable crystalline silica mass for each sample based
on the sample weight and the median percent silica content for each
commodity and occupation. All the unanalyzed samples with imputed
concentrations were estimated to be <25 [micro]g/m\3\, and thus
including these unanalyzed samples in the analysis leads to lower
estimates of estimated lifetime excess cases for both MNM and coal
miners.
When including the imputed values for the unanalyzed samples, the
new PEL would result in 2,327 fewer cases of non-fatal silicosis among
MNM miners and 171 fewer cases among coal miners, over their lifetimes.
The new PEL would also result in 666 fewer deaths (due to all 4
diseases) among MNM miners and 46 fewer deaths among coal miners, over
their lifetimes. This yields a total reduction in lifetime excess
morbidity of 2,498 miner deaths and a total reduction in lifetime
excess mortality of 712 miner deaths. While these estimates are lower
than those presented in Table VI-4 (of 3,746 avoided lifetime cases of
non-fatal silicosis and 1,067 avoided lifetime excess deaths), MSHA
nonetheless believes that--even including these unanalyzed samples--the
new PEL would still reduce the risk of material impairment of health or
functional capacity in miners exposed to respirable crystalline silica.
Moreover, the possible positive bias that may arise when excluding
these samples would be offset by other negative biases discussed herein
(e.g., the healthy worker survivor bias and the assumption that full
compliance with the new PEL would not produce any reductions in
exposure below 50 [mu]g/m\3\).
It should be noted that the imputation method has some limitations.
For example, the method assumes that, if the insufficient mass samples
had been analyzed, every sample would have possessed a percentage of
quartz, by mass, equal to the median percentage for that sample's
associated commodity and occupation. (See Section 17.1 of the
standalone FRA document for a full discussion of the imputation
method.) However, within a given occupation, this percentage varies
substantially and is positively correlated with exposure concentration.
Suppressing the variation in this percentage quartz, by mass, produces
less variation in the resulting imputed concentrations. Consequently,
the imputation method may underestimate the number of unanalyzed
samples that would truly exceed 50 [mu]g/m\3\.
VII. Feasibility
A. Technological Feasibility
This section, technological feasibility, presents MSHA's
conclusions on the technological feasibility of the final rule for mine
operators. The section considers whether currently available
technologies, used alone or in combination with each other, can be used
by mine operators to comply with the final rule and notes and responds
to public comments received regarding technological feasibility. In the
proposed rule, MSHA preliminarily determined that it is technologically
feasible for mine operators to achieve the proposed requirements. In
the proposal, MSHA requested public comments on these preliminary
conclusions and any other aspects of the proposed rule. After receiving
public comments, the Agency has reviewed them and has determined that
it is technologically feasible for mine operators to conduct air
sampling and analysis and to achieve the final rule's PEL using
commercially available samplers. MSHA has also determined that these
technologically feasible samplers are widely available, and a number of
commercial laboratories provide the service of analyzing dust
containing respirable crystalline silica. In addition, MSHA has
determined that technologically feasible engineering controls are
readily available, can control crystalline silica-containing dust
particles at the source, provide reliable and consistent protection to
all miners who would otherwise be exposed to respirable dust, can be
monitored, and are achievable. MSHA has also determined that
administrative controls, used to supplement engineering controls, can
further reduce and maintain exposures at or below the final rule's PEL.
Moreover, MSHA has determined the final rule's respiratory protection
practices for respirator use are technologically feasible for mine
operators to implement. For MNM operators, MSHA has determined that the
final rule's medical surveillance requirements are technologically
feasible. This section focuses on technological feasibility; public
comments specifically related to technological feasibility are
addressed here, other comments are addressed in Section VIII.B.
Section-by-Section Analysis of this preamble.
MSHA is required to set standards to assure, based on the best
available evidence, that no miner will suffer material impairment of
health or functional capacity from exposure to toxic materials or
harmful physical agents over his working life. 30 U.S.C. 811(a)(6)(A).
The Mine Act also instructs MSHA to set health standards to attain
``the highest degree of health and safety protection for the miner''
while considering ``the latest available scientific data in the field,
the feasibility of the standards, and experience gained under this and
other health and safety laws.'' 30 U.S.C. 811(a)(6)(A). But the health
and safety of the miner is always the paramount consideration: ``[T]he
Mine Act evinces a clear bias in favor of miner health and safety,''
and ``[t]he duty to use the best evidence and to consider feasibility
are appropriately viewed through this lens and cannot be wielded as
counterweight to MSHA's overarching role to protect the life and health
of workers in the mining industry.'' Nat'l Min. Ass'n v. Sec'y, U.S.
Dep't of Lab., 812 F.3d 843, 866 (11th Cir. 2016); 30 U.S.C. 801(a).
The D.C. Circuit clarified the Agency's obligation to demonstrate
the technological feasibility of reducing occupational exposure to a
hazardous substance. MSHA ``must only
[[Page 28276]]
demonstrate a `reasonable possibility' that a `typical firm' can meet
the permissible exposure limits in `most of its operations.'' Kennecott
Greens Creek Min. Co. v. Mine Safety & Health Admin., 476 F.3d 946, 958
(D.C. Cir. 2007) (quoting American Iron & Steel Inst. v. OSHA, 939 F.2d
975, 980 (D.C. Cir. 1991)). Additionally, MSHA has authority to
promulgate technology-forcing rules. ``When a statute is technology-
forcing, the agency `can impose a standard which only the most
technologically advanced plants in an industry have been able to
achieve--even if only in some of their operations some of the time.' ''
Id. at 957 (quoting United Steelworkers of Am. v. Marshall, 647 F.2d
1189, 1264 (D.C. Cir. 1980)).
This section presents technological feasibility findings that
guided MSHA's selection of the final rule's requirements, including the
PEL. MSHA's technological feasibility findings are organized into two
main sections covering: (1) the technological feasibility of part 60:
PEL and action level; engineering and administrative controls; sampling
provisions, including methods of sampling, and sampler and sample
analysis requirements; and medical surveillance requirements for MNM
mines; and (2) the technological feasibility of the revision to
previous respiratory protection standards. Based on the analyses
presented in the two sections, MSHA concludes that the Agency's final
rule is technologically feasible. MSHA's feasibility determinations in
this rulemaking are supported by its findings that the majority of the
industry is already using technology that will allow it to effectively
comply with the final rule.
As noted above, MSHA has determined that part 60 is technologically
feasible. Many mine operators already maintain respirable crystalline
silica exposures at or below the final rule's PEL of 50 [micro]g/m\3\,
and at mines where there are elevated exposures, operators are able to
reduce exposures to at or below the PEL by properly maintaining
existing engineering controls and/or by implementing new engineering
and administrative controls that are currently available. In addition,
mine operators can satisfy the exposure monitoring requirements of part
60 with existing, validated, and widely used sampling technologies and
analytical methods.
Second, the analysis shows that the final rule's update to MSHA's
prior respiratory protection requirements is also technologically
feasible. The mining industry's existing respiratory protection
practices for selecting, fitting, using, and maintaining respiratory
protection include program elements that are similar to those of ASTM
F3387-19, ``Standard Practice for Respiratory Protection'', which MSHA
is incorporating by reference. Existing respiratory protection programs
must be in writing and developed by a person with relevant experience
and capabilities.
1. Technological Feasibility of the PEL
a. Methodology
The technological feasibility analysis for the PEL relies primarily
on information from three key sources:
MSHA's Standardized Information System (MSIS) respirable
crystalline silica exposure data, which includes 57,769 MNM and 63,127
coal mine compliance samples collected by MSHA inspectors; these
samples were of sufficient mass gain to be analyzed for respirable
crystalline silica by MSHA's analytical laboratory.\28\
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\28\ These respirable crystalline silica exposure data consist
of 15 years of MNM mine samples (January 1, 2005, through December
31, 2019) and five years of coal mine samples (August 1, 2016,
through July 31, 2021). These MSHA compliance samples represent the
conditions identified by MSHA inspectors as having the greatest
potential for respirable crystalline silica exposure during the
periodic inspection when sampling occurred. While MSHA's laboratory
also analyzes mine operators' respirable coal mine dust samples
containing respirable crystalline silica, those samples are not
included in the data used for this analysis.
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The NIOSH series on reducing respirable dust in mines,
including: ``Dust Control Handbook for Industrial Minerals Mining and
Processing, Second Edition'' (NIOSH, 2019b) and ``Best Practices for
Dust Control in Coal Mining, Second Edition'' (NIOSH, 2021a).\29\ With
cooperation from the MNM and coal mining industries, NIOSH has
extensively researched and documented engineering and administrative
controls for respirable crystalline silica in mines.
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\29\ Together, these two recent reports provide more than 500
pages of detailed descriptions, discussion, and illustrations of
dust control technologies currently used in mines.
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MSHA's knowledge of the mining industry. MSHA has over
four decades of experience inspecting surface mines at least twice per
year and underground mines at least four times per year and in
assisting mine operators and miners with technological issues, such as
control of respirable dust (including respirable crystalline silica)
exposure. MSHA provides compliance assistance, including informational
programs, training, publications, onsite evaluations, and
investigations that document conditions in mines and help mines operate
in a safe and healthy manner.\30\
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\30\ MSHA also analyzes RCMD samples collected by mine
operators, including those containing respirable crystalline silica,
in addition to the compliance samples collected by MSHA inspectors
(mentioned in the first bullet of this series).
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Additionally, MSHA consulted other published reports, scientific
journal articles, and information from equipment manufacturers and
mining industry suppliers.\31\
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\31\ Project personnel reviewed 104,365 samples collected and
analyzed by MSHA for respirable crystalline silica, plus another
103,745 samples collected but not analyzed due to insufficient
respirable dust collected in the sample. They examined over 200
published reports, proceedings, case studies, analytical methods,
and journal articles, in addition to inspecting more than 200 web
page, product brochures, user manuals, service/maintenance manuals
and descriptive literature for dust control products, mining
equipment, and related services.
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MSHA did not identify any comments specific to the technological
feasibility analysis methodology. This final rule retains the
methodology supporting the technological feasibility analysis of the
PEL in the proposed rule.
b. The Technological Feasibility Analysis Process
Mining Commodity Categories and Activity Groups
As described in the Preliminary Regulatory Impact Analysis (PRIA),
MSHA categorized mine types into six MNM ``commodity categories''
(using the method of Watts et al., 2012) based on similarities in
exposure characteristics. MNM mine categories include metal, nonmetal,
stone, crushed limestone, and sand and gravel. All coal mines are
categorized together as one commodity category.
Within each commodity, MSHA further separated mining operations
into the four activity groups widely used by the industry: (1)
development and production miners (drillers, stone cutters); (2) ore/
mineral processing miners (crushing/screening equipment operators and
kiln, mill, and concentrator workers in mine facilities); (3) miners
engaged in load/haul/dump activities (conveyor, loader, and large
haulage vehicle operators, such as dump truck drivers); and (4) miners
in all other occupations (mobile and utility workers, such as
surveyors, mechanics, cleanup crews, laborers, and operators of compact
tractors and utility trucks).
Before determining the feasibility of reducing miners' exposure to
respirable crystalline silica, MSHA gathered and analyzed information
to understand current miner exposures by creating an ``exposure
profile,'' identified the existing (i.e., baseline) conditions and the
exposure levels associated with
[[Page 28277]]
those conditions, and determined whether mines will need additional
control methods, and if so, whether those methods were available.
MSHA's exposure datasets for MNM and coal mining industries are
available as part of the rulemaking record under Docket ID MSHA-2023-
0001-1290.
Exposure Profiles
MSHA classified all valid respirable crystalline silica samples in
the Agency's MSIS data,\32\ grouping the data by commodity category,
followed by activity group.\33\ MSHA created an exposure profile to
better examine the sample data for each commodity category. These
profiles include basic summary statistics, such as sample count, mean,
median, and maximum values, presented as ISO 8-hour TWA values. They
also show the sample distribution within the following exposure ranges:
<=25 [micro]g/m\3\, >25 [micro]g/m\3\ to <=50 [micro]g/m\3\, >50
[micro]g/m\3\ to <=100 [micro]g/m\3\ (equivalent to 85.7 [micro]g/m\3\
in coal mines for a sample calculated as an 8-hour TWA), >100 [micro]g/
m\3\ to <=250 [micro]g/m\3\, >250 [micro]g/m\3\ to <=500 [micro]g/m\3\,
and >500 [micro]g/m\3\.\34\
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\32\ MSHA removed duplicate samples, samples missing critical
information, and those identified as invalid by the mine inspector,
for example because of a ``fault'' (failure) of the air sampling
pump during the sampling period.
\33\ MSHA MSIS respirable crystalline silica data for the MNM
industry, January 1, 2005, through December 31, 2019 (version
20220812); MSHA MSIS respirable crystalline silica data for the Coal
Industry, August 1, 2016, through July 31, 2021 (version 20220617).
All samples were collected by mine inspectors and were of sufficient
mass to be analyzed for respirable crystalline silica by MSHA's
laboratory.
\34\ MSHA selected these ranges based on the PELs under
consideration, then multiples of 100 [micro]g/m\3\ to show how data
are distributed in the higher ranges. Table VII-4 also presents
additional exposure ranges corresponding to the 85.7 [micro]g/m\3\
concentration for coal samples.
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In Table VII-1, the respirable crystalline silica exposure data for
MNM miners are summarized by commodity and for the MNM industry as a
whole, while Table VII-2 presents the exposure profile as the
percentage of samples in each exposure range. Overall, approximately 82
percent of the 57,769 MNM compliance samples were at or below the PEL
(50 [micro]g/m\3\). The exposure profile shows variability between the
commodity categories: approximately 73 percent of metal miner exposures
at or below the PEL (50 [micro]g/m\3\) (the lowest among all MNM
mines), compared with approximately 90 percent of the crushed limestone
miner exposures (the highest among all MNM mines).
Table VII-3 and Table VII-4 present the corresponding respirable
crystalline silica exposure information for coal miners by location
(underground or surface). Overall, approximately 93 percent of the
63,127 samples obtained by MSHA inspectors for coal miners were at or
below the PEL (50 [micro]g/m\3\). There was little variation between
samples for underground miners and surface miners (with approximately
93 and 92 percent of the samples at or below 50 [micro]g/m\3\,
respectively). Exposure values from the coal industry are expressed as
ISO 8-hour TWAs, compatible with the final rule's (see notes, Table
VII-3).
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Existing Dust Controls in Mines (Baseline Conditions)
MNM and coal mines are controlling dust containing respirable
crystalline silica in various ways. As shown in Tables VII-1 through
VII-4, respirable crystalline silica exposures exceeded the PEL of 50
[micro]g/m\3\ in about 18 percent of all MNM samples collected. About
seven percent of all coal samples exceeded the PEL. Overall, metal
mines and sand and gravel mines had higher exposure levels than other
commodity mines.
Despite the extensive dust control methods available, dust control
measures have been implemented in some commodity categories to a
greater degree than in others. This is partly because some commodity
categories tend to have larger mines. MSHA has found that the larger
the amount (tonnage) of material a mine moves (including overburden and
other waste rock), the faster the mine tends to operate its equipment
(i.e., closer to the equipment capacity), creating more air turbulence
and therefore generating more airborne respirable crystalline silica.
The amount of material moved also influences the number of miners
employed at a mine, and therefore, the number of miners can be
indirectly correlated to the amount of dust generated. MSHA has
observed that in large mines, dusty conditions typically prompt more
control efforts, usually in the form of added engineering controls.
MSHA has also found that metal mines, which are typically large
operations with higher numbers of miners, tend to have available
engineering controls for dust management. On the other hand, sand and
gravel mines, which generally employ fewer miners and handle modest
amounts of material, have very limited, if any, dust control measures.
This is because most of the mined material is a commodity that only
requires washing and screening into various sizes of product
stockpiles, generating little waste material. Nonmetal, stone, and
crushed limestone mines occupy the middle range in terms of employment,
existing engineering controls, and maintenance practices.
Over the years, staff from multiple MSHA program areas have worked
alongside miners and mine operators to improve safety and health by
inspecting, evaluating, and researching mine conditions, equipment, and
operations. These key programs, each of which has an onsite presence,
include (but are not limited to) Mine Safety and Health Enforcement;
Directorate of Educational Policy and Development, which includes the
National Mine Health and Safety Academy and the Educational Field and
Small Mine Services; and the Directorate of Technical Support, which
comprises the Approval and Certification Center and the Pittsburgh
Safety and Health Technology Center (including its Health Field
Division, Analytical and Laboratory Services Division, National Air and
Dust Laboratory, Ventilation Division, and other specialized
divisions). Table VII-5 reflects the collective observations of these
MSHA programs, presented in terms of existing dust control (baseline
conditions) and the classes of additional control measures that will
provide those mines with the greatest benefit to reduce exposures below
the PEL and action level.
Table VII-5 shows MSHA's assessment of existing dust controls in
mines (baseline conditions) and additional controls needed to meet the
PEL for each commodity category, including the need for frequent
scheduled maintenance. By conducting frequent scheduled maintenance,
mine operators can reduce the concentration of respirable crystalline
silica. Table VII-5 shows that metal mines have adopted extensive dust
controls, while sand and gravel mines tend to have minimal engineering
controls, if any.
[[Page 28282]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.149
BILLING CODE 4520-43-C
Based on MSHA's experience, NIOSH research, and effective
respirable dust controls currently available and in use in the mining
industry, MSHA finds that the baseline conditions include various
combinations of existing engineering controls selected and installed by
individual mines to address respirable crystalline silica generated
during mining operations.
Respirable Crystalline Silica Exposure Controls Available to Mines
Under the final rule, the mine operator must install, use, and
maintain engineering controls, supplemented by administrative controls,
when necessary, to keep each miner's exposure at or below the PEL.
Engineering controls reduce or prevent miners' exposure to hazards.\35\
Administrative controls establish work practices that reduce the
duration, frequency, or intensity of miners' exposures (under the final
rule, the rotation of miners is not considered an acceptable
administrative control to comply with the PEL).
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\35\ Control measures that reduce respirable crystalline silica
can also reduce exposures to other hazardous particulates, such as
RCMD, metals, asbestos, and diesel exhaust. Operator enclosures and
process enclosures also reduce hazardous levels of noise by creating
a barrier between the operator and the noise source.
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MSHA data and experience show that mine operators already have
numerous engineering and administrative control options to control
miners' exposures to respirable crystalline silica. These control
options are widely recognized and used throughout the mining industry.
NIOSH has extensively researched and documented engineering and
administrative controls for respirable crystalline silica in mines. As
noted previously, NIOSH has published a series on reducing respirable
dust in mines (NIOSH, 2019b, 2021a).
(1) Engineering Controls
Examples of existing engineering controls used at mines and
commercially available engineering controls that MSHA considered
include:
Wetting or water sprays that prevent, capture, or redirect
dust;
Ventilation systems that capture dust at its source and
transport it to a dust collection device (e.g., filter or bag house),
dilute dust already in the air, or ``scrub'' (cleanse) dust from the
air in the work area;
Process enclosures that restrict dust from migrating
outside of the enclosed area, sometimes used with an attached
ventilation system to improve effectiveness (e.g., crushing equipment
and associated dump hopper enclosure, with curtains and mechanical
ventilation to keep dust inside);
[[Page 28283]]
Operator enclosures, such as mobile equipment cabs or
control booths, which provide an environment with clean air for an
equipment operator to work safely;
Protective features on mining process equipment to help
prevent process failures and associated dust releases (e.g.,
skirtboards on conveyors, which protect the conveyor system from damage
and prevent material on the conveyor from falling off, which generates
airborne dust);
Preventive maintenance conducted on engineering controls
and mining equipment that can influence dust levels at a mine, to keep
them functioning optimally; and
Instrumentation and other equipment to assist mine
operators and miners in evaluating engineering control effectiveness
and recognizing control failures or other conditions that need
corrective action.\36\
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\36\ These instruments include dust monitors; water, air, and
differential air pressure gauges; pitot tubes and air velocity
meters; and video camera (NIOSH recommends software that pairs video
with a dust monitor to track conditions that could lead to elevated
exposures if not corrected). These instruments are discussed in
NIOSH's best practices guides and dust control handbooks.
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(2) Administrative Controls
Administrative controls include practices that change the way tasks
are performed to reduce a miner's exposure. Administrative controls can
be very effective and can even prevent exposure entirely. MSHA has
determined that various administrative controls are readily available
to provide supplementary support to engineering controls. Examples of
administrative controls include housekeeping procedures; proper work
positions of miners; walking around the outside of a dusty process area
rather than walking through it; cleaning of spills; and measures to
prevent or minimize contamination of clothing to help decrease miners'
exposure to respirable crystalline silica. However, these control
methods depend on human behavior and intervention and are less reliable
than properly designed, installed, and maintained engineering controls.
Therefore, administrative controls will be permitted only as
supplementary measures, with engineering controls required as the
primary means of protection. Nevertheless, administrative controls play
an important role in reducing miners' exposure to respirable
crystalline silica.\37\
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\37\ Paragraph 60.11(b) prohibits the use of rotation of miners
as an administrative control used for compliance with this part.
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(3) Combinations of Controls
Various control options can also be used in combinations. NIOSH has
documented in detail most control methods and has confirmed that they
are currently used in mines, both individually and in combination with
each other (2019b, 2021a).
Maintenance
MSHA finds that a strong preventive maintenance program plays an
important role in achieving consistently lower respirable crystalline
silica exposure levels. MSHA has observed that when engineering
controls are installed and maintained in working condition, respirable
dust exposures tend to be below the existing exposure limits. When
engineering controls are not maintained, dust control efficiency
declines and exposure levels rise. When engineering controls fail due
to a lack of proper maintenance, a marked rise in exposures can occur,
resulting in noncompliance with MSHA's existing exposure limits. Some
examples of the impact that proper maintenance can have on respirable
dust levels include:
Water spray maintenance: An experiment using water spray
bars that could be turned on or off showed that dust reduction was less
effective each time additional spray nozzles were deactivated. A 10
percent decrease occurred when three of 21 sprays were shut off, but a
50 percent decrease occurred when 12 out of the 21 sprays were shut
off. Decreased total water spray volume and gaps in the spray pattern
(due to deactivated nozzles) were both partially responsible for the
decreased dust control (Seaman et al., 2020).
Water added to drill bailing air: When introduced into the
drill hole (with the bailing air through a hollow drill bit), water
mixes with and moistens the drill dust ejected from the hole and can
reduce respirable dust by more than 90% (NIOSH, 2019b, 2021a). NIOSH
reports that this same control measure, and others, are similarly
effective for MNM and surface coal mine drills preparing the blasting
holes used to expose the material below (whether ore or coal).
Ventilation system maintenance: The amount of air cleaned
by an air scrubber is decreased by up to one-third (33 percent) after
one continuous mining machine cut. Cleaning the scrubber screens
restores scrubber efficacy, but this maintenance must be performed
after every cut. Spare scrubber screens make frequent cleaning
practical without slowing production (NIOSH, 2021a).
Operator enclosure maintenance: Tests with mining
equipment showed that maintenance activities such as repairing weather
stripping and replacing clogged and missing cab ventilation system
filters (intake, recirculation, final filters) increased miner
protection by up to 95 percent (NIOSH, 2019b, 2021a).
Filter selection during maintenance: Airflow is as
important as filtration and pressurization in operator enclosures;
during maintenance, filter selection can influence all three factors.
Performing serial end-shift testing of enclosed cabs (on a face drill
and a roof/rock bolter) at an underground crushed limestone mine, NIOSH
compared installed HEPA filters and an alternative (MERV 16 filters).
The latter provided an equal level of filtration and better overall
miner protection by allowing greater airflow and cab pressurization. As
an added advantage, NIOSH showed that these filters cost less and
required less-frequent replacement, reducing maintenance expenses in
this mining environment (Cecala et al., 2016; NIOSH, 2019b,
2021a).38 39
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\38\ NIOSH believes this study, like many of its other mining
studies on operator enclosures and surface drill dust controls, is
relevant to both MNM mining and coal mining. NIOSH reports on this
study, conducted at an underground limestone mine, in detail in both
its Dust Control Handbook for Industrial Minerals Mining and
Processing (second edition) (2019b) and its Best Practices for Dust
Control in Coal Mining (second edition) (2021a).
\39\ Acronyms: High efficiency particulate air (HEPA). Minimum
efficiency reporting value (MERV).
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Proper design and installation--foundation for effective
maintenance: A new replacement equipment operator enclosure (control
booth) installed adjacent to the primary crusher at a granite stone
quarry initially provided 50 to 96 percent respirable dust reduction,
even with inadequate pressurization. The protection it offered miners
tripled after the booth's second pressurization/filtration unit was
activated (Organiscak et al., 2016).
MSHA has observed that when engineering controls are properly
maintained, exposure levels decrease or stay low. Metal mines, which
typically have substantial controls already installed, primarily need
reliable preventive maintenance programs to achieve the PEL. It is also
important to repair equipment damage that contributes to dust exposure
(for example, damage to conveyor skirtboards that protect the conveyor
system from damage and prevent spillage which generates airborne dust).
Maintenance and repair programs must
[[Page 28284]]
ensure that dust control equipment is functioning properly.
Some commenters described conditions where they found engineering
controls were not feasible. The NSSGA, the NVMA, and US Silica (a MNM
mine operator) cited examples such as water sprays that freeze in
winter or are not practical where the product must be kept dry so mine
workers can bag it; and enclosures and ventilation systems that are
sometimes impractical for portable operations at some locations and
limited (so made less effective) by the physical constraints of others
(Document ID 1448; 1441;1455). The MNM mine operator commenter
indicated that at their worksite, these physical conditions cause
engineering controls to be ineffective more than does lack of effort
(Document ID 1455).
In MSHA's considerable experience providing technical support to
mines, there is always a way to eliminate overexposures to respirable
dust (including respirable crystalline silica) by using the information
contained in NIOSH best practice guides for mines. MSHA has found that
the number of control options and level of detail in the guides make
compliance achievable through engineering controls alone. By adding
administrative controls (or procedural practices) mines routinely
achieve consistent compliance. MSHA agrees with commenters that exposed
water sprays are not effective in freezing weather, however, the Agency
has found that one or more other options is available for every
circumstance. For example, enclosing the process equipment is one
alternative to using water sprays for dust control. Rather than
suppressing dust, as water spray does, enclosing the dusty process
equipment limits the amount of dust that escapes from the process
enclosure, in turn limiting the amount of dust in the equipment
operator's breathing zone. A process equipment enclosure can be
constructed with baffles to help calm the air inside the enclosure, so
dust settles more quickly inside the enclosure. As another option, a
ventilation dust collection system can be paired with a process
equipment enclosure to make both even more effective. Yet another
example is to enclose the equipment operators (e.g., in a booth or
mobile cab). Furthermore, MSHA observes that a number of surface mines
operate intermittently; many of them are closed in seasons with harsh
weather. Typically, those mines can use water sprays effectively when
they are operating. MSHA notes that ventilation systems are effective
in every season; a large variety of system components and designs
provide a ventilation system that can be constructed for almost every
situation. As noted in the proposed rule, some mines might need to work
harder than others (layering different engineering controls and adding
administrative controls) to achieve compliance.
The Brick Industry Association (BIA) noted that their industry
usually operates with the minimum number of personnel even under
optimal staffing conditions and explained that it can be difficult to
avoid rotating workers to achieve efficient workflow (Document ID
1422). This commenter also stated that it could be difficult to
maintain productive operations if management is not able to either
rotate workers to minimize exposure levels or allow personnel to wear
respirators for day-to-day tasks.
As MSHA stated in the proposed rule and, and included in this final
rule, miner rotation is not considered an acceptable administrative
control for minimizing miner exposure levels or complying with any
provision of part 60. MSHA understands that mine operators may assign a
variety of work tasks for business reasons unrelated to compliance with
the PEL. However, MSHA will not consider as compliance a mine
operator's implementation of a varied task schedule for particular
miners for purposes of avoiding conflict with the PEL, as engineering
and administrative controls can feasibly reduce exposure levels below
the PEL.
This final rule prioritizes engineering controls for reducing miner
exposures, because they (1) control crystalline silica-containing dust
particles at the source; (2) provide reliable, predictable, effective,
and consistent protection to miners who would otherwise be exposed to
dust from that source; and (3) can be monitored. MSHA maintains that as
described earlier in this section, a combination of engineering
controls and administrative controls can reduce miner exposures to
levels below the PEL and that equipment maintenance will help minimize
exposures. Some examples of engineering controls include wet dust
suppression methods; enclosure; ventilation--permanent or portable
trunks; pre-cleaning--by washing or HEPA vacuuming; and controlling
dust sources. Examples of administrative controls include proper miner
positioning and improved housekeeping. For a detailed discussion on
rotation of miners, see Section VIII.B.4. Section 60.11--Methods of
Compliance.
MSHA finds that the technological feasibility analysis process was
effective and controlling exposure levels to the PEL or lower using
engineering controls is both feasible and practical. The final rule, as
did the proposed rule, emphasizes engineering controls, supplemented
with administrative controls, to control miner exposure.
c. Feasibility Determination of Control Technologies
MSHA's final PEL is 50 [mu]g/m\3\ for MNM and coal mines. As NIOSH
(2019b, 2021a) has documented, the mining industry has a wide range of
options for controlling dust exposure that are already in various
configurations in mines. NIOSH has carefully evaluated most of the dust
controls used in the mining industry and found that many of the
controls may be used in combination with other control options. NIOSH
has documented protective factors and exposure reductions of 30 to 90
percent or higher for many engineering and administrative controls.
Effective maintenance will also help mine operators comply with the
final rule. MSHA finds that maintaining (including adjusting) or
repairing existing equipment will help achieve exposures at or below 50
[mu]g/m\3\. For example, NIOSH (2019b) found that performing
maintenance on an operator enclosure can restore enclosure
pressurization and reduce the respirable dust exposure of a miner by 90
to 98.9 percent (e.g., by maintaining weather stripping, reseating or
replacing leaking or clogged filters, and upgrading filtration). When
an equipment operator remains inside a well-maintained enclosure for a
portion of a shift (for example 75 percent of an 8-hour shift), the cab
can reduce the exposure of the equipment operator proportionally, to a
level of 50 [mu]g/m\3\ (or lower). This point is demonstrated by the
following example involving a bulk loading equipment operator in a
poorly maintained booth, exposed to respirable crystalline silica near
the existing exposure limit (in the MNM sectors, 100 [mu]g/m\3\, as ISO
8-hour TWA value; in the coal sector, 85.7 [mu]g/m\3\ ISO, calculated
as an 8-hour TWA). During the 25 percent of their shift (two hours of
an eight-hour shift) that the miner works in the poorly maintained
enclosure, their exposure will be 100 [mu]g/m\3\, while for the other
six hours (operating mobile equipment with a fully refurbished
protective cab), the exposure level will be 90 percent lower, or 10
[mu]g/m\3\, resulting in an 8-hour TWA exposure of 33 [mu]g/m\3\ for
that miner's shift.\40\ Greater
[[Page 28285]]
exposure reductions could also be achieved by repairing or replacing
the poorly maintained enclosure, or modifying the miner's schedule so
that the miner works seven hours, rather than six, inside the well-
maintained enclosure.
---------------------------------------------------------------------------
\40\ Calculating the exposure for the shift: 8-hour TWA = [(10
[mu]g/m\3\ x 6 hours) + (100 [mu]g/m\3\ x 2 hours)]/8 hours = 33
[mu]g/m\3\.
---------------------------------------------------------------------------
Other engineering controls (e.g., process enclosure, water dust
suppression, dust suppression hopper, ventilation systems) could reduce
dust concentrations in the area surrounding the poorly maintained
enclosure, which reduces the exposure of the equipment operator inside.
As a hypothetical example, if the poorly maintained enclosure was an
open-air control booth (windows do not close) at a truck loading
station, adding a dust suppression hopper (which reduces respirable
dust exposure by 39 to 88 percent during bulk loading) (NIOSH, 2019b),
will lead to lower exposure during the two hours the miner is inside
the open-air booth. The calculated respirable crystalline silica 8-hour
TWA exposure of that miner could be reduced from 33 [mu]g/m\3\ (with
improved equipment operator enclosure alone) to 23 [mu]g/m\3\ (improved
equipment operator enclosure plus dust suppression hopper).\41\ As an
added benefit, any helper or utility worker in the truck loading area
will also experience reduced exposure.
---------------------------------------------------------------------------
\41\ Calculating the exposure with both the well-maintained
operator enclosure (6 hours) and dust suppression hopper, assuming
only the minimum documented respirable dust concentration reduction
(39 percent): [(10 [mu]g/m\3\ x 6 hours) + (100 [mu]g/m\3\ x (1-
0.39) x 2 hours)]/8 hours = 23 [mu]g/m\3\.
---------------------------------------------------------------------------
A similar hypothetical example is a coal miner helper who spends 90
minutes (1.5 hours) per 8-hour shift assisting a drilling rig operator
(in a protective operator's cab) drilling blast holes. The combination
of controls used to control drilling dust (including water added to the
bailing air, which can reduce airborne respirable dust emissions by up
to 96 percent) can keep the helper's respirable crystalline silica
exposure in the range of 35 [mu]g/m\3\ (ISO) as an 8-hour TWA. If,
however, the drill's on-board water tank runs dry due to poor
maintenance, the respirable crystalline silica concentration near the
drill will rise by 95 percent, meaning that the concentration is 20
times greater than the usual level (NIOSH, 2021a). If the drill
operator idles the drill and calls for water resupply, the helper will
not experience an elevated exposure. The hypothetical helper's exposure
level rises higher the longer the drill is operated. If the drill is
operated dry for another 30 minutes until water resupply arrives, the
helper will experience a respirable crystalline silica exposure of 77
[mu]g/m\3\ (ISO) as an 8-hour TWA. If dry drilling continued for 1.5
hours, the helper would have an exposure of 160 [mu]g/m\3\ ISO as an 8-
hour TWA.\42\ After water is delivered, drill respirable dust emissions
will return to their normal level once water is again introduced into
the drill bailing air.
---------------------------------------------------------------------------
\42\ The 8-hour TWA exposure level of the helper, including the
30-minute period of elevated exposure, is calculated as: [(35 [mu]g/
m\3\ x 7.5 hours) + (35 [mu]g/m\3\ x 20 x 0.5 hours)]/8 hours = 77
[mu]g/m\3\. Drill bits designed for use with water may need to be
replaced sooner if used dry.
---------------------------------------------------------------------------
Based on these examples and the wide range of effective exposure
control options available to the mining industry, MSHA finds that
control technologies capable of reducing miners' respirable crystalline
silica exposures are available, proven, effective, and transferable
between mining commodities; however, they must be well-designed and
consistently used and maintained. MSHA also finds that methods of
maintaining engineering controls are known, available, and effective.
Feasibility Findings for the PEL
Based on the exposure profiles in Table VII-1 and Table VII-2 for
MNM mines, and in Table VII-3 and Table VII-4 for coal mines, and the
examples in the previous section that demonstrate the beneficial effect
of combined controls, MSHA finds that the PEL of 50 [mu]g/m\3\ is
technologically feasible for all mines.
Table VII-6 summarizes the technological feasibility of control
technologies available to the mining industry, by commodity. MSHA finds
that control technologies are technologically feasible for all six
commodities and their respective activity groups. Under baseline
conditions, mines in each commodity category have already achieved
respirable crystalline silica exposures at or below 50 [mu]g/m\3\ for
most of the miners represented by MSHA's 57,769 samples for MNM miners
and 63,127 samples for coal miners.
BILLING CODE 4520-43-P
[[Page 28286]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.150
BILLING CODE 4520-43-C
Feasibility Findings for the Action Level
MSHA finds that mine operators can achieve exposure levels below
the action level of 25 [mu]g/m\3\ for most miners by implementing
additional engineering controls and more flexible and innovative
administrative controls, in addition to the existing control methods
already discussed in this technological feasibility analysis. The
exposure profiles in Tables VII-1 and VII-2 for MNM mines, and Tables
VII-3 and VII-4 for coal mines, indicate that mine operators have
already achieved the action level for at least half of the miners MSHA
has sampled in each commodity category. However, to reliably maintain
exposures below the action level for all miners, operators will need to
upgrade equipment and facility designs, particularly in mines with
higher respirable crystalline silica concentrations, which may be due
to an elevated silica content in materials.
One control option is increased automation, such as expanding the
use of existing autonomous or remote-controlled drilling rigs, roof
bolters, stone cutting equipment, and packaging/bagging equipment. This
type of automation can reduce exposures by increasing the distance
between the equipment operator and the dust source. Other options
include completely enclosing most processes and ventilating the
enclosures with dust extraction equipment or controlling the speed of
mining equipment (e.g., longwall shearers, conveyors, dump truck
emptying) and process equipment (e.g., crushers, mills) to reduce
turbulence that increases dust concentrations in air. Additionally,
where compatible with the material, exposure levels can be reduced by
increased wetting to constantly maintain the material, equipment, and
mine facility surfaces damp through added water sprays and frequent
housekeeping (i.e., hosing down surfaces as often as necessary). In
addition, vacuuming minimizes the amount of dust that becomes airborne
and prevent dust that does settle on a surface from being resuspended
in air.
Mines that only occasionally work with higher-silica-content
materials may not be equipped with the controls required to achieve the
action level of 25 [mu]g/m\3\, or they may not currently have
procedures to ensure miners are protected when they do work with these
materials. Examples of these activities include cutting roof or floor
rock with
[[Page 28287]]
a continuous mining machine in underground coal mines; packaging
operations that involve materials from an unfamiliar supplier,
including another mine; and rebuilding or repairing kilns. To address
these activities, under the final rule, mine operators will have to add
engineering controls to address any foreseeable respirable crystalline
silica overexposures. Examples of additional controls include pre-
testing batches of new raw materials; improving hazard communication
when batches of incoming raw materials contain higher concentrations of
crystalline silica, and augmenting enclosure and ventilation (e.g.,
adding ventilation to all crushing and screening equipment, increasing
mine facility ventilation to 30 air changes per hour, and fully
enclosing and ventilating all conveyor transfer locations). NIOSH
(2019b, 2021a) describes all of the dust control methods outlined in
this section, which are already used in mines, although to a less
rigorous extent than will be necessary to reliably and consistently
achieve exposure levels of 25 [mu]g/m\3\ or lower for all miners.
MSHA finds that the action level of 25 [mu]g/m\3\ is
technologically feasible for most mines. This finding is based on the
exposure profiles, presented in Tables VII-1 and VII-2 for MNM mines,
and Tables VII-3 and VII-4 for coal mines, which show that within each
commodity category, the exposure levels are at or below 25 [mu]g/m\3\
for at least half of the miners sampled. MSHA's finding is also based
on the extensive control options documented by NIOSH, which can be used
in combinations to achieve additional reductions in respirable
crystalline silica exposure. Although most mines will need to adopt and
rigorously implement a number of the control options mentioned in this
section, the technology exists to achieve this level, is already in use
in mines, and is available for most mines.
MSHA received numerous comments related to exposure control
methods. Several commenters recommended that the standard incorporate
by reference certain materials to assist mine operators with
compliance. The International Society of Environmental Enclosure
Engineers (ISEEE) discussed ISO 23875 (Document ID 1377).\43\ The
commenter explained that this ISO standard is a widely adopted
international standard for cab air quality, as a practical and cost-
effective engineering control that would help mine operators meet the
final rule's requirements since the desired outcome in all ISO 23875
cabs is compliance with air quality regulations at the 25 [mu]g/m\3\
level. The commenter added that increased awareness of the standard and
compliant cabs would lead to the development of a standardized cab
design that could be mass-produced and therefore reduce costs. Another
commenter, the APHA, stated that guides prepared by NIOSH for coal
mines and metal and non-metal mines contain helpful illustrations of
technologically feasible engineering controls that reduce exposure to
respirable dust (Document ID 1416).
---------------------------------------------------------------------------
\43\ ISO 23875:2021 (Mining--Air quality control systems for
operator enclosures--Performance requirements and testing methods)
and Amendments.
---------------------------------------------------------------------------
MSHA has reviewed the comments and suggested material. The Agency
agrees that ISO 23875 is a useful tool that promotes feasible dust
control equipment manufacture and maintenance practices. Although MSHA
has not incorporated it into the final rule, the Agency will keep this
standard in mind during future initiatives. MSHA acknowledges that many
other organizations and agencies, including NIOSH with its detailed and
carefully illustrated best practice guides for the mining industries,
have published extensive information that may be helpful to mine
operators seeking methods to protect miners. The Agency encourages mine
operators to use these tools to identify proper and adequate
engineering controls, choose those that will be useful in their mines,
and ensure that the controls are correctly installed, implemented, and
maintained.
MSHA received several comments regarding the description and use of
feasible engineering controls. The NVMA requested that MSHA supply a
definition for what is ``feasible'' (Document ID 1441).
Within MSHA's standard development process, the term ``feasible''
generally means ``capable of being done.'' In the case of respirable
crystalline silica exposure controls, these controls exist already and
are not technology-forcing. Based on its extensive experience
inspecting and providing compliance assistance and technical support in
mines, MSHA has observed that U.S. mines are already using an extensive
array of engineering controls. As documented by NIOSH in its best
practices guides and other resources for the mining industry, the
numerous readily available engineering controls provide evidence that
it is technologically feasible for mine operators to reduce miner
respirable crystalline silica exposure to levels at or below the PEL
and, in some cases, below the action level (NIOSH, 2019b, 2021a).
These engineering controls, including examples and data, were
discussed in more detail previously in this Technological Feasibility
section (see Section VII.A.1.b. The Technological Feasibility Analysis
Process). That section explains that engineering controls reduce or
prevent miners' exposure to hazards, while administrative controls
establish work practices that reduce the duration, frequency, or
intensity of miners' exposures. The different functional types of
engineering controls (wetting or water sprays, ventilation systems,
process enclosures, equipment operator enclosures, the associated
preventive maintenance that keeps the control equipment operating
effectively, and instrumentation to monitor function and identify need
for corrective actions) work alone or in combination with the same or
other controls to provide additional protections. To further ensure
that mine operators can achieve the PEL under diverse mining
conditions, the final rule allows operators who seek an added measure
of protection for miners to supplement engineering controls with
administrative controls (e.g., housekeeping procedures; proper work
positions of miners; walking around the outside of a dusty process area
rather than walking through it; cleaning of spills; and measures to
prevent or minimize contamination of clothing to help decrease miners'
exposure). This strategy allows a mine operator to select the set of
engineering controls that will be most effective given the mining
conditions and the mine environment. MSHA acknowledges that some mines
will need to work harder than others; however, with the wide array of
control options, MSHA is confident that the PEL is technologically
feasible. As stated earlier with respect to a feasibility finding:
``MSHA does not need to show that every technology can be used in every
mine. The agency must only demonstrate a `reasonable possibility' that
a `typical firm' can meet the permissible exposure limits in `most of
its operations.' '' Kennecott Greens Creek Min. Co. v. Mine Safety &
Health Admin., 476 F.3d 946, 958 (D.C. Cir. 2007) (quoting Am. Iron &
Steel Inst. v. Occupational Safety & Health Admin., 939 F.2d 975, 980
(D.C. Cir. 1991)).
Some commenters, including the UMWA, American Federation of Labor
and Congress of Industrial Organizations (AFL-CIO), Black Lung Clinics,
and AIHA echoed the availability of effective engineering controls in
the mining industry
[[Page 28288]]
(Document ID 1398; 1449; 1410; 1351). Two labor organizations stated
that mine operators should already be utilizing engineering and
administrative controls in accordance with the law and their existing
ventilation plans (Document ID 1398; 1449). The Black Lung Clinics,
AIHA, and UMWA expressed support for engineering and administrative
controls as means to keep miners' exposures to respirable crystalline
silica below the proposed PEL (Document ID 1410; 1351; 1398). Agreeing
with MSHA that technologically feasible engineering controls are
available, the AIHA stated that these methods can control crystalline
silica-containing dust particles at the source and provide reliable and
consistent protection to all miners who would otherwise be exposed to
respirable dust (Document ID 1351).
MSHA concurs with these comments. MSHA's experience is consistent
with these comments. Based on MSHA's experience, consideration of the
OSHA silica rule (2016), and documentation from NIOSH as discussed in
this section of the preamble, MSHA determines that engineering controls
exist for mining operations to reduce miners' exposure to the level of
the PEL (50 [micro]g/m\3\). The Agency finds that engineering controls:
(1) control crystalline silica-containing dust particles at the source;
(2) provide reliable, predictable, effective, and consistent protection
to miners who would otherwise be exposed to dust from that source; and
(3) can be monitored. The technological feasibility analysis of the PEL
in the proposed rule remains in effect for this final rule.
MSHA received several comments on the technological feasibility of
the action level (25 [micro]g/m\3\). Commenters including the Arizona
Mining Association and American Iron Steel Institute (AISI) stated that
the action level would not be achievable with current technology
(Document ID 1368; 1426). The AIHA opposing the proposed action level,
stated that the action level should be removed and the PEL should
instead be set at the proposed action level of 25 [micro]g/m\3\
(Document ID 1351).
After careful consideration of the comments, MSHA has determined a
full-shift 8-hour TWA action level of 25 [micro]g/m\3\ is feasible, and
the final rule is the same as the proposal. MSHA acknowledges that its
FRA finds that there will be a greater reduction of risk for morbidity
and mortality at the action level than the final PEL of 50 [micro]g/
m\3\.\44\ Additionally, MSHA's exposure profile (Section VII.A.1.b,
Tables VII-1 through VII-4) indicates, based on MSHA compliance
samples, that operators at most mines are already achieving exposure
levels less than 25 [micro]g/m\3\ for most miners. Tables VII-1 and
VII-3 (in this section) show that the overall median MNM miner exposure
is 15 [micro]g/m\3\ and the overall median coal miner exposure is 16
[micro]g/m\3\.\45\ Although these medians indicate that mine operators
have already achieved exposure levels below 25 [micro]g/m\3\ for more
than half of all miners sampled by MSHA, the Agency acknowledges that,
for some mines, consistently achieving a PEL of 25 [mu]g/m\3\ for all
the miners it employs could present a substantial challenge (i.e., a
PEL of 25 [mu]g/m\3\ is technically feasible, but the actions required
might not be practical for many mines).\46\ MSHA finds, however, that
the concentration of 25 [micro]g/m\3\ is an appropriate and necessary
action level, which most mine operators can (and may already have)
achieve for many miners. The action level is consistent with MSHA's
statutory purpose under the Mine Act--to provide the highest level of
health protection for the miner. MSHA establishes the action level and
sets a sampling frequency for concentrations above the action level to
require mine operators to be proactive and act before miners are
overexposed. Under the final rule, where some miners have exposures at
or above the action level (25 [micro]g/m\3\), but not exceeding the
PEL, mine operators are not required to install additional controls,
but instead (in accordance with Sec. 60.12(a)(3)) must sample those
miners quarterly to confirm exposures remain below the PEL.
Alternatively, the mine operator may choose to take actions to further
reduce exposures below 25 [micro]g/m\3\ and, where successful,
discontinue sampling (after meeting the sampling requirements under
Sec. 60.12(a)(4)).
---------------------------------------------------------------------------
\44\ Some residual risks remain even at exposures of 25
[micro]g/m\3\ of respirable crystalline silica. For example, at 25
[micro]g/m\3\, end stage renal disease (ESRD) risk is 20.7 per 1,000
MNM miners and 21.6 per 1,000 coal miners.
\45\ The median exposure level is the midpoint concentration of
all samples; in other words, half (50%) of all the miner exposure
samples are below the median, and the remaining half are above.
Tables VII-2 (MNM mines) and VII-4 (coal mines) show the percent of
MSHA compliance exposure samples that are less than 25 [micro]g/
m\3\.
\46\ For example, MSHA preliminarily reviewed control measures
the could reliably maintain exposures throughout mines to levels of
25 [micro]g/m\3\ or lower and determined these likely would include,
as a minimum, installing multiple layers of engineering controls at
every point throughout the entire mine site by: concurrently
enclosing and installing ventilation along the full length of every
conveyor, fully enclosing all process equipment, doubling or
quadrupling all ventilation system airflow, rebuilding ventilation
systems to capture dust at its source, installing HEPA filters at
air exhaust points, converting to automated processes, and
maintaining all worksurfaces damp at all times.
---------------------------------------------------------------------------
Comments on the analytical limit of detection and reliability
relative to the action level relate to analytical methodology and are
addressed in Section VII.2.b. Analytical Methods and Feasibility of
Measuring Below the PEL and Action Level.
Section VIII.B.2.a. Action Level also addresses these and other
comments related to the action level (25 [micro]g/m\3\).
The action level is an important provision of this final rule,
necessary to protect miners' health. According to NIOSH research,
wherever exposure measurements are above one-half the PEL, the employer
cannot be reasonably confident that the employee is not exposed to
levels above the PEL on days when no measurements are taken (NIOSH,
1975). Thus, an action level (in this case set at one-half of the PEL)
allows mine operators to take action before overexposures occur. The
action level of 25 [micro]g/m\3\ remains unchanged in the final rule
and the methodology supporting the technological feasibility analysis
for the action level in the proposed rule remains in effect for this
final rule.
MSHA finds that the PEL of 50 [micro]g/m\3\ is technologically
feasible. This determination is based on MSHA's sound methodology and
process for analyzing technological feasibility and control technology
currently used in mines (described in this section and Section
VII.A.1.b.), including the MSHA exposure profiles in Tables VII-1
through VII-4, which show that using the exposure control measures
already in place, most mine operators are already achieving the PEL for
most miners.
2. Technological Feasibility of Sampling and Analytical Methods
a. Sampling Methods
MSHA's final rule requires mine operators in both MNM and coal
mines to conduct sampling for respirable crystalline silica using
respirable particle size-selective samplers that conform to the
``International Organization for Standardization (ISO) 7708:1995: Air
Quality--Particle Size Fraction Definitions for Health-Related
Sampling'' standard. The ISO convention defines respirable particulates
as having a 4 micrometer ([micro]m) aerodynamic diameter median cut-
point (i.e., 4 [micro]m-sized particles are collected with 50 percent
efficiency), which approximates the size distribution of particles that
when inhaled can reach the alveolar region of the lungs. For this
reason, the ISO
[[Page 28289]]
convention is widely considered biologically relevant for respirable
particulates and provides appropriate criteria for equipment used to
sample respirable crystalline silica.
MSHA received supportive comments from Badger Mining Corporation
(BMC), National Mining Association (NMA), and SKC Inc., regarding the
requirement for samplers to conform to ISO 7708:1995 (Document ID 1417;
1428; 1366). BMC reported having no objection to MSHA's sampling device
provisions proposed here (Document ID 1417). NMA encouraged MSHA to
clarify that any sampling technology that meets the characteristics for
respirable-particle-size-selective samplers that conform to the ISO
7708:1995 standard is acceptable for air sampling under the rule
(Document ID 1428). NMA, BMC, and SKC, Inc. each mentioned currently
available sampling equipment that meets the ISO criteria (Document ID
1428; 1417; 1366), and the manufacturer SKC, Inc. pointed out that, for
respirable crystalline silica sampling, mine operators can use any
respirable dust sampling device that conforms to ISO 7708:1995 (and
where appropriate, meets MSHA permissibility requirements) (Document ID
1366). In the Section-by-Section analysis of this preamble, MSHA
clarifies that mine operators are allowed to use any type of sampling
device for respirable crystalline silica sampling, as long as the
device is designed to meet the characteristics for respirable-particle-
size-selective samplers that conform to the ISO 7708:1995 standard and,
where appropriate, meet MSHA permissibility
requirements.47 48
---------------------------------------------------------------------------
\47\ To comply with the final rule requirement for using
respirable particulate samplers that meet the ISO 7708:1995
criteria, those coal mine operators that currently use coal mine
dust personal sampler units (CMDPSU) will need to adjust their
samplers to the flow rate specified by the sampler manufacturer for
complying with the ISO standard. This means that mine operators who
wish to use sampling devices that include a Dorr-Oliver cyclone can
adjust the associated sampling pumps so they operate at a flow rate
of 1.7 L/min to meet the ISO criteria. MSHA reminds mine operators
that they must continue to ensure any sampling equipment used in
underground coal mines is approved under Title 30 Part 74--Coal Mine
Dust Sampling Devices.
\48\ Mine operators must continue to ensure sampling equipment
used in underground coal mines is approved under Title 30 Part 74--
Coal Mine Dust Sampling Devices.
---------------------------------------------------------------------------
The American Exploration & Mining Association (AEMA), NMA, and
Portland Cement Association expressed concern that sufficient samplers
(and sampling pumps) might not be available by the proposed compliance
date (Document ID 1424; 1428; 1407).
As discussed in more detail in Section VIII.B. Section-by-Section
Analysis, MSHA has extended the compliance dates for the final rule (24
months from publication of the final rule for MNM and 12 months from
publication for coal) in response to concerns about the availability of
sampling equipment, among other things. MSHA believes that this will
resolve compliance date concerns but if concerns are not resolved by
the time operators must comply, MSHA may exercise enforcement
discretion as necessary.
MSHA received comments both for and against the proposed
requirement of sampling within 180 days after the effective date of the
final rule to complete the baseline sampling requirements, with most
commenters stating, for a variety of reasons, that it was not enough
time and recommending a longer period ranging from 1 year to 3 years.
The Metallurgical Coal Producers Association (MCPA) and MSHA Safety
Services, Inc. stated that providing only 180 days to complete baseline
sampling is not sufficient because of the limitation of available
resources for conducting sampling (Document ID 1406; 1392). The
Portland Cement Association, SSC, and the NMA stated that this
requirement may not be feasible for many operators because of
competition for outsourced resources such as rental equipment, media,
professional services, and laboratory sample analysis (Document ID
1407; 1432;1428). Concerned that mine operators will be competing to
obtain these resources, the Portland Cement Association and National
Lime Association (NLA) stated that small mines are likely to have the
greatest difficulty in finding these resources in a short period of
time (Document ID 1407; 1408). The NSSGA, NLA, BMC, and the Arizona
Mining Association each expressed concerns about performing other tasks
within the proposed timeframe for compliance, including establishing
contracts with accredited laboratories and other service providers
necessary for sampling, performing sampling for all miners who may
reasonably be expected to be exposed to respirable crystalline silica,
and designing and implementing new engineering controls (Document ID
1448; 1408; 1417; 1368). The NSSGA also urged MSHA to factor in the
increased demand that might result from the state of California's
effort to promulgate an Emergency Temporary Standard on silica
(Document ID 1448). The MCPA and the Portland Cement Association
recommended a phased timeline similar to the OSHA silica rule (which
gave employers one year before the commencement of most requirements
and two years before the commencement of sample analysis methods) and
the MSHA 2014 RCMD Standard (which gave operators 18 months after the
rule became effective) for completing sampling (Document ID 1406;
1407).
Other commenters considered the rule feasible and practical. The
AFL-CIO stated that technologically feasible air sampling and analysis
exist to achieve the proposed PEL using commercially available samplers
(Document ID 1449). This commenter noted that these technologically
feasible samplers are widely available, and a number of commercial
laboratories provide the service of analyzing dust containing
respirable crystalline silica. One individual supported the proposed
requirement that baseline sampling be conducted within 180 days of the
rule's effective date (Document ID 1367).
Samplers used in both MNM and coal mines can be used to perform the
sampling, and because other commercially available (already on the
market) samplers also conform to the ISO standard, MSHA finds that
sampling in accordance with the ISO standard is technologically
feasible and the technological feasibility analysis supporting the
sampling methods provisions in the proposed rule remain in effect for
this final rule.
b. Analytical Methods and Feasibility of Measuring Below the PEL and
Action Level
After a respirable dust sample is collected and submitted to a
laboratory, it must be analyzed to quantify the mass of respirable
crystalline silica present. The laboratory method must be sensitive
enough to detect and quantify respirable crystalline silica at levels
below the applicable concentration. The analytical limit of detection
(LOD) and/or limit of quantification (LOQ), together with the sample
volume, determine the airborne concentration LOD and/or LOQ for a given
air sample. MSHA's final PEL for respirable crystalline silica is 50
[mu]g/m\3\ as a full shift, 8-hour TWA for both MNM and coal mines.
Several analytical methods are available for measuring respirable
crystalline silica at levels well below the PEL of 50 [mu]g/m\3\ and
action level of 25 [mu]g/m\3\.
MSHA uses two main analytical methods (1) P-2: X-Ray Diffraction
Determination Of Quartz And Cristobalite In Respirable Metal/Nonmetal
Mine Dust (analysis by X-ray diffraction, XRD) for MNM mines and (2) P-
7: Determination Of Quartz In Respirable Coal Mine Dust By Fourier
Transform Infrared Spectroscopy
[[Page 28290]]
(analysis by infrared spectroscopy, FTIR or IR) for coal mines.\49\ The
MSHA P-2 and P-7 methods reliably analyze compliance samples collected
by MSHA inspectors. The exposure profile portion of this technological
feasibility analysis included 15 years of MNM compliance samples and 5
years of coal industry compliance samples MSHA analyzed with these
methods. These methods can measure respirable crystalline silica
exposures at levels below the PEL and action level.
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\49\ Other similar XRD methods include NIOSH-7500 and OSHA ID-
142. XRD methods distinguish between the different polymorphs--
quartz, cristobalite and tridymite. Other IR methods include NIOSH
7602 and 7603. IR methods, while efficient, are prone to
interferences and should only be used with a well-characterized
sample matrix (e.g., coal dust).
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For an analytical method to have acceptable sensitivity for
determining exposures at the PEL of 50 [mu]g/m\3\ and action level of
25 [mu]g/m\3\, the LOQ must be at or below the amount of analyte (e.g.,
quartz) that will be collected in an air sample where the concentration
of analyte is equivalent to the PEL or action level. To determine the
minimum airborne concentration that can be quantified, the LOQ mass is
divided by the sample air volume, which is determined by the sampling
flow rate and duration. Table VII-7 presents minimum quantifiable
quartz concentrations that can be measured using particle size-
selective samplers under various sampling parameters and established
analytical method reporting limits.
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Two commenters mentioned the need for sampling devices with real-
time or near real-time sample analysis capabilities for respirable
crystalline silica (Document ID 1428; 1449). One of these commenters,
the NMA, noted that personal dust monitoring devices with real-time
analysis did not appear in the proposed respirable crystalline silica
rule, noting that this equipment was included in MSHA's 2014 Coal Dust
Rule (Document ID 1428). The commenter recommended that MSHA adopt new
technology from the domestic or international mining community to
better protect miners. Also interested in new technology, the AFL-CIO
stated that, to more appropriately characterize exposures, MSHA should
incorporate continuous and rapid quartz monitoring systems into the
rule (Document ID 1449).
MSHA agrees with these commenters that new technology, such as
real-time dust monitors and NIOSH's rapid field-based quartz monitoring
(RQM) system with end-of-shift reporting \50\ can help mine operators,
for example by identifying overexposure conditions while the operator
evaluates and implements controls to reduce exposure. MSHA is not,
however, including instruments such as those mentioned by the
commenters in the
[[Page 28291]]
final rule because the Agency has reviewed the information on these
instruments and decided that analysis of samples using accredited
laboratories is the most accurate and reliable method of determining
respirable crystalline silica exposures for compliance purposes. The
final rule is the same as the proposal. Nevertheless, MSHA recommends
that operators stay aware of and evaluate advances in technologies to
identify control options that facilitate compliance, improve mine
operator and miner awareness, and improve miner health.
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\50\ NIOSH Information Circular 9533, ``Direct-on-filter
Analysis for Respirable Crystalline Silica Using a Portable FTIR
Instrument'' provides detailed guidance on how to implement a field-
based end-of-shift respirable crystalline silica monitoring program.
---------------------------------------------------------------------------
A commenter, AISI, expressed concern that the action level was too
close to the limit of accurate detection of respirable crystalline
silica (Document ID 1426) and one commenter, SSC, stated that there is
little confidence in the reliability of sampling results below 50
[mu]g/m\3\ (Document ID 1432).
MSHA agrees that limits of detection and reliability are important
considerations, and, in this context, the agency carefully reviewed
currently available sampling equipment and analytical methods as part
of the final rule and in Table VII-7. In Table VII-7, MSHA demonstrates
how exposure levels well below the PEL and action level can be reliably
quantified using particle size-selective samplers under various
sampling parameters and established analytical method reporting limits.
The minimum quantifiable quartz concentrations shown in Table VII-7 are
all less than 25 [mu]g/m\3\ and all but one are 12 [mu]g/m\3\ or less,
therefore well below the action level (25 [mu]g/m\3\).
MSHA finds that current analytical methods are sufficiently
sensitive to meet the PEL and action level in the final rule. This
finding is based on information presented in this section showing the
availability and sensitivity of MSHA, NIOSH, and OSHA analytical
methods capable of measuring respirable crystalline silica
concentrations below 50 [mu]g/m\3\ and 25 [mu]g/m\3\.
c. Laboratory Capacity
MSHA's final rule requires, for sample analysis, that mine
operators use laboratories that meet ISO 17025, General Requirements
for the Competence of Testing and Calibration Laboratories (ISO 17025).
The majority of U.S. industrial hygiene laboratories that perform
respirable crystalline silica analysis are accredited to ISO 17025 by
the American Industrial Hygiene Association (AIHA) Laboratory
Accreditation Program (LAP). The AIHA LAP lists 30 accredited
commercial laboratories nationwide that, as of November 2023, performed
respirable crystalline silica analysis using an MSHA, NIOSH, or OSHA
method.
MSHA received comments in support of the requirement for sample
analysis by the AIHA and the American Association for Laboratory
Accreditation (A2LA) (Document ID 1351; 1388). Both commenters agreed
that MSHA should rely on laboratories accredited to the ISO 17025
standards. The A2LA explained that relying on accredited laboratories'
impartiality, expertise, and accuracy will permit MSHA to focus time
and resources on policy, enforcement actions and other Agency
responsibilities (Document ID 1388).
MSHA interviewed three AIHA LAP accredited laboratories (one small-
capacity laboratory,\51\ one medium-capacity laboratory,\52\ and one
large-capacity laboratory \53\) to estimate their sample-processing
capacity. Insights from these interviews suggest that laboratories have
the ability to provide demand capacity during the phase-in of the final
rule. Collectively, these three laboratories could process
approximately 33,240 samples by XRD (suitable for MNM mines) and 1,752
samples by FTIR or IR (suitable for coal mines) within a 6-month
period. Extrapolating this across all laboratories that can analyze
respirable crystalline silica samples, MSHA estimates that analysis
will be available for 664,800 samples for MNM mines and 35,000 samples
for coal mines over any one-year period. Separately, in its FRIA (and
summarized in Table VII-8), MSHA estimates the numbers of miners for
whom the various types of sampling is required under the final rule, in
the first and each subsequent year after the final rule goes into
effect.\54\ As shown in Table VII-8, MSHA anticipates that within the
first 12 months after the final rule effective date, mines will seek
analysis for a total of 41,599 respirable crystalline silica samples
(all for coal mines). In the subsequent 12-month period, mines will
require analysis for 216,183 samples (primarily for MNM mines). The
number of analyses will begin declining in Year 3, as mine operators
reduce some miner exposures below the action level. Comparing these
figures with the demand capacity estimates noted above, MSHA finds that
there is sufficient processing capacity to meet the sampling analysis
schedule in the final rule.
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\51\ The small capacity laboratory has a maximum respirable
crystalline silica sample analysis capacity of 300 samples per month
(280 additional samples per month above the current number of
samples analyzed), a level which the laboratory could sustain for
two months.
\52\ The medium capacity laboratory has a maximum respirable
crystalline silica sample analysis capacity of 2,025 samples per
month. Surge from the mining industry is considered to replace,
rather than be in addition to the current number of samples
analyzed.
\53\ The large capacity laboratory has a maximum respirable
crystalline silica sample analysis capacity of 4,500 samples per
month (3,700 additional samples per month above the current number
of samples analyzed).
\54\ The estimated sample counts are based on MSHA's existing
mine population data and its exposure profile, developed using 15
years of MNM compliance sampling exposure data and 5 years of data
from the coal industry, stratified by exposure level (less than the
action level, from the action level to the final rule PEL, and above
the final rule PEL). That process was described in the proposed rule
and is summarized in Section VII.A Technological Feasibility (see
Subsections VII.A.1.a Methodology and VII.A.1.b The Technological
Feasibility Analysis Process). From these data, MSHA estimated for
its FRIA how many first- and second-time samples will represent
miners likely to have exposure below the action level and require no
further sampling. Based on its knowledge and experience of the
mining industry, MSHA further estimated how rapidly mine operators
will be able to reduce the exposures of the remaining miners to
levels below the anticipated PEL or action level, and calculated how
many quarterly, corrective actions, and post-evaluation samples that
the mines will collect (and require analysis for) over time.
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[[Page 28292]]
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First- and Second-Time Sampling
MSHA's final rule requires mine operators to commence sampling, by
the compliance date in the final rule, for each miner who is or may
reasonably be expected to be exposed to respirable crystalline
silica.\55\ This requirement simplifies the initial sampling
requirement described in the proposed rule, which called for a baseline
sample followed by a confirmatory sample (or other data, as described
below) if samples revealed concentrations below the action level. The
final rule eliminates the option of using objective data or historical
sample data (mine operator and MSHA sample data from the prior 12
months); all exposure samples used to comply with the rule must be
collected and analyzed in accordance with the final rule. The changes
to the proposed rule increase the number of samples that mine operators
will collect and send to laboratories for analysis. The increased
sampling will require an initial increase in analytical laboratory
capacity of approximately 41,599 FTIR sample analyses in the first year
(between the final rule's effective date and the coal mine compliance
date), with 29,796 of these for first-time and second-time sampling. In
the following year, MSHA estimates that MNM mine operators will require
196,708 XRD sample analyses (in the second year due to the extended MNM
mine compliance date) of which approximately 124,288 will be first-time
and second-time samples.\56\
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\55\ Where several miners perform similar activities on the same
shift, only a representative fraction of miners (minimum of two
miners) would need to be sampled, including those expected to have
the highest exposures.
\56\ Also in the second year, MSHA anticipates that the coal
mining industry will require 19,475 analysis by FTIR method;
relatively few (596) of these will be for first- and second-time
samples.
---------------------------------------------------------------------------
All mine operators covered by the rule must initiate sampling by
the compliance dates, potentially creating a peak demand for analysis
around those dates. MSHA finds, however, that the final rule is
feasible for mine operators to secure the services of analytical
laboratories. First, the extended MNM compliance date permits more time
to accommodate and prepare for any increase in demand. MSHA expects
many mine operators will avoid last-minute sampling and begin the
sampling process earlier than required; thus, the sampling and
associated analysis will be spread over many months, meaning that any
eventual peak period for laboratory analysis will be longer and less
intense (i.e., fewer analyses per month required) than it might be
otherwise. Additionally, MSHA expects that the extended lead time will
be sufficient for laboratories to increase their analytical capacity.
For example, laboratories may acquire additional instrumentation, train
additional analysts, or add a second or third operating shift. This is
particularly
[[Page 28293]]
likely given that demand will be based on a regulatory requirement.
MSHA has determined that the final rule is technologically feasible for
mine operators to secure laboratories' analytical services.
Above-Action-Level, Corrective Actions, and Post-Evaluation Sampling
Under Sec. 60.12(a), (b), and (d), mine operators may be required
to conduct additional sampling. First, when the most recent sampling
indicates that miner exposures are at or above the action level (25
[micro]g/m\3\) but at or below the PEL (50 [micro]g/m\3\), the mine
operator is required to sample within 3 months of that sampling and
continue to sample within 3 months of the previous sampling until two
consecutive samplings indicate that miner exposures are below the
action level. Second, where the most recent sampling indicates that
miner exposures are above the PEL, the mine operator is required to
sample after corrective actions are taken to reduce overexposures and
continue conducting corrective actions sampling until sampling results
indicate miner exposures are at or below the PEL. Third, if the mine
operator determines, as a result of the periodic evaluation, that
miners may be exposed to respirable crystalline silica at or above the
action level, the mine operator is required to perform sampling to
assess miners who are or may reasonably be expected to be exposed at or
above the action level.
In its standalone Final Regulatory Impact Analysis (FRIA) document
(referred to as the standalone FRIA document throughout the preamble),
Table 4-5 ``Estimated Number of Samples Taken by Type and Year,'' MSHA
estimates that, starting in the first 12-month period after the rule's
effective date, coal mine operators will secure laboratory services for
analysis of 5,423 above-action-level samples (those samples required
when the previous sample is at or above the action level, but at or
below the PEL), 1,991 corrective actions samples, and 4,390 post-
evaluation samples, in addition to the 29,796 first-time and second-
time samples mentioned in the previous subsection. MSHA assumes that
coal industry analytical needs will be reduced in subsequent years as
mine operators reduce miner exposures to levels below the PEL or action
level. In the second 12-month period, in addition to 596 first-time and
second time samples, coal mine operators will secure laboratory
services for analysis for 10,556 above-action-level, 3,934 corrective
actions, and 4,390 post-evaluation samples.
Similarly, starting in the second 12-month period (due to the
extended MNM compliance date), MSHA estimates that MNM mine operators
will secure laboratory analysis for 36,442 above-action-level, 23,414
corrective actions, and 12,564 post-evaluation samples (plus the
124,288 first-time and second-time samples discussed previously). MSHA
estimates that the MNM industry's need for analysis will be lower in
the following years as mine operators reduce miner exposures to levels
below the PEL or action level. In the third 12-month period after the
rule goes into effect, MNM mines are projected to need analysis for
2,486 first-time and second-time, 66,764 above-action-level, 43,041
corrective actions, and 12,564 post-evaluation samples.\57\ Together,
mine operators will require fewer sample (at least 10,000 fewer)
analyses in each subsequent year than in the first 12-month period
(coal sector) and second 12-month period (MNM mines), which are
considered the ``worst case'' or highest demand periods for analysis
under this rule.
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\57\ As noted in Section VII.A.2.c (First- and second-time
sampling) coal mines will have completed most of their first- and
second-time sampling during the first year after the rule's
effective date and MNM mines will complete most of it in the second
year after the rule goes into effect. MSHA expects only a relatively
modest amount of this sampling to continue in subsequent years (coal
mining industry requiring 596 analyses per year and MNM mining
industry 2,486 analyses per year) due to a steady background level
of new activities starting or new mines opening.
---------------------------------------------------------------------------
MSHA estimated that the total number of analyses (699,800) that
laboratories will be able to perform per year is nearly three times the
maximum total estimated number of samples analyses required
(216,183).\58\ The maximum number of sample analyses required will
occur in the second year after the rule goes into effect.\59\ Based on
MSHA's evaluation, the Agency finds that above-action-level, corrective
actions, and post-evaluation sampling are technologically feasible for
mine operators both in the early years after the rule becomes
effective, and in subsequent years.\60\
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\58\ Excess capacity calculated as: (estimated annual demand
capacity of 30 AIHA LAP accredited laboratories for sample analysis)
divided by (maximum number of XRD and FTIR samples for which mines
will seek analysis) = 699,800/216,183 = 3.2 times more analysis
available on a yearly basis than the number of sample analyses labs
will complete in the peak year.
\59\ The maximum number of samples (the peak) will occur in the
second 12-month period (second year) after rule's effective date,
which is the period when MNM mines will conduct most of their first-
time and second-time sampling as well as initiate above-action-
level, corrective actions, and post-evaluation sampling.
Concurrently, coal mines will continue conducting first-time and
second-time, above-action-level, corrective actions, and post-
evaluation sampling at somewhat lower rates. See Table 4-5 of the
standalone FRIA document (estimates presented here are as of 11/26/
2023).
\60\ Surplus analyses calculated: estimated annual surge
capacity of 30 AIHA LAP accredited laboratories for sample analysis)
minus (maximum number of XRD and FTIR samples for which mines will
seek analysis) = 699,800-216,183 = 483,617 surplus analyses.
---------------------------------------------------------------------------
The AEMA and NMA expressed concern that laboratory capacity might
not be available by the proposed compliance date (Document ID 1424;
1428). As discussed in more detail in Section VIII.B. Section-by-
Section Analysis, MSHA has extended the compliance dates in the final
rule for MNM and coal (24 months and 12 months from publication of the
final rule, respectively) in response to concerns about the
availability of laboratory capacity, among other things. MSHA believes
that this will resolve compliance date concerns but if concerns are not
resolved by the time operators must comply, MSHA may exercise
enforcement discretion as necessary.
As part of the proposed rule, MSHA examined the capacity of
laboratories that meet the ISO 17025 standard to conduct respirable
crystalline sample analyses. MSHA made the preliminary determination
that there would be sufficient processing capacity to meet the sampling
analysis schedule envisioned by the proposed rule, and that the
proposed rule is technologically feasible for laboratories to conduct
baseline sampling analyses (88 FR 44923). MSHA also preliminarily
determined that the availability of samplers needed to conduct the
required baseline sampling is technologically feasible (88 FR 44921).
This preliminary determination, however, only examined whether sampler
technology exists to conduct the respirable crystalline silica sampling
as required under the proposal, not the availability of that technology
to meet the demands that the final rule will impose.
MSHA agrees with commenters that the sampling requirements of the
final rule will create an initial rush for sampling devices and related
equipment and services. MSHA understands that there are more sampling
devices (as well as related services and supplies) currently available
in the market now than prior to OSHA's proposed silica rule.
Nevertheless, based on OSHA's successful promulgation of that Agency's
2016 respirable crystalline silica final rule that included new silica
sampling requirements (with similar
[[Page 28294]]
ISO compliant sampling equipment and analytical method provisions for
both general industry and the construction industry), MSHA expects that
there will be another additional increase in demand (for equipment,
services, and supplies) caused by this final rule. MSHA expects that
the sampling device market will respond to the Agency's rule. MSHA does
not expect that mines will experience a shortage of sampling resources
due to a California emergency temporary standard (ETS) to address
silicosis among engineered stone fabrication facility workers (e.g.,
kitchen countertop shop employees who often use powered hand tools to
grind/shape engineered stone, which has a quartz content greater than
most natural stone).\61\ Any increased demand of sampling equipment,
services, or silica analysis for the mining industry will be related to
MSHA's rule.
---------------------------------------------------------------------------
\61\ The California ETS went into effect on December 29, 2023.
The ETS includes revisions to protect workers engaged in high-
exposure tasks (cutting, grinding, etc.) involving artificial stone
and natural stone containing more than 10% crystalline silica.
---------------------------------------------------------------------------
Resource limitations may be an issue for MNM mine operators since
there are far more MNM mines in the U.S. compared to coal mines (in
2021, there were 11,231 MNM mines compared to 931 coal mines). As such,
the expected demand for sampling devices, supplies, and services to
meet the sampling requirements of this final rule is expected to be
greater for MNM mines compared to coal mines.
MSHA carefully considered the above information about availability
of laboratory capacity and sampling devices, including the likely
increase in demand for such services and devices. MSHA acknowledges
commenters' concerns about the need for more time to conduct sampling
and implement necessary engineering controls. Accordingly, MSHA has
adjusted the requirements in the final rule to allow MNM mine operators
a total of 24 months after the publication date of the final rule to
comply. This will provide sufficient time for MNM mine operators to
comply with the requirements of part 60. Actions the operator may take
in preparation for compliance with part 60 may include, for example,
purchasing sampling equipment, securing sampling services, making
arrangements with laboratories, and performing sampling. MSHA has
changed the requirements in the final rule to allow coal mine operators
a total of 12 months after publication of the final rule to come into
compliance. MSHA expects that the extended time for compliance will
provide coal mine operators with time to purchase additional sampling
equipment and acquire necessary laboratory services. MSHA also notes
that the AIHA, an accrediting body for commercial laboratories that
analyze respirable crystalline silica, concurred with MSHA's findings
that technologically feasible samplers are widely available, and a
number of commercial laboratories provide the service of analyzing dust
containing respirable crystalline silica (Document ID 1351). Additional
discussion of the compliance dates can be found in Section VIII.A.1.c.
Compliance Dates.
3. Technological Feasibility of Respiratory Protection (Within Part 60)
Under MSHA's final rule, respiratory protection will not be allowed
for compliance. As discussed elsewhere, MSHA has determined that the
PEL is feasible for all mines and all mines must comply with it.
However, when exposures are above the PEL, mine operators must take
immediate corrective actions, provide miners with respirators, and
ensure that they are worn until exposures are below the PEL. There is a
sufficient supply of respirators for mine operators to obtain and
maintain for temporary use. Therefore, MSHA has determined that the
requirements in the final rule for respirator use are technologically
feasible. This finding is supported by the Agency's knowledge of and
experience with the mining industry, evidence presented by NIOSH
(2019b, 2021a), and Tables VII-1 through VII-4 (exposure profiles for
MNM and coal mines). These tables indicate that the PEL (50 [mu]g/m\3\)
has already been achieved for approximately 82 percent of the MNM
miners and approximately 93 percent of the coal miners sampled by MSHA.
MSHA believes that this data supports the Agency's approach to
respirator use in the final rule.
Section 60.14(b) requires that any miner unable to wear a
respirator must receive a temporary job transfer to an area or to an
occupation at the same mine where respiratory protection is not
required. The paragraph also requires that a miner transferred under
this requirement continue to receive compensation at no less than the
regular rate of pay in the occupation held by that miner immediately
prior to the transfer. MNM mine operators must already comply with the
job transfer provisions under the existing standard in Sec.
57.5060(d)(7) that requires mine operators to transfer miners unable to
wear a respirator to work in an existing position in an area of the
mine where respiratory protection is not required. Section 60.14(b) is
similar to these existing requirements. MSHA finds that mine operators
will have a similar experience implementing the job transfer provisions
of Sec. 60.14(b). As discussed in Section VIII.B.7.b. Section
60.14(b)--Miners unable to wear respirators, MSHA concludes that
temporary transfer of miners unable to wear respirators to a separate
area or occupation to ensure their health and safety is feasible. As
noted elsewhere in the preamble, any respirator use will be temporary
to protect miners from overexposures during activities such as the
implementation or development engineering controls. Therefore, MSHA
finds that the requirement in Sec. 60.14(b) is technologically
feasible.
For miners who need to wear respiratory protection on a temporary
basis, section 60.14(c)(1) requires the mine operator to provide NIOSH-
approved atmosphere-supplying respirators or NIOSH-approved air-
purifying respirators equipped with high-efficiency particulate filters
in one of the following NIOSH classifications under 42 CFR part 84: 100
series or High Efficiency (HE). As discussed below in the Section-by-
Section analysis, MSHA finds that particulate respirators meeting these
criteria will offer the best filtration efficiency (99.97 percent) and
protection for miners exposed to respirable crystalline silica and are
widely available and used by most industries. This finding is based on
the characteristics of the 100 series as compared to the other two most
common series (95 and 99). The 95- and 99-series particulate
respirators do not offer as high a degree of protection as the 100-
series (95 percent and 99 percent efficiency, respectively), and are
less likely to provide the expected level of protection due to concerns
about poor fit and vulnerability to mishandling such as folding or
crushing. The NIOSH-approved 100-series particulate respirators also
have broad commercial availability.\62\ NIOSH publishes a list of
approved respirator models along with manufacturer/supplier
information. In November 2022, the NIOSH-approved list contained 221
records on atmosphere-supplying respirator models, 160 records on
elastomeric respirators with P-100 classification, and 23 records on
filtering facepiece respirators with P-100 classification (NIOSH, 2022a
list P-100 elastomeric, P-100 filtering facepiece, and atmosphere-
supplying respirator
[[Page 28295]]
models).\63\ Based on this information regarding the level of
protection and the market availability, MSHA finds that Sec.
60.14(c)(1) is technologically feasible.
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\62\ Class 100 particulate respirators (currently the most
widely used respirator filter specification in the U.S.) are
available from numerous sources including respirator manufacturers,
online safety supply companies, mine equipment suppliers, and local
retail hardware stores.
\63\ The NIOSH list of approved models does not guarantee that
each model is currently manufactured. However, the list does not
include obsolete models, and the more popular models are widely
available, including in bulk quantities.
---------------------------------------------------------------------------
Section 60.14(c)(2) incorporates the ASTM F3387-19 ``Standard
Practice for Respiratory Protection'' to ensure that the most current
and protective respiratory protection practices are implemented by mine
operators who temporarily use respiratory protection to control miners'
exposures to respirable crystalline silica. The Agency is also
incorporating this respiratory protection consensus standard under
Sec. Sec. 56.5005, 57.5005, and 72.710. This update is also addressed
in the next section (see Technological feasibility of updated
respiratory protection standards). Based on the information contained
in that section, MSHA finds that Sec. 60.14(c)(2) is technologically
feasible.
4. Technological Feasibility of Updated Respiratory Protection
Standards (Amendments to 30 CFR Parts 56, 57, and 72)
a. Incorporation by Reference
This section discusses the update to MSHA's existing respiratory
protection standards in 30 CFR 56.5005, 57.5005, and 72.710 which deal
with other airborne contaminants and do not include respirable
crystalline silica. Respiratory protection requirements for respirable
crystalline silica are in final Sec. 60.14 and are substantially
similar to MSHA existing standards. Respirators are used by mine
operators to protect miners against respiratory hazards, including
particulates, gases, and vapors. Under existing standards, for MNM and
coal mine operators, respirators must not be used in place of
engineering controls to control airborne contaminants. If respirable
coal mine dust samples exceed the standard, coal mine operators must
make approved respiratory equipment available to affected miners while
taking immediate corrective actions to lower the concentration of
respirable dust to at or below the respirable dust standard. Metal and
nonmetal mine operators must provide miners with respirators and miners
must use respirators while engineering control measures are being
developed or when necessary by the nature of work involved (for
example, while establishing controls or occasional entry into hazardous
atmospheres to perform maintenance or investigation).
Where respirators are used, they must seal and isolate the miner's
respiratory system from the contaminated environment. The risk that a
miner will experience an adverse health effect from a contaminant when
relying on respiratory protection is a function of the toxicity or
hazardous nature of the air contaminants present, the concentrations of
the contaminants in the air, the duration of exposure, and the degree
of protection provided by the respirator. When respirators fail to
provide the expected protection, there is an increased risk of adverse
health effects. Therefore, it is critical that respirators perform as
they are designed.
Accordingly, MSHA is incorporating by reference ASTM F3387-19 by
amending Sec. Sec. 56.5005, 57.5005, and 72.710 to replace the
Agency's existing respiratory protection standard in those sections.
Final Sec. Sec. 56.5005, 57.5005, and 72.710 requires mine operators
to develop a written respiratory protection program meeting the
requirements in accordance with ASTM F3387-19. These requirements allow
for achieving expected protection levels from respirator use. This
revision to MSHA's existing standards will better protect miners who
temporarily wear respiratory protection.
The American National Standards Practices for Respiratory
Protection ANSI Z88.2--1969 was previously incorporated by reference in
Sec. Sec. 56.5005, 57.5005, and 72.710.\64\ Since MSHA adopted these
standards, respirator technology and knowledge on respirator protection
have advanced and as a result, changes in respiratory protection
standard practices have occurred. ASTM F3387-19 is the most recent
respirator practices consensus standard and provides more comprehensive
and detailed guidance. MSHA finds, based on observations during
enforcement inspections and compliance assistance visits to mines, that
mines using respiratory protection have also already implemented
current respiratory protection recommendations and standards such as
ANSI/ASSE Z88.2--2015 ``Practices for Respiratory Protection''
standard, its similar ASTM replacement (the F3387-19 standard), or OSHA
29 CFR 1910.134--Respiratory protection. ASTM F3387-19 standard
practices are substantially similar to the standard practices included
in ANSI/ASSE Z88.2--2015 or OSHA's respiratory protection standards.
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\64\ ASTM 3387-19 is the revised version of ANSI/ASSE Z88.2--
2015. In 2017, the Z88 respirator standards were transferred from
ANSI/ASSE to ASTM International (source: F3387-19, Appendix XI).
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b. Availability of Respirators
The updated respiratory protection standard reflects current
practice at many mines that use respiratory protection and does not
require the use of new technology. Thus, MSHA finds that the update is
technologically feasible for affected mines of all sizes.
c. Respiratory Protection Practices
By amending existing standards to incorporate the updated
respiratory protection consensus standard (ASTM F3387-19), MSHA intends
that mine operators will develop effective respiratory protection
practices that meet the updated consensus standard and that will better
protect miners from respiratory hazards.
MSHA presumes that most mines with respiratory protection programs,
and particularly those MNM mines that have operations under both MSHA
and OSHA jurisdiction, are already following either the ANSI/ASSE
Z88.2--2015 standard, the ASTM F3387-19 standard, or OSHA 29 CFR
1910.134. As several commenters noted, consistency between OSHA and
MSHA requirements is beneficial for organizations regulated by both
agencies, as it permits them to more easily comply with a single,
consistent set of requirements. Mine operators with operations under
OSHA jurisdiction would, by this logic, choose to comply with 29 CFR
1910.134 across all operations rather than develop separate programs
for MSHA-regulated facilities. The respiratory protection program
elements under ASTM F3387-19 are largely similar to those in the
previous standard.
MSHA expects that some operators may need to adjust their current
respiratory protection practices and standard operating procedures to
reflect ASTM F3387-19 standard practices. Examples of adjustments
include formalizing annual respirator training and fit testing;
updating the training qualifications of respirator trainers, managers,
supervisors, and others responsible for the respiratory protection
program; reviewing the information exchanged with the physician or
other licensed health care professional (PLHCP) conducting medical
evaluations; and formalizing internal and external respiratory
protection program reviews or audits.
Overall, MSHA finds that the amendments to parts 56, 57, and 72 are
technologically feasible because the requirements of ASTM F3378-19 have
already been implemented at many mines.
MSHA received several comments on the Agency's decision to limit
respirator
[[Page 28296]]
use to temporary and non-routine use. Many commenters opposed this
limitation in the proposal, including AIHA, Miners Clinic of Colorado,
ACLC, and Black Lung Clinics (Document ID 1351; 1418; 1445; 1410),
while others requested more information to help them properly interpret
the requirement, including SSC, AMI Silica LLC, NSSGA, and AFL-CIO
(Document ID 1432; 1440; 1448; 1449). The AFL-CIO requested that MSHA
clarify temporary and non-routine to specify circumstances and time
limitations (Document ID 1449). Appalachian Voices stated that mine
construction and coal production should be excluded from the temporary
and non-routine use of respirators (Document ID 1425).
The Construction Industry Safety Coalition (CISC) suggested that
coal miners should be prohibited from working in overexposures while
using respirators, stating that the working conditions, especially in
underground coal mines, make it very difficult for miners to
communicate and work safely while wearing respirators (Document ID
1430). Many commenters suggested that MSHA utilize the full hierarchy
of controls to recognize respirators as an acceptable solution when
combined with other efforts to lower exposure levels, including Arizona
Mining Association, AEMA, NMA, NVMA, NSSGA, US Silica, SSC, BMC,
Illinois Association of Aggregate Producers (IAAP) (Document ID 1368;
1424; 1428; 1441; 1448; 1455; 1432; 1417; 1456). Advocating expanded
use of respiratory protection, but differing in their approach, a few
commenters, including SSC, NSSGA, US Silica, and IAAP, wrote that
respirators are the only feasible means of protection for certain
tasks, including housekeeping, dust collector maintenance and repair,
and bagging operations (Document ID 1432; 1448; 1455; 1456). The AEMA
stated that MSHA should allow the use of respirators, including PAPRs,
whenever miners are working in exposures above the PEL (Document 1424).
Another commenter stated that miners should always use respirators, to
ensure complete protection from respirable crystalline silica
exposures. MSHA finds that engineering controls, supplemented by
administrative controls, are technologically feasible and provide
reliable, consistent protection for miners engaged in the identified
tasks; MSHA declines to expand the allowable use of respiratory
protection. MSHA emphasizes that both in the existing standards for MNM
mines and in Sec. 60.14, respiratory protection use is required to be
temporary. The Agency emphasizes that it will continue to enforce
``temporary'' use of respirators as meaning that respirators are used
for only a short period of time.
MSHA clarifies that the final rule does not permit the use of
respirators in lieu of feasible engineering and administrative
controls. If anything, MSHA has provided greater protection for miners
by requiring (as opposed to making available) usage of respirators for
all miners when exposed to respirable crystalline silica above the PEL.
5. Technological Feasibility of Medical Surveillance (Within Part 60)
Under the final rule, MNM mine operators will be required to
provide periodic medical examinations performed by a physician or other
licensed health care professional (PLHCP) or specialist, at no cost to
the miner. 30 CFR 60.15. The medical surveillance standards extend to
MNM miners similar protections to those available to coal miners under
existing standards in 30 CFR 72.100. The requirements in Sec. 60.15
are consistent with the Mine Act's mandate to provide maximum health
protection for miners, which includes making medical examinations and
other tests available to miners at no cost. 30 U.S.C. 811(a)(7).
Under the final rule, all MNM miners who are employed or have
already worked in the mining industry must be provided the opportunity
for an initial voluntary examination starting during an initial 12-
month period that begins no later than the compliance date or during a
12-month period that begins whenever a new mine commences operations.
Subsequent medical examinations must be available at least every 5
years during a 6-month period that begins no less than 3.5 years and
not more than 4.5 years from the end of the previous 6-month period.
MNM miners who begin work in the mining industry for the first time
must receive an initial examination within 60 days of beginning
employment. After their initial examination, these new miners must be
provided a follow-up examination within 3 years. If the 3-year follow-
up examination indicates any medical concerns associated with chest X-
ray findings or decreased lung function, these miners must have another
follow-up examination in 2 years. After this 2-year follow-up
examination, or if the 3-year follow-up examination indicates no
medical concerns associated with chest X-ray findings or decreased lung
function, these miners will be eligible for voluntary periodic 5-year
examinations, transferring them into the larger cohort of miners
already employed in the mining industry.
The final rule requires that medical examinations include a review
of the miner's medical and work history, a physical examination with
special emphasis on the respiratory system, a chest X-ray, and a
pulmonary function test. The medical and work history covers a miner's
present and past work exposures, illnesses, and any symptoms indicating
respirable crystalline silica-related diseases and compromised lung
function. The required chest X-ray must be classified by a NIOSH-
certified B Reader, in accordance with the Guidelines for the Use of
the International Labour Office (ILO) International Classification of
Radiographs of Pneumoconioses. The ILO recently made additional
standard digital radiographic images available and has published
guidelines on the classification of digital radiographic images (ILO,
2022). These guidelines provide standard practices for detecting
changes of pneumoconiosis, including silicosis, in chest X-rays. The
required pulmonary function test must be conducted by either a
spirometry technician with a current certificate from a NIOSH-approved
Spirometry Program Sponsor, or, as discussed in Section VIII.B.8.a.
60.15(a)--Medical surveillance of this preamble, a pulmonary function
technologist with a current credential from the National Board for
Respiratory Care.
MSHA has determined that it is technologically feasible for MNM
mine operators to provide periodic examinations as described in the
previous paragraph. Under the rule, a PLHCP, as defined, does not have
to be an occupational medicine physician or a physician to conduct the
initial and periodic examinations required by the rule, but can be any
health care professional who is state-licensed to provide or be
delegated the responsibility to provide those services. The procedures
required (i.e., medical history, physical examination, chest X-ray,
pulmonary function test) for initial and periodic medical examination
are commonly conducted in the general population by a wide range of
practitioners with varying medical backgrounds. Because the medical
examinations consist of procedures conducted in the general population
and because MSHA will be giving MNM mine operators flexibility in
selecting a PLHCP or specialist able to offer these services, MSHA
determined that operators will not experience difficulty in finding
PLHCPs or specialists who are licensed to provide these services.
[[Page 28297]]
Overall, MSHA finds that the medical surveillance provisions are
technologically feasible and in the final rule maintains the proposed
medical surveillance provisions, with some modifications.
MSHA received several comments on the feasibility of proposed Sec.
60.15(a). The AIHA, the American Association of Nurse Practitioners
(AANP), and CertainTeed, LLC supported MSHA's proposal to require MNM
mine operators to provide MNM miners with medical examinations
performed by a PLHCP or specialist (Document ID 1351; 1400; 1423). The
Arizona Mining Association and the BIA expressed concerns with this
requirement and asserted that many MNM mines may experience issues with
access to a PLHCP or specialist qualified to perform the examinations
(Document ID 1368; 1422). The APHA, the AOEC, and the ACOEM advocated
for medical surveillance to be performed by physicians who are board-
certified in occupational medicine or pulmonary medicine (Document ID
1416; 1373; 1405). The Hon. Rep. Robert C. ``Bobby'' Scott and an
individual recommended that MNM miners should be able to choose their
own health care provider (Document ID 1439; 1412). The AIHA and Black
Lung Clinics stated that MSHA should require MNM miners to use NIOSH-
approved facilities (Document ID 1351; 1410) while the AEMA and the NMA
(Document ID 1424; 1428) expressed concerns about the limited
availability of these facilities. The NMA, the Portland Cement
Association, and the AEMA noted that there are only a limited number of
B Readers available (Document ID 1428; 1407; 1424).
MSHA reviewed these comments and made one change to Sec. 60.15(a)
in the final rule. Under the proposed rule, a pulmonary function test
must be administered by a spirometry technician with a current
certificate from a NIOSH-approved Spirometry Program Sponsor. In the
final rule, paragraph 60.15(a)(2)(iv) retains that language but adds
pulmonary function technologists with current credentials from the
National Board for Respiratory Care as individuals who may administer
pulmonary function tests. This addition to the final rule text should
further expand the pool of individuals eligible to administer pulmonary
function tests.
MSHA determined that MNM mine operators should not experience any
significant issues identifying a PLHCP or specialist to conduct medical
examinations and emphasizes the final rule allows flexibility by not
mandating that the medical examinations be conducted by full-time
health care professionals employed by mine operators. As stated in the
proposal, a PLHCP is an individual whose legally permitted scope of
practice (i.e., license, registration, or certification) allows that
individual to independently provide or be delegated the responsibility
to provide some or all of the required health services (i.e., chest X-
rays, pulmonary function test, symptom assessment, and occupational
history). Specialist is defined in Sec. 60.2 as an American Board-
Certified Specialist in Pulmonary Disease or an American Board-
Certified Specialist in Occupational Medicine. MSHA also clarifies that
if medical examinations are integrated within health care plans, mine
operators must ensure that the examinations are conducted in accordance
with the requirements in Sec. 60.15. MSHA determined that the
requirements for testing and interpretation of results are
technologically feasible.
The Agency has reviewed the comments related to availability of B
Readers. MSHA has determined that, based on technological improvements
that remove the need for geographic proximity between patients and
technicians such as B Readers, as well as widespread availability of
tests such as X-rays, getting X-ray tests and the results classified by
B Readers is technologically feasible. With respect to chest X-ray
classification, the availability of digital X-ray technology permits
electronic submission to remotely located B Readers for interpretation.
After consulting NIOSH, MSHA determined there are B Readers with remote
reading capabilities available to meet the demands of the final rule.
Therefore, MSHA finds that the limited number of B Readers in certain
geographic locations will not be an obstacle for MNM operators. MSHA
further concludes that any increase in demand for these services can be
addressed by providers. Further discussion regarding NIOSH-approved
facilities and B Readers can be found in Section VIII.B.8.a. Section
60.15(a)--Medical Surveillance of this preamble.
MSHA's experience with the coal mine medical surveillance program
has shown the Agency that PLHCPs who have the required NIOSH or other
certifications have the training to effectively examine miners and
identify the occurrence or progression of silica-related diseases, even
if they may not operate within NIOSH-approved facilities. MSHA's
updated research continues to support OSHA's conclusion in its 2016
silica final rule that the number of B Readers in the United States is
adequate to classify chest X-rays (OSHA 2016a, 81 FR 16286, 16821).
Further, an increased demand for B Readers as a result of this final
rule will lead to additional training for many health care providers.
In addition, digital X-rays can be easily transmitted electronically to
B Readers anywhere in the United States. The final rule ensures that
medical examinations are comprehensive and tailored to discern and
mitigate potential health risks associated with miners' occupational
exposures to respirable crystalline silica. The final rule will ensure
that the medical examinations are both robust and flexible enough to
accommodate advancements and variations in medical evaluation
techniques. Further discussion regarding NIOSH-approved facilities and
B Readers can be found in Section VIII.B.8.a. Section 60.15(a)--Medical
Surveillance of this preamble.
The final rule does not require that examinations conducted under
this section occur in NIOSH-approved facilities. There are only 168
NIOSH-approved health clinics nationwide. NIOSH manages the Coal
Workers' Health Surveillance Program and the program's facilities are
concentrated in geographies where coal mining is prevalent (e.g.,
Appalachia, the Illinois Basin, and Powder River Basin). The NIOSH-
approved facilities are not uniformly distributed across the U.S. and
there are many areas that have MNM mines but do not have NIOSH-approved
facilities (e.g., the states California, Idaho, Nevada, and
Washington). Therefore, MSHA has determined that it is not feasible to
require NIOSH-approved facilities for medical surveillance in MNM
mines.
[[Page 28298]]
6. Conclusions
Based on MSHA's technological feasibility analysis, MSHA has
determined that all elements of the rule on Lowering Miners' Exposure
to Respirable Crystalline Silica and Improving Respiratory Protection
are technologically feasible.
B. Economic Feasibility
MSHA considers economic feasibility in terms of industry-wide
revenue and overall costs incurred by the mining industry (inclusive of
MNM and coal) under a given rule. To establish economic feasibility,
MSHA uses a revenue screening test--whether the estimated yearly costs
of a rule are less than 1 percent of estimated revenues or are negative
(i.e., provide net cost savings)--to presumptively establish that
compliance with the regulation is economically feasible for the mining
industry. If annualized compliance costs comprise less than 1 percent
of revenue, the Department concludes that the entities can incur the
compliance costs without significant economic impacts.\65\ MSHA
received comments on economic feasibility. Several commenters argued
that it would cost thousands or millions of dollars in exposure control
costs to meet the new PEL (Document ID 1419; 1441; 1448; 1455). Others
noted that the action level will result in more sampling above the
action level and additional engineering controls needed to get below
the action level, leading to greater costs (Document ID 1419, 1455).
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\65\ MSHA is not required to produce hard and precise estimates
of cost to establish economic feasibility. Rather, MSHA must provide
a reasonable assessment of the likely range of costs of its
standard, and the likely effects of those costs on the industry. See
United Steelworkers, 647 F.2d at 1264; see also Nat'l Min. Ass'n,
812 F.3d at 865.
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Based on its analysis of the Agency's sampling database, MSHA
believes roughly 90 percent of mines will be able to meet the PEL
without incurring additional costs, and only 580 mines will need to
install engineering control to meet the new PEL (see standalone FRIA
document Section 4). In response to public comments that MSHA
underestimated the cost of implementing necessary exposure controls,
MSHA increased its estimate of the number of mine operators that will
have to implement additional exposure controls to meet the requirements
of the final rule.
One commenter pointed out that engineering controls need to factor
in site-specific conditions (Document ID 1441). MSHA acknowledges that
the exposure control costs will differ depending on the size of the
mine, the current level of exposure to respirable crystalline silica,
existing engineering and administrative controls, the mine layout, work
practices, and other variables. MSHA's price and cost estimations are
based on a variety of sources including market research and MSHA's
experience and sample data. Some of the cost estimates from
commenters--such as those from very large mines or those representing
many mines controlled by one operator--are impossible to meaningfully
compare to MSHA's estimates. Nonetheless, these and other public
comments about the costs of the final rule are addressed in more detail
below in Section IX. Summary of Final Regulatory Impact Analysis and
Regulatory Alternatives, as well as in Section 8 of the standalone FRIA
document.
For the MNM and coal mining sectors, MSHA estimates the projected
impacts of the rule by calculating the annualized compliance costs for
each sector as a percentage of total estimated revenues for that
sector. To be consistent with costs that are calculated in 2022
dollars, MSHA first inflated estimated mine revenues in 2019 to their
2022 equivalent using the GDP Implicit Price Deflator. See Table VII-9.
[[Page 28299]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.153
Table VII-10 compares aggregate annualized compliance costs for the
MNM and coal sectors at a 0 percent, 3 percent, and 7 percent discount
rates to each sector's total annual revenues. At a 3 percent discount
rate, total aggregate annualized compliance costs for the entire mining
industry are projected to be $90.3 million (including both 30 CFR part
60 and 2019 ASTM costs), while aggregate revenues are estimated to be
$124.2 billion in 2022 dollars. MSHA estimates that the mining industry
is expected to incur compliance costs that comprise 0.07 percent of
total revenues.
For the MNM sector, MSHA estimated that the annualized compliance
costs of the final rule (including both 30 CFR part 60 and 2019 ASTM
update costs) would be $82.1 million at a 3 percent discount rate,
which is approximately 0.09 percent of the total estimated annual
revenue of $95.1 billion for MNM mine operators. For the coal sector,
MSHA estimated that the annualized cost of the final rule (including
both 30 CFR part 60 and 2019 ASTM costs) will be $8.2 million at a 3
percent discount rate, which is approximately 0.03 percent of the total
estimated annual revenue of $29.1 billion for coal mine operators.
The ratios of screening analysis are well below the 1.0 percent of
total revenues threshold. Therefore, MSHA concludes that the
requirements of the final rule are economically feasible, and no sector
will likely incur a significant cost.
[GRAPHIC] [TIFF OMITTED] TR18AP24.148
VIII. Summary and Explanation of the Final Rule
As previously mentioned, under the final rule, MSHA amends its
existing standards on respirable crystalline silica or quartz, after
considering all the testimonies and written comments the Agency
received from a variety of stakeholders, including manufacturers,
medical professionals, miners, mining associations, mining companies,
labor organizations that represent mine workers, health associations,
and safety associations in response to its notice of proposed
rulemaking. The final rule establishes a PEL of respirable crystalline
silica at 50 [micro]g/m\3\ for a full-shift exposure, calculated as an
8-hour TWA for all mines. The final rule also establishes an action
level for respirable crystalline silica of 25 [micro]g/m\3\ for a full-
shift exposure, calculated as an 8-hour TWA for all mines. In addition
to the PEL and action level, the final rule includes provisions for
methods of compliance, exposure monitoring, corrective actions,
respiratory protection, medical surveillance for MNM mines, and
recordkeeping. The final rule also replaces existing requirements for
respiratory protection and incorporates by reference ASTM F3387-19
Standard Practice for Respiratory Protection.
[[Page 28300]]
The sections that follow address testimonies and written comments
received on general issues and specific provisions in the proposal and
MSHA provides its responses and final conclusions.
A. General Issues
In this section, MSHA addresses comments that relate to the
rulemaking as a whole and that are not specific to a single section of
the final rule. MSHA identified six general issues for discussion
below: Existing Respirable Dust Standards for Coal Mines; Training for
Miners--Respirable Crystalline Silica; Sorptive Minerals; OSHA Table 1
Approach for Compliance; Medical Removal/Transfer; and Compliance
Assistance.
1. Existing Respirable Dust Standards for Coal Mines
MSHA will enforce the final rule's requirements for respirable
crystalline silica in coal mines within the context of the Agency's
existing standards for miners' exposure to respirable coal mine dust in
30 CFR parts 70, 71, and 90.
Some commenters, including the Wyoming County WV Black Lung
Association, AFL-CIO, and two individuals, were concerned that controls
implemented as immediate corrective actions for respirable crystalline
silica at coal mines would not be incorporated into an underground coal
mine's approved ventilation plan required under 30 CFR part 75
(Document ID 1393; 1449; 1399; 1412).
Under the final rule, mine operators are required to install, use,
and maintain feasible engineering and administrative controls to keep
each miner's exposure to respirable crystalline silica at or below the
PEL. Mine operators must use feasible engineering controls as the
primary means of controlling respirable crystalline silica;
administrative controls can only be used, when necessary, as a
supplementary control. Rotation of miners--that is, assigning more than
one miner to a high-exposure task or location, and rotating them to
keep each miner's exposure below the PEL--is prohibited as a means of
complying with the rule.
For underground coal mines, the necessary controls to maintain
compliance with existing respirable coal mine dust and respirable
crystalline silica standards are contained in the ventilation plan that
is approved by the appropriate District Manager. Under 30 CFR
75.370(a)(1), the approved ventilation plan shall control methane and
dust and contains the detailed engineering controls that the operator
will use to comply with the existing dust standards.
Under the existing respirable dust standards for coal mines, MSHA
evaluates the approved ventilation plan to ensure that it is suitable
to current conditions and mining systems at the mine. During each
shift, the plan must be followed to protect miners from overexposure to
respirable coal mine dust, which includes respirable crystalline
silica. Currently, only MSHA sampling is used to evaluate miners'
exposure to respirable crystalline silica. When respirable coal mine
dust or respirable crystalline silica overexposures are documented,
MSHA may consider the relevant portion of the ventilation plan
deficient and require that the plan be revised to include additional
ventilation controls, or the plan can be revoked by the Agency, as
appropriate. MSHA evaluates the approved ventilation plan at least
every 6 months, or more often if there are changes in the mine, mining
processes, dust controls, or conditions at the mine affecting miners'
exposure to respirable coal mine dust or respirable crystalline silica
dust. MSHA typically samples all mechanized mining units and Part 90
miners (coal miners with evidence of pneumoconiosis) during each
quarterly regular inspection of underground coal mines. MSHA typically
samples the Designated Areas (DA)--outby areas of the mine--at least
annually. This sampling represents an evaluation of dust exposure
compliance and dust controls that are in the approved ventilation plan
to ensure that they are effective. MSHA intends to continue conducting
this sampling.
Under the existing respirable dust standards for coal mines, as in
the final silica rule, when miners are overexposed, the operator must
take immediate corrective actions to lower the miner's exposure to at
or below the standard and sample to verify that the corrective actions
are effective. The mine operator determines necessary engineering
controls but must address the underlying conditions and practices which
caused the overexposure. Corrective action sampling will be conducted
with the control measures in place. Under the final silica rule, mine
operators must report overexposures to the District Manager and
corrective actions must be described in the record mandated in Sec.
60.16. If a silica overexposure occurs, operators remain responsible
for adjusting ventilation plans to account for additional controls
needed to prevent future overexposures.
The existing respirable dust standards for coal mines will also
maintain silica controls through mine operators' pre-shift and on-shift
examinations. These examinations must ensure the ventilation controls
that have been evaluated and found effective are maintained. The
examinations protect miners from health and safety hazards between and
on sampling shifts.
The UMWA, AFL-CIO, Wyoming County WV Black Lung Association, and an
individual requested that additional sampling be conducted at coal
mines (Document ID 1398; 1449; 1393; 1382). UMWA and an individual
supported the standalone silica PEL but urged MSHA to retain the
reduced dust standard concept due to the large number of quarterly dust
samples operators must take that indirectly monitor silica exposure
(Document ID 1398; 1382).
MSHA's enforcement of respirable coal mine dust under the existing
respirable coal mine dust standards will continue. The final rule
establishes a standalone silica PEL and adds operator silica sampling
that may result in additional operator silica sampling (every three
months) in many underground coal mines. It also requires immediate
corrective actions and resampling if exposures exceed the PEL. The
final rule also requires periodic evaluations at least every 6 months,
or whenever there is a change in production; processes; installation
and maintenance of engineering controls; installation and maintenance
of equipment; administrative controls; or geologic conditions.
Dependent on the results of the periodic evaluation in this final rule,
coal mine operators may have to perform additional sampling. MSHA
expects the final rule's requirements will result in sufficient
sampling to accurately detect miners' exposures to silica at coal
mines.
The final rule requires that mine operators sample miners exposed
or reasonably expected to be exposed to respirable crystalline silica.
If samples are above the action level and below the PEL, mine operators
must continue to sample within three months. Operators must conduct
representative sampling (at least two samples) of the occupations at
highest risk of respirable crystalline silica exposure. The existing
standards for respirable coal mine dust sampling require 15 valid
representative consecutive shift samples for certain high-dust
occupations, followed by more samples in other identified occupations
and areas the District Manager designates based on anticipated or
actual exposures.
The final rule decouples silica sampling and enforcement from the
existing respirable dust standard requirements that reduce the total
[[Page 28301]]
respirable coal mine dust limit based on the percentage of silica in
the dust (an indirect way of controlling silica). Occupations and areas
designated for dust sampling are likely to be the occupations and areas
with the highest levels of respirable crystalline silica exposure. MSHA
expects many of the same occupations will be sampled under this final
rule and that the requirement that two samples be taken will mean an
increased ability to accurately assess exposure. Also, the standalone
respirable crystalline silica PEL allows for immediate MSHA oversight
of corrective actions and resampling. Unlike the existing reduced dust
standard protocols under which silica overexposures are not directly
citable except through enforcement of the reduced dust standard, under
the final rule, MSHA can withdraw miners under Mine Act section 104(b)
if respirable crystalline silica overexposure citations are not
corrected and occupations resampled within the abatement time MSHA
sets. In response to comments, and to ensure that MSHA is informed of
silica overexposures, the final rule requires that mine operators
immediately report respirable crystalline silica samples above the PEL
to the District Manager or other office designated by the District
Manager.
2. Training for Miners--Respirable Crystalline Silica
MSHA received several comments both in favor of and against
including respirable crystalline silica training for miners in 30 CFR
part 46 (Training and Retraining of Miners Engaged in Shell Dredging or
Employed at Sand, Gravel, Surface Stone, Surface Clay, Colloidal
Phosphate, or Surface Limestone Mines) (part 46) and 30 CFR part 48
(Training and Retraining of Miners) (part 48). Two mining trade
associations suggested that existing training requirements under parts
46 and 48 for new miner training, experienced miner training, annual
refresher training, and task training remain sufficient and that an
additional training requirement would be unnecessary (Document ID 1424,
1441). Other commenters, including a mining labor union and several
professional associations, stated that the final rule should include
new training requirements separate from parts 46 and 48 (Document ID
1398; 1351; 1377; 1373).
MSHA believes existing training standards in parts 46 and 48
require appropriate training regarding health hazards, including
exposure to respirable crystalline silica dust.
Part 46 requires new miners and newly hired experienced miners to
receive training on the health and safety aspects of the tasks to be
assigned, including the safe work procedures of such tasks, the
mandatory health and safety standards pertinent to such tasks,
information about the physical and health hazards of chemicals in the
miner's work area, the protective measures a miner can take against
these hazards, and the contents of the mine's HazCom program. They must
also receive instruction and demonstration on the use, care, and
maintenance of self-rescue and respiratory devices, if used at the
mine.
Annual refresher training conducted under part 46 must include
instruction on changes at the mine that could adversely affect the
miner's health or safety and other health and safety subjects relevant
to mining operations at the mine, including mandatory health and safety
standards, health, and respiratory devices.
For new task training, part 46 requires miners to receive training
in the health and safety aspects of the task to be assigned, including
the safe work procedures of such tasks, information about the physical
and health hazards of chemicals in the miner's work area, the
protective measures a miner can take against these hazards, and the
contents of the mine's HazCom program. Section 46.9 requires records of
training and includes specific provisions for the record requirements.
Part 48 requires new miners to receive training on health including
instruction on the purpose of taking dust, noise, and other health
measurements, and any health control plan in effect at the mine shall
be explained. New miners must also receive training in the health and
safety aspects of the tasks to be assigned, including the safe work
procedures of such tasks, the mandatory health and safety standards
pertinent to such tasks, information about the physical and health
hazards of chemicals in the miner's work area, the protective measures
a miner can take against these hazards, and the contents of the mine's
HazCom program.
Experienced miner training under Part 48 must include instruction
in health, including the purpose of taking dust, noise, and other
health measurements, where applicable, and review of the health
provisions of the Mine Act. Experienced miners must also receive
training in the health and safety aspects of the tasks to be assigned,
including the safe work procedures of such task, information about the
physical and health hazards of chemicals in the miner's work area, the
protective measures a miner can take against these hazards, and the
contents of the mine's HazCom program.
For new task training, part 48 requires miners to receive training
on the health and safety aspects and safe operating procedures for work
tasks, equipment, and machinery, including information about the
physical and health hazards of chemicals in the miner's work area, the
protective measures a miner can take against these hazards, and the
contents of the mine's HazCom program.
Annual refresher training conducted under part 48 must include
instruction on mandatory health and safety standard requirements which
are related to the miner's tasks and on the purpose of taking dust,
noise, and other health measurements, as well as an explanation of any
health control plan in effect at the mine. The health provisions of the
Mine Act and warning labels must also be explained. Sections 48.9
(Underground Miners) and 48.29 (Surface Miners) require records of
training.
Training is also a required element of the mine operator's
respiratory protection program. Miners required to wear a respirator
must be trained in accordance with the provisions of ASTM F3387-19 and
records must be retrained in accordance with the provisions of section
9.
MSHA expects mine operators to include information in their
existing training plans about respirable crystalline silica hazards and
protections, including: the PEL and action level; sampling
requirements; miners who are reasonably expected to be exposed to
respirable crystalline silica; engineering and administrative controls
used at the mine; the importance of maintaining controls; and, for MNM
mines, medical surveillance requirements, including the importance of
early disease detection. MSHA remains available to assist mine
operators with their training plans.
3. Sorptive Minerals
The SMI, EMA, and Vanderbilt Minerals, LLC requested that MSHA
follow OSHA's approach to sorptive minerals and exclude them from the
scope of the final rule (Document ID 1446; 1442; 1419). These
commenters asserted that lower toxicity of occluded and aged
crystalline silica indicates a lack of health risks stemming from
inhaling sorptive mineral dust containing respirable crystalline
silica.
After considering the commenters' statements and evidence, as well
as OSHA's approach to the issue, MSHA has determined that sorptive
minerals should not be excluded from the scope of this rulemaking.
[[Page 28302]]
MSHA evaluated all the evidence submitted by commenters during the
rulemaking process, including the hearings, and concludes that the
balance of the best available evidence supports that there is increased
risk of material impairment of health or functional capacity over the
course of a miner's working life associated with regular exposure to
respirable crystalline silica present at sorptive mineral mines. MSHA's
approach is consistent with NIOSH's recommendation for a single PEL for
respirable crystalline silica without consideration of surface
properties. MSHA is unable to substantiate one commenter's statement
that, in every instance, the silica in sorptive minerals is either
amorphous (i.e., opal) or occluded. Sorptive minerals occur as part of
a geological formation with its own depositional history beginning with
a volcanic eruption. The mining process will encounter all mineral
constituents in the deposit, including all forms of respirable
crystalline silica. To remove overburden and extract sorptive minerals,
miners use large mining equipment that can disturb sedimentary and
other silica-rich rock that could contain unoccluded respirable
crystalline silica. In addition, the milling, screening, crushing, and
bagging processes can and do affect the respirable crystalline silica
dust liberated at these mines. The commenter did not submit evidence
demonstrating that all sorptive mineral commodities mined in the United
States exclusively contain fully or even partially occluded quartz.
MSHA does not agree that occlusion is always present, that occlusion
definitively provides adequate protection from adverse health effects,
or that occlusion always provides any level of protection for miners
exposed to respirable crystalline silica in this industry.
MSHA's method for analyzing respirable dust samples cannot
differentiate between ``freshly fractured'' and occluded crystalline
silica. Respirable dust enforcement samples in MNM mines are prepared
for crystalline silica analysis using the MSHA P-2 method for X-ray
diffraction (XRD). Crystalline materials each have their own unique
diffraction patterns and are quantitatively discriminated between other
crystalline and non-crystalline materials through XRD analysis.
Potential interferences from other minerals are removed from the result
by scanning the sample at multiple diffraction angles specific to
crystalline silica and using profile fitting software to separate
adjacent diffraction peaks. MSHA cannot determine if crystalline silica
particles in the sample are ``freshly fractured'' or occluded with a
layer of clay, only that the diffraction pattern matches that of the
pure crystalline silica standard reference material.
MSHA's enforcement data in Table VIII-1 below show that miners
working in this industry are exposed to respirable quartz at
concentrations above both the former PEL (100 [micro]g/m\3\) and new
PEL (50 [micro]g/m\3\). Table VIII-1 shows exposure data by contaminant
code for respirable dust samples collected at ``clay'' or ``bentonite''
operations from 2005 to 2019. The samples were analyzed for respirable
crystalline silica (quartz) and the results were calculated based on an
8-hour TWA.
[GRAPHIC] [TIFF OMITTED] TR18AP24.155
The results in the table indicate that 5.1 percent of miners
working at these operations during the relevant period were exposed to
levels of respirable crystalline silica over the former PEL of 100
[micro]g/m\3\, and 17.6 percent were exposed over the new PEL of 50
[micro]g/m\3\.
MSHA disagrees with commenters' statements that the silica
contained in sorptive minerals does not pose health risks. MSHA does
not equate ``lower toxicity'' with other toxicological terms such as
``non-hazardous'', ``non-toxic'', or ``safe.'' ``Lower toxicity'' does
not mean the absence of adverse health effects, disease, or risk of
material impairment of health or functional capacity. For example, the
bioactivity of respirable crystalline silica (quartz) originating from
bentonite deposits is well-recognized and documented on sorptive
mineral-based pet litter safety data sheets (SDSs). MSHA concludes from
its own sampling data and analyses that the mining of sorptive minerals
creates an inhalation hazard. As confirmed by MSHA's review of
epidemiological and toxicological studies, these mineral dusts are
toxic and can lead to serious adverse health effects in miners such as
silicosis or lung cancer. Accordingly, MSHA concludes that there is a
risk of material impairment of health or functional capacity in mining,
whether or not that risk is equal to unoccluded quartz encountered in
other workplaces.
In its 2016 final rule, OSHA concluded that quartz originating from
bentonite deposits had some biological activity but ``lower toxicity''
than quartz encountered in most workplaces (81 FR 16377). OSHA also
found that the record provided no sound basis for determining
significance of risk for exposure to sorptive minerals containing
quartz, and thus decided to exclude sorptive minerals from the
[[Page 28303]]
scope of the final rule (OSHA, 2016). MSHA, unlike OSHA, has no
requirement to identify a ``significant risk'' before promulgating
rules to protect miners' health and safety. Nat'l Mining Ass'n v.
United Steel Workers, 985 F.3d 1309, 1319 (11th Cir. 2021) (``[T]he
Mine Act does not contain the `significant risk' threshold requirement
. . . from the OSH Act.''). The OSH Act is a ``differently worded
statute,'' and the Mine Act ``[a]rguably . . . does not mandate the
same risk-finding requirements as OSHA.'' Nat'l Min. Ass'n v. Mine
Safety & Health Admin., 116 F.3d 520, 527 (D.C. Cir. 1997). Moreover,
OSHA does not regulate mining; mining presents unique risks to miners'
health because it exposes miners to hazards that are not present in
operations regulated by OSHA, including hazards in overburden removal
and milling.
MSHA has examined research references from commenters and has
conducted its own review of the scientific literature. These studies do
not disprove the health-based risks associated with exposure to
respirable crystalline silica or support a conclusion that sorptive
minerals present no risk.
As presented by SMI, there have been few epidemiological studies of
workers exposed to dust generated from sorptive minerals (Document ID
1446, Attachment 2). Two examples include Phibbs et al. (1971) and
Waxweiler et al. (1988). These small cohort studies did not evaluate
exposures to a wide variety of sorptive minerals and relied on data
from outdated exposure assessment methods. MSHA finds that the limited
epidemiological data involving sorptive minerals do not refute the
conclusions drawn from other epidemiological studies included in MSHA's
standalone Health Effects document and in the Agency's standalone FRA
document (2023). MSHA concludes, from the best available evidence, that
exposure to the crystalline silica present in sorptive minerals poses a
risk of material impairment of health or functional capacity to miners.
MSHA disagrees with the comment that the occluded surface of the
silica that may be found in sorptive minerals protects miners from
material impairment of health, including silicosis and lung cancer.
Furthermore, there is no evidence to suggest that the occluded layer of
the quartz particles that are inhaled remains unchanged over time
following deposition throughout the respiratory tract. It is not
understood how conditions and physiological responses may alter the
characteristics of occluded quartz particles deposited in the
respiratory tract. Likewise, while animal studies involving respirable
crystalline silica suggest that the aged form has lower toxicity than
the freshly fractured form, the aged form still retains significant
toxicity (Shoemaker et al., 1995; Vallyathan et al., 1995; Porter et
al., 2002c).
MSHA considered commenters' statements and evidence regarding the
toxicity of quartz in sorptive minerals. MSHA's conclusions are
consistent with those that NIOSH provided to OSHA (NIOSH Posthearing
Brief to OSHA, 2014d). NIOSH corrected various erroneous statements
that referenced published papers (e.g., Waxweiler et al., 1988; Phibbs
et al., 1971) and reports (e.g., EPA, 1996; WHO, 2005), which are also
a part of this rulemaking record. Four examples are provided here.
First, as noted by NIOSH, Phibbs et al. (1971) advised that
``[b]entonite dust, once believed to be harmless, must now be added to
the list of potentially hazardous dusts because of its content of free
crystalline silica.'' (Document ID 0693, pg. 43). Second, NIOSH stated
that, ``[w]hile no exposure-response relationship can be drawn from the
Phibbs et al. [1971] study, it can be concluded that when exposures to
respirable crystalline silica are high enough in mining/processing
bentonite, severe and fatal occupational silicosis can occur among
exposed workers.'' (Document ID 0693, pg. 44). Third, contrary to
comments regarding the WHO report (2005), NIOSH stated, ``Although the
respirable crystalline silica particles to which these bentonite
workers were exposed may be less toxic than, say, respirable
crystalline silica particles resulting from sandblasting, there is no
way to assess relative toxicities from these two studies. Regardless of
relative toxicity, the findings from these two studies indicate that,
at the levels to which the workers in the studies were exposed, the
crystalline silica particles were toxic enough to cause severe,
disabling, and fatal silicosis in a relatively short period of time.''
Fourth, NIOSH disagreed with the commenter's reference to the lack of
reporting of silicosis among cohorts of coal miners with pneumoconiosis
to support its conclusion that aged/occluded silica particles do not
represent a risk for silica-related health outcomes.
NIOSH addressed a commenter's presumption that further study was
needed on occluded quartz before regulation was warranted. NIOSH
explained that further study on occluded quartz was less pertinent for
OSHA's rulemaking than the fact that the OSHA PEL was consistent with
the NIOSH REL in not distinguishing respirable crystalline silica
exposures based on relative age or degree of occlusion of particle
surfaces. MSHA concurs with NIOSH's conclusion that ``currently
available information is not adequate to inform differential
quantitative risk management approaches for crystalline silica that are
based on surface property measurements.'' For these reasons, MSHA does
not exempt the sorptive minerals sector from the requirements of this
final rule.
4. OSHA Table 1 Approach for Compliance
OSHA's ``Table 1--Specified Exposure Control Methods When Working
With Materials Containing Crystalline Silica'' (Table 1) (29 CFR
1926.1153(c)(1)) identifies common construction equipment and tasks
that, when properly controlled, are expected to generate levels of
respirable crystalline silica below the PEL. Construction employers who
follow these engineering and work practice control methods and provide
the required respiratory protection outlined in Table 1 are generally
not required to sample their workers' exposures to silica and are
presumed to be in compliance with OSHA's standard.
MSHA did not propose adopting specified exposure control methods
for task-based work practices, similar to OSHA's Table 1. However, in
the proposal, MSHA sought comments on specific tasks and exposure
control methods appropriate for a Table 1 approach for the mining
industry that would also adequately protect miners from risk of
exposure to respirable crystalline silica.
MSHA has decided not to include a Table 1 approach for the mining
industry in the final rule. After considering input from stakeholders
on specific tasks and exposure control methods suitable for a Table 1
approach, MSHA determined that such an approach would not provide the
necessary protection for miners against overexposure to respirable
crystalline silica under all mining conditions. The Agency has
concluded that because of the changing nature of the mining
environment, exposure monitoring is essential to ensure that controls
are functioning effectively, properly maintained, and adjusted as
necessary to ensure compliance.
Under the final rule, mine operators are required to implement
feasible engineering controls, and administrative controls, when
necessary, to maintain each miner's exposure below the PEL.
[[Page 28304]]
Operators are required to conduct exposure monitoring (sampling) in
accordance with Sec. 60.12 to verify that the implemented controls
effectively protect miners and ensure compliance with the final rule.
Compliance with the PEL and corrective actions after overexposures is
required. This final rule does not allow the use of respiratory
protection to achieve compliance.
Commenters from an industrial hygiene association and labor
organizations, supported MSHA's decision not to include a Table 1
approach for mining activities (Document ID 1351; 1398; 1449). The UMWA
stated that this approach is not necessary since mine operators already
have access to proper dust control systems and MSHA-approved
ventilation plans (Document ID 1398). This commenter also noted that,
because mining conditions are constantly changing, it would be
incorrect to assume that operators using a Table 1 approach to control
respirable crystalline silica exposure would always be in compliance.
Two commenters (a professional association and a labor union) stated
that the Table 1 approach would be neither protective nor feasible in
the mining context, while one of those commenters stated that delaying
the final rule to develop a Table 1 approach will create more harm for
workers (Document ID 1351; 1398).
MSHA agrees that due to constantly changing mining conditions,
OSHA's Table 1 is not the most effective approach for protecting
miners' health. A fundamental aspect of mining is that the mine
environment is dynamic, resulting in varying exposures to respirable
crystalline silica for miners. Silica exposures can fluctuate based on
the amount of silica present in rock, which depends on the geological
composition of the rock. Miners engaged in tasks that generate dust
from this rock material may face elevated exposure levels. For example,
activities that involve cutting, grinding, drilling, or crushing rock
with higher-silica levels can generate dust with high silica content.
In addition, mining operations are diverse, involving different types
of mining, each with various mining processes. Each process involves
specific equipment and methods tailored to the unique characteristics
of the material being mined.
Many commenters, including trade associations, mining related
businesses, a labor union, and a MNM operator urged MSHA to include a
provision like Table 1 in the final rule, with Portland Cement
Association, NSSGA, and CertainTeed, LLC submitting example tables for
MSHA to consider (Document ID 1407; 1408; 1424; 1441; 1448; 1404; 1409;
1429; 1442; 1417; 1431; 1423). SSC noted that certain tasks, processes,
and environments are at least somewhat similar or common across many
MNM mines and may be characterized by the extent to which they may
release respirable crystalline silica, mechanisms for doing so, and
effective exposure controls (Document ID 1432). This commenter also
stated that a Table 1 approach would provide mine operators with a
choice between using their own controls and sampling to evaluate
effectiveness (and compliance with the standard) or using the controls
listed in the table. SSC noted that a clear list of controls required
for each type of task, exposure, or process would simplify compliance
and enforcement. SSC further noted that if a mine operator relied on
the table and implemented or used all the engineering and
administrative controls in the table, they would know that, in so
doing, they would achieve compliance.
MSHA has determined that reliance on a task-based approach would
not address all mining tasks and situations that could result in
respirable crystalline silica exposures, leaving miners without
adequate protection. In addition, a task-based approach may not address
cumulative exposures over a shift for miners who perform multiple tasks
that generate respirable silica during a single shift. MSHA has
determined that because mining involves a wide range of activities,
each with its own potential for different dust generating sources and
potential silica exposure, a task-based approach does not protect
miners, especially those miners who perform multiple tasks involving
silica exposures during a single shift.
MSHA agrees with commenters that there are many job positions in
the mining industry that have similar exposure risks. However, as one
commenter testified, miners may work at multiple job positions or tasks
throughout the shift or a workweek. This commenter noted that a miner
may work as a laborer, crusher operator, or a loader operator in a
single shift. Another commenter acknowledged that it would be difficult
for a Table 1 approach to work because of the various tasks a miner
performs (this commenter referenced a discussion on this topic between
a mine operator and the Agency at the Denver, Colorado public hearing).
MSHA's data indicates that a significant number of miners are
classified as laborers, mobile workers, and utility workers.
Approximately 31 percent of the MNM miners are mobile workers and
approximately 39 percent of coal miners are laborers, utility workers
and other workers who do not have specific job categories. These are
job positions that perform different work activities during a shift.
MSHA has determined that OSHA's Table 1 would be difficult to implement
for most mines, especially mines that employ laborers, mobile workers,
and utility workers.
The Portland Cement Association and NSSGA stated that OSHA's 2019
RFI, which assessed the effectiveness of Table 1, demonstrated that it
was effective in lowering exposures and encouraged the adoption of
engineering controls (Document ID 1407; 1448). However, AIHA explained
that research indicates that worker exposure in the construction
industry can exceed the OSHA PEL of 50 [mu]g/m\3\ even with Table 1
controls in place (Document ID 1351).
Portland Cement Association recommended that MSHA should adopt an
OSHA Table 1 approach that encourages mine operators to install
engineering controls and remove the operator's obligation to assess
exposures in work environments where individual miner's respirable
crystalline silica exposures are controlled by engineered devices to
ensure compliance with the action level and the PEL (Document ID 1407).
Under OSHA's approach, prescribed engineering controls and work
practice methods, along with respiratory protection, are assumed to be
sufficiently effective in reducing miners' exposures; exposure
monitoring to ensure compliance with the PEL is not required. MSHA,
however, has determined that exposure monitoring is critical in
safeguarding miners' health. It provides the quantitative data needed
to assess the effectiveness of engineering controls and is essential to
ensuring that controls remain effective at all times. This is
consistent with NIOSH's recommendation to OSHA during its rulemaking
that Table 1 should not replace sampling requirements for the
construction industry because even fully implementing the control
methods and respiratory protection described in OSHA's Table 1 would
not ensure compliance with the PEL. In addition, MSHA, in this final
rule, does not allow respiratory protection as a means to achieve
compliance.
OSHA's Table 1 approach relies on respiratory protection when
engineering and administrative controls are not sufficient to limit
exposures. Respiratory protection is used for compliance when control
methods cannot reduce exposures below the PEL. MSHA has determined that
existing engineering controls are the most
[[Page 28305]]
effective way to protect miners from exposures to respirable
crystalline silica. Engineering controls, when properly designed,
implemented, and maintained, can reduce the concentration of respirable
crystalline silica and protect miners from overexposures. Well designed
and maintained controls can eliminate or minimize respirable silica
dust at the source, preventing dispersion of the silica dust into the
workplace. Respiratory protection, however, has limitations and is not
as reliable as engineering controls in reducing miners' exposures to
respirable crystalline silica. MSHA has determined that reliance on
respiratory protection would risk miners' exposure to silica and
undermine the Agency's mandate to address respiratory hazards at the
source, providing the highest level of health protection for miners.
The mining industry encompasses a wide range of processes and
equipment due to the diversity of mined commodities. However, as
commenters noted, processes and equipment are tailored to the type of
material mined. SSC noted that certain tasks, processes, and
environments are at least somewhat similar or common across many MNM
mines and may be characterized by the extent to which they may release
respirable crystalline silica, mechanisms for doing so, and effective
exposure controls (Document ID 1432). IME recommended that MSHA adopt a
Table 1 approach for rock drilling operations that use a dust
collection system around the drill bit and the use of low-flow water
spray to wet the dust discharged from the dust collector (Document ID
1404). This commenter also noted that all drill rigs used by the
explosives industry have fully enclosed cabs to isolate operators from
dusty conditions. EMA suggested that a Table 1 approach could include
processes with consistent/predicable dust generation characteristics,
such as mobile equipment cabs, control rooms with proper ventilation
and seals on doors and windows, utility vehicles, handheld power tools
such as jackhammers, and tasks performed in potentially high exposure
areas, such as crushing or bagging (Document ID 1442). This commenter
submitted that many engineering and administrative controls or work
practices can be gleaned from NIOSH's updated Dust Control Handbook for
Industrial Minerals Mining and Processing, Second Edition. The
commenter further noted that the NIOSH Dust Control Handbook is an
excellent resource and could reduce the amount of research necessary to
create a usable Table 1.
MSHA has determined that these controls cannot be relied on without
independent assessment (exposure monitoring) to ensure that they are
effective and continue to protect miners. For example, MSHA has found
that equipment operators who are working in enclosed cabs report some
of the highest exposures. These miners are exposed to high silica
exposures because the enclosures are not properly maintained. Under a
Table 1 approach, equipment operators would be presumed to be protected
by enclosed cabs and not exposed to silica above the PEL.
A fundamental feature of mining is that the mine environment
constantly changes. MSHA has concluded that miners' exposures to
respirable crystalline silica vary with much greater frequency than in
general industry, construction, or maritime settings. A feasible
engineering control implemented in a mine (including a mill) cutting
into or processing lower-quartz-containing rock might not be
appropriate for a mine cutting into rock with a higher percentage of
quartz or using a different mining process or modified equipment.
In addition, certain mining environments must take into account
bystander exposure. For example, in underground mining environments,
the ventilation is often in a series configuration, where the exhaust
of one miner's controls could be the intake for other miners downwind.
This results in the upwind engineering controls having an effect on all
of the miners that are downwind. In contrast, OSHA's construction and
general industry worksites have controls that can be exhausted to the
outside atmosphere and will not affect other workers nearby.
MSHA has determined that, in the context of mining, Table 1
controls cannot be relied on without independent assessment (exposure
monitoring) to ensure that they are effective, maintained, and continue
to protect miners. MSHA's enforcement experience and data show that
some of the highest respirable crystalline exposures result from mine
operators not maintaining engineering controls. Poor maintenance of
engineering controls, without exposure monitoring, can result in miners
working above the PEL for extended periods, jeopardizing their health.
For example, a miner working at a surface MNM mine was exposed to 192
[mu]g/m\3\ of respirable crystalline silica. The miner was working in a
control booth, but the control booth ventilation system was not
maintained, and the door seals were defective and leaking. A second
example involved a bulldozer operator working at a surface coal mine
who was exposed to 109 [mu]g/m\3\ of respirable crystalline silica. The
cab's door seals were crushed, and the cab filter was broken. A third
example involved a miner operating a front-end loader at surface MNM
mine, who was exposed to 213 [mu]g/m\3\ of respirable crystalline
silica. The cab air-conditioner was not functioning. These examples
illustrate the importance of regular exposure monitoring to alert mine
operators to take necessary corrective actions to repair and maintain
equipment to protect miners' health. The exposure monitoring
requirements in the final rule provide mine operators, miners, and MSHA
with information necessary to verify that miners' exposures remain
below the PEL at all times, therefore protecting miners' health. Also,
the final rule does not allow respiratory protection to achieve
compliance.
In addition, geological formations and quantities of quartz are not
always predictable and the Agency believes that controlling exposures
to respirable crystalline silica to below the PEL through sampling is
the best way to protect miners' health. Accordingly, MSHA has concluded
that because of the dynamic, constantly changing nature of the mining
environment, exposure monitoring is essential to ensure that controls
are functioning effectively, properly maintained, and adjusted as
necessary to ensure compliance.
In response to MSHA's solicitation for stakeholder input on a Table
1 approach, commenters representing the stone, sand, and gravel
industries provided information and data on an alternative Table 1 for
MSHA's consideration. The NSSGA provided a proposed Table 1 that
grouped various equipment operator positions by equipment and tasks
(including a description of operation and tasks performed) and
identified engineering and work practice control methods for the
equipment and tasks (Document ID 1448). The commenter noted that this
Table 1 is protective of workers and does not give operators an ``out''
when a worker performs a task that is listed on the table. The
commenter further noted that under their proposed Table 1, the operator
must ensure all engineering and work practice control methods are done
to comply with the table and not engage in exposure monitoring. The
commenter stated their Table 1 approach works because sampling has been
done that demonstrates these
[[Page 28306]]
controls work and keep workers below the action level.
The Portland Cement Association provided respirable crystalline
silica exposure data by job classification and an alternative Table 1
that identified equipment/tasks, engineering and work practice
controls, and required respiratory protection and assigned protection
factor (Document ID 1407). As the commenter noted, the table shows
control measures in widespread use in the cement manufacturing
industry, which the commenter believes some MNM mine operators use at
their operations.
MSHA considered commenters' Table 1 approaches. Like OSHA, the
commenters' alternative approaches provide specific guidance on how to
control work exposures to respirable crystalline silica for specific
tasks. The suggested Table 1 approaches list the equipment/task and
identify the similarly exposed positions and appropriate engineering
and work practice control methods.
MSHA has determined that because mining involves a wide range of
activities, from drilling and blasting to crushing and processing
materials, each with its own potential for different dust generating
sources and potential silica exposure, as well as differing silica-
bearing strata, a task-based approach does not protect miners,
especially those miners who perform multiple tasks involving silica
exposures during a single shift. A Table 1 approach can be effective
for construction activities. However, Table 1's applicability to mining
and milling operations is limited due to the complexity, variability,
and unique challenges inherent in mining and milling operations.
Activities in these operations are highly variable, due to the types of
ores, minerals, and materials processed. Mining and milling operations
run continuously, unlike some construction activities which may not be
continuous or steady. Continuous operations require different control
measures and monitoring strategies to address sustained miner exposures
over an extended period. In addition, MSHA has determined that
specified control methods may not provide a continued and verifiable
level of protection to miners. Exposure monitoring is essential to
ensure that the controls remain effective at all times. Further, as
stated earlier, this final rule does not allow respiratory protection
as a means to achieve compliance.
MSHA also received comments stating that a Table 1 approach would
benefit intermittent and seasonal mining operations. The NSSGA stated
that these mine operators do not have as much time to conduct sampling
and would benefit from a Table 1 approach (Document ID 1448).
Similarly, North America's Building Trades Unions (NABTU) noted that
being able to implement controls according to job function, without
having to take air samples, would help portable mines and construction
contractors to achieve compliance in dynamic work environments
(Document ID 1414). CISC explicitly requested that MSHA conduct a final
review and produce a report for comment analyzing silica exposure from
all jobs associated with quarrying operations, and either exclude them
from the proposed rule or create a Table 1 approach, indicating that
most jobs in surface quarrying operations are incapable of exceeding
the proposed PEL (Document ID 1430). As noted above, MSHA has
determined that, due to the diverse range of activities involved in
mining, and constantly changing mining conditions--including drilling,
blasting, crushing, and material processing, each with its unique
potential for silica exposure--a Table 1 approach does not adequately
protect miners. This is particularly true for miners who are engaged in
multiple tasks involving silica exposure within a single shift. MSHA
has also concluded that control methods must be assessed to ensure they
provide sufficient protection; therefore, exposure monitoring is
essential to verify the ongoing effectiveness of implemented controls.
The Agency also received comments about alternative approaches to
Table 1-type guidance. NSSGA stated that jobs where workers are in
enclosed cabs, booths, and buildings have consensus standards and
should be in Table 1 (Document ID 1448). Some commenters, including
AIHA and IEEE, suggested that MSHA incorporate or recommend relevant
control standards designed to protect workers performing certain tasks,
such as ISO 23875: 2021, to provide operators with more tools to
protect workers while continuing mandated exposure monitoring (Document
ID 1351; 1377). Draeger, Inc. stated that MSHA should consider
incorporating Table 1 content into a silica guidance document (Document
ID 1409). NVMA suggested that MSHA should allow operators to develop
their own Table 1 as part of their dust protection plan but cautioned
that MSHA should not be permitted to cite the development of an
internal tool unless the PEL is exceeded, and a respirator is not used
(Document ID 1441). Draeger, Inc. also acknowledged that creating a
Table 1 approach would be a significant effort and suggested that MSHA
initially consider high-risk tasks in developing the control methods
(Document ID 1409). EMA recommended that MSHA should consult the Dust
Control Handbook for Industrial Minerals Mining and Processing, Second
Edition, to reduce the amount of research necessary to create a Table 1
approach (Document ID 1442).
MSHA acknowledges that consensus standards can assist mine
operators in the development and selection of proper engineering
controls for their mine sites and supports the use of consensus
standards in the design of operator enclosures for hazardous
environments. MSHA also recognizes the value of providing guidance on
engineering and work practice control methods for similar exposure
groups to ensure compliance with the final rule. The Agency supports
and encourages the use of NIOSH's Dust Handbook by mine operators to
determine feasible and appropriate engineering controls for their mine
sites. MSHA will work with operators and miners to develop and
implement effective controls, including necessary exposure monitoring.
MSHA encourages mine operators to be proactive in their approach to
protecting miners from silica exposures. MSHA encourages operators to
develop dust control plans or other engineering tools in their
operations. MSHA also commits to developing guidance that includes
information on consensus standards related to control methods. MSHA
will collaborate with stakeholders, including industry and labor, as
well as NIOSH, to help mine operators and miners in implementing
appropriate control methods. MSHA will also provide education and
training to mine operators and miners covering all aspects of the final
rule.
5. Medical Removal/Transfer
MSHA does not include a medical removal/transfer option for MNM
miners with evidence of silica-related disease in the final rule. MSHA
intends to consider this issue in a future rulemaking.
In the proposed rule, MSHA solicited comments on whether the final
rule should include a medical removal/transfer option for MNM miners
who have developed evidence of silica-related disease that is
equivalent to the transfer rights and exposure monitoring provided to
coal miners in 30 CFR part 90 (part 90). Under part 90, any coal miner
who has evidence of the development of pneumoconiosis based on a chest
X-ray or other medical examination has the option to work in
[[Page 28307]]
an area of the mine where the average concentration of respirable dust
in the mine atmosphere during each shift to which that miner is exposed
is continuously maintained at or below the standard for Part 90 miners.
Part 90 miners are ``entitled to retention of pay rate, future actual
wage increases, and future work assignment, shift and respirable dust
protection.'' 30 CFR 90.3(b).
MSHA received comments from labor organizations, mining trade
associations, black lung clinics, a federal elected official, an
industrial hygiene professional association, an advocacy organization,
a medical professional association, and an individual generally
supporting medical removal/transfer rights. These commenters urged MSHA
to include the provisions of part 90 in the rule and stated these
protections should apply for a medically confirmed diagnosis of
silicosis for any miner (Document ID 1351; 1398; 1416; 1418; 1421;
1424; 1439; 1441; 1449). Many of these commenters, as well as the Black
Lung Clinics, the USW, and an individual stated that MNM miners should
be provided similar medical removal/transfer rights as coal miners
(Document ID 1410; 1447; 1437). The UMWA, Black Lung Clinics, and AFL-
CIO noted that a medical removal/transfer program helps address the
barriers related to fear of retaliation and income loss workers face
when choosing to participate in medical surveillance (Document ID 1398;
1410; 1449).
After reviewing the comments and based on its experience with part
90 for coal miners, MSHA agrees that medical removal/transfer would
enhance health protections for MNM miners who choose to exercise their
rights; however, the Agency has determined that this would be more
appropriately addressed in a future rulemaking. MSHA believes that the
NIOSH-established reporting system referenced in the final rule needs
to be developed and implemented before implementing medical removal/
transfer requirements. For example, under part 90, NIOSH administers
medical surveillance and notifies mine operators when a miner exercises
their part 90 rights. Under this final rule, MNM medical surveillance
is administered independent of NIOSH, and there are many more MNM
miners than coal miners. Because of these differences, the Agency
concluded that medical removal/transfer would benefit from additional
notice and comment on a number of decision points, including protecting
miners' privacy, adequacy of forms for notification, timing of
benefits, what area of the mine the miner would be transferred to,
whether NIOSH must make the determination, and consistent ILO
classification. Further, MSHA agrees with the many commenters that
urged the Agency to issue this final rule without delay.
MSHA also clarifies that, under final Sec. 60.14(b), a mine
operator must, upon receiving written notification from a PLHCP,
facilitate the temporary transfer of an affected miner who cannot wear
a respirator to a different area or occupation within the same mine
where respiratory protection is not necessary. The final rule requires
that transferred miners continue to receive compensation at no less
than the regular rate of pay in the occupation that they held
immediately prior to the transfer.
6. Compliance Assistance
MSHA will provide compliance assistance to the mining community
(including industry and labor) after publication of the final rule.
This assistance will include guidance to assist mine operators in
developing and implementing appropriate controls; outreach seminars
(onsite and virtual, dates and locations will be posted on MSHA's
website); dust control workshops held at the National Mine Health and
Safety Academy; support from the Educational Field and Small Mine
Services staff; support from MSHA's Technical Support staff; silica
training and best practice materials; and information on MSHA's
enforcement efforts.
Additionally, MSHA will continue its Silica Enforcement Initiative
by evaluating all sampling data and enforcement actions and providing
compliance assistance on specific engineering controls. MSHA will
continue to maintain a team of experts in regulatory compliance and
respirable dust control to conduct compliance assistance visits. These
visits will evaluate the conditions, mining practices, and controls
that lead to silica dust overexposures. MSHA will discuss its results
with mine operators and miners and make recommendations as a part of
the Agency's compliance assistance activities.
As a part of its ongoing alliance agreements, MSHA will discuss
issues and questions in regular alliance safety and health meetings.
MSHA will continue to work with NIOSH in the development and delivery
of compliance assistance materials. Compliance assistance materials
will be posted on MSHA's and NIOSH's website, some of which may be
reposted to the MSHA app. NIOSH's Dust Control Handbook is a useful
tool for mine operators to determine feasible and appropriate
engineering controls for their mine sites. MSHA encourages mine
operators to use this resource. MSHA will work with mine operators and
miners to develop and implement effective controls, including
evaluating exposure monitoring results. MSHA encourages mine operators
to be proactive in their approach to protecting miners from silica
exposures and to develop dust control plans or other engineering tools
in their operations. MSHA also commits to developing guidance that
includes information on consensus standards related to control methods.
MSHA will also provide education and training to mine operators and
miners covering all aspects of the final rule.
B. Section-by-Section Analysis
Part 60 of the final rule establishes uniform mandatory health
standards for exposure to respirable crystalline silica in MNM and coal
mines. Part 60 includes 10 sections: Scope and compliance dates;
Definitions; Permissible exposure limit (PEL); Methods of compliance;
Exposure monitoring; Corrective actions; Respiratory protection;
Medical surveillance for metal and nonmetal mines; Recordkeeping
requirements; and Severability. For each section below, MSHA discusses
the requirements of the final rule and addresses the public comments
received in response to the July 2023 proposed rule.
1. Section 60.1--Scope; Compliance Dates
The final rule establishes requirements for the scope of the rule
and the compliance dates in Sec. 60.1. Section 60.1 paragraph (a)
identifies the scope of the final rule, and the language is unchanged
from the proposal. In a change from the proposal, paragraph (b)
identifies the separate compliance dates for coal mine operators in
paragraph (b)(1) and for metal and nonmetal mine operators in paragraph
(b)(2). Paragraph (b)(1) establishes a compliance date for coal mine
operators of 12 months after publication of the final rule. Paragraph
(b)(2) establishes a compliance date for metal and nonmetal mine
operators of 24 months after publication of the final rule. Below is a
detailed discussion of the comments received on this section and
modifications made in response to the comments.
a. Scope
MSHA received many comments regarding the scope of the rule. Some
commenters, including the AIHA, ACOEM, APHA, expressed support for
[[Page 28308]]
the proposed rule's unified approach to regulating respirable
crystalline silica exposures at both MNM and coal mines, as well as at
both underground and surface mines (Document ID 1351; 1405; 1416;
1412). Several other commenters, including labor organizations,
advocacy organizations, mining trade associations, and MNM operators,
recommended separate approaches to regulating MNM and coal mines; those
commenters differed on which mines should or should not be regulated
and why (Document ID 1398; 1431; 1445; 1448; 1411; 1415; 1427; 1440;
1452; 1424; 1430; 1441; 1443; 1429; 1392; 1383). Several commenters,
including mining-related businesses and MNM operators, stated that the
proposed rule should not apply to MNM mines (Document ID 1392; 1383;
1411; 1415; 1427). The reasons for the commenters' position included:
past precedent of separate rules (e.g., Document ID 1448; 1440; 1445),
a need for consistency with OSHA's silica standard (e.g., Document ID
1392; 1383; 1411; 1415; 1427; 1431), lower incidence of silicosis among
MNM miners (e.g., Document ID 1431; 1413; 1448; 1456), and higher
compliance costs under the unified approach (Document ID 1392; 1411;
1415; 1427). The Pennsylvania Coal Alliance questioned the need for the
rule to apply to the coal industry, stating that there had been no
marked increase in compensation claims for pneumoconiosis or silicosis
in coal mines (Document ID 1378). Other commenters, including a black
lung clinic, a medical professional association, advocacy
organizations, and a labor union, noted the risks that silica exposure
poses to all miners (Document ID 1418; 1421; 1445; 1425; 1447). The
Miners Clinic of Colorado at National Jewish Health observed that
information about silicosis disease rates among MNM miners is less
readily available in part due to a lack of medical surveillance
(Document ID 1418). However, even with less information on silicosis
disease rates than in coal, this commenter relayed their observations
of substantial silicosis rates in MNM miners.
MSHA continues to believe that a unified approach to controlling
respirable crystalline silica provides the greatest level of health
protection for MNM and coal miners. The purpose of this final rule is
to reduce respirable crystalline silica-related occupational diseases
in miners and to improve respiratory protection against airborne
contaminants. Based on MSHA's review of the adverse health effects
related to respirable crystalline silica--a known carcinogen--MSHA
concludes that the health risks threaten all miners exposed to
respirable crystalline silica. It is important that the mandatory
health standards for MNM and coal miners be consistent to ensure that
all miners are equally protected from exposure. Selected surveillance
data for both silicosis cases and deaths are reported in the standalone
Health Effects document and in the preamble in Section V. Health
Effects Summary. Additionally, further discussion of risk related to
silica exposure is located in the standalone FRA document.
While MSHA acknowledges that MNM and coal mines have been regulated
separately in the past, there is precedent for a unified approach. For
example, MSHA's health standard for occupational noise covers both MNM
and coal mines, as discussed in ``Evaluating hearing loss risks in the
mining industry through MSHA citations'' (Sun and Azman, 2018). Like
respirable crystalline silica, occupational noise is a hazard for all
miners. MSHA's survey and enforcement data indicate that since the
occupational noise rule became effective in September of 2000, there
has been a drastic decrease in the rate of overexposures at both MNM
and coal mines. Because the hazards and control methods of respirable
crystalline silica are common to both coal and MNM, MSHA believes a
unified standard will offer miners consistent improvement of working
conditions in both sectors.
As addressed in the standalone Health Effects document, MSHA has
reviewed studies supporting increased risk of adverse health effects
for miners working in both coal and MNM mines. After decades of
declining prevalence of pneumoconiosis among underground coal miners in
the U.S., prevalence, including more advanced forms of disease, has
increased since the late 1990s (Laney and Weissman, 2012; Blackley et
al., 2014a, 2018a; Hall et al., 2019b).
MSHA does not agree with the assertion that silicosis or other
diseases linked to respirable crystalline silica are not risks for MNM
miners. MSHA reviewed a wide range of studies that demonstrated disease
risks among miners occupationally exposed to respirable crystalline
silica. These studies were not limited to coal miners and covered
occupations relevant to MNM mining such as sandblasters (Hughes et al.,
1982; Abraham and Wiesenfeld, 1997), industrial sand workers (Vacek et
al., 2019), hard rock miners (Verma et al., 1982, 2008), gold miners
(Carneiro et al., 2006a; Tse et al., 2007b), metal miners (Hessel et
al., 1988; Hnizdo and Sluis-Cremer, 1993; Nelson, 2013), and nonmetal
miners such as silica plant and ground silica mill workers, whetstone
cutters, and silica flour packers (Mohebbi and Zubeyri, 2007; NIOSH,
2000a,b; Ogawa et al., 2003a). Of the MNM exposure samples MSHA
collected over the 2005-2019 period, 17.7 percent exceed the new PEL of
50 [mu]g/m\3\, and 6.1 percent exceed the current PEL of 100 [mu]g/
m\3\. Further discussion on this analysis is presented in the
standalone FRA document.
This rule will strengthen miners' health protections by reducing
exposures to respirable crystalline silica, which is the root cause of
silica-related disease. MSHA believes that this uniform approach
provides a more protective, coherent, logical, and predictable standard
for miners and mine operators. Unlike the existing standards, this
final rule establishes a single, uniform PEL and action level, and
eliminates any need for conversion based on percent respirable
crystalline silica and any variations in calculation for different
silica polymorphs. The final uniform PEL will provide all miners with a
consistent level of protection that is similar to the protection
provided to workers in industries covered by OSHA's silica standards,
and consistent with the recommendations of NIOSH.
b. Applicability to Contractors, Portable Mines, and Sorptive Minerals
Industry
Several commenters requested clarification of applicability or
exemptions to specific sectors of the mining industry: mining
contractors, portable mines, and the sorptive minerals sector.
Contractors
Some commenters from industry trade associations and mining trade
associations requested that MSHA clarify the rule's applicability to
mining contractors in the final rule (Document ID 1422; 1433; 1424;
1428; 1378). Consistent with the Mine Act, MSHA's existing standards,
and the Agency's longstanding policy, independent contractors engaging
in mining activities, including construction, maintenance, and
drilling, are required to comply with the requirements in this final
rule. See 30 U.S.C. 802(d) (defining ``operator'' to include ``any
independent contractor performing services or construction'' at a mine)
and Sec. 802(g) (defining ``miner'' as ``any individual working in a
coal or other mine''). MSHA has a long history and practice of
enforcing its standards and regulations for mine operators and
[[Page 28309]]
independent contractors designated under part 45 of 30 CFR. The Agency
believes that the industry is familiar with and understands this
history and practice. Based on MSHA's experience and practice, and
depending upon the activities that they perform for production
operators, MSHA expects that some part 45 independent contractors will
comply with the requirements of this final rule, as it relates to their
miners. For example, MSHA expects that drilling and blasting
contractors, who perform services at different mines, generally
separate from production activities, will comply with the requirements
of the final rule. For other part 45 independent contractors, MSHA
anticipates that the production operator may comply with the
requirements of this final rule for their miners, depending upon the
types of services provided. For example, MSHA expects that production
operators will generally comply with the requirements of this final
rule for independent contractors that perform hauling services for
mines. This final rule provides improved health protections for miners
of both part 45 independent contractors and production operators. As
with the implementation of any new MSHA standard, the Agency expects
that production operators and part 45 independent contractors will
communicate and coordinate with each other, as appropriate, to comply
with the final rule and ensure that miners' safety and health are
protected.
Portable Mines
Some commenters (MNM operators and a mining-related business)
requested that MSHA exempt portable mine operations from exposure
monitoring (Document ID 1392; 1415; 1427; 1435; 1436). The mining-
related business commented that an exemption should be granted for
portable mines that are shut down for more than 3 months out of the
year or operate in a pit for less than 30 days before moving (Document
ID 1392). Several portable mine operators, including B & B Roads, Inc.,
stated that rock crushing jobs are typically completed within 4 to 10
days, at which point the portable mine moves to another job location,
which could be between 30 to 200 miles away (Document ID 1427; 1436).
These commenters specifically requested exemptions for sites that they
do not own, stating that sampling data would not be applicable if done
at pits where they do not conduct operations regularly. However, these
commenters expressed that they were not asking for exemptions to pits
where they regularly conduct operations or to locations they control.
MSHA reviewed the comments and determined that because of MSHA's
clear mandate to protect the health of all miners, the final rule does
not exempt portable mines. Under existing MNM standards for airborne
contaminants, portable operations are not exempt from any regulatory
requirements or any other health standards. This final rule, like
existing standards, requires portable mine operators to protect their
miners from overexposure to respirable crystalline silica and other
airborne contaminants, and to monitor miners' exposures to airborne
contaminants, including silica. Portable mine operations often involve
crushing, which can generate substantial amounts of dust, and they
handle a variety of commodities generating varying amounts of
respirable crystalline silica depending on the geological features of
the pit.
The final rule requires that all mine operators, including portable
mine operators, conduct exposure monitoring in accordance with Sec.
60.12, including first-time sampling. With respect to portable mine
operators, MSHA has taken into consideration that these mines are
unique and may move frequently. However, the final rule does not exempt
portable mine operators because miners must be protected at all times,
and the methods of compliance, sampling and evaluation provisions are
necessary to protect miners.
Sampling ensures engineering controls put in place by mine
operators are effective in protecting miners. If the portable mine
operator anticipates being at the site for at least three months, MSHA
expects the portable mine operator to conduct the second-time sampling
at that site within the three-month timeframe under Sec. 60.12(a)(2).
If the portable mine operator moves to a different site before
conducting its second-time sampling within three-months, the operator
is required to conduct the second-time sample at the next site. If
either operator or MSHA samples are at or above the action level and at
or below the PEL, portable operators must sample every three months
under Sec. 60.12(a)(3). Similarly, if the most recent sampling was
above the PEL, the portable mine operator must take immediate
corrective actions, immediately report the overexposure to MSHA, ensure
provided respirators are worn appropriately by affected miners before
the start of the next work shift, and resample, regardless of whether
the portable mine has moved to a different site by the time the
sampling results are received. Under the final rule, at least every 6
months or if there are any changes in processes, production, equipment,
or geological conditions, mine operators are required to conduct a
qualitative evaluation. Protecting miners' health requires monitoring
and controlling levels of respirable crystalline silica, and,
consistent with the Mine Act, miners at portable mines must be afforded
the same health protections and informational awareness of their
exposures as all other miners.
If the results of the evaluation reveal that their miners may be
reasonably exposed to respirable crystalline silica at or above the
action level but at or below the PEL, the sampling provisions of the
final rule apply. Also, if sampling indicates levels above the PEL,
under the final rule, portable mine operators must take immediate
corrective actions, resample, and record these actions.
MSHA provides two examples that illustrate how and why the final
rule will affect portable mine operators. In example 1, the portable
mine operator conducts first-time sampling on mine site A and the
sample result is below 25 [mu]g/m\3\. One month later, the portable
mine operator moves to mine site B. The operator performs a qualitative
evaluation, which the operator determines does not trigger post-
evaluation sampling. Within two months (three months from the date of
the first-time sample), the portable mine operator must take a second
sample. This sample result is also under 25 [mu]g/m\3\. Under the final
rule, this portable mine operator can discontinue sampling. The
portable mine operator then moves to mine site C. The portable mine
operator must conduct a qualitative evaluation and, depending on the
results of the evaluation, may need to perform sampling.
In example 2, the portable mine operator is located on mine site X.
The portable mine operator conducts a qualitative evaluation and
determines that miners' exposures may reasonably be at or above the
action level, triggering sampling. The portable mine operator conducts
sampling, and the results are above the PEL. The mine operator takes
immediate corrective actions, immediately reports the overexposure to
MSHA, ensures provided respirators are worn appropriately by affected
miners before the start of the next work shift, and resamples. The
operator then moves to mine site Y before corrective actions sampling
results are received. Depending on the results of the corrective
actions sampling from mine site X, the portable mine operator must
conduct either above-action-level sampling or corrective actions
sampling
[[Page 28310]]
at mine site Y. MSHA expects that all corrective actions, including any
new or improved engineering controls, will remain in place at mine site
Y. Additionally, at mine site Y, the operator must perform another
qualitative evaluation at the new mine site. Each time the operator
moves to a new site, it must perform a new qualitative evaluation.
These examples illustrate that when sampling is required at one
portable mine site, the requirement continues when the portable mine
moves to a new mine site. Sampling across different portable mine sites
is needed to determine whether the engineering controls applied to the
portable mine (for example, dust collection or water spray) are
effective to keep miners healthy. Periodic evaluations will also be
critical for mines that move frequently and encounter different
conditions that expose miners to respirable crystalline silica. These
evaluations and any related samplings will allow operators to verify
that adequate engineering controls are effective and are maintained
properly to protect miners as they move to different worksites,
regardless of mining location or commodity mined or milled.
MSHA encourages portable mine operators to work with their District
Managers to develop an appropriate compliance approach that protects
miners' health. MSHA will provide compliance assistance to portable
mine operators.
Sorptive Minerals
The applicability of the rule to one specific industry within MNM--
the sorptive minerals industry--was the subject of several comments
from SMI, EMA, and Vanderbilt Minerals, LLC (Document ID 1446; 1442;
1419). These commenters requested that the sorptive minerals industry
be exempted from the rule. The commenters stated that this industry
exposes workers only to aged quartz, and that aged quartz is less toxic
than freshly fractured quartz in other industries. After careful
consideration, MSHA has decided not to exempt sorptive minerals mines.
The Agency's rationale for this decision is discussed in detail above
in Section VIII.A. General Issues.
c. Compliance Dates
This final rule will take effect 60 days after publication in the
Federal Register. In response to comments, MSHA is establishing two
compliance dates for the final rule--one for MNM mine operators and the
other for coal mine operators. MNM operators will be required to comply
starting 24 months after publication of the final rule, whereas coal
mine operators will be required to comply starting 12 months after
publication of the final rule.
MSHA received comments both in support of and against having
compliance commence immediately when the final rule takes effect. Some
commenters, including labor organizations, an industrial hygiene
professional association, and an advocacy organization, supported the
proposed effective date, citing the need for the new rule to be
implemented as soon as possible to protect miners' health (Document ID
1398; 1425; 1351; 1449). Appalachian Voices and the AFL-CIO stated that
the technologies and practices necessary to reduce dust and silica
exposure are well-known and that mine operators have had ample notice
that this rule was forthcoming (Document ID 1425; 1449). In contrast,
several commenters, including multiple mining trade associations and a
mining industry organization, expressed the need for a longer
preparation period prior to compliance (Document ID 1428; 1407; 1408;
1442; 1441; 1448). Some commenters, including a state mining
association, a MNM operator, and an industry trade association,
suggested that MSHA allow more time, ranging from one to three years,
to comply with the final rule (Document ID 1441; 1432; 1442; 1448;
1392). Some cited reasons for allowing more time include: the two-year
preparation period that OSHA provided for compliance with its 2016
silica rule; the time needed for operators to plan, purchase, and
implement engineering controls; and the challenges that the rule could
present for MNM mine operators new to sampling and medical surveillance
(Document ID 1407; 1419; 1424; 1428). Other commenters, including a
professional association, industry trade associations, mining trade
associations, and MNM operators, suggested a phased approach to
implementation, with different compliance dates for the different
requirements in the rule (Document ID 1377; 1407; 1413; 1428; 1424;
1456; 1417; 1453). Examples given of past rules that had used this
approach included: OSHA's silica rule (which became effective 90 days
after publication, but, for example, for construction, allowed one year
after the effective date for compliance with most of the rule
requirements, and two years for compliance with certain laboratory
requirements); MSHA's diesel particulate matter rule (which included
incremental reductions in the PEL over two years); and MSHA's 2014 RCMD
Standard (which allowed operators 18 months after the effective date to
comply with sampling requirements and 24 months to implement the
standards) (Document ID 1407; 1424; 1441; 1442).
Several commenters, including three industry trade associations, a
mining trade association, and a MNM operator, expressed concern that
the rule would lead to excessive demand and backlogs for sampling
devices, industrial hygienists, labs, medical facilities, and B Readers
(Document ID 1407; 1404; 1413; 1428; 1419). The NSSGA stated that over
80 percent of aggregate companies have fewer than 25 employees and
therefore will likely rely on their insurance companies or industrial
hygiene consultants for sampling, and that scheduling of sampling will
be based on priorities outside the control of the mine operator
(Document ID 1448). A mining trade association, industry trade
associations, and a MNM operator also asserted that because post-
pandemic supply chain delays are continuing, and in some cases
escalating, operators are facing long lead times for procurement of
critical infrastructure items, including those essential for mandatory
health and safety requirements (Document ID 1428; 1404; 1407; 1419).
Finally, these commenters expressed concern that requiring mine
operators to comply with the final rule 120 days after publication
would not provide enough time for MSHA to issue guidance and for mine
operators to digest relevant implementation and compliance guidance
documents (Document ID 1428; 1404; 1407; 1419).
After careful consideration, MSHA has decided to provide additional
time for mine operators to prepare for compliance with the final rule.
MNM mine operators must comply with the final rule by 24 months after
publication of the final rule, while coal mine operators will have 12
months to come into compliance with the rule (except for medical
surveillance, which applies only to MNM mines). MSHA believes that this
final compliance date gives coal mine operators sufficient time to plan
and prepare for effective compliance with the new standards, while also
ensuring that improved protections for miners from the hazards of
respirable crystalline silica take effect as soon as practically
possible. Unlike MNM mines, underground and surface coal mine operators
have considerable experience with frequent sampling, and they can more
quickly integrate the sampling requirements in this final rule into
their existing underground mine ventilation plans and surface mine
respirable dust control plans. In addition, coal mines already have
[[Page 28311]]
existing controls in place that control for dust; therefore, coal mine
operators should not need as much time to maintain, repair or implement
controls. As mentioned earlier, coal mine operators will not have to
implement medical surveillance under this rule.
In the case of MNM mines, MSHA has adjusted the requirements in the
final rule to allow operators a total of 24 months after the
publication of the final rule to comply. MSHA is allowing this longer
period for compliance because MNM operators, particularly small mines,
may have less experience with sampling and may also need time to
prepare for compliance with medical surveillance. The longer period for
compliance is generally responsive to some commenters. The Agency
believes the longer period for compliance will provide operators
adequate time to meet their compliance obligations under the final
rule. MSHA believes that mine operators will use the compliance period
to familiarize themselves with the new standard; evaluate, update, and
enhance existing engineering controls; research, purchase, and install
new or additional engineering controls, if necessary; arrange for
sampling; and commence sampling. MSHA notes that the 24 months provided
for MNM operators is the same as that provided in the OSHA rule and the
same as MSHA provided in the 2014 RCMD Standard. MSHA believes that
there are enough laboratories, sampling equipment, medical service
providers, respiratory equipment, and contractor service providers for
sampling to meet any increase in demand for equipment or services
required by this final rule. The additional 24 months will provide MNM
operators additional time to procure equipment and services. For a
detailed discussion of the availability of respirators and laboratory
and medical services necessary for compliance with the rule, see
Section VII.A. Technological Feasibility.
MSHA believes that these compliance periods in the final rule
provide operators adequate time to prepare for successful
implementation, balanced against the Agency's priority goal and
statutory mandate to move quickly to protect miners against respirable
crystalline silica hazards. Mine operators in both MNM and coal have
had many years of experience with monitoring and controlling airborne
contaminants, including respirable crystalline silica, and this
experience should facilitate implementation of the final rule. MSHA
data show that many mines are already meeting the respirable
crystalline silica PEL of 50 [mu]g/m\3\ for a full-shift, calculated as
an 8-hour TWA, using a variety of engineering controls. In addition, to
ensure successful implementation, MSHA plans to provide compliance
assistance to the mining industry. This assistance will include the
development and distribution of compliance guidance materials for mine
operators and training materials for miners, as well as technical
assistance for small mines. Compliance assistance and training are
discussed in more detail above in Section VIII.A. General Issues.
2. Section 60.2--Definitions
The final rule, like the proposal, includes definitions for the
following terms in Sec. 60.2: ``action level,'' ``respirable
crystalline silica,'' and ``specialist.'' In a change from the
proposal, MSHA removes the definition of ``objective data'' from the
final rule. MSHA received multiple comments on the proposed definitions
of action level and objective data, as discussed in more detail below.
The Agency did not receive any comments on the proposed definitions of
respirable crystalline silica or specialist.
a. Action Level
The final rule, like the proposal, defines ``action level'' as ``an
airborne concentration of respirable silica of 25 micrograms per cubic
meter of air ([mu]g/m\3\) for a full-shift exposure, calculated as an
8-hour time-weighted average (TWA).'' If respirable crystalline silica
concentrations are at or above the action level but at or below the
PEL, operators are subject to the ongoing sampling requirements
detailed in Sec. 60.12. The action level enables mine operators to
maintain compliance with the PEL and provide necessary protection to
miners before overexposures occur.
MSHA received several comments in support of and against the
proposed adoption of an action level. Several commenters including
labor unions, medical professional associations, and advocacy
organizations supported the proposal to institute an action level of 25
[mu]g/m\3\ (Document ID 1398; 1447; 1416; 1421; 1393; 1438). The UMWA
and USW stated that the proposed action level was consistent with NIOSH
and IARC findings and would reduce the risk of death and disease
(Document ID 1398; 1447). Other commenters, including state mine
organizations, mining trade associations, and MNM mine operators, did
not support the proposed action level of 25 [mu]g/m\3\ for all mines
(Document ID 1368; 1441; 1424; 1432; 1440; 1378; 1392; 1408; 1426). The
commenters stated that it would not be achievable with current
technology (Arizona Mining Association, Document ID 1368) and would not
improve miners' health (AMI Silica LLC, Document ID 1440). The NLA
stated that MSHA should consider setting only a PEL and not an action
level because there is less need for an action level in the mining
industry than in OSHA-regulated industries (Document ID 1408). The
AEMA, NVMA, and Tata Chemicals Soda Ash Partners, LLC, stated that the
action level should be developed on a per-mine or per-company basis or
should be an internal control only (Document ID 1424; 1441; 1452). The
Arizona Mining Association suggested a phased approach with incremental
changes (Document ID 1368). The ACOEM, although in support of the
action level and proposed PEL, urged a further lowering of the PEL to
25 [mu]g/m\3\ in the future (Document ID 1405).
After careful consideration of the comments, MSHA has determined an
action level of 25 [mu]g/m\3\ is feasible, and the definition of action
level in the final rule is the same as the proposal. MSHA's FRA shows
that there will be a greater reduction of morbidity and mortality at
the action level, but acknowledges that it may not be achievable for
all mines to consistently maintain an exposure limit below 25 [mu]g/
m\3\. According to NIOSH research, wherever exposure measurements are
above one-half the PEL, the employer cannot be reasonably confident
that the employee is not exposed to levels above the PEL on days when
no measurements are taken (NIOSH, 1975). MSHA establishes the action
level and sets a sampling frequency for concentrations at or above the
action level to allow mine operators to act before overexposures occur.
MSHA acknowledges that, even at exposures of 25 [mu]g/m\3\, some
residual risks remain. For example, at 25 [mu]g/m\3\, end stage renal
disease (ESRD) risk is 20.7 per 1,000 MNM miners and 21.6 per 1,000
coal miners.
Commenters stated that MSHA should not have an action level. The
AEMA and NVMA said the Agency does not use an action level in other air
contaminant exposure rules (Document ID 1424; 1441).
At exposures of 25 [mu]g/m\3\ or lower, risk of adverse health
effects remains. The Agency has established action levels equivalent to
50 percent of the PEL for occupational noise exposure in MNM and coal
mines (30 CFR 62.101) and equivalent to 50 percent of the exhaust gas
monitoring standards for underground coal mines (30 CFR 70.1900). MSHA
survey and enforcement data indicate that the action levels in the
occupational noise
[[Page 28312]]
and exhaust gas rules have contributed to greater compliance and fewer
overexposures. Based on its experience, MSHA knows that action levels
encourage mine operators to be more proactive in providing necessary
health and safety protection to miners. Furthermore, MSHA was able to
learn about the health benefits of an action level for respirable
crystalline silica through the implementation of OSHA's silica final
rule (2016a). In developing this final rule, MSHA took into
consideration experience gained under other safety and health standards
including those established by OSHA. Several OSHA standards established
action levels for airborne contaminants, especially toxins such as
benzene, inorganic arsenic, ethylene oxide, and methylene chloride.
Some commenters, including trade associations, MNM operators, a
state mining association, and a mining-related business, stated that
the action level would increase costs for mine operators (Document ID
1408; 1442; 1419; 1440; 1441; 1392). MSHA recognizes that costs may
increase as a result of the sampling requirements in the final rule.
Mine operators are encouraged to reduce exposures below the action
level to avoid additional costs associated with the sampling
requirements triggered when exposures are at or above the action level.
The Agency emphasizes that the requirements of the final rule are
established to protect miners from the adverse health effects resulting
from exposure to respirable crystalline silica.
Several commenters, including industry trade associations, MNM
operators, and a mining trade association, cautioned that the action
level was too close to the limit of accurate detection of respirable
crystalline silica (Document ID 1426; 1413; 1432; 1440; 1448). SSC
stated that there is little confidence in the reliability of sampling
results below 50 [mu]g/m\3\ (Document ID 1432).
MSHA's analytical methods for air samples can reliably detect
respirable crystalline silica at or below the action level. The MSHA P-
2 and P-7 analytical methods have a reporting limit of 12 [mu]g for
quartz in mine dust. Both methods are sufficiently sensitive to
quantify levels of quartz collected on air samples from concentrations
at the action level. Most accredited laboratories that offer
crystalline silica analysis by X-ray diffraction use either the OSHA
ID-142 or NIOSH 7500 methods. The OSHA method specifies a reliable
quantification limit of 12 [mu]g/m\3\ for quartz, and the NIOSH method
states that the estimated detection limit for quartz is 5 [mu]g. The
NIOSH infrared methods, 7603 and 7602, state estimated detection limits
of 1 and 5 [mu]g of quartz, respectively.
The AEMA and NVMA disagreed with MSHA's calculation of the action
level as an 8-hour TWA (Document ID 1424; 1441). These commenters said
NIOSH recommends calculating exposure levels for a 10-hour shift.
The final rule includes an 8-hour TWA because it provides more
protection to miners who work extended shifts. Further discussion of
the 8-hour TWA is discussed below under Section 60.10--Permissible
Exposure Limit (PEL).
The Arizona Mining Association stated the proposed action level is
not achievable with current available technology (Document ID 1368).
The commenter provided testimonial information about a mine that
conducted a baseline test with a continuous dust monitor in an office
setting and was close to the proposed action level.
MSHA clarifies that the action level applies only to respirable
crystalline silica, which is a component of respirable dust. If an
office or other setting contains levels of respirable crystalline
silica that meet or exceed the action level, sampling is required under
the final rule.
After careful consideration of the rulemaking record, MSHA has
determined the action level is appropriate. The Agency's experience
with existing standards indicates that an action level of one-half the
PEL provides necessary information to mine operators on actions they
need to take to reduce miners' exposures below the action level, where
feasible. Operator sampling at or above the action level but at or
below the PEL also provides critical information to miners on their
exposures. Under Sec. 60.12(g), operators must share sampling records
and laboratory reports with miners so that they have an awareness and
understanding of the important role that engineering and administrative
controls play in protecting their health. Mine operators who keep their
exposures below the action level avoid the costs of required compliance
with provisions triggered by the action level, provide improved health
protection for miners, and may experience better miner health and less
turnover. MSHA concludes that an action level is needed at one-half the
PEL based on residual risk at the PEL of 50 [mu]g/m\3\; the feasibility
of measuring exposures at an action level of 25 [mu]g/m\3\; and the
administrative convenience of having the action level at one-half the
PEL, as it is in other MSHA standards. As discussed in the standalone
Health Effects document and standalone FRA document, risk remains at
the PEL of 50 [mu]g/m\3\. Accordingly, MSHA is finalizing these
additional requirements to reduce remaining risk when those
requirements will afford benefits to miners and are feasible.
b. Objective Data
Under the proposal, operators could use ``objective data'' to
confirm sampling results below the action level and discontinue
sampling.
MSHA removes the definition of ``objective data'' in the final
rule. The term ``objective data'' was defined in the proposed rule as
``information such as air monitoring data from industry-wide surveys or
calculations based on the composition of a substance that indicates the
level of miner exposure to respirable crystalline silica associated
with a particular product or material or a specific process, task, or
activity.''
MSHA received several comments on the proposed definition of
objective data, with numerous commenters stating that the definition
was vague and overly broad. Some commenters, including labor
organizations, a Federal elected official, and an industry trade
association, requested clarification on how to determine the validity
and acceptability of objective data and who should make the
determinations (Document ID 1398; 1449; 1439; 1442). Others, such as
AIHA, Black Lung Clinics, and AFL-CIO, commented that objective data is
not an accurate or reliable measure of exposure to respirable
crystalline silica and that objective data should not be used to exempt
operators from sampling. (Document ID 1351; 1410; 1449; 1412).
The Agency agrees with commenters who asserted sampling is more
accurate than using objective data as defined in the proposed rule.
Additional discussion on the comments received on objective data and
MSHA's response regarding the proposal are discussed in Section
VIII.B.5. Section 60.12.--Exposure Monitoring.
c. Respirable Crystalline Silica
The final rule, like the proposal, defines ``respirable crystalline
silica'' as ``quartz, cristobalite, and/or tridymite contained in
airborne particles that are determined to be respirable by a sampling
device designed to meet the characteristics for respirable-particle-
size-selective samplers that conform to the International Organization
for Standardization (ISO) 7708:1995: Air Quality--Particle Size
Fraction Definitions for Health-Related Sampling.''
[[Page 28313]]
MSHA did not receive any comments on the definition of respirable
crystalline silica. The final rule's definition has two main
advantages. First, the ISO 7708:1995 definition of respirable
particulate mass represents an international consensus, and by adopting
the ISO 7708:1995 criterion, MSHA is able to harmonize its standards
with the standards used by other occupational health and safety
organizations in the U.S. and internationally, including ACGIH, OSHA
(29 CFR 1910.1053 and 29 CFR 1926.1153), NIOSH (2003b, Manual of
Analytical Methods), and the European Committee for Standardization
(CEN) (ISO 7708:1995). Second, the definition eliminates
inconsistencies in the existing standards for MNM and coal mines.
Defining respirable crystalline silica to include quartz, cristobalite,
and/or tridymite and establishing a PEL for exposure to respirable
particles of any combination of these three polymorphs provides
consistency across different mining sectors.
d. Specialist
The final rule, like the proposal, defines ``specialist'' as ``an
American Board-Certified Specialist in Pulmonary Disease or an American
Board-Certified Specialist in Occupational Medicine.'' The definition
is applicable to Sec. 60.15, which addresses medical surveillance for
MNM mines. Under the medical surveillance requirements, MNM mine
operators are required to provide miners with medical examinations
performed by a specialist in pulmonary disease or occupational medicine
or a PLHCP.
MSHA did not receive any comments on the definition of specialist.
The medical surveillance provisions for MNM mines require a specialist
to conduct a follow-up medical examination no later than 2 years after
the follow-up examination for new miners if the chest X-ray shows
evidence of pneumoconiosis or the spirometry examination indicates
evidence of decreased lung function (Sec. 60.15(c)(3)). The provision
is intended to ensure that any miner who shows evidence of
pneumoconiosis or decreased lung function is seen by a professional
with expertise in respiratory disease. The definition is important
because it ensures miners benefit from expert medical judgment and
receive advice regarding how work practices and personal habits could
affect their health.
3. Section 60.10--Permissible Exposure Limit (PEL)
The final rule, like the proposal, requires the mine operator to
ensure that no miner is exposed to respirable crystalline silica in
excess of 50 [mu]g/m\3\ for a full-shift exposure, calculated as an 8-
hour TWA for all mines. The PEL is the same for both MNM mines and coal
mines. For coal mines, this provision establishes a PEL for respirable
crystalline silica independent from the existing respirable coal mine
dust standards. The PEL in the final rule replaces the Agency's
existing exposure limits for respirable crystalline silica or
respirable quartz in 30 CFR parts 56, 57, 70, 71, and 90. (The existing
respirable coal mine dust standards unrelated to quartz remain the
same.) Below is a detailed discussion of the comments received on this
section and modifications made in response to the comments.
a. PEL of 50 [mu]g/m\3\
MSHA analyzed and considered the comments received in response to
the proposed PEL of 50 [mu]g/m\3\. Most commenters supported lowering
the existing quartz or silica exposure limits, and many specifically
expressed support for the proposed PEL, including labor organizations,
an advocacy organization, medical professional associations, and mining
trade associations, (Document ID 1398; 1447; 1449; 1416; 1421; 1424;
1428; 1418; 1439; 1443). Some of these commenters, including AEMA and
NMA, noted that the proposed PEL aligns with OSHA's PEL for non-mining
industries, as well as with NIOSH recommendations (Document ID 1424;
1428). Several commenters, including Black Lung Clinics, APHA, and
Miners Clinic of Colorado, underscored that substantial risk of silica-
related disease exists at 100 [mu]g/m\3\ compared to lower risks at 50
[mu]g/m\3\ (Document ID 1410; 1416; 1418). Black Lung Clinics noted
that the indirect approach to limiting silica exposure in coal miners
has not been effective (Document ID 1410). Other commenters, including
the AFL-CIO and NABTU, stated that the proposed PEL is technologically
and economically feasible and would reduce the risk of death and
disease to miners (Document ID 1449; 1414). Other commenters similarly
expressed support for the proposed PEL, with the USW stating that the
proposed PEL is necessary and feasible, and The American Thoracic
Society et al. stating that it is supported by science and could be
readily achieved with currently available engineering interventions
(Document ID 1447; 1421).
AIHA and MSHA Safety Services did not believe the proposed PEL was
appropriate, with the AIHA stating that the proposed PEL of 50 [mu]g/
m\3\ does not protect miners from adverse health effects and
recommending a PEL of 25 [mu]g/m\3\ instead (Document ID 1351; 1392).
While some commenters such as the USW and the AFL-CIO did support
MSHA's proposal to lower the existing exposure limits, these commenters
noted that several other countries or jurisdictions have set standards
reducing legal permissible limits to 25 [mu]g/m\3\ (Document ID 1447;
1449). One commenter, MSHA Safety Services Inc., opposed the rule
stating that the existing standards (i.e., 100 [mu]g/m\3\), if
followed, would be more than sufficient (Document ID 1392). This
commenter, citing data retrieved from MSHA's Mine Data Retrieval System
(MDRS), stated that silicosis and pneumoconiosis affect only
underground coal miners and not MNM miners.
After considering the data and evidence in the rulemaking record,
the final rule establishes a PEL of 50 [mu]g/m\3\. MSHA's examination
of health effects evidence (discussed in the preamble in Section V.
Health Effects and Section VI.--Final Risk Analysis Summary, as well as
in the standalone Health Effects document and standalone FRA document)
demonstrates that exposure to respirable crystalline silica at the
existing exposure limits results in a risk of material impairment of
health or functional capacity, and that exposure at the lower level of
the PEL will reduce that risk. MSHA's FRA indicates that 45 years of
exposure to respirable crystalline silica under the new PEL would lead
to a total of 1,067 lifetime avoided deaths, including 248 avoided
deaths from silicosis, 536 avoided deaths from all forms of non-
malignant respiratory disease (including silicosis as well as other
diseases such as chronic bronchitis and emphysema), 82 avoided deaths
from lung cancer, and 200 avoided deaths from renal diseases.
As some commenters noted, the PEL is consistent with NIOSH's
respirable crystalline silica recommended exposure limit of 50 [mu]g/
m\3\ for workers and with the PEL of 50 [mu]g/m\3\ for respirable
crystalline silica covering U.S. workplaces regulated by OSHA. In 1974,
NIOSH recommended that occupational exposure to crystalline silica be
controlled so that ``no worker is exposed to a TWA of silica
[respirable crystalline silica] greater than 50 [mu]g/m\3\ as
determined by a full-shift sample for up to a 10-hour workday over a
40-hour workweek'' (NIOSH, 1974). In 2016, OSHA promulgated a rule
establishing that, for construction, general industry, and the maritime
industry, workers' exposures to respirable crystalline silica must not
exceed 50 [mu]g/m\3\, averaged over an 8-hour day (29 CFR
[[Page 28314]]
1910.1053(c); 29 CFR 1926.1153(d)(1)).\66\
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\66\ NIOSH conducted a literature review of studies containing
environmental data on the harmful effects of exposure to respirable
crystalline silica. Based on these studies, and especially fifty
years' worth of studies on Vermont granite workers during which time
dust controls improved, exposures fell, and silicosis diagnoses
neared zero, NIOSH recommended an exposure limit of 50 [mu]g/m\3\
for all industries. OSHA's examination of health effects evidence
and its risk assessment led to the conclusion that occupational
exposure to respirable crystalline silica at the previous PELs,
which were approximately equivalent to 100 [mu]g/m\3\ for general
industry and 250 [mu]g/m\3\ for construction and maritime
industries, resulted in a significant risk of material health
impairment to exposed workers, and that compliance with the revised
PEL would substantially reduce that risk. (81 FR at 16755). OSHA
considered the level of risk remaining at the revised PEL to be
significant but determined that a PEL of 50 [mu]g/m\3\ is
appropriate because it is the lowest level feasible.
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As discussed in the standalone Health Effects document,
occupational exposure to respirable crystalline silica is detrimental
to an individual's health. Silicosis and other diseases caused by
respirable crystalline silica exposure are irreversible, disabling, and
potentially fatal. At the same time, these diseases are exposure-
dependent and are therefore preventable. The lower a miner's exposure
to respirable crystalline silica, the less likely that miner is to
suffer from adverse health effects.
Regarding the comments recommending MSHA adopt a PEL of 25 [mu]g/
m\3\ and some comments noting that other countries or provinces have
set standards reducing permissible limits to 25 [mu]g/m\3\, MSHA
considered establishing a PEL of 25 [mu]g/m\3\ as part of MSHA's
Regulatory Alternative 2. Under this regulatory alternative, a more
stringent PEL of 25 [mu]g/m\3\ is combined with less stringent
monitoring provisions compared to the final rule. MSHA estimated that
there will be a greater reduction of morbidity and mortality cases as a
result of lowering the PEL to 25 [mu]g/m\3\. MSHA also estimated that
the compliance costs would outweigh the benefits resulting in negative
net benefits. MSHA's enforcement experience shows that for mining
occupations exposed to the highest levels of respirable crystalline
silica, in both MNM mines and coal mines, a PEL of 25 [mu]g/m\3\ is not
generally achievable. For example, MSHA reviewed exposures of
designated occupations in underground coal mines and crusher and
equipment operators in MNM mines, and determined that on average, miner
exposures exceed 25 [mu]g/m\3\ when all feasible engineering controls
are used. Although other countries and jurisdictions may have adopted a
PEL of 25 [mu]g/m\3\, MSHA did not choose this regulatory alternative
because a PEL of 25 [mu]g/m\3\ may not be achievable for all mines
(Document ID 1447; 1449). For some mines, a PEL of 25 [mu]g/m\3\ would
present a substantial challenge. Commenters did not provide specific
information on the regulatory programs for the countries and
jurisdictions that have established a PEL of 25 [mu]g/m\3\. Further
explanation and discussion of the regulatory alternatives can be found
in the standalone FRIA document and in the preamble in Section IX.
Summary of Final Regulatory Impact Analysis and Regulatory
Alternatives.
An individual urged MSHA to adopt, in addition to the proposed PEL
of 50 [mu]g/m\3\, an upper exposure level of 100 [mu]g/m\3\ that would
trigger the withdrawal of miners from the affected area rather than
permit continued miner work in affected jobs in extremely elevated
concentrations above the PEL (Document ID 1367). Because MSHA has
determined that the final rule's sampling obligations will reduce
overexposures and that the corrective actions requirements establish
strong protections for miners when they are exposed over the PEL, the
Agency has not set an upper limit that would automatically trigger the
withdrawal of miners. As discussed at the public hearings and required
in Sec. 60.12, operators must immediately report all exposures above
the PEL from operator sampling to the MSHA District Manager or any
other MSHA office designated by the District Manager, so that MSHA
enforcement will be apprised of exposures above the PEL and can take
appropriate actions. As discussed above in Section VIII.A. General
Issues, failure to abate miners' exposures above the PEL could merit a
withdrawal order under section 104(b) of the Mine Act.
In conclusion, MSHA has determined, as presented in the standalone
FRA document accompanying this final rule, that: (1) under previous
respirable crystalline silica or quartz standards, miners were exposed
to respirable crystalline silica at concentrations that result in a
risk of material impairment of health or functional capacity and (2)
lowering the PEL to 50 [mu]g/m\3\ will substantially reduce this risk.
According to the CDC, between 1999 and 2014, miners died from
silicosis, COPD, lung cancer, and NMRD at substantially higher rates
than did members of the general population; for silicosis, the
proportionate mortality ratio for miners was 21 times as high.\67\
Evidence in the standalone Health Effects document demonstrates that
exposure to respirable crystalline silica at levels permitted under
previous standards contributes to this excess mortality. Based on the
evidence and data evaluated during the rulemaking process, MSHA has
determined that a PEL of 50 [mu]g/m\3\ is appropriate and is
technologically and economically feasible for all mines. Mine operators
will be able to maintain miner exposures at or below the PEL of 50
[mu]g/m\3\ through some combination of properly maintaining existing
engineering controls, implementing new engineering controls (e.g.,
ventilation systems, dust suppression devices, and enclosed cabs or
control booths with filtered breathing air), and requiring changes to
work practices through administrative controls. MSHA determined not to
set the PEL at 25 [mu]g/m\3\. MSHA's enforcement experience shows that
for mining occupations exposed to the highest levels of respirable
crystalline silica, in both MNM mines and coal mines, a PEL of 25
[mu]g/m\3\ is not generally achievable. For example, MSHA reviewed
exposures of designated occupations in underground coal mines and
crusher and equipment operators in MNM mines, and determined that on
average, miner exposures exceed 25 [mu]g/m\3\ when all feasible
engineering controls are used. While MSHA estimated that there would be
a greater reduction of morbidity and mortality cases as a result of
lowering the PEL to 25 [mu]g/m\3\, the Agency estimates that compliance
costs of Regulatory Alternative 2 establishing a PEL of 25 [mu]g/m\3\
would outweigh the benefits, resulting in negative net benefits. A PEL
of 25 [mu]g/m\3\ may not be achievable for all mines. MSHA did not
choose this regulatory alternative.
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\67\ Data on occupational mortality by industry and occupation
can be accessed by visiting the CDC website at https://www.cdc.gov/niosh/topics/noms/default.html (last accessed Jan. 10, 2024). The
NOMS database provides detailed mortality data for the 11-year
period from 1999, 2003 to 2004, and 2007 to 2014.
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b. PEL in Coal Mines
In the case of coal mines, the final rule establishes a PEL for
respirable crystalline silica independent from the respirable coal mine
dust (RCMD) standard. The 2014 RCMD Standard does not directly limit
coal miners' exposure to respirable crystalline silica; under the
existing coal mine respirable dust standard, MSHA cannot issue a
separate citation for silica or quartz.
Separating the respirable crystalline silica PEL from the
respirable coal mine dust standard allows for coal miners' exposure to
respirable crystalline silica to be controlled directly, rather than
only indirectly through the respirable
[[Page 28315]]
coal mine dust standard. This will ensure greater health protection for
coal miners.
MSHA solicited comments on whether to eliminate the reduced
standard for total respirable dust when quartz is present at coal mines
and received feedback from stakeholders generally agreeing with the
Agency's proposal to establish a standard for respirable crystalline
silica that is independent from the respirable coal mine dust standard,
including other mine industry organizations, a labor union, mining
trade associations, and Black Lung Clinics (Document ID 1378; 1398;
1406; 1428; 1410). The ACLC expressed support for a standalone and
separately enforceable PEL, but recommended maintaining a reduced
standard for respirable dust when silica is present in coal mines,
which would ensure that standalone effects of silica and coal dust are
accounted for and allow for better monitoring overall (Document ID
1445). The NMA, the MCPA, and the Pennsylvania Coal Alliance supported
the removal of the respirable dust standards when quartz is present
(i.e., Sec. Sec. 70.101 and 71.101, and 90.101), reasoning that they
are no longer needed since the rule proposes a standalone standard for
respirable crystalline silica (Document ID 1428; 1406; 1378).
MSHA has concluded that establishing an independent and lower PEL
for respirable crystalline silica for coal mines allows more effective
control of respirable crystalline silica than the existing reduced
standards because the separate standard is less complicated and more
protective. MSHA believes that the adoption of a separate improved
standard that carries risk of a citation and monetary penalty when
overexposures of the respirable crystalline silica PEL occur is thus
more protective than the indirect method under the existing reduced
standards. MSHA clarifies that mine operators will continue to sample
for respirable coal mine dust under existing Sec. Sec. 70.100, 71.100,
and 90.100. MSHA agrees with the commenters supporting the removal of
Sec. Sec. 70.101, 71.101, and 90.101. With the PEL and action level
(both calculated as a full-shift 8-hour TWA), sampling, recordkeeping,
and reporting requirements in this final rule, MSHA does not believe
that retaining the reduced standard is necessary. MSHA believes that
the implementation of the separate silica standard will ensure that
operators are correctly evaluating and implementing controls to protect
miners from respirable crystalline silica. Further, MSHA will continue
its sampling. Under the final rule, MSHA is removing these sections in
their entirety since they are no longer needed. See Section VIII.C.
Conforming Amendments for additional details.
c. Full Shift, 8-Hour TWA
Under the final rule, the PEL and the action level apply to a
miner's full-shift exposure, calculated as an 8-hour TWA. This limit
means that over the course of any work shift, exposures can fluctuate
but the average exposure to respirable crystalline silica cannot exceed
50 [mu]g/m\3\ for the PEL and 25 [mu]g/m\3\ for the action level. Under
this final rule, a miner's work shift exposure is calculated as
follows:
[GRAPHIC] [TIFF OMITTED] TR18AP24.083
Regardless of a miner's actual working hours (full shift), 480
minutes is used in the denominator. This means that the respirable
crystalline silica collected over an extended period (e.g., a 12-hour
shift) is calculated (or normalized) as if it were collected over 8
hours (480 minutes). For example, if a miner was sampled for 12 hours
and 55 [mu]g of respirable crystalline silica was collected in the
sample over that 12-hour period, the miner's respirable crystalline
silica 8-hour TWA exposure would be 67 [mu]g/m\3\, calculated as
follows:
[GRAPHIC] [TIFF OMITTED] TR18AP24.084
This calculation method (i.e., full shift, 8-hour TWA) is the one
that MSHA uses to calculate exposures of MNM miners to respirable
crystalline silica and other airborne contaminants under the existing
standards (30 CFR 56.5001, 57.5001); it differs from the existing
method of calculating a coal miner's exposure to respirable coal mine
dust (30 CFR 70.101, 71.101, and 90.101). For coal miners, the existing
calculation method uses the entire duration of a miner's work shift in
both the numerator and denominator, resulting in the total mass of
respirable coal mine dust collected over an entire work shift scaled by
the sample's air volume over the same period. This is referred to as
``full shift TWA'' hereafter.
MSHA received comments both in agreement with the proposed
calculation method and against it. Some commenters, including the AFL-
CIO and USW, stated that they support the proposed calculation method
of full-shift monitoring and calculating exposures over an 8-hour
period (i.e., using 480 minutes in the denominator) to actively capture
the total cumulative exposure to silica dust (Document ID 1449; 1447).
The American Thoracic Society et al. stated that working longer shifts
means miners have longer exposure periods, which increases the
cumulative burden of exposure and reduces the rest time miners have for
recuperating and clearing their lungs (Document ID 1421). In contrast,
other commenters, including other mine industry organizations, mining
trade associations, state mining associations, and MNM operators
preferred the use of the full shift time period in the calculation
method denominator (i.e., using the entire duration of the miner's
extended work shift in the denominator), stating that normalizing the
extended shift sampling result to an 8-hour period (i.e., using 480
minutes in the denominator) inaccurately skews the results (Document ID
1378; 1424; 1428; 1441; 1443; 1432). These commenters stated that the
proposed method improperly inflates the sampling results and actually
makes the standard more stringent by effectively lowering the PEL for
longer shifts. Some of these commenters, including MSHA Safety Services
Inc. and NVMA, further stated that MSHA's statement in the proposal
that the Agency uses NIOSH's recommendation is misleading because the
NIOSH recommendation is,
[[Page 28316]]
according to the commenters, for a 10-hour workday during a 40-hour
workweek (Document ID 1392; 1441).
Under the final rule, the PEL and action level applies to a miner's
full-shift exposure, calculated as an 8-hour TWA. MSHA agrees with
commenters who stated that the full shift, 8-hour TWA captures
cumulative exposure to silica dust accurately. The goal of the
respirable crystalline silica final rule is to prevent miners at all
times from suffering a body burden high enough to cause adverse health
effects.
``Body burden'' refers to the total amount of a substance that has
accumulated in the body at any given time (ATSDR, 2009). This reflects
the interplay between cumulative exposure, pulmonary deposition, and
lung clearance, in the case of respirable crystalline
silica.68 69 As discussed in the standalone FRA document,
cumulative exposure to respirable crystalline silica is well
established as an important risk factor in the development of silica-
related disease.
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\68\ The pulmonary uptake and clearance of airborne mine dust
are dependent upon many factors, including a miner's breathing
patterns, exposure duration, concentration (dose), particle size,
and durability or bio-persistence of the particle. These factors
also affect the time it takes to clear particles, even after
exposure ceases.
\69\ Respirable crystalline silica is cleared slowly from the
body and remains in the lungs longer than most other, more soluble
minerals and organic particulates in mine air. Pairon et al. (1994)
counted respirable crystalline silica particles in the
bronchoalveolar fluid of individuals occupationally exposed to
silica-bearing respirable dust and confirmed that respirable
crystalline silica was one of the most persistent (i.e., most slowly
eliminated) mineral particles in the lung. The slow clearance of
silica particles explains the accumulation (build-up) of particles
in the human lung that can occur with repeated exposures to airborne
silica as well as its detection in lung tissue years after exposure
stops (Dobreva et al., 1975; Case et al., 1995; Loosereewanich et
al., 1995; Dufresne et al., 1998; Borm and Tran, 2002).
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MSHA has determined that it is important to specify that exposures
be normalized to 8-hour TWAs.\70\ This is because working longer hours
can lead to the inhalation of more respirable crystalline silica into
the lungs, and the PEL and action level must take this into account.
For example, working 12 hours leads to 50% more silica entering the
lung compared with working 8 hours, assuming other factors are equal
(e.g., concentration of respirable crystalline silica and breathing
parameters). By normalizing daily exposures to 8-hour workdays, the
final rule provides miners working longer shifts a level of protection
against cumulative inhaled doses that is reasonably equivalent to the
protection provided to miners working shorter shifts. This is a
relevant issue because MSHA has observed that miners commonly work
extended shifts, with many working 10-hour or longer
shifts.71 72 MSHA's calculation method (like the existing
MNM calculation method) normalizes to an 8-hour TWA. If a miner works
an extended shift of 12 hours and a sample of 55 [mu]g of respirable
crystalline silica is collected, the full shift 8-hour TWA calculation
for that sample is 67 [mu]g/m\3\. This result treats the full
cumulative exposure occurring over the entire shift in the same way as
if it occurred over 8 hours. The full shift TWA (the existing
calculation method for coal miners) would yield a calculated exposure
of 45 [mu]g/m\3\, based on the entire duration of the miner's work
shift. The full shift 8-hour TWA calculation provides more protection
for miners than the full shift TWA calculation that makes no adjustment
for extended shifts.
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\70\ The ACGIH (2022) acknowledges the issue of extended work
shifts for airborne contaminants, including respirable crystalline
silica, stating, ``numerous mathematical models to adjust for
unusual work schedules have been described. In terms of toxicologic
principles, their general objective is to identify a dose that
ensures that the daily peak body burden or weekly peak body burden
does not exceed that which occurs during a normal 8-hour/day, 5-day/
week shift.'' There are associated concerns with the body burden
from an ``unusual work schedule'' such as a 10- or a 12- hour shift.
As Elias and Reineke (2013) stated, ``if the length of the workday
is increased, there is more time for the chemical to accumulate, and
less time for it to be eliminated. It is assumed that the time away
from work will be contamination free. The aim is to keep the
chemical concentrations in the target organs from exceeding the
levels determined by the TLVs[supreg] (8-hour day, 5-day week)
regardless of the shift length. Ideally, the concentration of
material remaining in the body should be zero at the start of the
next day's work.''
\71\ Sampling hours of coal mine dust samples approximate the
working hours of coal miners who were sampled. According to the coal
mine dust samples for a 5-year period (August 2016-July 2021), 90
percent of the samples by MSHA inspectors were from miners working 8
hours or longer and about 43 percent of the samples from miners
working 10 hours or longer. The dust samples by coal mine operators
show that over 98 percent of them were from miners working 8 hours
or longer and over 26 percent from the miners working 10 hours or
longer. Of the MNM dust samples by MSHA inspectors for a 15-year
period (January 2005-December 2019), approximately 78 percent were
from miners working longer than 8 hours. These dust samples are
available at Mine Data Retrieval System [bond] Mine Safety and
Health Administration (MSHA), https://www.msha.gov/data-and-reports/mine-data-retrieval-system (last accessed Jan. 10, 2024).
\72\ Unlike workers in many other sectors, miners not only work
longer shifts but also typically work much longer than 40 hours per
week. According to BLS data, between 2017 and 2022, the average
number of weekly working hours for all miners ranged from 45.1 to
46.7. (Bureau of Labor Statistics, Average weekly hours of
production and nonsupervisory employees, mining (except oil and
gas), not seasonally adjusted, Series ID CEU1021200007, data for
2017-2022, retrieved March 9, 2024.) From a body burden standpoint,
this means that longer working shifts for miners are likely also
associated with a greater number of cumulative hours of exposure.
That suggests that it is not the case that miners are working four
10-hour shifts instead of five 8-hour shifts, giving them shorter
recovery time between some shifts but then a longer recovery time
(e.g., 3 days off continuously). Instead, many miners are likely
working more long shifts--e.g., five 10-hour shifts in a week, given
the average of more than 45 hours for all miners--leaving their
lungs very little recovery time after silica exposure.
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Because the full shift, 8-hour TWA calculation takes this
additional factor into account, sampling using this calculation method
likely results in more sampling results that show overexposures, which
leads to exposure monitoring, corrective actions, and/or respiratory
protection for miners that may not have otherwise been provided using
the full shift TWA calculation. The concept of adjusting occupational
exposure limits for ``extended shifts'' has been addressed by
researchers (Brief and Scala, 1986; Elias and Reineke, 2013). Their
research is based on the industrial hygiene concept that longer
workdays lead to more time for the workplace chemical to accumulate in
the body and less time for it to be eliminated. To account for this,
the research establishes models that adjust (i.e., lower) the exposure
limits using formulas that factor in the longer workdays and the
corresponding shorter recovery periods.
This final rule establishes a lower PEL and applies it to all
miners using a consistent method for calculating exposures. These
changes improve the health and safety of miners while making compliance
more straightforward and transparent. NIOSH has also supported the use
of the TWA and has discussed this term since the publication of the
NIOSH Pocket Guide to Chemical Hazards (First Edition, 1978) (the
``White Book'').
MSHA's PEL for a miner's full-shift exposure calculated as an 8-
hour TWA differs from OSHA standards for extended work shifts. In the
OSHA standards, sampling for extended work shifts is conducted using
the worst (i.e., highest-exposure) 8 hours of a shift or collecting
multiple samples over the entire work shift and using the highest
samples to calculate an 8-hour TWA. 81 FR 16286, 16765. This differs
from MSHA's calculation method because, under MSHA's standards, miners
are sampled for the duration of their work shift and the total
respirable crystalline silica collected over the entire duration of
that extended work shift, not the worst 8 hours only, is used in the
calculation.
The NMA and AEMA disagreed with how MSHA calculates the full shift
8-hour TWA and stated that if MSHA does not use the entire duration
worked, the Agency should instead use OSHA's method of sampling for the
worst 8-hour
[[Page 28317]]
time period for extended work shifts (Document ID 1428; 1424).
MSHA has not included the commenter's suggestion in the final rule.
MSHA's requirement in the final rule to sample miners for the entire
duration of their work shift will provide an accurate representation of
their exposures. Calculating the full shift 8-hour TWA will better
protect the health of miners who work extended shifts because it
considers the heightened risks posed by increased cumulative exposure
and shorter recovery time. The final rule full shift 8-hour TWA
calculation is consistent with MSHA's longstanding MNM calculation
method, which is based on the guidance provided by the ACGIH in 1973
(TLVs[supreg] Threshold Limit Values for Chemical Substances in
Workroom Air Adopted by ACGIH for 1973). This calculation method is
supported by NIOSH and continues to be supported in the current
guidance provided by the ACGIH.
d. Error Factor
Some commenters, including NSSGA and SSC, expressed concerns about
whether silica can be accurately and consistently measured at the
action level and PEL (Document ID 1448; 1432). The AIHA suggested that
statistics of sampling and sample analysis should be considered to
identify upper and lower confidence limits (Document ID 1351). Several
commenters, including NMA and West Virginia Coal Association (WVCA),
recommended that the PEL and action level should have a margin of
error, or error factor, to account for sampling and analysis errors
(Document ID 1428; 1443). WVCA recommended that, as in the 2014 RCMD
Standard, MSHA should apply an error factor to the PEL to normalize
results to account for errors in sampling and weighing that cause
deviations in individual concentration measurements (Document ID1443).
The NMA cited sources to assist with determining the error factor
(Document ID 1428).
In Section VII.A. Technological Feasibility, MSHA determined that
current methods to sample respirable dust and analyze samples for
respirable crystalline silica by XRD and IR methods are capable of
reliably measuring silica concentrations in the range of the final
rule's PEL and action level. This finding is based on the following
considerations: (1) there are many sampling devices available that
conform to the ISO specification for particle-size selective samplers
with an acceptable level of measurement bias, and (2) both the XRD and
IR methods can measure respirable crystalline silica with acceptable
precision at amounts that would be collected by samplers when airborne
concentrations are at or around the PEL and action level. Thus, MSHA
finds that the sampling and analysis requirements under the final rule
are technologically feasible.
MSHA is confident that current sampling and analytical methods for
respirable crystalline silica provide accurate estimates of measured
exposures. Because there are multiple sampling methods that comply with
the ISO 7708:1995 standard and variations in laboratory analysis
methods, this final rule does not include a specific error factor. Mine
operators can rely on sampling results from ISO-accredited laboratories
to meet the sampling requirements of Sec. 60.12(f) to determine their
compliance with the PEL and action level under the final rule. Miners
should be confident that those exposure results provide them with
reasonable estimates of their exposures to respirable crystalline
silica.
4. Section 60.11--Methods of Compliance
The final rule identifies the methods for compliance in Sec.
60.11. Section 60.11 paragraph (a), unchanged from the proposal,
requires mine operators to install, use, and maintain feasible
engineering controls, supplemented by administrative controls when
necessary, to keep each miner's exposure to respirable crystalline
silica at or below the PEL. Paragraph (b), unchanged from the proposal,
states that rotation of miners shall not be considered an acceptable
administrative control used for compliance with the PEL. Below is a
detailed discussion of the comments received on this section and
modifications made in response to the comments.
a. 60.11(a)--Engineering and Administrative Controls
Paragraph (a) requires mine operators to use feasible engineering
controls as the primary means of controlling respirable crystalline
silica; administrative controls can be used, when necessary, as
supplementary controls.
Examples of engineering controls include, but are not limited to,
ventilation systems, dust suppression devices, enclosed cabs or control
booths with filtered breathing air, and changes in materials handling
or equipment used. Engineering controls generally suppress (e.g., using
water sprays, wetting agents, foams, water infusion), dilute (e.g.,
ventilation), divert (e.g., water sprays, passive barriers,
ventilation), or capture dust (e.g., dust collectors) to minimize the
exposure of miners working in the surrounding areas. The use of
automated ore-processing equipment and remote monitoring can also help
to reduce or eliminate miners' exposures to respirable crystalline
silica.
Examples of administrative controls include, but are not limited
to, work practices that change the way tasks are performed to reduce a
miner's exposure. These practices could include work process training;
housekeeping procedures; proper work positions of miners; cleaning of
spills; and measures to prevent or minimize contamination of clothing
to help decrease miners' exposure to respirable crystalline silica.
MSHA requested comments on the proposed requirement that mine
operators install, use, and maintain feasible engineering and
administrative controls to keep miners' exposures to respirable
crystalline silica at or below the proposed PEL. The Agency received
comments both supporting and opposing the proposal.
Several commenters, including an industrial hygiene professional
association, a labor union, and black lung clinics, expressed support
for the use of feasible engineering controls and administrative
controls to keep miners' exposures to respirable crystalline silica
below the proposed PEL (Document ID 1351; 1398; 1410; 1353). AFL-CIO,
UMWA, and NMA stated that mine operators should already be utilizing
feasible engineering and administrative controls to comply with law and
with their existing ventilation plans (Document ID 1449; 1398; 1428).
Black Lung Clinics urged MSHA to require that mine operators rely
primarily on engineering controls to limit dust exposure, with
administrative controls serving as supplemental measures (Document ID
1410).
Other commenters identified limitations with engineering controls.
NSSGA, US Silica, and a presenter at one of the hearings provided the
following examples where engineering controls will not suffice due to
the nature of the work: non-routine maintenance tasks; periodic
maintenance tasks; tasks of limited duration; and seasonal tasks
(Document ID 1448; 1455; 1353). US Silica also stated that MSHA must
offer more flexible options for control methods and give more
consideration to the challenges of implementing certain controls at
certain mines (Document ID 1455).
After carefully considering the comments, MSHA has concluded that
the requirement for installation, use, and maintenance of feasible
engineering
[[Page 28318]]
controls, supplemented by administrative controls, when necessary, will
remain unchanged from the proposal. In MSHA's experience, engineering
controls are the most effective method of compliance and the most
protective means of controlling dust generation at the source.
Engineering controls, which address the generation of dust at its
source, minimize respirable crystalline silica exposures of all miners,
including those in surrounding work areas, who may not be working at
the dust generating source. In contrast to other controls and other
interventions, engineering controls can be regularly evaluated and
monitored, which increase their effectiveness.
NIOSH has long promoted the use of engineering controls to control
miners' exposures to respirable crystalline silica. This final rule
aligns with the 1995 NIOSH recommendation that ``the mine operator
shall use engineering controls and work practices [administrative
controls] to keep worker exposures at or below the REL [recommended
exposure limit]'' (NIOSH, 1995, page 5). Specifically, NIOSH recommends
the use of engineering controls to keep free silica dust exposures
below the REL of 50 [mu]g/m\3\ (NIOSH, 1974). NIOSH also supported the
use of engineering controls as the primary means of protecting miners
from exposure to respirable crystalline silica in its public response
to MSHA's 2019 RFI (AB36-COMM-36). NIOSH stated that ``[r]espirators
should only be used when engineering control systems are not feasible.
Engineering control systems, such as adequate ventilation or scrubbing
of contaminants, are the preferred control methods for reducing worker
exposures.''
Requiring engineering controls as the primary method of compliance
is consistent with generally accepted industrial hygiene principles,
existing Agency standards, and the Mine Act. See 30 U.S.C. 801(e)
(explaining that operators have the ``primary responsibility to prevent
the existence of [unhealthy] conditions'' in mines); 30 U.S.C. 841(b)
(requiring underground coal mine operators to keep work environments
sufficiently free from respirable dust); 30 U.S.C. 842(h) (stating
primacy of engineering controls for underground coal mines). MSHA's
existing MNM standards for airborne contaminants require that mine
operators control miners' exposure to airborne contaminants, where
feasible, through preventing contamination, using exhaust ventilation
to remove contaminants, or diluting with uncontaminated air (30 CFR
56.5005 and 57.5005). The existing MSHA standards for respirable coal
mine dust (RCMD) require mine operators to implement engineering
controls to maintain compliance. In MSHA's 2014 RCMD Standard, the
Agency required operators to use engineering and administrative
controls and did not permit the use of respirators, including powered
air-purifying respirators (PAPRs), as a method to achieve compliance.
Additionally, numerous commenters representing industry, labor, and
public health supported the proposal's priority of engineering controls
as the primary means of reducing exposure to respirable crystalline
silica.
Some commenters provided specific examples when discussing
engineering control limitations. The IME stated that MSHA should allow
the use of equivalent dust suppression methods, where an alternative
exists, and its effectiveness can be demonstrated (Document ID 1404).
USW explained that engineering controls must be capable of dealing with
all belt speeds for collection and suppression and be protected from
freezing in cold weather which can increase their exposure (Document ID
1447). Conspec Controls questioned whether MSHA will explain how to
reduce dust particulate during operations and how different systems
will be prioritized in instances where an action improves the dust
conditions but exacerbates gas readings (Document ID 1324).
After reviewing these comments, the Agency agrees that differences
in mine size, job duties, commodity mined, equipment, and environmental
conditions across the mining industry necessitate different types of
engineering controls. However, in MSHA's experience, the mine operator
has the information and experience at their mine to determine which
engineering controls are feasible and effective at reducing respirable
crystalline silica exposures for their mining conditions. For example,
MSHA agrees with commenters that exposed water sprays are not effective
in freezing weather; however, the Agency has found that at least one,
or more, option is available for every circumstance. For example,
enclosing the process equipment or using water sprays are two options
for controlling dust. Water sprays suppress dust, and enclosures limit
the amount of dust in the equipment operator's breathing zone.
Equipment enclosures can be constructed with baffles to slow the
airflow inside the enclosure, so dust settles more quickly inside the
enclosure. As another option, a ventilation dust collection system can
be paired with an equipment enclosure to make both more effective for
controlling dust. MSHA intends to work with stakeholders, mine
operators, and the mining community to develop compliance assistance
materials and share best practices on engineering controls during and
after the implementation of the final rule.
MSHA received several comments on the use of administrative
controls. AIHA emphasized that administrative controls, when used to
supplement engineering controls, can further reduce exposures, and
maintain them at or below the PEL (Document ID 1351). Several
commenters, including mining trade associations, state mining
associations, and MNM operators, stated that OSHA's 2016 silica rule
treats engineering and administrative controls as equally effective in
reducing silica dust exposures and urged MSHA to consider broader use
of administrative controls and personal protective equipment to achieve
compliance (Document ID 1428; 1424; 1432; 1455; 1441; 1443).
MSHA has reviewed the comments and concludes that administrative
controls are effective in protecting miners from respirable crystalline
silica exposures when they are used as a supplement to engineering
controls. For example, NIOSH has co-developed a clothes cleaning system
that can clean dusty work clothes throughout the workday. This is an
example of an administrative control that is a safe and effective
method to remove silica dust from a miner's clothing, reducing
exposures to respirable crystalline silica. In the final rule,
administrative controls are secondary to engineering controls because
administrative controls require significant oversight by mine operators
to ensure miners understand and follow the prescribed work processes.
If not properly implemented, understood, or followed, administrative
controls may not be effective in preventing miners' overexposure to
respirable crystalline silica.
MSHA clarifies that administrative controls, except for rotation of
miners, can be used as a method of compliance if engineering controls
are not feasible. However, as MSHA discussed in the RFI and in its
previous 2014 RCMD Standard, engineering controls remain the primary
means to control all forms of respirable dust, including respirable
crystalline silica, in the mine atmosphere (84 FR 45454; 65 FR 4214; 68
FR 10798-10799, 10818).
For these reasons, final paragraph Sec. 60.11(a) is the same as
the proposal.
[[Page 28319]]
b. 60.11(b)--Rotation of Miners
Paragraph (b) prohibits mine operators from using miner rotation as
an administrative control.
As noted above, prioritizing engineering controls is consistent
with accepted industrial hygiene principles, MSHA's existing standards,
and the Mine Act. In particular, the prohibition against rotation of
miners to achieve compliance with the PEL is consistent with MSHA's
June 6, 2005, diesel particulate matter (DPM) final rule (70 FR 32867)
and its 2014 Coal Dust Rule (79 FR 24813). Under the existing standards
in the 2014 Coal Dust Rule, MSHA does not permit rotation of miners to
reduce exposures to coal mine dust if feasible engineering controls are
in use (79 FR 24909). In the DPM final rule, MSHA prohibited rotation
of miners to reduce miners' exposure to diesel particulate matter, an
airborne contaminant that is also a carcinogen. 71 FR 28926; 30 CFR
57.5060(e).
MSHA received several comments on the feasibility of prohibiting
miner rotation. AISI and SSC requested that MSHA permit the use of
rotation of miners when engineering controls are not feasible (Document
ID 1426; 1432). Some commenters, including Portland Cement Association,
NSSGA, Pennsylvania Coal Alliance, Pennsylvania Aggregates & Concrete
(PACA), BMC, CISC, and Tata Chemicals Soda Ash Partners, LLC, added
that, because miner rotation historically has been used to lower
miners' exposures, it should continue to be a part of the hierarchy of
controls (Document ID 1407; 1448; 1378; 1413; 1417; 1430; 1452; 1364).
BIA stated that, in their operations, which are already understaffed,
worker rotation is necessary to ensure miners are not exposed to levels
above the PEL, particularly if MSHA also discontinues the use of
respirators as a method of control (Document ID 1422). Other
commenters, including MSHA Safety Services, Inc., and BIA, stated that
some mine operators will be substantially impacted by prohibiting miner
rotation (Document ID 1392; 1422), while a few commenters, including
NSSGA and IAAP stated that worker rotation is sometimes the only
feasible control to limit overexposure, such as when miners perform
periodic or non-routine tasks that do not allow for engineering
controls (Document ID 1448; 1456).
UMWA, AFL-CIO, and Black Lung Clinics stated that worker rotation
could be acceptable to minimize musculoskeletal stress, but not for
work involving respirable dust or carcinogens, since the practice would
expose more miners to the hazards (Document ID 1398; 1449; 1410). Black
Lung Clinics further stated that, because the risk of silica-related
disease appears to be continuous, rather than associated with a
threshold exposure, worker rotation does not reduce the risk of disease
(Document ID 1410).
However, some commenters disagreed. NVMA stated that miner rotation
is standard practice when dealing with non-carcinogens and since there
is not enough data on whether silica exposure alone, as opposed to in
combination with tobacco use, is the carcinogen causing respiratory
issues, worker rotation should not be prohibited (Document ID 1441).
NSSGA provided literature expressing a well-established threshold for
silicosis and lung cancer and stated that the use of miner rotation to
reach that limit of exposure should be allowed (Document ID 1448).
After considering the comments, the final rule prohibits rotation
of miners. MSHA does not consider it to be an effective control because
it does not address the root cause of the hazard, requires continuous
attention and actions on the part of miners and management, and
increases risks to additional miners. MSHA considers that worker
rotation, which may be an appropriate control to minimize
musculoskeletal stress or heat stress, is not an acceptable control for
silica, which is classified as a Group 1 human carcinogen (IARC, 1997).
For example, MSHA's existing standards for diesel particulate matter
prohibit rotation of miners as an acceptable administrative control
because diesel particulate matter is a probable human carcinogen. 30
CFR 57.5060. MSHA's risk assessment for the diesel particulate matter
rule noted the majority of scientific data for regulating exposures to
carcinogens supports that job rotation is an unacceptable method for
controlling exposure to both known and probable human carcinogens
because it increases the number of persons exposed. The Agency
concludes that the rotation of miners would increase the number of
miners exposed to the hazard of respirable crystalline silica.
MSHA considered these comments in light of the Agency's
longstanding prohibition against rotation of miners as a means of
compliance for exposures to carcinogens. Commenters did not provide
specific data in support of their position that mine operators will be
substantially impacted by the prohibition of miner rotation for
reducing silica exposure. The intent of this final rule is to provide
health protection to as many miners as possible from the adverse health
effects of respirable crystalline silica exposure. The Agency has found
that a combination of engineering and administrative controls can
reduce miner exposures to levels at or below the PEL and is feasible
for mine operators.
MSHA also received comments requesting clarification on the
implementation of the prohibition of rotation of miners under the final
rule. NLA and NSSGA stated that MSHA has not adequately explained the
proposed prohibition of miner rotation, which creates confusion as to
whether worker rotation can be used for other purposes and how the
provision will be enforced (Document ID 1408; 1448). NSSGA further
stated that, if MSHA does not remove the prohibition in the final rule,
it should at a minimum, confirm that it will not prohibit miner
rotation for purposes other than compliance with the PEL, or rotating
employees to maintain exposure below the action level (Document ID
1448). Similarly, some commenters, including NLA, AEMA, NMA, and NSSGA
suggested that MSHA should clarify that miner rotation can still occur
for legitimate reasons, including avoidance of heat stress or
musculoskeletal stress (Document ID 1408; 1424; 1428; 1448). SSC asked
MSHA to explain whether an operator who rotates workers to comply with
part 62 will be cited if part 60 prohibits the rotation of that miner
(Document ID 1432).
MSHA clarifies that this provision is not a general prohibition of
worker rotation wherever workers are exposed to respirable crystalline
silica and is intended only to prohibit its use as a compliance method
for the PEL. It is not intended to bar the use of miner rotation as
deemed appropriate by the mine operator in activities such as cross-
training or to allow workers to alternate physically demanding tasks
with less strenuous activities.
MSHA received comments on the proposed rule's alignment with
industry standards. MSHA Safety Services, Inc. stated that the rotation
of miners is accepted by everyone except MSHA (Document ID 1392).
California Construction and Industrial Materials Association (CalCIMA)
stated that miner rotation is recommended by NIOSH, and under the OSHA
respirable crystalline standard, the rotation of employees as an
administrative control is not prohibited (Document ID 1433). A couple
commenters, including NSSGA, an individual, and Vanderbilt Minerals,
LLC, stated that MSHA had mischaracterized the NIOSH recommendations on
worker rotation
[[Page 28320]]
since, according to the commenters, it selectively used only parts of
the language in the NIOSH Chemical Carcinogen Policy document to
justify its position on worker rotation (Document ID 1448; 1367; 1419).
Because of this alleged mischaracterization, an individual warned that
MSHA's prohibition against miner rotation is ripe for litigation, not
because MSHA chose to ban the practice, but because MSHA has not
sufficiently explained their basis for doing so (Document ID 1367).
MSHA acknowledges that the Agency may have mischaracterized NIOSH's
position on worker rotation since its Chemical Carcinogen Policy is
silent on the issue of worker rotation. In this final rule, MSHA
clarifies its reference to the NIOSH policy.
Respirable crystalline silica has long been recognized as a
carcinogen (IARC, 1997). The Agency considers it more protective of
miner safety and health to limit the number of miners exposed to
respirable crystalline silica. MSHA does not consider rotation of
miners to be an effective control because it does not address the
source of the hazard. NIOSH's publication entitled ``Current
Intelligence Bulletin 68: NIOSH Chemical Carcinogen Policy,''
recommends that occupational exposures to carcinogens should be reduced
as much as possible through the hierarchy of controls, most
importantly, the elimination or substitution of other chemicals that
are known to be less hazardous and engineering controls (NIOSH, 2017b).
According to Stewart (2011), ``rotation of workers may reduce overall
average exposure for the workday but it provides periods of high short-
term exposure for a larger number of workers. As more becomes known
about toxicants and their modes of action, short-term peak exposures
may represent a greater risk than would be calculated based on their
contribution to average exposure.'' Miner rotation is not allowed in
assessing coal miners' exposure to respirable coal mine dust; coal
operators must sample occupations or areas, not individual miners, to
ensure that the environment is controlled. The Agency has determined it
more protective of miner safety and health to limit the number of
miners exposed to respirable crystalline silica and require engineering
controls, supplemented by administrative controls, excluding rotation
of miners.
For these reasons, final paragraph Sec. 60.11(b) is the same as
the proposal.
c. Feasible Engineering Controls
MSHA received comments regarding the definition of the term
``feasible'' and the use of feasible engineering controls. NVMA
requested that MSHA supply a definition for what is ``feasible''
(Document ID 1441). Arizona Mining Association stated that the cost-
benefit analysis of the proposed standard is flawed and that many mines
will face more financial hardship and require far longer implementation
times than MSHA has anticipated (Document ID 1368). NMA stated that
engineering controls are not always economically feasible, particularly
for small businesses (Document ID 1428).
MSHA clarifies that the courts have interpreted the term
``feasible'' as meaning `` `capable of being done, executed, or
effected,' both technologically and economically.'' See Kennecott
Greens Creek Min. Co. v. Mine Safety & Health Admin, 476 F.3d 946, 957
(D.C. Cir. 2007) (quoting Am. Textile Mfrs. Inst. v. Donovan, 452 U.S.
490, 508-09 (1981)). Further, ``MSHA does not need to show that every
technology can be used in every mine. The agency must only demonstrate
a `reasonable possibility' that a `typical firm' can meet the
permissible exposure limits in `most of its operations.' '' Id. at 958
(quoting Am. Iron & Steel Inst. v. Occupational Safety & Health Admin.,
939 F.2d 975, 980 (D.C. Cir. 1991)).
Based on MSHA's experience and enforcement and sampling data,
consideration of the OSHA silica rule, and documentation from NIOSH as
discussed in Section VII.A. Technological Feasibility, MSHA has
determined that feasible engineering controls exist for mining
operations to reduce miners' exposures so that they would not exceed
the PEL. The Agency has found that feasible engineering controls: (1)
control crystalline silica-containing dust particles at the source; (2)
provide reliable, predictable, and consistent protection to all miners
who would otherwise be exposed to dust from that source; and (3) can be
monitored. Additionally, MSHA believes this rule is feasible because a
review of the Agency's available silica sampling data showed that many
mines are already in compliance with the PEL in Sec. 60.10. Further
explanation and discussion of the economic feasibility can be found in
the standalone FRIA document and in the preamble in Section IX. Summary
of Final Regulatory Impact Analysis and Regulatory Alternatives.
d. Hierarchy of Controls and Respiratory Protection
MSHA received comments about how the proposed rule related to the
hierarchy of controls. Several commenters, including NMA, SSC, US
Silica, AEMA, WVCA, and American Road and Transportation Builders
Association, stated MSHA should allow mine operators to effectively
utilize the hierarchy of controls to comply with the proposed silica
standard (Document ID 1428; 1432; 1455; 1424; 1443; 1353). These
commenters defined the most effective controls according to the
hierarchy as: elimination, substitution, engineering, administrative,
and personal protective equipment (i.e., respirators). Arizona Mining
Association stated that the hierarchy of controls is recognized world-
wide, including by OSHA, and provides flexibility to allow mine
operators to make decisions for maintaining safe production (Document
ID 1368).
Other commenters stated that respirators should be permitted to be
used as a method of compliance. WVCA stated that the differences
between mining environments across the industry mean that while
engineering controls may be the most effective controls in some mines,
other controls, like respirators, might protect miners more effectively
in others (Document ID 1443). US Silica asked MSHA to treat respirators
as engineering controls (Document ID 1455). IME stated that although
engineering controls are preferred, it does not make sense to require
the use of engineering and work practice controls the operator believes
or knows would be inadequate to meet the PEL, knowing that respirators
may be more effective for a given task (Document ID 1404). Some
commenters, including the Arizona Mining Association, NVMA, and US
Silica, stated that the OSHA standard recognizes the priority of
engineering controls but allows respiratory protection programs as
substitutes when engineering controls are not feasible (Document ID
1368; 1441; 1455; 1353; 1424; 1428).
Some commenters provided specific situations or conditions in which
they believe respirators should be used as a method of compliance.
NSSGA suggested that to prevent mine operators from relying on
respirators for compliance, MSHA could require operators to outline
their process for determining when respirators will be used in their
respiratory protection plans (Document ID 1448). A few commenters,
including SSC, WVCA, Vanderbilt Minerals, LLC, and IME,
[[Page 28321]]
asked MSHA to allow for NIOSH-approved respirators as a recognized
control, and not just for instances of unexpected exposures where
respirator use may be temporary (Document ID 1432; 1443; 1419; 1404).
The AEMA and NMA suggested adding language as reflected in OSHA's lead
standard (Document ID 1424; 1428). US Silica stated that MSHA is
inconsistently recognizing when the use of personal protective
equipment for compliance purposes may occur since MSHA's occupational
noise exposure health standards in 30 CFR part 62 allow it, while the
proposed rule does not (Document ID 1455).
MSHA also received comments that supported this provision of the
proposed rule, stating that respirators are an ineffective method of
compliance. Black Lung Clinics discussed the limitations of
respirators, stating that facial hair can interfere with the use of
respirators, respirators do not provide real-time feedback on their
effectiveness, miners' communication abilities may be impeded, and
there is uncertainty about whether respirators are actually effective
in the working environment in coal mines (Document ID 1410). USW stated
that respiratory protection must never be defined as an engineering
control because its effectiveness depends on too many variables
(Document ID 1447). BlueGreen Alliance also supported the prohibition
on respirators as a method of compliance and suggested that MSHA should
strengthen the penalties for noncompliance (Document ID 1438).
MSHA understands that employers across many industries follow the
NIOSH Hierarchy of Controls in structuring and applying their
industrial hygiene programs and practices. This reflects a generally
accepted industrial hygiene principle that recommends the use of
engineering and administrative controls to implement effective control
solutions, in the following order (1) elimination; (2) engineering
controls; (3) administrative controls; and finally, (4) personal
protective equipment. MSHA recognizes that while elimination of all
respirable crystalline silica from a mine environment would be the most
effective means of risk reduction, it is generally not feasible. Under
the final rule, mine operators are required to use engineering or
environmental controls as the primary means of maintaining compliance.
MSHA acknowledges that administrative controls may be necessary to
further lower exposure levels and encourages mine operators to use such
controls (with the exclusion of miner rotation).
MSHA does not agree that respirators are an engineering control.
Engineering controls provide consistent and reliable protection to
miners; these controls work independently and verifiably. Engineering
controls do not depend on individual performance, supervision, or
intervention, to function as intended, and they can be continually
evaluated and monitored relatively easily. Unlike PAPRs or supplied-air
helmets, engineering controls operate at the hazard generation source,
providing protection against both primary (miners directly involved in
the task or immediate area) and secondary (miners not directly in the
task or working in surrounding areas) exposures to the hazard.
MSHA's enforcement and compliance assistance experience
substantiate that respirators are not as reliable as engineering
controls in reducing miners' exposure to toxic substances such as
respirable crystalline silica. Respirator effectiveness depends on a
number of factors, including a properly developed and fully implemented
respiratory protection program; individual performance in donning,
wearing, and doffing the respirator; and proper supervision to ensure
that the protection factor is fully achieved.
In response to comments regarding the use of respirators, MSHA
amended the final rule, paragraph 60.14(a), to require MNM operators to
provide respiratory protection for temporary use when miners' exposures
are above the PEL. For MNM operators, temporary use of respirators is
required while engineering control measures are being developed and
implemented, which includes taking corrective actions to ensure miner
exposures are at or below the PEL. Under the final rule, MNM mine
operators are also required to use respirators, on a temporary basis,
when exposures are above the PEL, and it is necessary by the nature of
work involved (for example, occasional entry into hazardous atmospheres
to perform maintenance or investigation). The Agency believes this will
provide MNM miners additional protection during these specific
circumstances. However, respiratory use under this provision does not
constitute compliance with the PEL; all exposures above the PEL violate
the standard. Further discussion on respiratory use in the final rule
is located in Section 60.14--Respiratory protection.
e. Consensus Standards and Other Guidance
MSHA received one comment from ISEEE suggesting that the Agency
incorporate by reference ISO 23875, Cab Air Quality Standard, to assist
mine operators with compliance for installing and using filtration
systems to maintain exposures at or below the PEL in operator cabs
(Document ID 1377). ISO 23875 is an international standard that unifies
the design, testing, operation, and maintenance of air quality control
systems for heavy machinery cabs and other operator enclosures. ISEEE
stated that the standard provides practical and cost-effective
requirements and testing methods for engineering controls that would
meet the proposed rule's requirements, given that the desired outcome
in all cabs that meet the standard's requirements is compliance with
air quality regulations at the 25 [mu]g/m\3\ level. The commenter added
that by implementing this consensus standard, it would lead to the
development of a standardized design that could be mass-produced and
therefore reduce costs.
MSHA has reviewed the comment and has determined that an evaluation
of the costs and benefits for economic and technological feasibility
would need to be conducted, along with an examination of the costs to
implement the standard for mine operators. Therefore, the Agency does
not include the requirements of ISO 23875 in this final rule; however,
the Agency will evaluate the standard and encourages the use of new
technologies and consensus standards to improve miner safety and
health.
APHA stated that guides prepared by NIOSH for MNM mines and coal
mines contain helpful illustrations of feasible engineering controls
that reduce exposure to respirable dust (Document ID 1416). MSHA
acknowledges that NIOSH and other organizations and agencies have
published information that may be helpful to mine operators. MSHA has
worked in partnership with NIOSH in developing this final rule and will
continue to do so and use information from NIOSH to facilitate
implementation of the final rule. The Agency encourages mine operators
to use NIOSH information to ensure that feasible and effective
engineering controls are installed, used, and maintained.
5. Section 60.12--Exposure Monitoring
The final rule establishes requirements for exposure monitoring in
Sec. 60.12. Section 60.12 paragraph (a) establishes the requirements
for sampling. Paragraph (a)(1) requires mine operators to commence
sampling by the compliance date to assess the full shift, 8-hour TWA
exposure of respirable crystalline silica for each miner who is or may
reasonably be expected to be exposed to respirable crystalline silica.
[[Page 28322]]
Paragraph (a)(2) is restructured from the proposal and states how the
mine operator shall proceed if the sampling under (a)(1) is: (i) below
the action level, (ii) at or above the action level, or (iii) above the
PEL. Paragraph (a)(3) mirrors language in the proposal indicating that
where the most recent sampling indicates that miner exposures are at or
above the action level but at or below the PEL, the mine operator shall
continue to sample within 3 months of the previous sampling. Paragraph
(a)(4) states that mine operators may discontinue sampling when two
consecutive samplings indicate that miner exposures are below the
action level. In a change from the proposal, paragraph (a)(4) also
specifies that the second sampling must be taken after the operator
receives the results of the prior sampling but no sooner than 7 days
after the prior sampling was conducted. Paragraph (b) states that where
the most recent sampling indicates that miner exposures are above the
PEL, the mine operator shall sample after corrective actions are taken
pursuant to Sec. 60.13 until the sampling indicates that miner
exposures are at or below the PEL. In a change from the proposal,
paragraph (b) also requires the mine operator to immediately report all
operator samples above the PEL to the MSHA District Manager or to any
other MSHA office designated by the District Manager. Paragraph (c)
requires mine operators to conduct periodic evaluations at least every
6 months to determine whether changes may reasonably be expected to
result in new or increased respirable crystalline silica exposures. In
a change from the proposal, paragraph (c) also requires mine operators
to conduct an evaluation whenever there is a change in production,
processes, installation and maintenance of engineering controls,
installation and maintenance of equipment, administrative controls, or
geological conditions. Paragraph (c)(1) requires mine operators to make
a record of the evaluation and the date of the evaluation. In a change
from the proposal, paragraph (c)(1) also requires the record of the
evaluation to include the evaluated change and the impact on respirable
crystalline silica exposure. Paragraph (c)(2) requires mine operators
to post the record on the mine bulletin board and, if applicable, by
electronic means, for the next 31 days. Paragraph (d) is unchanged from
the proposal and includes the requirements for post-evaluation
sampling. Paragraph (e) includes requirements for how mine operators
must take samples. Paragraph (e)(1) requires that sampling be performed
for the duration of a miner's regular full shift and during typical
mining activities. In a change from the proposal, paragraph (e)(1)
specifically includes shaft and slope sinking, construction, and
removal of overburden. Paragraph (e)(2) requires the full-shift, 8-hour
TWA exposure for miners to be measured based on: (i) personal
breathing-zone air samples for metal and nonmetal operations and (ii)
occupational environmental samples collected in accordance with Sec.
70.201(c), Sec. 71.201(b), or Sec. 90.201(b) of this chapter for coal
operations. Paragraph (e)(3) includes the requirement for sampling a
representative fraction of miners and is unchanged from the proposal.
Paragraph (e)(4), unchanged from the proposal, includes the requirement
for mine operators to use respirable-particle-size-selective samplers
that conform to ISO 7708:1995 to determine compliance with the PEL.
Paragraph (f) is unchanged from the proposal and includes the methods
of sample analysis. Paragraph (g) is unchanged from the proposal and
includes the requirements for sampling records.
The exposure monitoring requirements help facilitate operator
compliance with the PEL and harmonize MSHA's approach to monitoring and
evaluating respirable crystalline silica exposures to better protect
all miners' health. Below is a discussion of the comments received on
this section and modifications made in response to the comments.
a. Section 60.12(a)--Sampling
Under the final rule, mine operators are required to commence
sampling by the compliance date to assess miners' exposures to
respirable crystalline silica. Samples will be compared to the action
level and the PEL to determine the effectiveness of existing controls
and the need for additional controls.
Change in Terminology
Under the final rule, MSHA removes references to ``baseline
sampling'' and ``periodic sampling'' and only uses the term
``sampling''. MSHA also removes proposed Sec. 60.12(a)(2)(i), which
allowed mine operators to discontinue sampling based on objective data
or historical sample data, i.e., sampling conducted by the Secretary or
mine operator sampling conducted within the previous 12 months.
MSHA determined that the terms ``baseline sampling'' and ``periodic
sampling'' are no longer needed to describe the sampling requirements
under the final rule. With the removal of objective data and historical
sample data, under the final rule, discontinuing sampling is contingent
upon the results of two consecutive samplings indicating that miner
exposures are below the action level.
Removal of Objective Data
Under the final rule, MSHA removes the use of ``objective data'' as
a method of discontinuing sampling. Proposed paragraph (a)(2) allowed
operators to discontinue sampling when, among other things, objective
data indicated that miner exposures were below the action level. As
discussed earlier, in the proposal, MSHA defined objective data as
information such as air monitoring data from industry-wide surveys or
calculations based on the composition of a substance, demonstrating
miner exposure to respirable crystalline silica associated with a
particular product or material or a specific process, task, or
activity. The data must reflect mining conditions closely resembling or
with a higher exposure potential than the processes, types of material,
control methods, work practices, and environmental conditions in the
operator's current operations.
MSHA received several comments on its proposed use of objective
data as a means for operators to discontinue periodic sampling, with
some commenters in support of using objective data and some commenters
against it. Several commenters, including mining and industry trade
associations and a state mining association, expressed support for the
use of objective data, with some commenters noting that it would reduce
the sampling burden on mine operators (Document ID 1442; 1406; 1408;
1441; 1424; 1428). Some commenters, including the AEMA, NMA, and
Vanderbilt Minerals, LLC, stated that objective data more than 12
months old should be permitted because exposures may not change, or the
data may still be valid in certain circumstances (Document ID 1424;
1428; 1419). Several other commenters, including AIHA, UMWA, USW, and
Appalachian Voices, opposed the use of objective data, with most
arguing that sampling is more accurate than objective data and that
such data should not be used to exempt operators from sampling
(Document ID 1351; 1398; 1447; 1425; 1412). AFL-CIO, NVMA, and Rep.
Robert C. ``Bobby'' Scott, stated that the term ``objective data'' is
unclear, too subjective, and capable of being manipulated; that various
mining aspects could invalidate or skew objective data results; and
that the proposal's use of objective data is at odds with the Mine
Act's requirement that newly promulgated health and
[[Page 28323]]
safety standards do not reduce protection for miners (Document ID 1449;
1441; 1439).
While the Agency acknowledges that the use of objective data would
ease operators' sampling burden, MSHA has determined that objective
data cannot be used to discontinue sampling because it is not likely to
represent mining conditions closely resembling the processes, types of
material, control methods, work practices, and environmental conditions
in the mine operator's current operations. The Agency agrees with
commenters who stated that sampling is more accurate than using
objective data and that the use of objective data as a means for
operators to discontinue sampling, may be too subjective to confirm
that sample results are below the action level. Furthermore, objective
data, as defined in the proposal, utilized a historical approach, while
the collection of samples will more accurately reflect respirable
crystalline silica concentrations under current mining conditions.
Removal of Operator and Secretary Sampling From Preceding 12 Months
MSHA also removes the provisions in proposed paragraph (a)(2)
allowing operators to discontinue sampling when sampling conducted by
the Secretary or the mine operator within the preceding 12 months
confirmed that miner exposures were below the action level.
Some commenters, including SSC, NVMA, Vanderbilt Minerals, LLC, and
Portland Cement Association, supported the use of past sampling to
discontinue sampling, noting that many operators already use such data
to implement their current monitoring programs (Document ID 1432; 1441;
1419; 1407). However, the UMWA opposed allowing past sampling to be
used to discontinue sampling (Document ID 1398). The UMWA stated that
exempting mine operators from sampling based on past sampling fails to
protect miners from unhealthy levels of respirable crystalline silica
or ensure that operators are complying with the standard. The UMWA
recommended that MSHA, not mine operators, regularly sample all miners.
MSHA agrees that operators cannot rely on samples taken within the
preceding 12 months prior to the first sampling under the final rule to
discontinue sampling. This is because past samples may not accurately
represent miners' current exposures. However, operators still have
pathways to discontinue sampling; the final rule requires two
consecutive sample results below the action level that may come from
operator or MSHA sampling. MSHA will continue to perform its own dust
samplings as part of its regular health inspections and take necessary
enforcement actions.
Change in Sampling Compliance Date
In a change from the proposal, the final rule requires MNM mine
operators to comply with the requirements and commence sampling within
24 months of the publication date and requires coal mine operators to
comply with the requirements and commence sampling within 12 months
after the publication date.
Under the proposal, both MNM and coal mine operators would have
been required to perform the first sampling under this standard within
the first 180 days (6 months) after the effective date of the final
rule. MSHA received comments both for and against the proposed 180-day
compliance period, with many commenters from the MNM mining industry
stating that it was not enough time and recommending a longer period
ranging from 1 year to 3 years (Document ID 1408; 1432; 1433; 1417;
1392). Some commenters, including Portland Cement, SSC, CalCIMA, and
NLA, stated that providing only 180 days to commence sampling was not
sufficient because of the limitation of available resources for
conducting sampling (Document ID 1407; 1432; 1433; 1408). Portland
Cement, SSC, and AEMA stated that this requirement may not be feasible
for many operators because of competition for outsourced resources such
as rental equipment, media, professional services, and laboratory
sample analysis (Document ID 1407; 1432; 1424). Commenters expressed
concerns about performing other tasks within the proposed timeframe for
compliance, including establishing contracts with accredited
laboratories and other service providers necessary for sampling;
performing sampling for all miners who may reasonably be expected to be
exposed to respirable crystalline silica; and designing and
implementing new engineering controls. These commenters recommended a
phased timeline similar to OSHA's final requirement in its silica rule
(which gave employers one year before the commencement of most
requirements and two years before the commencement of sample analysis
methods) and MSHA's final requirement in its 2014 RCMD Standard (which
gave operators 18 months after the rule became effective). The NLA
stated that small mines are likely to have the greatest difficulty
competing for resources in a short period of time (Document ID 1408).
In contrast, some commenters, including AIHA and SKC Inc., stated
that technologically feasible air sampling and analysis exists to allow
mine operators to achieve compliance with the PEL using commercially
available samplers (Document ID 1351; 1366). These commenters stated
that technologically feasible samplers are widely available, and a
number of commercial laboratories provide the service of analyzing dust
containing respirable crystalline silica. Other commenters, including
AFL-CIO and UMWA, supported requiring first-time sampling within 180
days of the rule's effective date (Document ID 1449; 1398). Some
commenters, including Appalachian Voices, Rep. Robert C. ``Bobby''
Scott, and Robert Cohen, emphasized the need to implement the final
rule quickly to protect miners (Document ID 1425; 1439; 1372).
Appalachian Voices stated that the technologies and practices necessary
to reduce dust and silica exposure are well-known and that mine
operators have had ample warning that this rule was forthcoming
(Document ID 1425).
Under the proposal, MSHA examined the capacity of laboratories that
meet the ISO/IEC 17025 standard to conduct respirable crystalline
sample analyses. MSHA made the preliminary determination that there
would be sufficient processing capacity to meet the sampling analysis
schedule and that it would be technologically feasible for laboratories
to conduct the required sampling analyses (88 FR 44923). MSHA also
preliminarily determined that the availability of samplers needed to
conduct the required sampling is technologically feasible (88 FR
44921). This preliminary determination, however, only examined whether
sampler technology exists to conduct the respirable crystalline silica
sampling as required under the proposed rule, not the availability of
that technology to meet the demands that the final rule would impose.
MSHA agrees with commenters that the sampling requirements of the
final rule may create initial increased demand for sampling devices and
related equipment and services. MSHA understands that there are more
sampling devices (as well as related services and supplies) currently
available based on the increased demand resulting from the promulgation
of the OSHA silica rule in 2016, and MSHA expects that there may be
another increase in demand because of this final rule. MSHA expects
that the sampling device market will respond, as it did for OSHA, with
an increase in the supply of sampling devices to meet the
[[Page 28324]]
increased demand because of this final rule. However, AIHA stated that
they concur with MSHA that technologically feasible samplers are widely
available, and a number of commercial laboratories provide the service
of analyzing dust containing respirable crystalline silica. The AIHA is
the organization that is responsible for the AIHA-Laboratory
Accreditation Program (AIHA LAP) that accredits the majority of
laboratories analyzing industrial hygiene samples. MSHA has also
identified more AIHA laboratories with respirable crystalline silica
analysis in their scope of accreditation in 2023 compared to 2022,
indicating an increase in such capabilities.
MSHA carefully considered the above information about availability
of laboratory capacity and sampling devices, including the likely
increase in demand for such services and devices. MSHA acknowledges
commenters' concerns about the need for more time to conduct sampling
and implement necessary engineering controls. All mine operators
covered by the rule must initiate sampling by the compliance dates,
potentially creating a peak demand for sampling and analysis around
those dates. The extended compliance dates permit more time to
accommodate and prepare for any increase in demand. MSHA expects many
mine operators will avoid last-minute sampling and begin the sampling
process earlier than required; thus, the sampling and associated
analysis will be spread over many months, meaning that any eventual
peak period for laboratory analysis will be longer and less intense
(i.e., fewer analyses per month required) than it might be otherwise.
Additionally, MSHA expects that the extended lead time will be
sufficient for laboratories to increase their analytical capacity. More
discussion can be found in Section VII.A. Technological Feasibility.
Additional discussion of the compliance date requirements can be found
under Section 60.1--Scope; compliance dates.
Sampling Requirements for New Mines
A few commenters, including Petsonk PLLC and Appalachian Voices,
requested that MSHA clarify the sampling requirement for mines that
begin operations after the rule goes into effect (Document ID 1399;
1425). Petsonk PLLC suggested amending proposed Sec. 60.12(a)(1) to
require sampling within 180 days after the rule becomes effective or
180 days after the mine commences production, whichever occurs later.
MSHA disagrees with the commenters regarding the need to specify a
separate sampling schedule for new mines since mine operators would
have knowledge of the sampling requirements before commencing
operations. The Agency expects that new mines begin sampling
immediately upon commencing operations in accordance with the exposure
monitoring requirements in Sec. 60.12. Coal mine operators are
required to begin sampling within 12 months of the publication of the
final rule. Operators of new coal mines that begin operation after the
12 months must begin sampling upon commencing operations. MNM mine
operators are required to begin sampling within 24 months of the
publication date of the final rule. Operators of new MNM mines that
begin operation after the 24 months must begin sampling upon commencing
operations.
Reasonably Be Expected
Under the final rule, mine operators are required to assess the
exposure of each miner ``who is or may reasonably be expected to be
exposed to respirable crystalline silica.''
In the proposal, MSHA requested comments on the Agency's assumption
that most miners are exposed to at least some level of respirable
crystalline silica, and on the proposed requirement that these miners
should be subject to sampling. MSHA described its assumption that most
occupations related to extraction and processing would meet the
``reasonably be expected'' threshold for sampling. Further, MSHA
assumed that some miners may work in areas or perform tasks where
exposure is not reasonably expected, if at all.
MSHA received many comments from advocacy organizations, mining and
industry trade associations, MNM mine operators, labor organizations,
and a state mining association on the ``reasonably be expected'' basis
for sampling (Document ID 1398; 1407; 1417; 1419; 1424; 1425; 1428;
1441; 1445; 1448; 1449). Commenters were generally divided on whether
most miners are exposed to at least some level of respirable
crystalline silica. The UMWA agreed with MSHA's assumption and stated
that most mining occupations would reasonably be expected to be exposed
to silica and thus meet the threshold for sampling, while some miners
may not be reasonably expected to be exposed to silica, depending on
their occupation (Document ID 1398). In contrast, Vanderbilt Minerals,
LLC stated that it is not reasonable to assume that most miners are
exposed to at least some level of respirable crystalline silica
(Document ID 1419). This commenter cited MSHA's Mine Data Retrieval
System (MDRS) data that shows many mine locations do not have any
detectable exposure to respirable crystalline silica. Appalachian
Voices, questioning MSHA's assumption about occupations related to
extraction and processing meeting the ``reasonably be expected''
threshold for sampling, described testimony from several miners who
worked in non-production positions and were exposed to high levels of
silica dust (Document ID 1425). This commenter requested expansion of
the interpretation to include or consider non-production work above
ground because of the placement of engineering controls, such as return
air entries near mine offices. Further, other commenters, including
NSSGA and BMC, requested clarification on what the ``reasonably be
expected'' threshold means since it was not defined in the proposal
(Document ID 1448; 1417).
MSHA has considered these comments. Based on the Agency's
enforcement and compliance assistance experience and sampling data, the
final rule retains the language in the proposal. This data considers
MSHA and operator sampling experience, miners' job tasks and
occupations, and mining conditions when overexposures are identified
and need to be corrected. Operators already are expected to know
whether their miners are exposed or reasonably are expected to be
exposed to respirable crystalline silica, given coal operators'
existing sampling regimen (that includes regular sampling) and MNM's
requirements under Sec. Sec. 56.5002 and 57.5002 to conduct surveys
(sampling) ``as frequently as necessary to determine the adequacy of
control measures.'' MSHA believes that most occupations related to
extraction and processing which generate dust are likely to meet the
``reasonably be expected'' threshold. However, MSHA clarifies that
sampling should not be limited to extraction and processing
occupations; in every instance, the mine operator must determine
whether exposure to respirable crystalline silica is or may reasonably
be expected. In the example given by the commenter, miners performing
above-ground non-production work who were exposed to high levels of
silica dust would reasonably be expected to be exposed to respirable
crystalline silica and thus would be required to be sampled. On the
other hand, MSHA recognizes that some miners are not exposed to
respirable crystalline silica in day-to-day mining operations, may work
in areas or perform tasks where respirable crystalline silica exposures
are not
[[Page 28325]]
reasonably likely, or may work in silica-free environments. Based on
the Agency's experience, mine operators have familiarity with the
occupations, work areas, and work activities where respirable
crystalline silica exposures occur or are most likely to occur. Based
on this knowledge, MSHA expects that operators will be able to assess
the threshold conditions for sampling.
Many commenters stated that MSHA should require an exposure
``trigger'' level to be used as a basis for conducting sampling.
Several commenters, including NMA, BMC, NSSGA and AEMA, stated that the
``reasonably be expected'' threshold for sampling should be associated
with the action level of 25 [micro]g/m \3\, similar to the OSHA
standard (Document ID 1428; 1417; 1448; 1424). Some of these commenters
stated that without a trigger level, even the general public would meet
the criterion of ``reasonably expected to be exposed'' because the
proposed requirement is too broad and lacks any meaning in the context
of a standard.
Under the final rule, MSHA concludes that an action level trigger
for initial sampling is not appropriate for mining conditions. The
extraction and milling of minerals can reasonably be expected to expose
most miners to some level of respirable crystalline silica. In MSHA's
experience, dust generation is common in the mining process, and the
approach in the final rule ensures that mine operators have the
necessary data and information to understand which miners may be
exposed to respirable crystalline silica, can make determinations
regarding the adequacy of existing engineering and administrative
controls, and can make necessary changes to ensure miners are not
overexposed.
Sampling
In the final rule, MSHA requires mine operators to sample within 3
months of the previous sampling when the most recent sampling indicates
that miner exposures are at or above the action level but at or below
the PEL. The most recent sampling could be a first sample under the
standard, a corrective action sample, a post-evaluation sample, or a
sample taken by MSHA during its inspections. Sampling must continue
until two consecutive sample analyses show miners' exposures are below
the action level. Once this happens, mine operators may discontinue
sampling for miners whose exposures are represented by these samples,
until such time that a subsequent MSHA sampling or post-evaluation
sampling by the mine operator indicates that miners may be exposed at
or above the action level. MSHA clarifies that during the compliance
period, the two consecutive samplings needed to discontinue further
sampling may not begin with an MSHA sampling followed by an operator
sampling conducted within 3 months of that MSHA sampling; however, it
may begin with an operator sampling (e.g., the operator's first
sampling during the compliance period) followed by an MSHA sampling
conducted within 3 months of that operator sampling. This is because
the first sampling that operators must conduct during the compliance
period includes a larger group of miners (i.e., each miner who is or
may reasonably be expected to be exposed to respirable crystalline
silica) as compared to the targeted group of miners sampled by MSHA
during its inspections.
MSHA received many comments on the proposed frequency of sampling,
with some commenters stating that the 3-month sampling frequency is too
frequent and other commenters stating that the sampling is not frequent
enough. Some MNM mine operators, including SSC and NLA, stated that
mines with sampling results consistently above the action level but
below the PEL should not be required to sample every 3 months, and
instead the frequency should be annual (Document ID 1432; 1408). The
NVMA stated that the 3-month frequency should be associated with the
PEL rather than the action level (Document ID 1441). The AISI stated
that the frequency of sampling should be dictated by the history of
miner exposures, noting that some miners should not be sampled as
frequently as others and some miners should not be sampled at all
(Document ID 1426). Portland Cement Association, NSSGA, BMC, and
Vanderbilt Minerals, LLC, stated that MSHA should model its sampling
requirements after OSHA's silica rule, where repeat monitoring is
conducted within 6 months for exposures above the action level but
below the PEL and within 3 months for exposures above the PEL (Document
ID 1407; 1448; 1417; 1419). The AEMA and NMA, stated that follow-up
sampling should occur no more frequently than every 6 months, as
proposed in MSHA's Regulatory Alternative #1 (Document ID 1424; 1428).
The commenters stated that sampling each miner whose exposure is at or
above the action level but at or below the PEL every 3 months is
excessive and causes undue burden on mine operators.
Other commenters, including advocacy organizations and labor
unions, stated that MSHA's proposed sampling frequency was not enough
(Document ID 1434; 1447; 1449; 1412; 1445; 1398; 1385). The USW and the
AFL-CIO stated that the periodic sampling requirement in the proposal
is not sufficient to assess silica concentrations in mining and prevent
overexposures and noted the coal mining industry is already required to
perform quarterly periodic sampling which they believe is not frequent
enough (Document ID 1447; 1449). An individual stated that MSHA's
proposed sampling frequency is not aligned with a 2014 NIOSH study
cited by the Agency that referenced a 2020 report from DOL's Inspector
General, which recommended more frequent monitoring where there is wide
variability in silica levels (Document ID 1412). ACLC recommended that
MSHA require weekly sampling (over multiple shifts) by operators and
monthly sampling by MSHA inspectors (Document ID 1445). The USW, AFL-
CIO, and Nicholas County Black Lung Association supported more frequent
sampling by MSHA without suggesting a specific schedule and stated that
mines should be constantly checking for silica dust, especially where
continuous mining machine operators and roof bolters are working
(Document ID 1447; 1449; 1385).
As commenters noted, OSHA requires a 6-month sampling interval for
monitoring exposures between the action level and PEL and a 3-month
interval for monitoring exposures above the PEL. 29 CFR
1910.1053(d)(3)(iii) and (iv). OSHA explained, ``[i]n general, the more
frequently periodic monitoring is performed, the more accurate the
employee exposure profile.'' 81 FR 16766. Accordingly, OSHA noted that
``[s]electing an appropriate interval between measurements is a matter
of judgment,'' and determined that the 6-month and 3-month frequencies
were both ``practical for employers and protective of employees.'' Id.
MSHA took into account OSHA's approach in developing its final rule.
MSHA's sampling provisions differentiate between miners based on
their exposure levels. The sampling provisions require first-time
sampling of miners exposed or reasonably expected to be exposed to
respirable crystalline silica, and subsequent sampling of miners
exposed at or above the action level. In MSHA's experience, ever-
changing mining conditions require a shorter interval between samplings
to ensure that miners are protected. MSHA's monitoring approach is
consistent with NIOSH's recommendation to monitor miners' silica
exposures frequently due to the variability of silica content in mining
[[Page 28326]]
environments (NIOSH, 2014e). The 3-month interval is appropriately
protective of miners, providing a higher degree of confidence that
miners will not be exposed to concentrations of respirable crystalline
silica above the PEL. As discussed in Section VII. Feasibility and
Section IX. Summary of Final Regulatory Impact Analysis, this sampling
frequency is technologically and economically feasible for mine
operators.
Under the final rule, when exposures are above the PEL, mine
operators must take immediate corrective actions and sample until
exposures are at or below the PEL. Like the proposal, the final rule
does not define a specific sampling frequency above the PEL but
anticipates that operators will sample upon taking corrective actions
and sample as frequently as needed until corrective actions have
resolved the overexposure. Once at or below the PEL, mine operators
will resume the 3-month schedule.
Two Consecutive Samplings Below the Action Level
In the final rule, MSHA allows mine operators to discontinue
sampling when two consecutive samplings indicate that miner exposures
are below the action level. MSHA believes a short period of time--
within three months--between samples is needed to verify current
conditions and lack of exposure to respirable crystalline silica. In
addition, MSHA sampling may indicate exposure levels that require mine
operators to commence sampling. The Agency also requires operators to
conduct periodic evaluations at least every 6 months or whenever there
is a change in production, processes, installation or maintenance of
engineering controls, installation or maintenance of equipment,
administrative controls, or geological conditions, to evaluate whether
the change may reasonably be expected to result in new or increased
respirable crystalline silica exposures. This will ensure that mine
operators continue to monitor changes in mining conditions and
practices that may impact exposure levels and lead to further sampling.
MSHA received several comments on using two consecutive samples as
a means of discontinuing sampling requirements. The AIHA and AFL-CIO
expressed doubt that two samples can provide confidence that a task is
safe from harmful exposures (Document ID 1351; 1449). A MNM operator
noted that one or two sample results below the action level do not
necessarily equate to overall lower exposures and it is likely that
many two-samples below action level results will occur merely by chance
(Document ID 1417). In contrast, the NMA agreed with using two
consecutive samples and stated that OSHA has a similar requirement
(Document ID 1428). The NMA stated that two samples should be enough to
confirm lack of exposure in theory and in practice. Other comments from
professional associations, labor organizations, and a miner health
advocate questioned whether mine operators should be permanently
exempted from sampling at all (Document ID 1372; 1377; 1398; 1449;
1405).
MSHA agrees with the commenter who stated that two consecutive
samples should be enough to confirm lack of exposure to respirable
crystalline silica. In response to the commenters' concern about
discontinuing sampling, MSHA is confident that the results from two
consecutive samplings will provide data to confirm that the operator's
controls are working effectively and that miners' exposures are below
the action level. MSHA also believes that two consecutive samplings
below the action level indicate a low probability that, under the
prevailing conditions, exposure levels exceed the PEL. As such,
unchanged from the proposal, the final rule includes a requirement for
two consecutive samples below the action level to discontinue sampling.
Mine operators may discontinue sampling once two consecutive sample
analyses show the miners' exposures are below the action level.
Specifically, in paragraph 60.12(a)(4), to discontinue sampling, the
second sampling must be taken after the operator receives the results
of the prior sampling but no sooner than 7 days after the prior
sampling was conducted. However, MSHA clarifies that the final rule
includes two scenarios where mine operators are required to resume
sampling with actual or expected miner exposures at or above the action
level but below the PEL. First, mine operators must conduct sampling
within 3 months if sampling by the operator or MSHA indicates that
miner exposures are at or above the action level but at or below the
PEL (Sec. 60.12(a)(3)), and mine operators must continue to sample
until two consecutive samplings indicate that miner exposures are below
the action level. Second, mine operators must conduct post-evaluation
sampling if they determine, as a result of their periodic evaluation,
that miners may be exposed to respirable crystalline silica at or above
the action level (Sec. (60.12(d)).
A miner health advocate stated that an inadequacy of the proposal
was that it failed to address a situation in which a mine operator took
multiple samples at the same time (Document ID 1372). The commenter was
concerned that if one of these samples was under the action level and
others were over, the operator would choose the sample under the action
level as the basis for discontinuing sampling.
MSHA clarifies that, under the final rule, as in the proposal,
mines that have any miners with silica exposures at or above the action
level but at or below the PEL are required to continue conducting
sampling for those miners at or above the action level but at or below
the PEL in accordance with Sec. 60.12(a).
Minimum Time Between Samplings
Under final paragraph (a)(4), for the purposes of discontinuing
sampling, MSHA clarifies that subsequent sampling must be taken after
the operator receives the results of the prior sampling but no sooner
than 7 days after the prior sampling was conducted. In response to
comments, this is a change from the proposed rule.
In the proposal, MSHA requested comment on whether consecutive
samples should be taken at least 7 days apart. MSHA received comments
from AIHA, MCPA, and SSC in response to the minimum time period between
consecutive samplings (Document ID 1351; 1406; 1432). The MCPA
expressed concern that requiring 7 days between samplings, combined
with the time it would take a laboratory to process the samples, could
result in a miner having to wear a respirator for 3-4 weeks despite
effective engineering controls being in place (Document ID 1406). This
commenter also asked if MSHA considered the time it takes to obtain
sample results from a laboratory. The AIHA stated that consecutive
samples do not necessarily need to be at least 7 days apart, depending
on workplace circumstances (Document ID 1351). The SSC stated that a
time limit between consecutive samples is not needed and stated that
MSHA has not offered any reason or justification for requiring 7 days
(Document ID 1432). The ISEEE cautioned that, without a clear
requirement in the rule, mine operators might take consecutive samples
only during the most favorable times, i.e., when exposures are
naturally mitigated by snow or rain (Document ID 1377).
MSHA reviewed the comments and decided that a minimum time between
samplings is necessary to ensure that controls are in place and are
effective in reducing miners' exposures to respirable crystalline
silica. The final rule requires that, to discontinue sampling,
subsequent sampling must be taken after the operator receives the
results of the
[[Page 28327]]
prior sampling but no sooner than 7 days after the prior sampling was
conducted. This requirement is necessary to prevent situations where
operators attempt to rely on samples taken too close together that do
not adequately reflect representative exposure levels during regular
operations, for instance, while performing a low dust generating task.
MSHA notes that OSHA's silica final rule provides a 7-day minimum
period between consecutive samplings under the standard for general
industry and maritime (29 CFR 1910.1053 (d)(3)(v)) and construction (29
CFR 1926.1153 (d)(2)(iii)). In addition, MSHA understands that it
typically takes 2 weeks or less for mine operators to receive sampling
results from the laboratory. MSHA also clarifies that the 7-day minimum
interval is not included in Sec. 60.12(b) or between samples not used
as a basis for discontinuation.
b. Section 60.12(b)--Corrective Actions Sampling
In the final rule, as in the proposal, where the most recent
sampling indicates that miner exposures are above the PEL, MSHA
requires the mine operator to conduct sampling after corrective actions
are taken and until sampling indicates that miner exposures are at or
below the PEL. In a change from the proposal, MSHA also requires mine
operators to immediately report all exposures above the PEL from
operator sampling to the District Manager or to any other MSHA office
designated by the District Manager.
Portland Cement Association recommended that MSHA adopt OSHA's
standard for corrective actions sampling and suggested that operators
repeat sampling at 3-month intervals until exposures are at or below
the PEL (Document ID 1407). An individual expressed concern that the
proposal does not require a minimum number of full-shift samples to
validate the effectiveness of corrective actions (Document ID 1412).
Section 60.13 requires mine operators to take corrective actions
when sampling results show exposure levels above the PEL. Sampling
after taking corrective actions provides operators with specific
information regarding the effectiveness of the corrective actions for
the mine environment and provides additional data for use in making
decisions about updating or improving controls. Once sampling shows
that exposures are at or below the PEL, the Agency requires mine
operators to conduct repeat sampling within 3-month intervals as long
as previous sampling results indicate miners' exposures are at or above
the action level but at or below the PEL. Corrective action sampling is
required for all samples over the PEL at all mines, including portable
operations.
Some commenters, including a miner health advocate and an advocacy
group, questioned whether citations will be issued if exposures are
over the PEL, with Hon. Robert C. ``Bobby'' Scott suggesting that MSHA
incorporate reporting requirements for dust samples (Document ID 1425;
1439; 1399). AMI Silica, LLC stated that requiring operators to report
overexposures was a departure from MSHA's current practice and requires
operators to ``self-incriminate'' (Document ID 1440). However, other
commenters including labor organizations and a miner health advocate
requested more MSHA oversight of operator sampling to ensure compliance
(Document ID 1449; 1398; 1399).
Under the final rule, MSHA requires mine operators to immediately
report all exposures above the PEL to the District Manager or to any
other MSHA office designated by the District Manager. This is
responsive to comments requesting that the Agency be more actively
involved in operator sampling and consistent with the approach MSHA
outlined at a public hearing. Requiring mine operators to report
sampling results over the PEL will ensure that MSHA is aware of all
overexposures and can take appropriate action, including compliance
assistance and enforcement action. Samples indicating concentrations
over the PEL should be reported immediately, without delay once the
operator becomes aware of the information, and in accordance with
guidance from the MSHA District Office. Once MSHA is aware that a
sample indicates overexposure, the Agency can provide appropriate
assistance and monitor progress toward abatement of the condition.
Enforcement actions for samples that are over the PEL, where
appropriate, will be handled on a case-by-case basis. Enforcement
practices are discussed in Section VIII.A. General Issues.
c. Section 60.12(c) and (d)--Periodic Evaluation and Post-Evaluation
Sampling
Under the final rule, mine operators are required to conduct
periodic evaluations at least every 6 months or whenever there is a
change in: production; processes; installation and maintenance of
engineering controls; installation and maintenance of equipment;
administrative controls; or geological conditions. Mine operators are
required to make a record of the periodic evaluation and post it on the
mine bulletin board and, if applicable, by electronic means, for the
next 31 days. If the mine operator determines, as a result of the
periodic evaluation, that miners may be exposed to respirable
crystalline silica at or above the action level, the mine operator
shall perform sampling for each of those miners who may be exposed at
or above the action level.
Periodic Evaluation
The final rule is modified from the proposal, which would have only
required operators to conduct periodic evaluations every 6 months. In
addition to requiring mine operators to conduct periodic evaluations at
least every 6 months, the final rule also requires mine operators to
conduct an evaluation whenever there is a change in production,
processes, installation and maintenance of engineering controls,
installation and maintenance of equipment, administrative controls, or
geological conditions.
MSHA received comments from mining trade associations, labor
unions, miner health advocates, professional associations, an advocacy
organization, a black lung clinic, and a federal elected official on
the proposed semi-annual evaluation requirement. The UMWA, ACOEM, APHA,
and AEMA stated that mine operators should be constantly conducting
qualitative evaluations any time a change occurs that may reasonably be
expected to result in new or increased respirable crystalline silica
exposures (Document ID 1398; 1405; 1416; 1424). The ISEEE stated that
it is crucial to regularly reevaluate and address any deficiencies
across all aspects of the mine site to prevent unnecessary exposures
and emphasized that conducting timely risk assessments is a standard
practice in the mining industry (Document ID 1377). The UMWA and AFL-
CIO stated the proposed evaluation requirement could create the
possibility for miners to be exposed to dangerous levels of silica for
up to six months (Document ID 1398; 1449). The AEMA believed the
proposed evaluation requirement would be excessive given the lack of
frequency with which changes occur (Document ID 1424). The AEMA and NMA
recommended MSHA require an annual evaluation (Document ID 1424; 1428).
The NSSGA stated that MSHA should adopt OSHA's requirement to reassess
respirable crystalline silica exposures whenever there has been a
change that may reasonably be expected to result in new or additional
exposures at or above the action level, or when the employer has any
reason to believe that new or
[[Page 28328]]
additional exposures at or above the action level have occurred (29 CFR
1910.1053(d)(4) and 29 CFR 1926.1153(d)(2)(iv)) and eliminate the 6-
month qualitative evaluation requirement (Document ID 1448). Finally,
the AFL-CIO stated mine operators should report significant changes
that could increase silica concentrations to MSHA, while the Miners
Clinic of Colorado and a miner health advocate stated that MSHA, not
mine operators, should be responsible for deciding whether additional
sampling should be conducted as a result of the qualitative evaluation
(Document ID 1449; 1418; 1399).
MSHA agrees with commenters who stated that mine operators should
be required to conduct a qualitative evaluation when a change occurs to
help minimize overexposures to respirable crystalline silica. The
requirement to conduct a qualitative evaluation at least every 6 months
or whenever a change occurs in production, processes, controls, or
geological conditions ensures that mine operators are assessing
changing processes, conditions, and practices that may impact miner
exposure levels on a regular basis to determine if additional sampling
is needed. The requirement to conduct an evaluation whenever a change
occurs is consistent with the existing MNM requirement to conduct
surveys as frequently as necessary to determine the adequacy of control
measures (Sec. Sec. 56.5002 and 57.5002), while the minimum 6-month
requirement is consistent with the underground coal requirement to
review the ventilation plan every 6 months to assure that it is
suitable to current conditions (Sec. 75.370(g)). This requirement is
also consistent with the existing MNM standard for controlling diesel
particulate matter (DPM), which requires that mine operators monitor as
often as necessary to effectively determine, under conditions that can
be reasonably anticipated in the mine, whether the average personal
full-shift airborne exposure to DPM exceeds the DPM limit (57.5071(a)).
Under the final rule, mine operators are responsible for conducting
periodic evaluations. The Agency emphasizes that it will not conduct
periodic evaluations but may use its enforcement discretion to review a
mine's records of periodic evaluations, when necessary.
In response to a comment from a miner health advocate, the final
rule modifies proposed paragraph(c)(1), which required operators to
``[m]ake a record of the evaluation and the date of the evaluation.''
The commenter stated MSHA should require the record of the evaluation
to specify all changes that could affect respirable crystalline silica
exposures and the effect of the changes on exposure levels (Document ID
1372). MSHA agrees with the commenter who stated the record of the
evaluation needs to be more informative and responds by requiring the
record of the evaluation to also include the evaluated change and the
impact the change has on respirable crystalline silica exposure. The
additional required data will provide MSHA, mine operators, and miners
with information on the specific changes that may reasonably be
expected to result in new or increased respirable crystalline silica
exposures.
Unchanged from the proposal, under the final rule, MSHA requires
mine operators to post the record on the mine bulletin board and, if
applicable, by electronic means, for 31 days. The NSSGA stated that
MSHA's requirement to post results on a bulletin board is too
prescriptive and may cause an issue for operators who do not have a
bulletin board (Document ID 1448). The final rule includes this
requirement because it is consistent with MSHA's existing standards and
gives miners ready access to recent sampling results, providing
additional accountability for mine operators, and necessary information
for miners. Also, section 109(a) of the Mine Act requires mines to have
a bulletin board where information can be posted and shared with miners
and their representatives. 30 U.S.C. 819(a). For portable operations
and other operators who prefer to communicate electronically, the final
rule permits electronic notification in addition to posting the record
on the bulletin board.
Post-Evaluation Sampling
Under the final rule, like the proposal, mine operators are
required to conduct post-evaluation sampling to assess the full shift,
8-hour TWA exposure of respirable crystalline silica when the results
of the periodic evaluation show that miners may be exposed to
respirable crystalline silica at or above the action level.
MSHA received some comments on the post-evaluation sampling
proposal from an advocacy organization, a labor union, a federal
elected official, a medical professional association, and a black lung
clinic stating that MSHA should require sampling whenever there are any
changes in mine conditions that could lead to an increased risk of
respirable crystalline silica exposures (Document ID 1416; 1398; 1439;
1405; 1418). A miner health advocate stated that mine operators should
not have the discretion to decide whether miners may be exposed to
respirable crystalline silica at or above the action level or whether
they should perform sampling to assess miners' exposure levels as a
result (Document ID 1399). The same commenter suggested that MSHA
should provide simple and straightforward triggers that mandate
sampling, rather than just the requirement to conduct an evaluation
that might lead to additional sampling.
Post-evaluation sampling is needed to ensure workers are protected
from respirable crystalline silica when a change may increase their
exposure. MSHA believes that mine operators have the most knowledge
about their mine's operations and conditions. Mine operators are aware
of the extent and degree of miners' exposures to respirable crystalline
silica because they have been complying with respirable dust standards
for over 40 years. Mine operators are also aware of the occupations,
work areas, and work activities where overexposures to respirable
crystalline silica are most likely to occur. Further, MSHA believes
that mine operators will make good-faith efforts to comply with the
post-evaluation sampling requirements to ensure healthy working
conditions for miners. The final rule, in a change from the proposal,
requires mine operators to conduct an evaluation whenever there are
changes that may reasonably be expected to result in new or increased
respirable crystalline silica exposures and to require operators to
maintain more detailed records of the evaluation. These records will
allow miners, their representatives, and MSHA to hold operators
accountable for conducting timely and appropriate evaluations and
required sampling.
d. Section 60.12(e)--Sampling Requirements
The final rule includes sampling requirements to ensure mine
operators' respirable crystalline silica monitoring is representative
of miners' actual exposure levels. The sampling requirements in the
final rule are the same sampling requirements from the proposal, with a
few modifications. Each of the sampling requirements is discussed in
more detail below.
Typical Mining Activities
In the final rule, MSHA includes shaft and slope sinking,
construction, and removal of overburden to clarify that these mining
activities are within the scope of the final rule.
Several commenters stated the proposal was vague and did not
clearly specify what ``typical mining activities'' includes. Black Lung
Clinics, Hon. Robert C. ``Bobby'' Scott, and a miner
[[Page 28329]]
health advocate emphasized that MSHA should ensure the final rule
covers all aspects of mining operations, including construction and
development activities (Document ID 1410; 1439; 1372). The American
Thoracic Society et al. and Appalachian Voices stated it was unclear
whether slope mining, shaft mining, or exploratory mining were
considered typical mining activities under the proposal (Document ID
1421; 1425). The UMWA, Miners Clinic of Colorado, AFL-CIO, and a miner
health advocate asserted that high silica-cutting activities such as
blasting, drilling, excavation, cutting overcasts, cutting belt
channels, and other outby construction should be considered typical
mining activities under the final rule (Document ID 1398; 1418; 1449;
1399).
MSHA agrees with commenters that construction and development
activities are typical mining activities and clarifies this in the
final rule. The Agency is aware that many construction and development
activities generate silica dust, which can lead to respirable
crystalline silica exposures well above the PEL. MSHA stated at the
public hearings and clarifies in this final rule that typical mining
activities include shaft and slope mining, construction, and removal of
overburden. In June 2022, MSHA implemented its Silica Enforcement
Initiative (SEI) for MNM and coal mines. The purpose of the SEI is to
reduce silica exposures in MNM and coal mines, and to provide
compliance assistance to mine operators, where appropriate. The SEI was
posted on MSHA's website and discussed with the mining community at
safety and health conferences and during frequent MSHA stakeholder
calls.\73\ The SEI specifically addresses silica exposures in shaft and
slope mining, construction, and removal of overburden. MSHA's
Enforcement and Educational Field and Small Mine Services staff also
discussed the SEI with the mining community. In response to commenters'
examples, MSHA agrees that exploratory mining, and blasting, drilling,
or cutting rock are all considered typical mining activities.
---------------------------------------------------------------------------
\73\ https://www.msha.gov/safety-and-health/safety-and-health-initiatives/2022/06/08/silica-enforcement-initiative (last accessed
Jan. 10, 2024).
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MSHA also clarifies that the existing requirements for respirable
coal mine dust sampling differ from this final rule's requirements for
respirable crystalline silica sampling. Under the existing standards
for respirable coal mine dust sampling, the operator is required to
sample coal mine dust exposures for specific occupations and areas
during consecutive normal production shifts where coal mine dust is
generated from production activities. Under the final rule, MSHA
interprets construction and development activities as typical mining
activities subject to respirable crystalline silica sampling, even
though they may not be considered production activities under the
requirements for respirable coal mine dust sampling.
Environmental Conditions
Under the final rule, MSHA does not specify any operating
conditions or environmental conditions for the purposes of conducting
respirable crystalline silica sampling.
In the proposal, MSHA requested comments on whether the Agency
should specify environmental conditions for sampling. The AEMA, NMA,
and NSSGA recommended that MSHA not specify typical operating
conditions or environmental conditions (Document ID 1424; 1428; 1448).
MSHA Safety Services Inc. stated that it is impossible to predict the
weather (Document ID 1392). The AFL-CIO cautioned that sampling while
it is raining--a natural dust suppressant--could skew results, while
two commenters stated that some mines operate in areas where rain,
snow, and wind are common and requiring sampling in their absence is
not feasible (Document ID 1449; 1424; 1428). The NLA stated that
sampling should be performed under normal or typical operating
conditions while also emphasizing the need for mine operators to have
flexibility to determine whether conditions for testing are appropriate
on any day (Document ID 1408). Black Lung Clinics specified that
sampling should be conducted at something approaching full production
for typical tasks (Document ID 1410).
MSHA recognizes the existence of exposure variability due to
changing mining operations and environmental conditions and agrees with
commenters that operators should have the flexibility, within reason,
to determine what constitutes typical operating conditions and normal
production levels at their mine. MSHA also agrees with the commenters
who stated it would be impossible to predict the weather, and thus
determined that including specific environmental conditions would make
conducting exposure sampling unduly complicated or at times difficult
to achieve. MSHA believes that the consistent use of effective
engineering controls and workplace practices will help reduce exposure
variability and provide operators with greater confidence that they are
complying with the PEL. However, MSHA acknowledges that an operator's
conscientious application and maintenance of all feasible engineering
controls and workplace practices cannot eliminate exposure variability.
Sampling Device Placement
Under the final rule, MSHA requires personal breathing-zone air
samples for MNM operations and requires occupational environmental
samples collected in accordance with Sec. 70.201I (underground coal
mines), Sec. 71.201(b) (surface coal mines and surface work areas of
underground coal mines), or Sec. 90.201(b) (coal miners who have
evidence of the development of pneumoconiosis) for coal operations.
MSHA received a few comments on the proposed sampling device
placement requirements. The AIHA and NMA expressed support for taking
samples from MNM miners' personal breathing-zones with the latter
commenter stating that the approach makes sense because MNM miners
perform various job functions over the course of a shift (Document ID
1351; 1428). NMA also reasoned that the personal breathing-zone method
would be preferable for coal miners, rather than the proposed
occupational environmental sampling, because occupational environmental
samples may measure several miners performing the same job function
over the course of a shift and make it more difficult to maintain
compliance with the PEL. The NVMA stated that providing two different
sampling methods under the same standard does not make sense and
suggested MSHA have two separate rulemakings--one for coal mines and
one for MNM mines (Document ID 1441).
The Agency reiterates that the final rule creates a uniform
standard that establishes consistent, industry-wide requirements to
address the adverse health effects of overexposure to respirable
crystalline silica for all miners, while still recognizing the
differences between MNM and coal operations. MSHA believes that the
consistent use of effective engineering controls and workplace
practices will help all mines--MNM and coal--maintain compliance with
the PEL and ensure effective health protection of miners. MSHA
established the requirements for personal breathing-zone air samples
for MNM miners and occupational environmental samples for coal miners
to mirror existing sampling requirements for both industries. These
sampling methods are tools that, when used appropriately, achieve the
purpose
[[Page 28330]]
of the Mine Act by identifying the need for additional controls to help
operators to maintain good air quality.
A miner health advocate recommended that MSHA require coal mine
operators to conduct both designated area sampling and designated
occupation sampling, rather than allowing them the discretion to sample
either (Document ID 1399). This is a misinterpretation of the rule.
Final paragraph (e)(2)(ii), which was proposed as paragraph (f)(2)(ii),
states that ``[t]he full-shift, 8-hour TWA exposure for such miners
shall be measured based on . . . Occupational environmental samples
collected in accordance with Sec. 70.201(c), Sec. 71.201(b), or Sec.
90.201(b) of this chapter for coal operations.'' Sections 70.201(c) and
71.201(b) both prescribe processes for occupational samples, including
conversion of designated areas to Other Designated Occupations and
requirements for how sampling devices must be used and worn. Paragraph
(e)(2)(ii) does not change operators' discretion under section
70.201(c) or 71.201(b).
Representative Sampling
As a general principle, mine operators must accurately characterize
miners' exposure to respirable crystalline silica. In some cases, this
requires sampling all exposed miners, while in other cases, sampling a
``representative'' fraction of miners is sufficient. When a mine
operator elects to engage in representative sampling, the mine operator
may take, and submit for analysis, fewer samples. Under this rule, mine
operators must assess the typical circumstances of each shift and each
employee to identify miners most at risk for overexposure (for example,
miners working near where dust collector cleaning or bagging operations
are taking place) and choose those miners to be ``representative'' for
sampling purposes. This approach allows mine operators to assess the
highest likely exposure levels and implement and adjust engineering
controls to address the highest likely concentrations of respirable
crystalline silica. MSHA finds that representative sampling is
sufficient to measure the effectiveness of the engineering controls in
place. This applies to miners who were not included in the sampling but
who are represented by the representative samples.
Under the final rule, like the proposal, where several miners
perform the same tasks on the same shift and in the same work area,
mine operators may sample a representative fraction (at least two) of
these miners. When sampling a representative fraction of miners, mine
operators are required to select the miners expected to have the
highest exposure to respirable crystalline silica. For example,
sampling a representative fraction may involve monitoring the exposure
of those miners who are closest to the dust source. The sampling
results for these miners can then be attributed to the remaining miners
in the group. When miners are performing different tasks, a
representative sample of miners in the same working area is not
sufficient to characterize actual exposures, and therefore individual
samples are necessary.
MSHA received many comments on the proposed representative sampling
requirements from MNM mine operators, mining and industry trade
associations, labor unions, and an industrial hygiene professional
association, with many commenters supporting the proposal (Document ID
1398; 1392; 1351; 1407; 1432; 1448; 1417; 1378; 1424; 1419; 1441; 1378;
1399). The AIHA, Portland Cement Association, SSC, and NSSGA suggested
that ``similar exposure groups,'' or SEGs, be used as a method to
determine which miners to sample for representative sampling and to
reduce operator costs for complying with the exposure monitoring
requirements in the rule (Document ID 1351; 1407; 1432; 1448). Arizona
Mining Association stated that mine operators should be allowed to use
SEGs because the alternative of viewing all miners' exposure as the
same will result in large cost increases and wasted resources (Document
ID 1368).
MSHA did not adopt an SEG approach in the final rule. The Agency
agrees that mine operators do not always need to conduct sampling for
every exposed miner. Sampling for a representative fraction of miners
is similar to the SEG concept because both approaches group miners with
similar exposure characteristics for the purpose of sampling a smaller
subset of the group.
However, there is likely more room for error and misclassification
using SEGs in mining, especially among smaller mines. SEGs rely on the
principle of grouping workers into exposure profiles and assessing the
health risks to those workers based on similar exposure conditions.
Accordingly, SEGs are commonly established by experienced environmental
health and safety (EHS) professionals using a combination of exposure
characteristics, including location, job, task, and equipment used.
Small mines may not have EHS professionals to correctly define SEGs and
validate data using proper statistical analyses. There is also risk for
SEG misclassification if, for example, sampling data is incorrectly
grouped, not representative of all exposures on all shifts, or not
collected for the full shift. MSHA is also concerned with variability
in silica concentrations in the ore body in mining (especially in
coal). Mines are constantly changing, which means that miners'
exposures will also change. SEGs would need to be continuously reviewed
by EHS professionals to ensure that they are correctly defined over
time.
The NSSGA, BMC, Pennsylvania Coal Alliance, and AEMA stated that
samples from miners performing the same task in the same area but on
different shifts should qualify as representative, with the
Pennsylvania Coal Alliance stating that MSHA's limitation of samples to
a single shift is unduly restrictive (Document ID 1448; 1417; 1378;
1424).
The final rule requires representative sampling to be restricted to
the same shift, rather than spanning across multiple shifts. MSHA
believes that where miners are not performing the same tasks on the
same shift and in the same work area, representative sampling will not
adequately characterize actual exposures. In the Agency's experience,
mine operators may schedule high hazard-generating activities during
one shift and not others, which would create differences in the
environment. Humidity, changes in geology, and other environmental
conditions that might impact sampling results could change across
shifts, as well; for example, a typically warm and sunny day shift
versus a cooler shift where temperatures approach or move further from
the dewpoint. MSHA finds that rather than trying to control for
potentially significant and unanticipated variables across shifts,
miner health and safety is better protected if representative sampling
is confined to the same shift, where conditions are more likely to be
consistent across miners represented by the sampling. MSHA notes that
OSHA's requirements for representative sampling for general industry
and construction are also applied to individual shifts. See 29 CFR
1910.1053(d)(3)(i).
Sampling Devices: Incorporation of ISO 7708:1995 by Reference
ISO 7708:1995(E), ``Air quality--particle size fraction definitions
for health-related sampling,'' First Edition, 1995-04-01, is an
international consensus standard that defines sampling conventions for
particle size fractions used in assessing possible health effects of
airborne particles in the workplace and ambient environment. It defines
conventions for the inhalable,
[[Page 28331]]
thoracic, and respirable fractions. The ISO standard also provides
formulas for determining the fractions based on the aerodynamic
diameter of the particles present. MSHA is incorporating by reference
ISO 7708:1995 in Sec. 60.12(e)(4) to ensure consistent sampling
collection by mine operators through the utilization of samplers
conforming to ISO 7708:1995.
Under the final rule, MSHA requires mine operators to use
respirable-particle-size-selective samplers that conform to the ISO
7708:1995 standard to determine compliance with the PEL. Mine operators
are allowed to use any type of sampling device for respirable
crystalline silica sampling, as long as the device is designed to meet
the characteristics for respirable-particle-size-selective samplers
that conform to the ISO 7708:1995 standard and, where appropriate, meet
MSHA permissibility requirements.
Sampling devices, such as cyclones \74\ and elutriators,\75\ can
separate the respirable fraction of airborne dust from the non-
respirable fraction in a manner that simulates the size-selective
characteristics of the human respiratory tract and that meets the ISO
standard. These devices enable collection of dust samples that contain
only particles small enough to penetrate deep into the lungs. Size-
selective cyclone sampling devices are typically used in the U.S.
mining industry. These samplers generally consist of a pump, a cyclone,
and a membrane filter. The cyclone uses a rapid vortical flow of air
inside a cylindrical or conical chamber to separate airborne particles
according to their aerodynamic diameter (i.e., particle size). As air
enters the cyclone, the larger particles are centrifugally separated
and fall into a grit pot, while smaller particles pass into a sampling
cassette where they are captured by a filter membrane that is later
analyzed in a laboratory to determine the mass of the respirable dust
collected. The pump creates and regulates the flow rate of incoming
air. As the flow rate of air increases, a greater percentage of larger
and higher-mass particles are removed from the airstream, and smaller
particles are collected with greater efficiency. Adjustment of the flow
rate changes the particle collection characteristics of the sampler and
allows calibration to a specified respirable particle size sampling
definition, such as the ISO criterion.
---------------------------------------------------------------------------
\74\ A cyclone is a centrifugal device used for extracting
particulates from carrier gases (e.g., air). It consists of a
conically shaped vessel. The particulate-containing gas is drawn
tangentially into the base of the cone, takes a helical route toward
the apex, where the gas turns sharply back along the axis, and is
withdrawn axially through the base. The device is a classifier in
which only dust with terminal velocity less than a given value can
pass through the formed vortex and out with the gas. The particle
cut-off diameter is calculable for given conditions.
\75\ An elutriator is a device that separates particles based on
their size, shape, and density, using a stream of gas or liquid
flowing in a direction usually opposite to the direction of
sedimentation. The smaller or lighter particles rise to the top
(overflow) because their terminal sedimentation velocities are lower
than the velocity of the rising fluid.
---------------------------------------------------------------------------
A cyclone sampler calibrated to operate at the manufacturer's
specified air flow rate that conforms to the ISO standard can be used
to collect respirable crystalline silica samples under this final rule.
MSHA reviewed OSHA's feasibility analysis for its 2016 silica final
rule and agrees that there are commercially available cyclone samplers
that conform to the ISO standard and allow for the accurate and precise
measurement of respirable crystalline silica at concentrations below
both the action level and PEL (OSHA, 2016a). Cyclone samplers include,
but are not limited to, the Dorr-Oliver 10-mm nylon cyclone, as well as
the Higgins-Dewell, GK2.69, SIMPEDS, and SKC aluminum cyclone. Each of
these cyclones has different operating specifications, including flow
rates, and performance criteria, but all are compliant with the ISO
criteria for respirable dust with an acceptable level of measurement
bias. MSHA's determination is that cyclone samplers, when used at the
appropriate flow rates, can collect a sufficient mass of respirable
crystalline silica to quantify atmospheric concentrations lower than
the action level and meet MSHA's crystalline silica sample analysis
specifications for samples collected at MNM and coal mines.
MNM mine operators who currently use a Dorr-Oliver 10 mm nylon
cyclone can continue to use it at a flow rate of 1.7 L/min, which
conforms to the ISO standard, to comply with the requirements. For coal
mine operators, the gravimetric samplers previously used to sample RCMD
(i.e., coal mine dust personal sampling units (CMDPSUs)) were operated
at a 2.0 L/min flow rate. Those CMDPSUs can be adjusted to operate at a
flow rate of 1.7 L/min to conform to the ISO standard.
The NMA, AEMA, and SKC Inc., noted that samplers other than
cyclones and elutriators should be considered acceptable under the
final rule (Document ID 1428; 1424; 1366). A miner health advocate
stated that when conducting sampling under OSHA requirements, they
currently use a type of sampler called a ``parallel particle
impactor,'' or PPI sampler, that meets the ISO 7708:1995 standard
(Document ID 1375). This commenter stated that there is a disconnect
between the cyclone samplers mentioned in the proposed rule and the use
of PPI samplers as an acceptable sampling device, implying that PPI
samplers are not acceptable because they were not included in the list
of example samplers that meet the ISO 7708:1995 standard in the
Sampling Methods section of the proposed rule. This commenter also
suggested that the PPI sampling device be considered acceptable under
this final rule. Similarly, the NMA, AEMA and SKC stated that MSHA's
proposal implies that only cyclone and elutriator type samplers meet
the specifications for acceptable sampling devices.
MSHA clarifies that cyclone and elutriator type samplers are not
the only acceptable sampling devices that can be used to conduct
sampling for respirable crystalline silica under this rule. In the
Sampling Methods section of the proposed rule, MSHA included a list of
example samplers that conform to the ISO 7708:1995 standard. This list
was not meant to be all-inclusive, but rather provide several examples
of samplers currently available in the marketplace that conform to the
ISO 7708:1995 standard (88 FR 44921). As stated above, mine operators
can use any type of sampling device, as long as it is designed to meet
the characteristics for respirable-particle-size-selective samplers
that conform to the ISO 7708:1995 standard and, where appropriate, meet
MSHA permissibility requirements. MSHA clarifies that under this final
rule, any sampling device that meets the ISO 7708:1995 particle size
selective criteria for respirable dust samplers are acceptable for
respirable crystalline silica sampling, even if the sampler is not
specifically mentioned in the list of examples. Under the final rule,
the PPI sampler would be acceptable.
Several commenters, including labor organizations and a federal
elected official, noted the need for sampling devices with real-time or
near real-time sample analysis capabilities for respirable crystalline
silica (Document ID 1449; 1447; 1398; 1412; 1399; 1439). The AFL-CIO
stated that one of the most significant items not included in the
proposal (that was included in the 2014 Coal Dust Rule) was personal
dust monitoring devices with real-time analysis (Document ID 1449). The
commenter recommended the adoption of new technology used by the
domestic or international mining community to better protect miners. An
individual stated that MSHA should consider and incorporate continuous
and rapid quartz
[[Page 28332]]
monitoring systems to more appropriately characterize exposures
(Document ID 1412).
MSHA is aware of NIOSH's rapid field-based quartz monitoring (RQM)
approach as an emerging technology. It provides a field-based method
for providing respirable crystalline silica exposure measurements at
the end of a miner's shift. With such an end-of-shift analysis, mine
operators can identify overexposures and mitigate hazards more quickly.
NIOSH Information Circular 9533, ``Direct-on-filter Analysis for
Respirable Crystalline Silica Using a Portable FTIR Instrument''
provides detailed guidance on how to implement a field-based end-of-
shift respirable crystalline silica monitoring program.\76\ The current
RQM monitor, however, was designed as an engineering tool specifically
for quartz in coal mines and has not been used for measurements of
cristobalite and tridymite. MSHA has determined that the RQM monitor
lacks tamper-proof components and is susceptible to interferences
(e.g., in MNM mines) which can affect its accuracy. Thus, the RQM may
not be used for compliance with the sampling requirements of the final
rule. MSHA continues to support NIOSH efforts to develop the RQM
monitor.
---------------------------------------------------------------------------
\76\ National Institute for Occupational Safety and Health
(NIOSH). 2022b. Direct-on-filter analysis for respirable crystalline
silica using a portable FTIR instrument. By Chubb LG, Cauda EG.
Pittsburgh PA: U.S. Department of Health and Human Services, Centers
for Disease Control and Prevention, National Institute for
Occupational Safety and Health, DHHS (NIOSH) Publication No. 2022-
108, IC 9533. https://doi.org/10.26616/NIOSHPUB2022108 (last
accessed Jan. 10, 2024). The document is intended for industrial
hygienists and other health and safety mining professionals who are
familiar with respirable crystalline silica exposure assessment
techniques, but who are not necessarily trained in analytical
techniques. It gives general instructions for setting up the field-
based monitoring equipment and software. It also provides case
studies and examples of different types of samplers that can be used
for respirable crystalline silica monitoring. Guidance on the use,
storage, and maintenance of portable IR instruments is also provided
in the document.
---------------------------------------------------------------------------
While the current RQM cannot be used for compliance with the
sampling requirements under this final rule, MSHA encourages mine
operators to use the RQM as an engineering tool as the Agency believes
it could assist operators in identifying areas of concern, including
samples that would be most appropriate for further laboratory analysis.
MSHA notes that samples taken by operators using the RQM with results
above the PEL are not subject to the requirements of the final rule
(i.e., the mine operator need not report them to MSHA, take corrective
actions, or conduct additional sampling, etc.). MSHA continues to
support NIOSH efforts to develop the RQM monitor to be used in mines.
MSHA maintains that analysis of samples using accredited
laboratories is an accurate and reliable method of determining
respirable crystalline silica exposures. Accurate laboratory analysis
is needed as a reference measurement at the beginning and again at the
end of an initial exposure assessment as well as when completing
follow-up assessments to validate compliance. However, end-of-shift
monitoring can reduce the number of samples taken and provide quick
results that can be used to reduce the expense of more frequent
sampling and laboratory analysis, during implementation of corrective
actions, to validate the effectiveness of corrective actions between
collection of gravimetric samples, and to increase awareness of
potential overexposures in a timely manner.
Seasonal and Intermittent Mines
Seasonal and intermittent mines may have less time to conduct 3-
month sampling. Under the rule, all operators, including seasonal and
intermittent, must conduct initial sampling when commencing operations
after the listed compliance dates. If that initial sampling is below
the action level, MSHA believes that, although the operator may wait up
to 3 months to conduct the next sample, most operators would have an
incentive to take another sample as soon as practicable under Sec.
60.12(a) in order to be relieved from the continuing 3-month sampling
requirements if a second consecutive sample result is below the action
level. In that situation, the operator would need only to conduct its
periodic evaluation every six months or when circumstances change
pursuant to Sec. 60.12(c). If the initial sample is at or above the
action level and at or below the PEL, all operators would need to take
a second sample within 3 months, and within every three months after
that unless they meet the criteria to discontinue sampling. Operators
that are active during the 3-month period would need to meet these
sampling deadlines, even if the operator is not active full-time during
the 3-month period. Once operators have closed for the season, or for
an extended period (more than 3 months), they would not be expected to
continue sampling every 3 months. However, when they re-open, if they
have not met the requirements for discontinuing sampling, they would
need to start sampling immediately and every three months. MSHA
encourages operators to work with their District Managers to develop a
workable sampling schedule that protects miners as this rule intends.
e. Section 60.12 (f)--Methods of Sample Analysis
The final rule, like the proposal, specifies the methods to be used
for analysis of respirable crystalline silica samples, including
details regarding the specific analytical methods to be used and the
qualifications of the laboratories where the samples are to be
analyzed.
ISO/IEC 17025 Accreditation
Mine operators are required to use laboratories that are accredited
to the International Organization for Standardization (ISO) or
International Electrotechnical Commission (IEC) (ISO/IEC) 17025,
``General requirements for the competence of testing and calibration
laboratories'' with respect to respirable crystalline silica analyses,
where the accreditation has been issued by a body that is compliant
with ISO/IEC 17011 ``Conformity assessment--Requirements for
accreditation bodies accrediting conformity assessment bodies.''
Accredited laboratories are held to internationally recognized
laboratory standards and must participate in quarterly proficiency
testing for all analyses within the scope of the accreditation.
The ISO/IEC 17025 standard is a consensus standard developed by
ISO/IEC and approved by ASTM International (formerly the American
Society for Testing and Materials). This standard establishes criteria
by which laboratories can demonstrate proficiency in conducting
laboratory analysis through the implementation of quality control
measures. To demonstrate competence, laboratories must implement a
quality control program that evaluates analytical uncertainty and
provides estimates of sampling and analytical error when reporting
samples. The ISO/IEC 17011 standard establishes criteria for
organizations that accredit laboratories under the ISO/IEC 17025
standard. For example, the American Industrial Hygiene Association
(AIHA) accredits laboratories for proficiency in the analysis of
respirable crystalline silica using criteria based on the ISO/IEC 17025
and other criteria appropriate for the scope of the accreditation.
MSHA received a few comments regarding the proposed requirement for
mine operators to use laboratories accredited to ISO/IEC 17025 where
the accreditation has been issued by a body that is compliant with ISO/
IEC 17011 from AIHA, NVMA, BMC, and A2LA (Document ID 1351; 1441; 1417;
1388). AIHA and A2LA stated that they agree
[[Page 28333]]
with MSHA's proposed requirement and BMC stated that they have no
objection to the proposal. A2LA further stated that relying on
accreditation for the approval of testing laboratories assures quality,
technical competence, accuracy, compliance, and international
recognition. A2LA stated that it provides confidence in the reliability
of measurement results and supports regulatory compliance.
Under the final rule, all mine operators will have to use third-
party laboratories accredited to ISO/IEC 17025 to have respirable dust
samples analyzed for respirable crystalline silica. Many MNM mine
operators already use third-party laboratories to perform respirable
crystalline silica sample analyses. For most coal mine operators, using
a third-party laboratory to analyze respirable crystalline silica
samples is a new requirement because respirable coal mine quartz
samples are currently analyzed by MSHA. Under the final rule, coal mine
operators are responsible for directly monitoring crystalline silica
(quartz) exposures in addition to coal dust. Requiring all mines to use
third-party laboratories ensures that sample analysis requirements and
MSHA enforcement efforts are consistent across all mines.
Analytical Methods for Sampling
The final rule requires mine operators to ensure that laboratories
evaluate all samples using analytical methods for respirable
crystalline silica that are specified by MSHA, NIOSH, or OSHA. These
are validated methods currently being used by third party accredited
laboratories for measuring respirable crystalline silica in mine dust
matrices. MSHA expects that samples collected in MNM mines will be
analyzed by X-ray diffraction (XRD) and samples collected in coal mines
will be analyzed by Fourier transform infrared spectroscopy (FTIR).
MNM samples are currently analyzed by XRD because the XRD method
can distinguish and isolate respirable crystalline silica for
measurement, thereby avoiding interference or confounding of respirable
crystalline silica analysis results. For MNM samples, the methods used
for respirable crystalline silica sample analysis using XRD include
MSHA P-2, NIOSH 7500, and OSHA ID-142. All three methods can
distinguish between the three silica polymorphs.
MSHA and NIOSH have specific FTIR methods for analyzing quartz in
coal mine dust. The NIOSH 7603 method is based on the MSHA P-7 method
which was collaboratively tested and specifically addresses the
interference from kaolinite clay. Current FTIR methods, however, cannot
quantify quartz if either of the other two forms of crystalline silica
(cristobalite and tridymite) are present in the sample. Additional
steps such as acid treatment can be taken to remove respirable
crystalline silica interferences from other minerals that can be found
in mine dust sample matrices. For coal samples, the methods used for
respirable crystalline silica sample analysis using FTIR include MSHA
P-7, NIOSH 7602, and NIOSH 7603.
MSHA received some comments from mining trade associations, a MNM
mine operator, and a labor union regarding the proposed requirements
for specified analytical methods (Document ID 1398; 1424; 1417; 1428;
1443). BMC stated that they have no objection to MSHA's proposed
provisions and UMWA stated that they are supportive of MSHA's proposed
requirements. The AEMA, NMA and WVCA cautioned that many minerals
interfere with the laboratory's analysis of silica and cited a list
produced by OSHA of 18 mineral types that might interfere. Some of
these commenters expressed concern that interference could erroneously
elevate silica sample levels and cause mine operators to spend
resources on corrective actions that are not needed.
As discussed above, MSHA expects that samples collected in MNM
mines will be analyzed by XRD and samples collected in coal mines will
be analyzed by FTIR. In response to the commenters' concern about
mineral types that could erroneously elevate silica sample levels, MSHA
disagrees with the commenters and notes that the OSHA method cited by
the commenters (i.e., OSHA ID-142) addresses mineral interference and
is one of the XRD methods that can be used for respirable crystalline
silica sample analysis under the final rule.
f. Section 60.12 (g)--Sampling Records
Under the final rule, the mine operator is required to create a
record for each sample taken that includes the sample date, the
occupations sampled, and the concentrations of respirable crystalline
silica and respirable dust. The mine operator is also required to post
the record and the laboratory report on the mine bulletin board and, if
applicable, by electronic means, for the next 31 days, upon receipt.
MSHA received a few comments on the proposed sampling records
provision. The APHA recommended that MSHA update Sec. 60.12(h) to
require mine operators to provide a description or data that shows the
sample was taken during typical mining activities (Document ID 1416).
The same commenter also recommended that MSHA require the person
collecting the samples and recording the data to certify the accuracy
of the records in writing. The Hon. Robert C. ``Bobby'' Scott, The
American Thoracic Society et al. and AFL-CIO supported greater
accessibility of records (Document ID 1439; 1421; 1449). Two of these
commenters also recommended that sampling records be sent to the
miners' representatives (Document ID 1439; 1449).
In MSHA's experience, commercial laboratories that produce reports
for respirable crystalline silica exposures include information on
sample locations and/or activities being performed. In some cases, the
name of the person that was sampled is also included. The final rule
only requires the sampling record to include the date, occupations
sampled, and concentrations of respirable crystalline silica and
respirable dust since the laboratory report may contain additional
information. MSHA believes the elements it requires as part of the
sampling record provide mine operators and miners with the most
important pieces of information while balancing concerns about
recordkeeping burden. As required in Sec. 60.16(b), any sampling
record that is created may be requested at any time by, and must
promptly be made available to, miners, authorized representatives of
miners, or an authorized representative of the Secretary.
6. Section 60.13--Corrective Actions
The final rule establishes the requirements for corrective actions
in Sec. 60.13. Section 60.13 paragraph (a) requires mine operators to
take certain actions when any sampling result indicates that a miner's
exposure to respirable crystalline silica exceeds the PEL. Paragraph
(a) has three subparagraphs--(1), (2), and (3). Paragraph (a)(1)
requires mine operators to make NIOSH-approved respirators available to
affected miners before the start of the next work shift. In a change
from the proposal, paragraph (a)(1) specifies that this requirement
must be made in accordance with Sec. 60.14 (b) and (c). Paragraph
(a)(2), unchanged from the proposal, requires mine operators to ensure
that affected miners wear respirators properly for the full shift or
during the period of overexposure until miner exposures are at or below
the PEL. Paragraph (a)(3), unchanged from the proposal, requires mine
operators to immediately take corrective actions to lower the
concentration of respirable crystalline silica to at or below the PEL.
Paragraph (b) mirrors language from the
[[Page 28334]]
proposal and specifies the mine operator's responsibility to conduct
sampling and implement additional or new corrective actions until a
subsequent sampling result indicates miner exposures are at or below
the PEL once corrective actions have been taken. Paragraph (c),
unchanged from the proposal, requires the mine operator to make a
record of corrective actions and the dates of those actions. Below is a
detailed discussion of the comments received on this section and
modifications made in response to the comments.
MSHA received several comments including an individual who is a
director at a pulmonary rehab center, advocacy organizations, and a
miner health advocate, recommending that mine operators stop all
production work and withdraw miners if samples are above the PEL
(Document ID 1445; 1395; 1396; 1425; 1394; 1399). Some commenters
(e.g., AFL-CIO and an individual) suggested MSHA should include an
upper exposure limit, above which operators would be required to
withdraw miners, with ACLC suggesting miners be withdrawn at 100 [mu]g/
m\3\ (Document ID 1449; 1367; 1445). Some commenters expressed concern
that allowing miners to continue working in hazardous dust levels
violates the Mine Act, with one stating that conditions above the PEL
should be considered an ``imminent danger'' under section 107(a) of the
Mine Act.
MSHA's existing health standards do not require the withdrawal of
miners when sampling is over the PEL and mine operators are taking
corrective actions, except in certain circumstances based on the risk
and exposure to the miner according to section 104(b) of the Mine Act.
Accordingly, under Sec. 60.13, mine operators must ensure that
affected miners wear respirators properly for the full shift or during
the period of overexposure while the mine operators are taking
immediate corrective actions to lower miner exposures to at or below
the PEL.
MSHA received several comments on the use of respirators while
corrective actions are being taken by the operator. A law firm said
respirators should be used permanently as a corrective action (Document
ID 1353). UMWA and Rep. Robert ``Bobby'' Scott opposed the mandatory
use of respirators and stated that mandating respirator use is
inconsistent with the Mine Act; UMWA instead supported the voluntary
usage of respirators as a supplement to engineering controls (Document
ID 1353; 1398; 1439). USW cautioned that the provision could allow mine
operators to justify respirator usage on more than a temporary basis
(Document ID 1447). The UMWA was also concerned that using respirators
as a mandatory temporary solution might lead to reduced use of
engineering and environmental methods as the primary means of
controlling exposures (Document ID 1398). ACLC stated that the language
is vague and unclear on how long miners will be required to rely on
respirators while corrective actions are being taken (Document ID
1445). Further, commenters including advocacy organizations, labor
organizations, MNM operators, an industry trade association, and a
medical professional association stated that the final rule needs to
clarify how long miners are allowed to wear respirators when their
exposure is over the PEL (Document ID 1404; 1421; 1425; 1432; 1439;
1440; 1445; 1447; 1449; 1393; 1395; 1396). AFL-CIO stated that
corrective actions should be strengthened to include actions other than
respirator use and if sampling shows that there is continued non-
compliance with the PEL there needs to be more significant corrective
actions taken to ensure that dust concentrations are reduced
permanently (Document ID 1449; 1353).
As explained earlier, respirator use is not allowed for compliance.
Under Sec. 60.13, if sampling shows exposure above the PEL, mine
operators are required to provide miners with approved respirators
before the next shift begins, and affected miners must wear respirators
properly for the full shift or during the period of overexposure until
miner exposures are at or below the PEL. This provides miners with
protection from respirable crystalline silica dust and thereby limits
the serious health effects associated with respirable crystalline
silica exposures until engineering controls are in place. Mine
operators must also immediately take corrective actions to lower the
concentration of respirable crystalline silica to at or below the PEL.
This approach is consistent with the NIOSH 1995 Criteria Document in
which NIOSH recommends the use of respirators as an interim measure
when engineering controls and work practices are not effective in
maintaining worker exposures at or below the PEL. Under this section,
MSHA emphasizes that respirators are to be used only while mine
operators take corrective actions to lower the concentration of
respirable crystalline silica to at or below the PEL. MSHA clarifies
that whenever exposures are over the PEL, corrective actions must be
taken and MSHA must be notified immediately.
Further, MSHA emphasizes that section 202(h) of the Mine Act, an
interim standard applicable to underground coal mine operators,
specifically prohibits operators from using respirators as a substitute
for engineering controls in the active workings. Section 202(h) of the
Mine Act provides that ``Respiratory equipment approved by the
Secretary and the Secretary of Health and Human Services shall be made
available to all persons whenever exposed to concentrations of
respirable dust in excess of the levels required to be maintained under
this chapter. Use of respirators shall not be substituted for
environmental control measures in the active workings.'' 30 U.S.C.
842(h). The final rule is consistent with the Mine Act, MSHA's existing
standards, and case law. See, e.g., Nat'l Min. Ass'n v. Sec'y, U.S.
Dep't of Lab., 812 F.3d 843, 884 (11th Cir. 2016) (upholding MSHA's
Lowering Miners' Exposure to Respirable Coal Mine Dust, Including
Continuous Personal Dust Monitors rule and noting ``MSHA has
interpreted the statutory command correctly, however, in requiring that
mine air quality meet the regulatory standard without resort to a
personal control''). MSHA clarifies that the final rule does not permit
the use of respirators in lieu of feasible engineering and
administrative controls.
MSHA believes the corrective actions provisions are appropriate and
requires mine operators to make changes to reduce miners' exposures to
respirable crystalline silica when exposures are above the PEL. MSHA
clarifies that respirator use is not a corrective action; the
corrective actions are those actions--such as watering roadways,
repairing or installing new water sprays, or repairing or installing a
new dust collection system--that reduce the respirable crystalline
silica concentration to at or below the PEL. MSHA will determine, on a
case-by-case basis, the adequacy of the corrective action that must be
taken immediately and the appropriate timeframe within which it must
occur. Although each engineering control employed as a corrective
action is different, mine operators are expected to minimize the time
spent performing corrective actions and, as a result, the time affected
miners spend using respirators. Any exposures over the PEL are a
violation of the standard. Additionally, when engineering controls are
being developed and implemented as a part of corrective actions, mine
operators are to continue corrective action sampling. Any operator
samples over the PEL, including corrective action sampling,
[[Page 28335]]
are to be reported to the District Manager. If sampling continues to be
over the PEL, the District Manager will take appropriate enforcement
actions and may provide assistance, depending on the circumstances.
Once corrective actions have been taken, the mine operator shall
conduct sampling pursuant to paragraph 60.12(b). The operator will need
to take additional or new corrective actions until sampling indicates
miner exposures are at or below the PEL. Further corrective action
sampling is discussed in Section VIII.B.5. Exposure Monitoring. Once
corrective actions have been implemented, the mine operator is expected
to make a record of the corrective actions promptly including the dates
of the corrective actions. Record keeping is further discussed in
Section VIII.B.9. Recordkeeping Requirements.
7. Section 60.14--Respiratory Protection
Section 60.14 expands on the requirements for the use of
respiratory protection for respirable crystalline silica. Section 60.14
paragraph (a) addresses MNM mines only. This paragraph requires the
temporary use of respirators at MNM mines when concentrations of
respirable crystalline silica are above the PEL. In a change from the
proposal, the final rule specifies that the requirements in paragraph
(a) only apply to MNM mines; coal mines are not covered under this
paragraph--coal mines are addressed under section 60.13 paragraph (a).
The Agency also removed the term ``non-routine'' from proposed
paragraph (a).
Paragraph (b), unchanged from the proposal, applies to all mines
and addresses circumstances where miners are medically unable to wear
respirators. Paragraph (c) also applies to all mines and addresses the
respiratory protection requirements. Paragraph (c)(1), which requires
mine operators to provide NIOSH-approved respirators to affected
miners, is unchanged from the proposed rule. Paragraph (c)(2) is
changed from the proposal and specifies that where approved respirators
are used mine operators must have a written respiratory protection
program in accordance with ASTM F3387-19 and lists the mandatory ASTM
program elements.
MSHA received many comments regarding the respiratory protection
provisions, with some commenters supporting the proposal and some
opposing it. After reviewing all the comments, MSHA concludes that the
proposed respiratory protection provisions should be retained, with
some modifications.
a. Section 60.14(a)--Temporary Use of Respirators at Metal and Nonmetal
Mines
Final 60.14(a) states that when MNM miners must work in
concentrations of respirable crystalline silica above the PEL while
engineering controls are being developed and implemented or it is
necessary by nature of the work involved, the mine operator shall use
respiratory protection as a temporary measure. In a change from the
proposal, MSHA removed the term ``non-routine'' from the paragraph
heading and clarified that the requirement for temporary use of
respirators is applicable only to MNM mines.
MSHA received several comments on the proposed temporary non-
routine use of respirators, with many commenters opposing the proposed
mandatory use requirement for coal mines. Commenters identified
difficulties in wearing respirators and stated that coal mine operators
must comply with existing standards for ventilation and dust control
plans, which have to be submitted to and approved by MSHA. Other
commenters expressed concern that there was an absence of a time limit
for which silica levels over the PEL are permitted.
Some advocacy organizations and a miner health advocate asked that
MSHA require mine operators to withdraw miners when sampling indicated
exposures above the PEL (Document ID 1445; 1395; 1367; 1396; 1425). A
medical professional also requested that MSHA require operators to
withdraw miners from hazardous conditions when sampling indicates they
are exposed to respirable silica above the PEL (Document ID 1394).
An individual stated that mine construction and coal production, in
particular, should be excluded from the circumstances in which
temporary and non-routine use of respirators are allowed (Document ID
1412). Many commenters including advocacy organizations, black lung
clinics, miner health advocates, and labor organizations suggested that
coal miners should be prohibited from working in overexposures while
using respirators, stating that the working conditions, especially in
underground coal mines, make it very difficult for miners to
communicate and work safely while wearing respirators (Document ID
1372; 1399; 1398; 1447; 1449; 1421; 1393; 1395; 1396; 1402; 1425; 1445;
1410; 1342; 1363; 1391; 1394). One of the labor organizations noted
that respirators do nothing to address bystander exposures (Document ID
1449).
After considering the comments, MSHA agrees, and clarifies that
paragraph (a) does not apply to coal mine operators. MSHA determined
that coal mine operators control silica and coal mine dust through
their approved ventilation and dust control plans. Underground coal
mine operators are required to have ventilation plans, which include a
respirable dust control plan, which must be submitted to and approved
by MSHA. See 30 CFR 75.370(a)(1). These plans must be revised to
address any overexposures to airborne contaminants. Surface coal mines
that have had a dust overexposure are required to develop and implement
respirable dust control plans that are approved by MSHA. See 30 CFR
71.300. For those areas of a surface coal mine where methane
accumulation is a hazard, such as tunnels and other enclosed working
areas, mine operators are required to dilute airborne contaminants with
ventilation controls.
In MSHA's experience, if there are overexposures to respirable
crystalline silica or coal mine dust, coal mine operators will adjust
their ventilation and dust controls to address these overexposures.
MSHA's experience has shown that these adjustments have generally been
successful in protecting miners from silica and dust exposures without
the need for respirators and that most conditions can be corrected
within a day. Additionally, as is currently the case when a respirable
coal dust overexposure occurs, under the final rule, citations for
respirable crystalline silica overexposures will require abatement
through immediate corrective actions before the citation is terminated.
MSHA sets any citation abatement deadline with the protection of the
miners as the primary consideration.
Also, the proposal was a departure from existing standards for coal
mine operators. Under the existing standards, coal mine operators have
to provide respiratory protection, but miners did not have to wear
respirators. Therefore, MSHA has changed this requirement in the final
rule to apply to MNM mines only for paragraph (a). MSHA reiterates
under Sec. 60.13(a) that coal mine operators must use respirators when
sampling indicates that a miner's respirable crystalline silica
exposure exceeds the PEL.
Commenters including advocacy organizations, labor organizations,
MNM operators, an industry trade association, and a medical
professional association requested that MSHA clarify the meaning of
``temporary non-routine''
[[Page 28336]]
to specify circumstances and time limitations (Document ID 1393; 1395;
1396; 1425; 1445; 1447; 1449; 1432; 1440; 1404; 1421; 1409; 1439;
1364). Some advocacy organizations and a labor organization asked that
MSHA define ``temporary'' use for coal mines (Document ID 1393; 1395;
1449). One of the labor organizations noted that, without defined time
limits, operators could require miners to wear respirators for weeks or
months (Document ID 1449).
MSHA agrees with the commenters who stated that the meaning of
``temporary non-routine'' needed to be clarified. MSHA removed ``non-
routine'' from the paragraph heading for clarity and to be more
consistent with the existing requirements for MNM mine operators in
Sec. Sec. 56.5005 and 57.5005. Final paragraph (a) applies only to MNM
operators, is consistent with the existing requirements for controlling
exposure to airborne contaminants in Sec. Sec. 56.5005 and 57.5005 and
is responsive to comments.
Final paragraph (a)(1) requires respirator use as a temporary
measure while MNM miners must work in concentrations of respirable
crystalline silica above the PEL while engineering control measures are
being developed and implemented. Final paragraph (a)(2) includes a
clarifying change from the proposal to include an example in the
existing MNM standard that requires MNM mine operators to use
respirators in temporary situations when it is necessary by the nature
of work involved (for example, occasional entry into hazardous
atmospheres to perform maintenance or investigation) when miners are
working in concentrations of respirable crystalline silica above the
PEL. Several existing MSHA standards use the term ``temporary''
although the Agency does not specify a time limit. The mining industry
is familiar with these standards. MSHA expects ``temporary'' to have
the same meaning as in existing standards--a short period of time.
Under existing standards, MNM miners can work for reasonable
periods of time in concentrations of airborne contaminants exceeding
permissible levels if they are protected by approved respirators when
developing and implementing engineering control measures or when
necessary by the nature of work involved. Under these existing MNM
standards, mine operators who have overexposures and are required to
provide respiratory protection to miners are issued a citation for the
overexposure. Generally, if MNM mine operators have a written
respiratory protection program in place, the citation would be non-
Significant and Substantial.
MSHA has always intended for miners to work in these conditions
temporarily and the agency has enforced it as such. The final rule thus
does not make any substantive changes from the existing standard in
MNM. The update in language from ``reasonable periods of time'' to
``temporary'' in the final rule is an update in line with MSHA's
original intent and as previously noted, with other existing MSHA
standards. Husch Blackwell (on behalf of the SSC), NSSGA, U.S. Silica,
and IAAP stated that respirators are the only feasible means of
protection for certain tasks in mining environments, such as
housekeeping, working on dust collectors, and bagging operations
(Document ID 1432; 1448; 1455; 1456). MSHA emphasizes that respiratory
protection under Sec. 60.14 (a) is required to be temporary. The
Agency intends for temporary to mean that miners wear respiratory
protection only for short periods of time; for example, the time
necessary to conduct maintenance and repair of engineering controls.
Similar to existing MNM standards, the Agency, under this final rule,
does not intend that miners will wear respirators for extended periods
of time. As an example, when a crusher needs maintenance or repair
after an overexposure resulting from a defective water spray bar,
miners must wear respiratory protection when performing maintenance or
conducting repairs to the spray bar. Another example includes when
miners change defective dust bags that can cause overexposures to
respirable crystalline silica; when replacing the dust bags, miners
must wear respiratory protection.
After reviewing these comments, MSHA revised paragraph (a)(2) to
provide a clarifying example on when MNM mine operators would
temporarily use respirators due to the nature of the work involved.
Under the final rule, the Agency prohibits use of respirator to achieve
compliance with the PEL. In response to the comment that respirators
are the only means to achieve compliance for certain mining tasks, MSHA
has reviewed its sample data and has determined that mine operators are
generally able to achieve compliance with existing engineering
controls, supplemented by administrative controls. MSHA is aware that
certain mining tasks related to maintenance and repair of engineering
controls will require respiratory protection. However, MSHA anticipates
that respirator use will be temporary, until controls are repaired and
effective, and respirator use will not be considered as a means to
achieve compliance. This clarifying change on the use of respirators
for certain tasks such as the occasional entry into hazardous
atmospheres to perform maintenance or investigation, is consistent with
the Agency's existing standards.
A joint comment by The American Thoracic Society et al. suggested
that temporary reliance on respirator use be limited to miners actively
working at the time it is noted that silica exceeds the PEL, and only
for as long as it takes to safely shut down operations (Document ID
1421). The AFL-CIO suggested that MSHA treat respirator use as a
variance from normal activity, requiring operators to prove when
respirator use is necessary (Document ID 1449).
MSHA understands that respirator use under paragraphs (a)(1) and
(a)(2) will be different depending on the facts and circumstances in
the MNM mines and that the temporary nature of respirator use will
depend on the time needed to correct an overexposure. MSHA will
determine the time required for temporary respirator use on a case-by-
case basis. MSHA emphasizes that the District Manager will be informed
of all overexposures under 60.12(b). MSHA can take enforcement action,
including issuing a withdrawal order under 104(b) of the Mine Act, if
the facts and circumstances at the mine require it.
An individual stated that the proposed rule rejected respirator use
as a method of compliance in the preamble to Sec. 60.11 but proposed
Sec. 60.14 appeared to contradict the prohibition (Document ID 1412).
The Black Lung Clinics stated there is no real-time feedback for
determining whether a respirator is effectively reducing exposure
levels (Document ID 1410) which may provide a false sense of security
that the miner is protected from cumulative exposures to respirable
crystalline silica.
In response, MSHA clarifies that there is not a contradiction
between Sec. 60.11 and Sec. 60.14. Final rule Sec. 60.11 requires
engineering controls supplemented by administrative controls to reduce
exposures. In MSHA's experience, miners who use respirators under a
respiratory protection program that is in accordance with MSHA's
standards are protected from cumulative exposures to airborne hazards.
Final Sec. 60.14(a) additionally requires the use of respirators in
MNM mines in case of an overexposure; however, MNM mine operators will
be cited for the overexposure. This is consistent with MSHA's existing
standards and enforcement practice for MNM mines.
[[Page 28337]]
Comments from MNM mining operators, mining trade associations, and
state mining associations suggested that, consistent with the OSHA
rule, MSHA should allow operators to use respirators as a method of
compliance where engineering and administrative controls are unable to
reduce silica levels below the PEL (Document ID 1368; 1424; 1428; 1441;
1448; 1455). The NMA stated that respirators, including PAPRs, should
be allowed to be used whenever miners are working in exposures above
the PEL (Document ID 1428). The Pennsylvania Coal Alliance and
Vanderbilt Minerals, LLC stated that PAPRs are comfortable to wear for
long periods and do not restrict breathing (Document ID 1378; 1419). In
contrast, three labor organizations opposed the use of respirators
(Document ID 1398; 1447; 1449). These commenters stated that the Mine
Act forbids respirator use as a mandatory administrative control or as
a substitute for environmental controls and noted that the proposed
rule allowed for continued production with respirators in hazardous
silica dust levels. A medical professional stated that miners should
always use respirators, to ensure complete protection from respirable
crystalline silica exposures (Document ID 1375).
MSHA disagrees with these commenters that respirators should be
used as a method of compliance or that miners should always use
respirators. MSHA has determined that respirators cannot be used as a
method of compliance. Respirators do not provide effective protection
from overexposures for various reasons that include: (1) without a
proper fit, dust particles enter the miner's breathing zone; (2)
inconsistent or incorrect use can compromise the effectiveness of the
respirator; and (3) respirators can hinder effective communication
among miners. MSHA has decided that respirators must not be used for
compliance because they do not address the dust generation at the
source. Engineering controls are reliable, provide consistent levels of
protection to many miners, allow for predictable performance levels,
can be monitored continually, and can remove harmful levels of airborne
contaminants, including respirable crystalline silica, from the miner's
environment. However, MSHA recognizes that respirators must be used, on
a temporary basis, for certain mining tasks.
MSHA has provided greater health protection for miners by requiring
(as opposed to making available) use of respirators for coal miners
when exposed to respirable crystalline silica above the PEL, while
continuing necessary protection for MNM miners. Also, in Section VII.A.
Technological Feasibility, MSHA has determined that it is
technologically feasible for mine operators to achieve the PEL using
commercially available engineering controls.
Engineering controls are reliable, provide consistent levels of
protection to many miners, allow for predictable performance levels,
can be monitored continually, and can remove harmful levels of airborne
contaminants, including respirable crystalline silica, from the miner's
environment.
The AFL-CIO stated that mine operators should be required to submit
scenarios where respirators are necessary under limited circumstances
and if MSHA does not have evidence respirators are needed for a
particular task, they should not be permitted (Document ID 1449). After
considering this comment, MSHA has decided not to require MNM mine
operators to submit scenarios, or plans, for the temporary use of
respirators because MSHA approval takes time and, in the Agency's
experience, there are unforeseen circumstances in a mine that may
require the immediate implementation of engineering controls. When
overexposures to respirable crystalline silica occur, paragraph
60.13(a)(3) requires the mine operator to take immediate corrective
actions to lower concentrations of respirable crystalline silica to at
or below the PEL. Therefore, requiring mine operators to submit a plan
and receive MSHA approval before implementing changes would allow
respirable crystalline silica exposures above the PEL to remain
uncorrected for longer than necessary, and put miners' health at risk.
b. Section 60.14(b)--Miners Unable To Wear Respirators at All Mines
The final rule is changed from proposed paragraph 60.14(b). MSHA
has revised the heading for paragraph (b) to include ``at all mines''
so that it is clear that paragraph (b) is applicable to miners unable
to wear respirators at MNM and coal mines. Paragraph (b)(2) is also
changed from the proposal to remove ``non-routine.'' This change is
made to be consistent with the change discussed in paragraph (a). The
rest of paragraph (b) is unchanged from the proposal. Paragraph (b)
requires that, upon written determination by a PLHCP that an affected
miner is unable to wear a respirator, the miner be temporarily
transferred to work in a separate area of the same mine or to an
occupation at the same mine where respiratory protection is not
required. Paragraph (b)(1) states that the affected miner shall
continue to receive compensation at no less than the regular rate of
pay in the occupation held by that miner immediately prior to the
transfer. Paragraph (b)(2) states the affected miner may be transferred
back to the miner's initial work area or occupation when temporary use
of respirators is no longer required.
The USW supported the temporary transfer of miners unable to wear
respirators (Document ID 1447) while the Arizona Mining Association
stated that it would be challenging to transfer miners who cannot wear
respirators to another location or occupation where respirators are not
needed (Document ID 1368).
After reviewing the comments, MSHA has determined that no change to
the proposal is necessary. MSHA believes that it should not be
difficult for a mine operator to temporarily transfer miners to a
separate area or occupation to ensure their health and safety. Under
the rule, the concentration of respirable crystalline silica to which
the miner is exposed must be controlled through feasible engineering
and administrative controls; therefore, instances in which a miner is
transferred because of an inability to wear a respirator should be
infrequent. Miners may be able to work in other areas of the mine where
respirable crystalline silica concentrations are under the PEL.
Furthermore, under paragraph (b)(2) the miner may be transferred back
to the initial work area or occupation when the limited use of
respirators is no longer required.
c. Section 60.14(c)--Respiratory Protection Requirements at All Mines
The final rule is changed from proposed paragraph (c). MSHA has
revised the heading for paragraph (c) to include ``at all mines'' so
that it is clear that paragraph (c) is applicable to MNM and coal
mines. Paragraph (c)(1) is adopted as proposed and requires mine
operators to provide affected miners with a NIOSH-approved atmosphere-
supplying respirator or NIOSH-approved air-purifying respirator
equipped with particulate protection classified as 100 series under 42
CFR part 84 or particulate protection classified as High Efficiency
``HE'' under 42 CFR part 84.
Some commenters, including mining and industry trade associations,
stated that the NIOSH Pocket Guide to Chemical Hazards recommends the
use of N-, R-, or P-95 and 99 series respirators to lower miners'
exposures to respirable crystalline silica and suggested MSHA revise
the final rule to also allow for these respirators
[[Page 28338]]
(Document ID 1407; 1419; 1424; 1428; 1442; 1448). Some mining trade
associations and MNM mine operators recommended that MSHA specifically
allow the use of PAPRs, (Document ID 1424; 1428; 1378; 1419; 1452).
After reviewing comments, MSHA has decided to maintain paragraph
(c)(1) in the final rule, as proposed. N-, R-, or P-95 and 99
respirators may provide an appropriate level of filtration when
properly fitted, worn, and maintained; however, MSHA has observed that
the structural integrity of these respirators is very easily
compromised in the harsh mining environment. N-, R-, or P-95 and 99
respirators are not as durable as other types of air-purifying
respirators. N-, R-, or P-95 and 99 respirators are easily
contaminated, damaged, and deformed and must be routinely replaced to
maintain effectiveness. Also, the N-, R-, or P-95 and 99 respirators do
not hold their shape or maintain an effective seal when they become
wet. N-, R-, or P-95 and 99 respirators that are damaged or deformed
provide little, if any, protection and may offer a false sense of
security to miners. MSHA recognizes that PAPRs may be more comfortable
to wear than full-face or half-face, tight-fitting air purifying
respirators; however, PAPRs are still not as reliable or effective as
engineering controls and are not a permanent solution. PAPRs add noise
from the fan and the full-face covering making it difficult for the
miner to hear or communicate effectively, which could subject the miner
to hazards while working. They may also reduce the miner's peripheral
vision and decrease the wearer's situational awareness around equipment
or other mining hazards. PAPRs, like full-face or half-face, tight-
fitting air purifying respirators, must be worn only as a temporary
measure in accordance with paragraph 60.14(b).
MSHA believes that air-purifying respirators classified as 100
series or High Efficiency under the NIOSH classifications for
particulate protection will provide the maximum level of protection
when miners are wearing respirators and are most suitable in protecting
the health and safety of miners from occupational exposure to
respirable crystalline silica when exposures are above the PEL.
Paragraph (c)(2) is modified from the proposal and requires that
when approved respirators are used, the mine operator must have a
written respiratory protection program that meets the following
requirements in accordance with ASTM F3387-19: program administration;
written standard operating procedures; medical evaluation; respirator
selection; training; fit testing; maintenance, inspection, and storage.
The proposal did not specify the requirement for a written respiratory
protection program or list the mandatory program elements. The language
in the final rule is consistent with the requirements of ASTM F3387-19,
Standard Practice for Respiratory Protection, which is incorporated by
reference.
MSHA received comments on the incorporation by reference of ASTM
F3387-19, with some commenters supporting the proposal and some
commenters opposing it. An industrial hygiene professional association,
labor organization and a mining related business supported the proposal
to update the existing respirator protection standard (Document ID
1351; 1398; 1392). The AIHA and UMWA stated that the proposed
incorporation by reference of ASTM F3387-19 to amend the Agency's
respiratory protection program to current and comprehensive
requirements was appropriate (Document ID 1351; 1398). The AEMA and
NMA, who opposed the proposal, stated that MSHA should not reference
the ASTM F3387-19 requirements if the Agency does not allow the use of
respirators for compliance purposes (Document ID 1424; 1428).
Vanderbilt Minerals, LLC asserted that incorporating ASTM F3387-19 is
beyond MSHA's statutory authority and conflicts with the intent of the
Mine Act (Document ID 1419).
As discussed in Section II Pertinent Legal Authority, the Mine Act
requires the Secretary to develop and promulgate improved mandatory
health or safety standards to prevent hazardous and unhealthy
conditions and protect the health and safety of the nation's miners. 30
U.S.C. 811(a). Section 101(a) of the Mine Act gives the Secretary the
authority to develop, promulgate, and revise mandatory health standards
to address toxic materials or harmful physical agents. Under Section
101(a), a standard must protect lives and prevent injuries in mines and
be ``improved'' over any standard that it replaces or revises. MSHA
believes the incorporation by reference of ASTM F3387-19 is an
improvement over the ANSI 1969 standard which it replaces. MSHA's
incorporation by reference of ASTM F3387-19 is consistent with the Mine
Act and OMB Circular A-119, ``Federal Participation in the Development
and Use of Voluntary Consensus Standards and in Conformity with
Assessment Activities'' (81 FR 4673). The OMB Circular directs agencies
to use voluntary consensus standards in lieu of government-unique
standards, except where inconsistent with law or otherwise impractical.
The AIHA, NMA, and EMA stated that the proposed ASTM F3387-19
standard's requirements were too prescriptive and asked that MSHA give
operators the flexibility to select the elements of that standard that
are most applicable to their own needs and the hazards at their mines
(Document ID 1451; 1441; 1442). The AFL-CIO expressed concern that mine
operators would be allowed to determine which parts of the respiratory
standard they will follow and urged MSHA to require certain components
(Document ID 1449). The AEMA stated that the final rule should clarify
whether a specific written respiratory protection program is required
and under what standards (Document ID 1424). The AEMA also asked for
more clarity from MSHA on what elements of ASTM F3387-19 will be
required when respiratory protection for miners is needed.
The CISC, MSHA Safety Services, Inc., and Tata Chemicals Soda Ash
Partners, LLC recommended that MSHA align the respiratory protection
requirements with OSHA's requirements (Document ID 1430; 1392; 1452).
Draeger Inc. asked that MSHA include in the rule additional specific
provisions of ASTMF3387-19, such as the breathing gas requirements in
section 13 of the ASTM F3387-19 standard and wearer seal checks, and
also suggested that MSHA add requirements to the fit testing procedures
to include physical movements that are more relevant to low-seam coal
mines (Document ID 1409).
The Agency agrees with commenters who expressed that the
requirements of the respiratory protection program are appropriate, and
the Agency makes clarifying changes to the requirements in the final
rule. The Agency has clarified paragraph (c)(2) to state the specific
respiratory protection program requirements. In paragraph (c)(2), MSHA
has deleted ``as applicable'' and added that, when respirators are
used, a mine operator must have a written respiratory protection
program that meets the following requirements in accordance with ASTM
F3387-19: program administration; written standard operating
procedures; medical evaluation; respirator selection; training; fit
testing; maintenance, inspection, and storage. MSHA has the authority,
both under the Mine Act and Federal regulatory guidelines, to include
the incorporation by reference of consensus standards such as ASTM
F3387-19. The Mine Act specifically requires MSHA to issue improved
mandatory safety and
[[Page 28339]]
health standards. The incorporation by reference of ASTM F3387-19 is an
improved standard.
MSHA received a comment from the MCPA asserting that the medical
evaluation and fit testing requirements for respirators in ASTM F3387-
19 were too rigorous because there may be situations where a miner
fails a medical evaluation or fit test simply due to personal desires,
such as having a beard (Document ID 1406).
MSHA believes that the medical evaluation and fit testing
requirements for use of respirators are appropriate because they are
critical to ensuring proper protection and safe respirator use for
respirator wearers who are exposed to airborne contaminants. In
addition, medical evaluations and fit tests are required under MSHA's
current respiratory protection standard (ANSI Z88.2-1969). Therefore,
mine operators who have used respirators previously should be familiar
with these requirements.
MSHA incorporates by reference this consensus standard for two
reasons. ASTM F3387-19 reflects current respirator technology and
accepted effective respiratory protection practices. For example, ASTM
F3387-19 provides detailed information on respirator selection that is
based on NIOSH's research and long-standing experience of testing and
approving respirators for occupational use and OSHA's respiratory
protection standards. The ASTM F3387-19 standard is prepared and
maintained by subject matter experts, using a rigorous and well-defined
process. The standard is reviewed by internationally recognized experts
and is approved for use only if the appropriate procedures are
followed. In addition, adopting voluntary consensus standards is
consistent with OMB Circular A-119.
MSHA has observed that many operators, especially larger mine
operators, have already implemented respiratory protection programs
that meet many of the OSHA requirements, which are substantially
similar to many requirements in ASTM F3387-19. In response to
commenters who suggested that MSHA adopt the OSHA respiratory
protection standards, ASTM F3387-19 references OSHA's respiratory
standards that include assigned protection factors and maximum use
concentrations, and fit testing. MSHA believes that the mining industry
is familiar with many provisions in ASTM F3387-19. MSHA anticipates
that for many large mine operators, few changes to their respiratory
protection program may be warranted, whereas small mines may need to
revise their respiratory protection programs in accordance with the
requirements in ASTM F3387-19. The program requirements are discussed
in more detail in Section VIII.D. Updating MSHA Respiratory Protection
Standards: Incorporation of ASTM F3387-19 by Reference.
Other Comments
The AIHA stated that respirators should be used only under a
comprehensive respiratory protection program and under the supervision
of an industrial hygienist (Document ID 1351). AIHA suggested that MSHA
should refer to the most recent edition of ASTM's respiratory
protection standard and not the 2019 edition, which may become obsolete
by the time the silica standard is adopted.
According to the Office of the Federal Register, MSHA is required
to inform the public of the standard to be incorporated and the
specific edition that the Agency intends to require. In the proposed
rule, MSHA proposed to incorporate the 2019 edition of ASTM F3387,
which is the most recent respiratory protection standard. MSHA is
incorporating by refence ASTM F3387-19 in this final rule. MSHA is
aware that larger mines may have an industrial hygienist or safety
specialist administer their respiratory protection program; this
practice is consistent with, but not required by, the ASTM F3387-19
standard's requirements for program administration. ASTM F3387-19
specifies that responsibility and authority for the respirator program
should be assigned to a single qualified person with sufficient
knowledge of respiratory protection. Qualifications could be gained
through training or experience; however, the qualifications of a
program administrator must be commensurate with the respiratory hazards
at the mine site.
The program administrator should have access to and direct
communication with the site manager about matters impacting worker
safety and health. ASTM F3387-19 notes a preference that the
administrator be in the company's industrial hygiene, environmental,
health physics, or safety engineering department; however, a third-
party entity that meets the standard's requirements may also provide
this service. ASTM F3387-19 outlines the respiratory protection program
administrator's responsibilities, specifying that they should include:
measuring, estimating, or reviewing information on the concentration of
airborne contaminants; ensuring that medical evaluations, training, and
fit testing are performed; selecting the appropriate type or class of
respirator that will provide adequate protection for each contaminant;
maintaining records; evaluating the respirator program's effectiveness;
and revising the program, as necessary.
8. Section 60.15--Medical Surveillance for Metal and Nonmetal Mines
The final rule establishes requirements for medical surveillance
for MNM mines in Sec. 60.15. Paragraph (a) requires MNM mine operators
to provide each miner periodic medical examinations performed by a
PLHCP or specialist, at no cost to the miner. In a change from the
proposal, under paragraph (a)(2)(iv), MSHA adds that the pulmonary
function test may also be administered by a pulmonary function
technologist with a current credential from the National Board for
Respiratory Care. The rest of paragraph (a) remains unchanged from the
proposal.
Paragraph (b) establishes the requirements for each MNM mine
operator to provide voluntary medical examinations every 5 years to all
miners employed at the mine or who have already worked in the mining
industry. In a change from the proposal, new paragraph (b)(1) specifies
that the voluntary medical examinations must be offered during an
initial 12-month period. New paragraph (b)(2), the same as proposed
paragraph (b), requires mine operators to continue to offer voluntary
medical examinations after the period in paragraph (b)(1) at least
every 5 years during a 6-month period that begins no less than 3.5
years and not more than 4.5 years from the end of the last 6-month
period.
Paragraph (c) specifies that each mine operator is required to
provide the medical examinations specified in paragraph (a) to each
miner who begins work in the mining industry for the first time. In a
change from the proposal, paragraph (c)(1) requires the initial medical
examination to take place no later than 60 days after beginning
employment (instead of 30 days). Paragraphs (c)(2) and (c)(3) remain
unchanged from the proposal.
Paragraph (d) specifies the requirements for medical examination
results. In a change from the proposal, paragraph (d)(1) specifies that
the medical examination results must be provided from the PLHCP or
specialist within 30 days of the medical examination. Like the
proposal, the medical examination results must be provided to the
miner, and at the request of the miner, to the miner's designated
physician. In a change from the proposal, the medical examination
results may also be provided, at the request of the miner, to another
[[Page 28340]]
designee identified by the miner. In a change from the proposal,
paragraph (d)(2) specifies that within 30 days of the medical
examination, the mine operator must ensure that the PLHCP or specialist
also provide the results of chest X-ray classifications to NIOSH, once
NIOSH establishes a reporting system. Paragraph (e) specifies the
requirements for the written medical opinion and is unchanged from the
proposal. Paragraph (f) requires mine operators to maintain a record of
the written medical opinions received from the PLHCP or specialist
under paragraph (e) and is unchanged from the proposal.
MSHA received several comments regarding the medical surveillance
provisions for MNM mines, offering both support and opposition. The
PACA, IAAP, and CalCIMA opposed the proposal, stated that the
requirements were too prescriptive, and asked that MSHA give operators
more flexibility in implementing medical surveillance programs
(Document ID 1413; 1456; 1433). A mining-related business owner
asserted that medical surveillance requirements are not needed, stating
that there is a lack of silicosis cases in MNM miners (Document ID
1392).
Three commenters--an elected federal official, a miner health
clinic, and a medical association--supported the proposal and asserted
that the medical surveillance requirements would help MNM miners track
their respiratory health and mitigate risks for silica-related chronic
diseases (Document ID 1439; 1418; 1373). Two unions, the AFL-CIO and
the USW, stated that both MNM and coal miners should be provided with
the same level of protection and care through their medical
surveillance programs (Document ID 1449; 1447).
After reviewing the comments, MSHA concludes that the proposed
medical surveillance provisions for MNM mines should be retained, with
some modifications. As discussed in Section V. Health Effects Summary
and Section VI. Final Risk Analysis Summary of this preamble, many MNM
mining activities generate silica dust and could lead to respirable
crystalline silica exposures that result in adverse health effects such
as silicosis. MSHA agrees with commenters who stated that the medical
surveillance requirements will provide MNM miners with health
information that could prevent silica-related diseases and believes it
is necessary to include the medical surveillance requirements in the
final rule. The Agency has determined that all MNM miners receive the
same medical examination protections under the final rule.
Some commenters requested that the Agency use a risk-based approach
for medical surveillance. The NMA, NSSGA, AEMA, and SSC urged MSHA to
adopt OSHA's risk-based medical surveillance framework, which requires
medical monitoring only for those miners exposed to respirable silica
above the action level for more than 30 days per year (Document ID
1428; 1448; 1424; 1432).
The Agency disagrees with this approach. Unlike OSHA's silica
standard, the final rule does not include an exposure trigger provision
because the Agency believes it is important to maintain consistency
between the medical surveillance requirements for MNM and coal mines to
ensure all miners have the information necessary for the early
detection of silica-related disease. The purpose of medical
surveillance is to provide MNM miners necessary information to
determine if their health may be adversely affected by exposure to
respirable crystalline silica and enable miners to take appropriate
action to stop further disease progression.
Below is a detailed discussion of the comments received on this
section and modifications made in response to the comments.
a. 60.15(a)--Medical Surveillance
Paragraph Sec. 60.15(a) requires that each MNM mine operator make
medical examinations, performed by a PLHCP or specialist, available to
each MNM miner, at no cost to the miner. Mine operators must ensure
that medical examinations follow the requirements under Sec.
60.15(a)(2)(i)-(iv). In a change from the proposed rule, under
paragraph (a)(2)(iv), MSHA adds that the pulmonary function test may be
administered by a pulmonary function technologist with a current
credential from the National Board for Respiratory Care.
MSHA received several comments on proposed paragraph 60.15(a). The
AIHA, AANP, and CertainTeed, LLC supported MSHA's proposal to require
MNM mine operators to provide MNM miners with medical examinations
performed by a PLHCP or specialist and agreed with MSHA's broad
definition of PLHCP (Document ID 1351; 1400; 1423). The BIA and the
Arizona Mining Association expressed concerns with this requirement and
asserted that many MNM mines may experience issues with getting access
to a PLHCP or specialist qualified to perform the examinations
(Document ID 1422; 1368). The APHA and AOEC advocated for medical
surveillance to be performed only by physicians who are board-certified
in occupational medicine or pulmonary medicine, or who have experience
in silica medical surveillance (Document ID 1416; 1373). Two commenters
recommended that MNM miners should be able to choose their own health
care provider (Document ID 1439; 1412). The Arizona Mining Association
inquired about whether medical examinations may be incorporated within
the mine operator's health care plans (Document ID 1368).
After reviewing the comments, MSHA adds under paragraph (a)(2)(iv)
that the pulmonary function test may be administered by a pulmonary
function technologist with a current credential from the National Board
for Respiratory Care. This option will provide a larger pool of
qualified respiratory care professionals who may administer pulmonary
function tests.
MSHA believes that MNM mine operators should not encounter any
significant issues with identifying and hiring a qualified PLHCP or
specialist to conduct medical examinations. The final rule provides
flexibility in the selection of health care professionals. As discussed
in Sec. 60.1, the final rule allows MNM mine operators more time to
comply; MNM mine operators will have 24 months after the publication of
the final rule, rather than 4 months after the publication of the final
rule as specified in the proposed rule. This additional time addresses
commenters' concerns about time needed for establishing a medical
surveillance program.
The Agency also clarifies that mine operators may give miners the
option to choose their own health care provider, if the provider meets
the requirements of this section. As stated in the proposal, a
qualified PLHCP is an individual whose legally permitted scope of
practice (i.e., license, registration, or certification) allows that
individual to independently provide or be delegated the responsibility
to provide the required health services (i.e., chest X-rays,
spirometry, symptom assessment, and occupational history).
``Specialist'' is defined in Sec. 60.2 as an American Board-Certified
Specialist in Pulmonary Disease or an American Board-Certified
Specialist in Occupational Medicine.
MSHA does not require medical examinations in the final rule to be
performed only by physicians who are board-certified in occupational
medicine or pulmonary medicine, because PLHCPs may have the knowledge
and skills to conduct these examinations independently or under
[[Page 28341]]
the supervision of board-certified specialists. MSHA believes this will
provide mine operators more provider choices and improve accessibility
to PLHCPs for miners. MSHA also clarifies that medical examinations may
be integrated into mine operators' health care plans; while noting that
in such cases, mine operators must ensure that the examinations are
conducted in accordance with the requirements in Sec. 60.15. The final
rule ensures that medical examinations are comprehensive and tailored
to identify and mitigate potential health risks associated with miners'
occupational exposures to respirable crystalline silica. The final rule
will ensure that the medical examinations provide MNM miners with
health surveillance information so that they are aware of the early
development and advancement of any silica-related disease.
The Agency received comments regarding the use of NIOSH facilities
and NIOSH B Readers. The American Industrial Hygiene Association and
National Coalition of Black Lung and Respiratory Disease Clinics stated
that MSHA should require MNM operators to use NIOSH-approved facilities
(Document ID 1351; 1410). However, several commenters, including the
ACOEM, NLA, NVMA, and NSSGA, expressed concerns about the limited
availability and geographic distribution of these facilities (Document
ID 1405; 1408; 1441; 1448). The NMA, Portland Cement Association, and
AEMA noted that there are only a limited number of B Readers available
(Document ID 1428; 1407; 1424). The Black Lung Clinics supported MSHA's
assertion that the availability of digital radiography allows for the
electronic transmission of chest radiographs to remotely located B
Readers (Document ID 1410).
MSHA agrees with commenters who expressed concerns about the
accessibility of NIOSH-approved facilities, and, like the proposal, the
final rule does not include a requirement to use such facilities. MSHA
believes that requiring a NIOSH-certified B Reader to classify chest X-
rays and requiring either a spirometry technician with a current
certificate from a NIOSH-approved Spirometry Program Sponsor or a
pulmonary function technologist with a current credential from the
National Board for Respiratory Care to perform pulmonary function
tests, will ensure that miners receive the necessary standard of care
to protect their health while providing broader access to PLHCPs. As
did OSHA in its 2016 silica final rule (81 FR 16286, 16821), MSHA has
determined that the number of B Readers in the United States is
adequate to classify the additional chest X-rays that will be required
under this rule. In addition, digital X-rays can be transmitted
electronically to B Readers anywhere in the United States, so this
requirement will provide operators greater access to B Readers.
Further, as discussed more below, under Sec. 60.15(d)(2), mine
operators are required to ensure that, within 30 days of the medical
examination, the PLHCP or specialist provides the results of chest X-
ray classifications to NIOSH, once NIOSH establishes a reporting
system.
In the proposed rule, MSHA solicited comment on whether other
diagnostic technology, such as high-resolution computed technology
(CT), should be included in the final rule. The AOEC, APHA, USW, and a
medical professional urged MSHA to include a low-dose CT scan, either
as a primary test or if recommended by the examining clinician, because
such scans are more sensitive than conventional chest radiographs and
would facilitate earlier detection of disease or dysfunction (Document
ID 1373; 1416; 1447; 1437). The UMWA cautioned against requiring CT
scans because they are not as readily available and are more costly
(Document ID 1409). The American Thoracic Society et al. commented and
acknowledged the benefits of low-dose chest CT scans for individual
disease detection but noted that such a requirement might limit
population-level disease surveillance because of a lack of
standardization for interpreting CT scans for diagnosing pneumoconiosis
(Document ID 1421). The AFL-CIO highlighted other initiatives such as
the Worker Health Protection Program and the Building Trades National
Medical Screening Program that provide low-dose CT scans through a
mobile van to serve smaller population centers and suggested that
similar programs could be created for MNM miners (Document ID 1449).
MSHA agrees with commenters regarding the cost concerns and limited
availability of low-dose chest CT scans. MSHA is aware that there are
increased health risks from higher radiation exposures from screening
with low dose chest CT scans. MSHA is also aware that ``ultra-low-
dose'' methods for CT scans are available that would subject the miner
to lower radiation doses than other screening chest CT scans; however,
this method is not widely available and is therefore not a practical
resource for mine operators at this time. Also, as a medical
professional association acknowledged, low-dose chest CT scans do not
have a standard for the classification of the results, unlike
classification standards for chest X-rays (Document ID 1421). For the
reasons above, the final rule does not add CT scans to the medical
examination requirements in Sec. 60.15(a).
The Agency received some comments recommending adding testing
requirements. The Miners Clinic of Colorado and the Black Lung Clinics
suggested requiring diffusion capacity testing as a pulmonary function
test (Document ID 1418; 1410). MSHA considered these comments and
determined that diffusion capacity testing is not as widely available
as forced vital capacity (FVC) and forced expiratory volume tests
(i.e., spirometry tests). Spirometry is the most common and widely used
lung function test. The final rule does not add diffusion capacity
testing to the medical examination requirements in Sec. 60.15(a).
MSHA also received comments on tuberculosis testing requirements.
Commenters--the AOEC, APHA, and the NSSGA--recommended that a test for
latent tuberculosis be required as an initial test or if recommended by
the examining PLHCP, noting that it is included in OSHA's silica
standard (Document ID 1373; 1416; 1448). However, the Portland Cement
Association argued that testing for tuberculosis is unnecessary
(Document ID 1407). After considering these comments, MSHA has decided
not to include a tuberculosis test requirement because it would be
duplicative of the information provided in the medical and work history
examination, which requires an assessment of the miner's history of
tuberculosis under Sec. 60.15(a). The Agency determined that the
information gathered through the medical and work history examination
will effectively screen for tuberculosis. In MSHA's experience,
tuberculosis is not a significant health concern in the MNM mining
industry.
b. 60.15(b)--Voluntary Medical Examinations
Final 60.15(b) requires mine operators to provide the opportunity
to all miners employed at the mine to have the medical examinations
under 60.15(a). Based on its review of the comments, MSHA has modified
the language to clarify the timing of medical examinations. Under final
paragraph (b), MNM mine operators must provide the opportunity for
miners to receive medical examinations as specified under (b)(1) and
(b)(2). This applies to all MNM miners who are not new to the mining
industry. Miners who are new to the industry are required to receive
medical examinations as specified under paragraph (c).
[[Page 28342]]
Paragraph (b)(1) requires mine operators to provide medical
examinations during an initial 12-month period. This change ensures
that examinations are offered to miners during a 12-month period that
begins by the compliance date or during a 12-month period that begins
whenever a new mine commences operation.
Under paragraph (b)(2), mine operators must provide subsequent
medical examinations to miners not new to the mining industry at least
every 5 years after the period in paragraph (b)(1). The medical
examinations must be available during a 6-month period that begins no
less than 3.5 years and not more than 4.5 years from the end of the
last 6-month period. As discussed in Section VII.A. Technological
Feasibility, MSHA has determined that it is technologically feasible
for MNM mine operators to provide periodic examinations. Miner
participation would be voluntary, as is the case for coal miners in 30
CFR 72.100(b). In the proposal, MSHA solicited comments on possible
alternative surveillance strategies or schedules, including whether
each voluntary examination should be mandatory.
MSHA received many comments about proposed Sec. 60.15(b). Several
commenters, including the AEMA, NVMA, NSSGA, SSC, and USW, urged that
the medical examinations remain voluntary in the final rule (Document
ID 1424; 1441; 1448; 1432; 1447; 1437;1412). The NSSGA asked MSHA to
clarify that while operators are required to offer workers the option
of participating in medical surveillance, workers can decline if they
wish, unless employers require it as a condition of employment.
(Document ID 1448).
In response to comments, MSHA emphasizes that while MNM mine
operators are required to make the medical examinations available,
miner participation is voluntary. However, MSHA believes mine operators
should encourage miner participation because medical surveillance is
crucial for early detection and prevention of silica-related diseases
to ensure miners' well-being and safety. MSHA expects mine operators to
include information on medical surveillance in their parts 46 and 48
training plans. MSHA will provide guidance to mine operators on how
medical surveillance, as well as other silica requirements in this
final rule, can best be integrated in their existing training plans.
MSHA also considered comments supporting different timelines for
medical surveillance frequency for medical examinations. The American
Thoracic Society et al. and an industry expert recommended the adoption
of a 3-year surveillance frequency (Document ID 1421; 1437). ACOEM also
supported a 3-year frequency and suggested a more frequent timeline
based on the discretion of the physician (Document ID 1405). The AFL-
CIO stated that the examination frequency should be more than every 5
years but did not specify an alternative frequency (Document ID 1449).
The APHA stated that medical examinations every 5 years may not be
sufficient for all miners, particularly those with health issues or
early evidence of silica-related diseases and recommended that MSHA
revise this provision to allow for more frequent examinations if
recommended by a PLHCP or specialist (Document ID 1416). Arizona Mining
Association asked MSHA to clarify the required timing for medical
surveillance examinations (Document ID 1368).
Some commenters referenced the OSHA standard as a rationale for
more frequent medical examinations. The AOEC, a medical professional,
NSSGA, and USW said that all miners should have the same medical
examination frequency and should follow OSHA's standard of making
medical examinations available every 3 years (Document ID 1373; 1437;
1448; 1447). The Portland Cement Association expressed support for
using OSHA's exposure-based approach if medical surveillance is in the
final rule, but with a frequency of every 5 years as in MSHA's proposal
(Document ID 1407).
After considering the comments, MSHA has determined that the 5-year
period for voluntary medical examinations is appropriate, after an
initial examination within a 12-month period starting no later than the
compliance date or within an initial 12-month period of a new mine
commencing operations after the compliance date. The 5-year period
along with the initial examination will provide miners with information
needed for the timely detection of silica-related diseases. Miners
should use the information obtained from medical surveillance to
establish a baseline and make informed decisions regarding their
health. MSHA does not believe a schedule requiring more frequent
periodic examinations is necessary. . In the Agency's experience with
the coal miners' medical surveillance program, 5-year periodic
examinations are appropriate to provide miners with information needed
for early detection of silica-related disease. MSHA intends to provide
miners and mine operators with information and education to help them
recognize the signs and symptoms of silica related diseases. MSHA
expects miners will use this information to help inform their decisions
regarding their medical care. The Agency believes the medical
examinations under the final rule are comprehensive and will promote
miners' health and safety.
The Agency received comments on the timeline in proposed paragraph
60.15(b). NSSGA and IAAP stated that that prescribing a 6-month period
when examinations must be offered creates logistical challenges for
scheduling resources and accounting for miners' work schedules, and
they urged MSHA not to specify when examinations should be scheduled
(Document ID 1448; 1456). However, BMC offered support for this
language, stating that they supported MSHA's provision that mine
operators must provide medical surveillance to miners no later than a
specified number of years, but within a certain range (Document ID
1417).
MSHA agrees that operators must provide medical surveillance to
miners employed at the mine on a consistent schedule. However, in
response to comments, MSHA has modified the language in this paragraph
to clarify the timing of the voluntary medical examinations. Paragraph
(b)(1), changed from the proposed rule, requires mine operators to
provide medical examinations during an initial 12-month period. Under
paragraph (b)(2), the mine operators must provide medical examinations
at least every 5 years after the period in paragraph (b)(1). The final
rule specifies that medical examinations must be available during a 6-
month period that begins no less than 3.5 years and not more than 4.5
years from the end of the last 6-month period. The Agency believes the
change in paragraph (b)(1) will provide miners necessary health
information earlier than under the proposed rule. The final rule will
ensure miners have early detection of adverse health effects from
silica exposure. MSHA believes the final rule safeguards miners'
health, while fostering enhanced preventative and protective measures
within the mining industry.
MSHA received comments asking the Agency to clarify how to verify
whether miners have had previous medical evaluations. NVMA asked for
clarification about how operators should verify whether a miner new to
the operator but experienced in the industry has already completed a
medical examination (Document ID 1441). Other commenters, including the
USW, recommended that more efforts should be made to encourage
participation and educate workers (Document ID 1447; 1437). The USW
further stated that
[[Page 28343]]
MSHA should encourage participation, by reducing barriers such as lack
of awareness, privacy and medical confidentiality concerns, and the
fear of retaliation, job loss, loss of potential job advancement, and
future employment (Document ID 1447).
In response to the commenter regarding verification of medical
examinations of newly hired experienced miners, MSHA encourages mine
operators to work together to determine the completion of prior medical
examinations without compromising the confidentiality and privacy of
the miners' health information. MSHA clarifies that, under the final
rule, mine operators have no obligation to verify whether a newly-hired
experienced miner had a medical examination.
MSHA believes that the rule is designed to prioritize the health
and safety of miners by making medical examinations available to them.
MSHA requires operators offer medical examinations, ensuring that
miners are aware, through training, of their availability, purpose, and
health benefits. MSHA agrees with commenters that fostering an informed
environment where miners are made aware of the risk of silica exposure
will encourage miners to take advantage of the availability of medical
examinations. The final rule is designed to help miners become more
aware of how medical surveillance can protect them against silica
risks. In response to commenters' concern about discrimination and
retaliation, MSHA investigates, in accordance with its responsibility
under the Mine Act, discrimination complaints to encourage miners to
exercise their rights under the Mine Act, including the right to
medical evaluations. 30 U.S.C. 815(c).
c. 60.15(c)--Mandatory Medical Examinations
Final paragraph (c) requires MNM mine operators to provide a
mandatory initial medical examination for each MNM miner who is new to
the mining industry. Under paragraph (c)(1), the mandatory initial
medical examination must occur no later than 60 days after a miner new
to the industry begins employment. This is a change from the proposed
rule, which required the initial medical examination within 30 days.
Final paragraphs (c)(2) and (3) are unchanged from the proposed rule.
Under paragraph (c)(2), mine operators are required to provide a
mandatory follow-up medical examination to the miner no later than 3
years after the miner's initial medical examination. Final paragraph
(c)(3) requires that, if a miner's 3-year follow-up medical examination
shows evidence of pneumoconiosis or decreased lung function, the
operator provide the miner with another mandatory follow-up medical
examination with a specialist, as defined in Sec. 60.2, within 2
years.
MSHA determined that a 3-year follow-up is appropriate because
there are some individuals who respond adversely to respirable coal
mine dust exposure relatively quickly, and it is important to identify
those individuals early. A 3-year interval at the start of a miner's
career will provide necessary information for evaluating the results of
subsequent spirometry tests and final paragraph (c)(1) requires a
mandatory follow-up examination be given 3 years after the miner's
initial examination. This is consistent with the 2014 RCMD Standard.
See 30 CFR 72.100.
MSHA received comments on mandatory medical examinations. A couple
of commenters, including BMC and AOEC, offered support for mandatory
medical examinations, with some stating that medical examinations
should be a mandatory requirement for both new and existing miners
(Document ID 1417; 1373). MCPA opposed mandatory examinations even for
new miners, stating that participation in medical surveillance is a
personal choice that should be left up to each miner (Document ID
1406). NLA stated that making medical examinations mandatory for new
miners would make it difficult to retain new hires (Document ID 1408).
NSSGA, IAAP, and BMC stated that MSHA should not prohibit operators
from making participation in medical surveillance a mandatory condition
of employment, if the mine operator believes mandatory participation is
warranted (Document ID 1448; 1456; 1417). Some commenters, including
USW, were opposed to mine operators mandating medical examinations as a
condition of employment (Document ID 1447; 1437; 1412). One commenter
emphasized that miners could be terminated for declining to visit an
operator's selected PLHCP (Document ID 1412). The Brick Industry
Association stated that if participation in a medical surveillance
program is a condition of employment, companies will not be able to
staff their operations (Document ID 1422).
Arizona Mining Association requested clarification on whether
medical surveillance services are mandatory or are just required to be
made available to the miners upon request. (Document ID 1368). PACA,
IAAP, and NSSGA asked MSHA to clarify whether operators can make
medical surveillance mandatory, and whether operators may conduct more
extensive medical surveillance than required under the proposed rule
(Document ID 1413; 1456; 1448). BMC asked if operators can make medical
examinations mandatory as long as they meet MSHA's minimum medical
surveillance requirements (Document ID 1417).
In response to these comments, MSHA notes that it is aware that
some mine operators already have mandatory health screening as part of
their employment policies. MSHA is also aware that some operators
require periodic health examinations as part of their industrial
hygiene practices. As a result, mandatory medical examinations may not
be new for some mine operators. Many operators make participation in
medical surveillance a mandatory condition of employment as a part of
their overall safety and health program for their workforce. In
response to comments, operators can conduct more extensive medical
surveillance and can make medical examinations mandatory as long as
they meet MSHA's minimum medical surveillance requirements. The Agency
does not intend for the final rule's requirements to interfere with the
operator's decision-making process with respect to managing its
operation and miners.
The Agency has weighed USW and other commenters' concerns about the
final rule making medical examinations mandatory and determined that it
is critical to administer medical examinations when MNM miners first
enter the profession. Mandatory examinations provided in close
proximity to when miners are first hired and first exposed to
respirable coal mine dust are necessary in order to establish an
accurate baseline of each miner's health. Miners may not recognize
early symptoms of silica-related disease; therefore, they might not be
likely to seek medical assistance.
MSHA received comments requesting a longer period for initial
medical examinations. The NSSGA, PACA, CalCIMA, and IAAP suggested that
many miners new to the industry will not continue employment beyond an
initial probation period due to the physical demands of the work
(Document ID1448; 1413; 1433; 1456). During the Denver, Colorado public
hearing, one commenter suggested making the period for medical
examinations for new miners longer, so that mine operators would be
providing medical examinations for those new miners who are more likely
to remain employed (Document ID 1375). MSHA agrees with the commenter
and has changed final paragraph (c)(1) to require an initial medical
examination no later
[[Page 28344]]
than 60 days after beginning employment. This is a change from the
proposed rule, which would have required mine operators to ensure
miners had a medical examination within 30 days after beginning
employment. This will help mine operators use their resources to
provide medical examinations for new miners who are more likely to
continue employment.
The NSSGA and Vanderbilt Minerals, LLC suggested eliminating the
mandate for a follow-up examination after an observed decrease in lung
function, as that requirement is too broad, and the decrease could be
due to non-occupational contaminants (Document ID 1448; 1419). In
response to comments, the Agency has not included this change in the
final rule. MSHA acknowledges the complex nature of lung function
decrease; the final rule includes a medically sound approach that
aligns examinations and subsequent actions with individual miner's
health statuses and occupational exposure profiles. Evaluating lung
function and changes in lung burden is a normal function of assessing
the development of lung diseases. This provision will allow for a
uniform approach to medical surveillance that is already implemented in
the coal industry.
Some mining trade associations suggested that mandatory
examinations be triggered by a specific level of exposure, instead of
being required for all miners new to the industry (Document ID 1408;
1428; 1448; 1424). The final rule does not include a ``trigger
provisions because the Agency believes it is necessary to maintain
consistency between the final rule's requirements for MNM mines and
existing medical surveillance standards for coal mines. In MSHA's
experience, medical surveillance requirements benefit coal miners, and
the Agency has implemented outreach initiatives to expand coal miners'
participation. MSHA believes that aligning the MNM medical surveillance
requirements with the requirements for coal mines will effectively
protect the health and safety of MNM miners.
d. 60.15(d)--Medical Examinations Results
Proposed paragraph (d) would have required that the results of any
medical examination performed under this section be provided by the
PLHCP or specialist only to the miner and, at the request of the miner,
to the miner's designated physician. In response to comments, MSHA
added language under paragraph (d)(1) to require the PLHCP or
specialist to provide test results within 30 days of the medical
examination and added a requirement that the PLHCP provide test results
to another designee identified by the miner. Under paragraph (d)(2),
the proposed provision was changed to require mine operators to ensure,
within 30 days of the medical examination, that the PLHCP provide
results of the chest x-ray classifications to NIOSH, once NIOSH
establishes a reporting system.
MSHA received comments regarding the sharing of the medical
examination results. Several commenters from MNM operators and mining
industry organizations stated the medical examination results should be
shared with the operator (Document ID 1424; 1417; 1456; 1441; 1448).
The NSSGA suggested medical providers be required to send a written
medical opinion to the operator if the operator requires the miner to
sign a medical release form stating what information can be shared with
the operator (Document ID 1448). This commenter also stated that
examination results need to be shared with the operator as soon as
possible, so that the operator can take actions to protect miners'
health (Document ID 1448). Other commenters, including BMC, AEMA, and
NVMA, suggested that medical examination results should be shared with
mine operators (Document ID 1417; 1424; 1441). AEMA stated that the
failure to communicate a confirmed diagnosis to the mine operator may
inadvertently adversely hamper the miner's ability to receive
compensation under workers' compensation program (Document ID 1424).
However, commenters from labor organizations and medical professional
associations stated that the proposed standard ensures that miners'
medical confidentiality is protected when those miners undergo medical
surveillance (Document ID 1398; 1447; 1449; 1410; 1373).
MSHA agrees with the commenters who expressed concerns regarding
the confidentiality and timeliness of medical examination results.
Under final paragraph (d)(1), MSHA modified the language of the
proposal to clarify that the final rule requires the mine operator to
ensure the PLHCP or specialist provide the medical examination results
only to the miner, or to the miner's designated physician or another
designee identified by the miner, and that this be done within 30 days
of the examination. Paragraph (d)(1) ensures that the mine operator
does not receive the miner's medical examination results. MSHA also
added a provision to paragraph (d)(1) specifying that the miner can add
a designee to receive the examination results in addition to the
miner's physician, in case the miner needs to provide the examination
results to other persons, such as family members or a health care
professional who is not a physician. MSHA believes the timely receipt
of medical examination results is important to allow the miner to make
informed decisions regarding their health. Therefore, the Agency adds
the requirement that the mine operator must ensure that the PLHCP or
specialist provide the miner with their medical examination results
within 30 days.
Under paragraph (e), the mine operator will obtain a written
medical opinion from the PLHCP or specialist within 30 days of the
medical examination. The written opinion must contain only the
following: the date of the medical examination, a statement that the
examination has met the requirements of this section, and any
recommended limitations on the miner's use of respirators. No other
information from the miner's medical examination may be obtained by the
mine operator. Based on MSHA's experience with medical surveillance for
coal miners, the Agency believes that confidentiality regarding medical
conditions is essential, because it encourages miners to take advantage
of the opportunity to detect early adverse health effects caused by
respirable crystalline silica. (79 FR 24813, 24928).
The AIHA and the Black Lung Clinics expressed support for a
requirement that operators submit medical surveillance plans to NIOSH
for approval (Document ID 1351; 1410). ACOEM stated that if submitting
for NIOSH approval creates administrative bottlenecks, employers should
instead be allowed to contract with qualified physicians for these
examinations, with the requirement that the supervising physician be
board-certified in pulmonary disease or occupational medicine or
another American Board of Medical Specialties (ABMS) (Document ID
1405). Two commenters, the NVMA and AEMA, stated that NIOSH is not a
regulatory agency, and thus should not oversee medical surveillance
plans (Document ID 1441; 1424).
The Black Lung Clinics suggested that medical examination results
should be reported to NIOSH so that MSHA can monitor the effectiveness
of dust controls (Document 1410). This commenter further suggested that
MSHA create a repository for all screening results accessible to health
care providers that can help detect early disease (Document ID 1410).
The UMWA recommended that MSHA work with NIOSH to expand the Coal
Workers Health Surveillance Program's mobile
[[Page 28345]]
units to screen MNM miners as well or, alternatively, create new Health
Surveillance Program mobile units targeting MNM miners (Document ID
1398).
After considering the comments, MSHA agrees with commenters that
medical examination results should be submitted to NIOSH. MSHA has
added a new final paragraph (d)(2) that requires the mine operator to
ensure that, within 30 days of a miner's medical examination, the PLHCP
or specialist provides the results of chest X-ray classifications to
NIOSH, once NIOSH establishes a reporting system. The final rule does
not require medical surveillance plans or NIOSH approval of them. MSHA
agrees with commenters' concerns that having MNM mine operators develop
and submit a medical surveillance plan for approval could cause
administrative delays and adversely affect miners' health. The new
requirement to submit chest X-ray classifications to NIOSH for
occupational health research will provide the public important health
information related to respirable crystalline silica disease and MSHA
expects this information will provide a public health benefit.
This requirement is important because NIOSH intends to work with
MSHA and the MNM mining community to create a reporting system to help
mine operators ensure that PLHCPs or specialists may easily submit the
required information. MSHA and NIOSH will inform mine operators and
other stakeholders in a timely manner when the reporting system is
available. When NIOSH establishes the system, NIOSH and MSHA will issue
a joint notice to the mining community. In this notice, NIOSH and MSHA
will include the logistics of the reporting system, information on how
operators can ensure that the PLHCPs provide the required information
to NIOSH, and information on how miners and medical professionals can
effectively use the system. This information will be posted on both
Agencies' websites. MSHA enforcement and Educational Field and Small
Mine Services (EFSMS) staff will work with operators to facilitate
compliance.
e. 60.15(e)--Written Medical Opinion
As discussed above, final paragraph (e), unchanged from the
proposed rule, requires MNM mine operators to obtain a written medical
opinion from a PLHCP or specialist within 30 days of the medical
examination, and requires that this opinion include only the date of a
miner's medical examination, a statement that the examination has met
the requirements of this section, and any recommended limitations on
the miner's use of respirators. The purpose of the opinion is to enable
the mine operator to verify the examination has occurred and to provide
the operator with information on miners' ability to use respirators.
The Agency received several comments regarding proposed paragraph
(e). One commenter, the CalCIMA, was concerned about whether the
medical opinion would be available in a timely manner (Document ID
1433). MSHA understands the commenter's concern. The Agency believes
that the 30-day requirement to provide the medical opinion regarding
the recommended limitation on the miner's use of respirators should
provide the mine operator sufficient notice to address any issues.
The AOEC suggested that MSHA should follow OSHA in requiring
clinicians to prepare a written report to the worker and provide a
written medical opinion to the employer (Document ID 1373). That
commenter stated that under OSHA's rule, the report remains
confidential, the clinician discusses the examination results with the
worker, and the worker signs a medical release form that clarifies what
information the employer has received (Document ID 1373). MSHA notes
that its final rule includes requirements similar to OSHA's reporting
requirements in that the operator receives very limited information and
will not be apprised of the results of the examination. Because the
mine operator is receiving very limited information, MSHA determined
that a medical release form signed by the miner is not necessary.
f. 60.15(f)--Written Medical Opinion Records
Final paragraph (f), unchanged from the proposed rule, requires the
mine operator to maintain a record of the written medical opinion
obtained from the PLHCP or specialist under paragraph (e). This
requirement provides a record to ensure compliance with the standard.
MSHA received comments on the record retention requirements for written
medical opinion records that are discussed further in Section
VIII.B.9.a. Records retention periods.
g. Compliance Assistance
The NSSGA highlighted the importance of compliance assistance for
mines, especially small mines that do not have experience with medical
surveillance programs (Document ID 1448). MSHA agrees with the
commenter that compliance assistance is needed and will develop
compliance materials to assist mine operators in implementing the final
rule, including the medical surveillance requirements. MSHA will work
with the mining community to ensure the final rule is implemented
consistently and in a manner that adds to existing protections for
miners. See the more complete discussion on MSHA's compliance
assistance for this rulemaking under Section VIII.A. General Issues.
9. Section 60.16--Recordkeeping Requirements
Section 60.16 identifies recordkeeping retention requirements for
records created in part 60. The final rule requires mine operators to
retain evaluation, sampling, and corrective actions records for at
least 5 years. The final rule requires mine operators to retain written
determination records and written medical opinion records for the
duration of a miner's employment plus 6 months. It also requires mine
operators, upon request from an authorized representative of the
Secretary, from an authorized representative of miners, or from miners,
to promptly provide access to any record listed in Sec. 60.16.
In the proposal, MSHA sought comment on the utility of the
recordkeeping requirements in this section. MSHA received several
comments on the proposed recordkeeping requirements, including from an
industrial hygiene professional association and mining trade
association, supporting the Agency's proposed recordkeeping provisions
(Document ID 1351; 1424). A MNM operator and mining trade association
opposed the recordkeeping requirements, stating that the requirements
were duplicative and should be more flexible (Document ID 1419; 1448).
Below is a detailed discussion of the comments received on this
section.
a. Records Retention Periods
MSHA received comments from labor unions, advocacy organizations,
one MNM operator, and a federal elected official requesting an increase
in the retention periods for sampling records (Document ID 1398; 1416;
1417; 1425; 1439; 1447; 1449). Records that were to be retained by the
mine operator under this section include evaluation, sampling, and
corrective actions records, as described in proposed paragraphs
60.16(a)(1) to (3).
USW and AFL-CIO stated that increased record retention is
particularly important for MNM mines,
[[Page 28346]]
which are typically surface mines and are inspected less frequently
than underground coal mines (Document ID 1447; 1449). The UMWA
recommended that, for MNM miners, operators should be required to keep
records specified under paragraphs (a)(1) to (3) for 30 years and to
provide those records to the miner on termination of employment;
operators be required to transfer records to a successor employer; and
when an employer is ceasing operations and there is no successor
employer to receive the record, the employer notify affected employees
of their rights of access to records at least 3 months prior to the
cessation of the employer's business (Document ID 1398). BMC stated
that the sampling and corrective actions records proposed to be
retained for at least 2 years should be required to be preserved
indefinitely (Document ID 1417). Appalachian Voices recommended that
all records regarding sampling be retained for longer than the life of
the mine operation (Document ID 1425).
USW and AFL-CIO expressed concern that retaining records for 2
years would be insufficient to establish a pattern of exposure or
provide other critical information such as the evaluation of corrective
actions. Labor unions, advocacy organizations, a MNM operator, and an
individual suggested that MSHA should align its recordkeeping
requirements with the OSHA silica standard recordkeeping requirements
(29 CFR 1910.1020) (Document ID 1398; 1412; 1416; 1417; 1425; 1447).
In response to comments requesting an increase in the record
retention period, the final rule increases the record retention period
for evaluation, sampling, and corrective actions records in paragraphs
(a)(1) to (3) to at least 5 years. Increasing to the 5-year record
retention period for evaluation, sampling, and corrective actions
records will help mine operators, miners, and MSHA better evaluate and
monitor changes in exposures, understand health hazards, and ensure the
implementation and maintenance of proper controls to protect miners
from health hazards associated with respirable crystalline silica.
Under final (a)(1) and (2), evaluation and sampling records confirm
that sampling results accurately represent current exposure conditions.
The 5-year recordkeeping requirement for evaluation and sampling
records will provide mine operators with robust information to enable
them to understand a history of occupational exposures at the mines and
to take appropriate actions to protect miners, such as implementing
engineering and administrative controls. Evaluation and sampling
records can identify overexposures due to changes in production,
processes, controls, or geological conditions. These records help mine
operators develop, implement, and adjust controls and other measures
that protect miners from overexposures. In addition, these expanded
records will provide miners and their representatives with information
about exposure patterns over time to understand health hazards at their
mines and to make informed decisions about their health care. As some
commenters noted, this information can be invaluable to miners who have
already been diagnosed with an illness or experienced negative health
effects and help them to make decisions about their health and future
employment. The 5-year records of evaluation and sampling will also
enable MSHA staff in Technical Support and Educational Field and Small
Mine Services to provide needed compliance assistance.
The 5-year recordkeeping requirement for corrective actions records
in final paragraph (a)(3) will help mine operators and MSHA enforcement
staff determine if existing controls are effective, or if maintenance
or additional controls are needed. In MSHA's experience, the cumulative
record provides MSHA and mine operators with information to identify
trends in exposures and operational changes. Mine operators can use
trend information to determine the effectiveness of controls over time
and to take proactive measures to prevent future overexposures, while
miners and their representatives can use the trend information to
determine health hazards and protection needs at their mines.
MSHA has determined that the 5-year retention period in final
paragraphs (a)(1) to (3) balances the operator's burden to maintain
records and the need for this information to take appropriate action to
protect miners' health. The 5-year record retention is also consistent
with MSHA's record retention period for operator samples collected for
diesel particulate matter in underground metal and nonmetal mines
(Sec. 57.5071(d)(2)) and other injury and illness reports required for
all mines (Sec. 50.40). From MSHA's experience and observation,
informed miners who are aware of occupational health hazards around
them are more likely to follow safe work practices and to report these
hazards to their operators or MSHA when necessary. When miners are
aware of occupational health hazards and participate in the
identification, remediation, and control of those hazards, the overall
level of safety and health at the mine will be improved. In sum,
informed miners are more likely and better able to play an active role
in safety and health as the Mine Act envisions and better protect
themselves and other miners.
MSHA notes that minor changes have been made to final paragraphs
(a)(1) to (3) to change the citation for the records addressed and to
reflect changes discussed in Sec. 60.12 and 60.13. MSHA has similarly
revised the citations in Table 1 to Paragraph (a)--Recordkeeping
Requirements.
Like the proposal, final paragraphs (a)(4) and (5) require that the
written determination by a PLHCP that a miner is unable to wear a
respirator under Sec. 60.14(b), as well as the medical surveillance
records underSec. 60.15(f), be retained for the duration of the
miner's employment plus 6 months. MSHA received several comments
regarding the retention period for medical surveillance records, with
most commenters supporting a longer retention period.
UMWA recommended that medical surveillance records be kept for 30
years and provided to the miner on termination of employment; that
operators be required to transfer records to a successor employer; and
that when an employer is ceasing operations and there is no successor
employers to receive the record, the employer be required to notify
affected employees of their rights of access to records at least 3
months prior to the cessation of the employer's business Document ID
1398). AOEC, APHA, and USW suggested that MSHA should align its
recordkeeping requirements for medical surveillance records with the
OSHA silica standard recordkeeping requirements (29 CFR 1910.1020)
(Document ID 1373; 1416; 1447). These same commenters and a black lung
clinic and an individual suggested that, given the latency periods
associated with health effects from silica exposure, medical
surveillance records are invaluable for miners who are diagnosed with
silica-related health conditions (Document ID 1373; 1416; 1447; 1418;
1412).
In response to these comments, MSHA reiterates that mine operators
do not have access to a miner's medical information and therefore, do
not maintain a record of such information. Only the PLHCP's written
determination made under paragraph 60.14(b) on whether a miner is able
to wear a respirator must be provided to mine operators. Under the
final rule, as in the proposal, the mine operator will retain
[[Page 28347]]
the written determination record for the duration of miner employment
plus six months.
Under final 60.15(d), medical examination results must be provided
to the miner, at the request of the miner, to the miner's designated
physician or another designee identified by the miner, and to NIOSH,
once NIOSH establishes a reporting system. MSHA is not regulating the
retention of medical examination results since they are not provided to
the mine operator. The medical surveillance information (the written
medical opinion records) that the mine operator will retain under final
paragraph (a)(5) includes a record of the date of the medical
examination, a statement that the examination has met the requirements
of this section, and any recommended limitations on the miner's use of
respirators. MSHA believes that retaining these medical surveillance
records for the duration of the miner's employment plus 6 months is
appropriate. The requirement to retain records for an additional 6
months beyond the miner's employment gives a miner more time to request
records if the miner is employed at another mine. For example, a miner
who was determined to be medically unable to wear a respirator may need
this record for new mine operator. The final rule does not increase the
retention period because, as described above, the written medical
opinion that the operator receives contains only basic information
compared to the medical examination records that are in the miner's
possession and control.
NVMA asked for clarification on the medical surveillance
recordkeeping requirements, remarking that the rule does not include
provisions requiring tracking of miners' exposure throughout their
careers and noting that miners often change companies over the course
of their careers (Document ID 1441). This commenter asked whether it
would be assumed that a miner's occupational illness stems from work
with their current employer, even if all samples and medical
surveillance show the miner was not exposed above the PEL during their
current employment.
MSHA reiterates that each miner's medical examination results are
provided to that miner, to the miner's physician or other designee at
the request of the miner, and to NIOSH, once NIOSH establishes a
reporting system. NIOSH's reporting system, once established, will
provide public health information on rates of silica-related disease,
tenure, and prevalence in the MNM industry.
Miners will have access to all medical examination results obtained
under this part and will be able to track any impacts of exposure. The
purpose of the medical surveillance examination requirements is to help
miners seek help from medical professionals who can identify early
symptoms of respirable crystalline silica-related diseases and inform
them of their health status, so that they can take early and necessary
steps to protect their health.
Vanderbilt Minerals, LLC stated that medical records are required
to be collected under the Health Insurance Portability and
Accountability Act and that an additional requirement by MSHA would be
duplicative and unnecessary (Document ID 1419). MSHA clarifies that the
mine operator is not responsible for obtaining and preserving the
miner's medical examination results or records. Therefore, there is no
duplication of collecting medical records.
b. Access to Records Maintained Under 60.16
Final paragraph 60.16(b), like the proposal, requires mine
operators to make records in this section available promptly upon
request to miners, authorized representatives of miners, and authorized
representatives of the Secretary of Labor. A federal elected official
stated that MSHA should require sampling records and any other
information required to be posted on the mine bulletin board to be
submitted to miner representatives (Document ID 1439). This commenter
also urged MSHA to require operators to provide cumulative exposure
records to the miner upon request, similar to 30 CFR 57.5040. A miner
health advocate suggested that corrective actions records should be
required to be submitted to MSHA and miner representatives (Document ID
1372).
After considering the comments, MSHA determined that no change to
final paragraph (b) is necessary. The requirement to provide all the
listed records promptly upon request to miners, authorized
representatives of miners, and authorized representatives of the
Secretary of Labor ensures that miners and MSHA will have access to
records as needed which facilitates enforcement and transparency.
Miners, miners' representatives, and MSHA can request the records in
this section at any time; therefore, MSHA has determined that it is not
necessary to require operators submit records to miners, miners'
representatives, and MSHA without request.
c. Other Comments
The APHA suggested that all required records should be made
available to NIOSH (Document ID 1416). As discussed in response to
comments under paragraph 60.15(d)(2), MSHA is requiring that the
results of chest X-ray classifications obtained under medical
surveillance examinations be made available to NIOSH for its research.
MSHA has determined that it is not necessary to provide other records
required under part 60 to NIOSH.
The AIHA supported the proposed recordkeeping requirements and
recommended that operators be required to develop and maintain exposure
control plans that identify the tasks that involve miners' exposures
above the PEL and the methods used to protect miners, including
procedures to restrict access to work areas where high exposures may
occur (Document ID 1351).
After considering the comment, MSHA has concluded that an exposure
control plan record is not necessary, because of the sampling and
control methods required. As required under part 60, mine operators
must use engineering and administrative controls to prevent
overexposures to respirable crystalline silica. Under Sec. 60.12(c),
mine operators are required to evaluate these controls at least every 6
months or whenever there is a change in production, processes,
installation and maintenance of engineering controls, installation and
maintenance of equipment, administrative controls, or geological
conditions to determine if the change is reasonably expected to result
in new or increased respirable crystalline silica exposures. The
operator must make a record of the evaluation, including the evaluated
change, the impact on respirable crystalline silica exposure, and the
date of the evaluation and post the record on the mine bulletin board
and, if applicable, by electronic means, for the next 31 days.
Operators are expected to conduct these evaluations to assess changing
conditions on a regular basis to ensure miners are not exposed at
levels above the PEL. The evaluation records provide important
information to mine operators to enable them to implement effective
control methods to protect miners, to identify occupations and work
areas where there is a risk of overexposure, and to make necessary
adjustments. MSHA has determined requiring exposure control plan
records is not necessary.
Under paragraph 60.12(g), when mine operators sample for respirable
crystalline silica, operators must make a record of the sample date,
the occupations sampled, and the concentrations of respirable
crystalline silica and respirable dust, must obtain
[[Page 28348]]
the laboratory report, and must make the information available to the
miners. This record will enable operators and miners to identify those
tasks where overexposures may have occurred and individuals who may be
overexposed, as the commenter suggested. Under Sec. 60.13(b),
operators must make a record of any corrective actions. This record
will provide mine operators with necessary information to determine
which control methods should be developed, implemented, and maintained
to prevent exposures above the PEL. Miners can use this information to
take a proactive approach to their health.
10. Section 60.17--Severability
The final rule includes a statement of severability that each
section of this part, as well as sections in 30 CFR parts 56, 57, 70,
71, 72, 75, and 90 that address respirable crystalline silica or
respiratory protection, is separate and severable from the other
sections and provisions.
The severability clause under Sec. 60.17 serves two purposes.
First, it expresses MSHA's intent that if any section or provision of
the Lowering Miners' Exposure to Respirable Crystalline Silica and
Improving Respiratory Protection rule--including its conforming
amendments in sections of 30 CFR parts 56, 57, 70, 71, 72, 75, and 90
that address respirable crystalline silica or respiratory protection--
is held invalid or unenforceable or is stayed or enjoined by any court
of competent jurisdiction, the remaining sections or provisions should
remain effective and operative. Second, the severability clause
expresses MSHA's judgment, based on its technical and scientific
expertise, that each individual section and provision of the rule can
remain effective and operative if some sections or provisions are
invalidated, stayed, or enjoined. Accordingly, MSHA's inclusion of this
severability clause addresses the twin concerns of Federal courts when
determining the propriety of severability: identifying agency intent
and clarifying that any severance will not undercut the structure or
function of the rule more broadly. Am. Fuel & Petrochem. Mfrs. v. Env't
Prot. Agency, 3 F.4th 373, 384 (D.C. Cir. 2021) (``Severability
`depends on the issuing agency's intent,' and severance `is improper if
there is substantial doubt that the agency would have adopted the
severed portion on its own''') (quoting North Carolina v. FERC, 730
F.2d 790, 796 (D.C. Cir. 1984) and New Jersey v. Env't Prot. Agency,
517 F.3d 574, 584 (D.C. Cir. 2008)).
Under the principle of severability, a reviewing court will
generally presume that an offending provision of a regulation is
severable from the remainder of the regulation, so long as that outcome
appears consistent with the issuing agency's intent, and the remainder
of the regulation can function independently without the offending
provision. See K Mart Corp. v. Cartier, Inc., 486 U.S. 281, 294 (1988)
(invalidating and severing subsection of a regulation where it would
not impair the function of the statute as a whole and there was no
indication the regulation would not have been passed but for inclusion
of the invalidated subsection). Consequently, in the event that a court
of competent jurisdiction stays, enjoins, or invalidates any provision,
section, or application of this rule, the remainder of the rule should
be allowed to take effect.
MSHA did not receive any comments on this section. Final Sec.
60.17 is the same as proposed.
C. Conforming Amendments
The final rule makes conforming amendments in 30 CFR parts 56, 57,
70, 71, 72, 75, and 90 based on the new part 60. The compliance dates
for the conforming amendments align with the compliance dates for part
60. Compliance with the conforming amendments to parts 56 and 57 is
required by 24 months after publication, for MNM operators; and
compliance with the conforming amendments to parts 70, 71, 72, 75, and
90 is required by 12 months after publication, for coal mine operators.
The compliance dates for the conforming amendments assure that miners
are protected under the existing standards until mine operators are
required to comply with part 60.
In other words, existing sections in parts 56 and 57 will remain in
place for 24 months following publication. For MNM operators,
compliance with the conforming amendments in parts 56 and 57 is not
required until 24 months after publication. Existing sections in parts
70,71, 72, 75, and 90 will remain in place for 12 months following
publication. For coal operators, compliance with the conforming
amendments in these parts is not required until 12 months after
publication.
For the conforming amendments, a set of instructions involving the
establishment of temporary sections and redesignation of those sections
are required for the Federal Register to maintain existing standards
for parts 56, 57, 70, 71, 72, 75, and 90 until their respective
compliance dates. On the effective date of the final rule (60 days
after publication), the conforming amendments will be published to
temporary sections, designated by the suffix ``T'' at the end of the
section number (e.g., Sec. 56.5001T). These temporary sections
indicate how the paragraphs will read on the compliance dates. On the
compliance dates, the existing sections associated with conforming
amendments will be removed and the temporary sections will be
redesignated without the ``T'' to replace the removed section (e.g.
Sec. 56.5001T will be redesignated Sec. 56.5001). With the
redesignation, compliance with the conforming amendments will be
required.
The conforming amendment changes to respiratory protection
standards are discussed in Section VIII.D Updating MSHA Respiratory
Protection Standards: Incorporation of ASTM F3387-19 by Reference.
1. Part 56--Safety and Health Standards--Surface Metal and Nonmetal
Mines
a. Section 56.5001--Exposure Limits For Airborne Contaminants
The final rule, like the proposal, amends Sec. 56.5001(a) to add
respirable crystalline silica as an exception. Amended paragraph (a)
governs exposure limits for airborne contaminants other than respirable
crystalline silica and asbestos for surface MNM mines. MSHA did not
receive any comments on the proposed change.
In a change from the proposal, MSHA makes a non-substantive change
to paragraph (a) to update the terminology for the name of the MSHA
District Office to the Mine Safety and Health Enforcement District
Office. The Mine Safety and Health Enforcement District Office covers
both MNM mines and coal mines since the Agency no longer maintains
separate offices for both types of mines. The Agency no longer
differentiates between MNM District Offices and Coal District Offices.
This change was not discussed in the proposal.
b. Temporary Section Until Compliance Date
As described above, 60 days after publication of the final rule, a
new temporary section with the suffix ``T'' will be added for the
conforming amendments in part 56. Then, 720 days after publication of
the final rule, the existing section for the conforming amendments in
part 56 will be removed and the temporary section will be redesignated
without the ``T'' to replace the removed section. The result of these
[[Page 28349]]
technical changes is that mine operators must comply with the existing
standards until the compliance dates in part 60.
2. Part 57--Safety and Health Standards--Underground Metal and Nonmetal
Mines
a. Section 57.5001--Exposure Limits For Airborne Contaminants
The final rule, like the proposal, amends Sec. 57.5001(a) to add
respirable crystalline silica as an exception. Amended paragraph (a)
governs exposure limits for airborne contaminants other than respirable
crystalline silica and asbestos for underground MNM mines. MSHA did not
receive any comments on the proposed change.
In a change from the proposal, MSHA makes a non-substantive change
to paragraph (a) to update the terminology for the name of the MSHA
district office to the Mine Safety and Health Enforcement District
Office. The Mine Safety and Health Enforcement District Office covers
both MNM mines and coal mines since the Agency no longer differentiates
between MNM District Offices and Coal District Offices. This change was
not discussed in the proposal.
b. Temporary Section Until Compliance Date
As described above, 60 days after publication of the final rule, a
new temporary section with the suffix ``T'' will be added for the
conforming amendments in part 57. Then, 720 days after publication of
the final rule, the existing section for the conforming amendments in
part 57 will be removed and the temporary section will be redesignated
without the ``T'' to replace the removed section. The result of these
technical changes is that mine operators must comply with the existing
standards until the compliance dates in part 60.
3. Part 70--Mandatory Health Standards--Underground Coal Mines
a. Section 70.2--Definitions
The final rule, like the proposal, removes the quartz definition in
Sec. 70.2 since the Agency is adopting an independent respirable
crystalline silica standard in part 60. Therefore, the term quartz no
longer appears in part 70. MSHA did not receive any comments on the
proposed change.
b. Section 70.101--Respirable Dust Standard When Quartz Is Present
The final rule, like the proposal, removes Sec. 70.101 in its
entirety and reserves the section number. Section 70.101, Respirable
dust standard when quartz is present, is no longer needed because MSHA
is adopting an independent respirable crystalline silica standard in
part 60.
As discussed in greater detail in Section VIII.B.3.b PEL in coal
mines, of this preamble, MSHA solicited comments on whether to
eliminate the reduced standard for total respirable dust when quartz is
present at coal mines and received feedback from stakeholders generally
agreeing with the Agency's proposal to establish a standard for
respirable crystalline silica that is independent from the respirable
coal mine dust standard. For example, the NMA, the MCPA and the
Pennsylvania Coal Alliance supported the removal of the respirable dust
standards when quartz is present (i.e., Sec. Sec. 70.101 and 71.101,
and 90.101), reasoning that they are no longer needed since the rule
proposes a standalone standard for respirable crystalline silica
(Document ID 1428; 1406; 1378).
In response to commenters, MSHA has concluded that establishing an
independent and lower PEL for respirable crystalline silica for coal
mines allows more effective control of respirable crystalline silica
than the existing reduced standards, because the separate standard is
more transparent and protective. MSHA clarifies that the respirable
coal mine dust standard is not eliminated, only the sampling
requirements for when silica is present under Sec. 70.101. MSHA agrees
with the commenters supporting the removal of Sec. 70.101.
c. Section 70.205--Approved Sampling Devices; Operation; Air Flowrate
The final rule, like the proposal, amends paragraph 70.205(c) to
remove the reference to the reduced RCMD standard. References to the
RCMD exposure limit specified in Sec. 70.100 replace references to the
applicable standard. The rest of the section remains unchanged.
d. Section 70.206--Bimonthly Sampling; Mechanized Mining Units
The final rule, like the proposal, removes Sec. 70.206 and
reserves the section number. Section 70.206 included requirements for
bimonthly sampling of mechanized mining units which were in effect
until January 31, 2016, and are no longer applicable.
e. Section 70.207--Bimonthly Sampling; Designated Areas
The final rule, like the proposal, removes Sec. 70.207 and
reserves the section number. Section 70.207 included requirements for
bimonthly sampling of designated areas that were in effect until
January 31, 2016, and are no longer applicable.
f. Section 70.208--Quarterly Sampling; Mechanized Mining Units
The final rule, like the proposal, amends Sec. 70.208 to remove
references to a reduced RCMD standard. Paragraph (c) in Sec. 70.208 is
removed and the paragraph designation reserved. References to the
respirable dust standard specified in Sec. 70.100 replace references
to the applicable standard throughout the section.
A new table 1 is added to Sec. 70.208. The new table contains the
Excessive Concentration Values (ECV) for the section based on a single
sample, 3 samples, or the average of 5 or 15 full-shift coal mine dust
personal sampler unit (CMDPSU) or continuous personal dust monitor
(CPDM) concentration measurements. The new table contains the remaining
ECV after the removal of the reduced standard in Sec. 70.101 and was
generated from data previously contained in Tables 70-1 and 70-2 in
Subpart C of part 70. Conforming changes are made to paragraphs (e) and
(f)(1) and (2) to update the name of the table to table 1. MSHA did not
receive any comments on the proposed changes.
g. Section 70.209--Quarterly Sampling; Designated Areas
The final rule, like the proposal, amends Sec. 70.209 to remove
references to a reduced RCMD standard. Paragraph (b) in Sec. 70.209 is
removed and the paragraph designation reserved. References to the RCMD
exposure limit specified in Sec. 70.100 replace references to the
applicable standard.
A new table 1 is added to Sec. 70.209. The new table contains the
ECVs for the section based on a single sample, 2 or more samples, or
the average of 5 or 15 full-shift CMDPSU/CPDM concentration
measurements. This table contains the remaining ECV after the removal
of the reduced RCMD standard in Sec. 70.101 and was generated from
data previously contained in Tables 70-1 and 70-2 in Subpart C of part
70. Conforming changes are made to paragraphs (c) and (d)(1) and (2) to
update the name of the table to table 1. MSHA did not receive any
comments on the proposed changes.
h. Subpart C--Table 70-1 and Table 70-2
The final rule, like the proposal, removes Table 70-1 to Subpart C
of Part 70, Excessive Concentration Values (ECV) Based on Single, Full-
Shift CMDPSU/CPDM Concentration Measurements and Table 70-2 to
[[Page 28350]]
Subpart C of Part 70, Excessive Concentration Values (ECV) Based on the
Average of 5 or 15 Full-Shift CMDPSU/CPDM Concentration Measurements
because Sec. 70.101 is removed. These tables are replaced with new
tables in Sec. Sec. 70.208 and 70.209. MSHA did not receive any
comments on the proposed change.
i. Temporary Section Until Compliance Date
As described above, 60 days after publication of the final rule, a
new temporary section with the suffix ``T'' will be added for most of
the conforming amendments in part 70. Then, 360 days after publication
of the final rule, the existing section for these conforming amendments
in part 70 will be removed and the temporary section will be
redesignated without the ``T'' to replace the removed section. The
result of these technical changes is that mine operators must comply
with the existing standards until the compliance dates in part 60.
4. Part 71--Mandatory Health Standards--Surface Coal Mines and Surface
Work Areas of Underground Coal Mines.
a. Section 71.2--Definitions
The final rule, like the proposal, removes the Quartz definition in
Sec. 71.2 because the Agency is removing the respirable dust standard
when quartz is present in Sec. 71.101. The term quartz no longer
appears in part 71. MSHA did not receive any comments on the proposed
change.
b. Section 71.101--Respirable Dust Standard When Quartz Is Present
MSHA is removing Sec. 71.101 in its entirety and reserving the
section number. The respirable coal mine dust standard when quartz is
present in Sec. 71.101 is no longer needed because MSHA is adopting an
independent respirable crystalline silica standard in part 60.
As discussed in greater detail in Section VIII.B.3.b. PEL in coal
mines, of this preamble, MSHA solicited comments on whether to
eliminate the reduced standard for total respirable dust when quartz is
present at coal mines and received feedback from stakeholders generally
agreeing with the Agency's proposal to establish a standard for
respirable crystalline silica that is independent from the respirable
coal mine dust standard. For example, the NMA, the MCPA and the
Pennsylvania Coal Alliance supported the removal of the respirable dust
standards when quartz is present (i.e., Sec. Sec. 70.101 and 71.101,
and 90.101), reasoning that they are no longer needed since the rule
proposes a standalone standard for respirable crystalline silica
(Document ID 1428; 1406; 1378).
In response to commenters, MSHA has concluded that establishing an
independent and lower PEL for respirable crystalline silica for coal
mines allows more effective control of respirable crystalline silica
than the existing reduced standards, because the separate standard is
more transparent and protective. MSHA clarifies that the respirable
coal mine dust standard is not eliminated, only the sampling
requirements for when silica is present under Sec. 71.101. MSHA agrees
with the commenters supporting the removal of Sec. Sec. 71.101.
c. Section 71.205--Approved Sampling Devices; Operation; Air Flowrate
The final rule, like the proposal, amends paragraph (c) to remove
the reference to the reduced RCMD standard. References to the
respirable dust standard specified in Sec. 71.100 replace the
reference to the applicable standard.
d. Section 71.206--Quarterly Sampling; Designated Work Positions
The final rule, like the proposal, amends Sec. 71.206 to remove
references to the reduced RCMD standard. Paragraph (b) in Sec. 71.206
is removed and the paragraph designation reserved. Other conforming
changes for Sec. 71.206 remove references to the applicable standard
and replace them, where needed, with references to the respirable dust
standard specified in Sec. 71.100.
MSHA is also amending paragraph (l) by removing Table 71-1
Excessive Concentration Values (ECV) Based on Single, Full-Shift
CMDPSU/CPDM Concentration Measurements and Table 71-2 Excessive
Concentration Values (ECV) Based on the Average of 5 Full-Shift CMDPSU/
CPDM Concentration Measurements since reference to a reduced RCMD
standard in Sec. 71.101 is removed. A new table has been added to
Sec. 71.206.
Final paragraph (m), like the proposal, removes the language, ``in
effect at the time the sample is taken, or a concentration of
respirable dust exceeding 50 percent of the standard established in
accordance with Sec. 71.101,'' because the reduced standard in Sec.
71.101 is removed.
A new table 1 is added to Sec. 71.206. This table contains the ECV
for the section based on a single sample, two or more samples, or the
average of five full-shift CMDPSU/CPDM concentration measurements. This
table contains the remaining ECV after the removal of the reduced
standard in Sec. 71.101. It was generated from data contained in
existing Tables 71-1 and 71-2 to Subpart C of part 71. Conforming
changes are made to paragraphs (h) and (i)(1) and (2) to update the
name of the table to table 1. MSHA did not receive any comments on the
proposed changes.
e. Section 71.300--Respirable Dust Control Plan; Filing Requirements
Final Sec. 71.300, like the proposal, removes references to the
reduced RCMD standard. The respirable dust standard specified in Sec.
71.100 replaces references to the applicable standard. MSHA did not
receive any comments on the proposed change.
f. Section 71.301--Respirable Dust Control Plan; Approval by District
Manager and Posting
Final Sec. 71.301, like the proposal, removes references to the
reduced RCMD standard. The respirable dust standard specified in Sec.
71.100 replaces references to the applicable standard. MSHA did not
receive any comments on the proposed change.
g. Temporary Section Until Compliance Date
As described above, 60 days after publication of the final rule, a
new temporary section with the suffix ``T'' will be added for most of
the conforming amendments in part 71. Then, 360 days after publication
of the final rule, the existing section for these conforming amendments
in part 71 will be removed and the temporary section will be
redesignated without the ``T'' to replace the removed section. The
result of these technical changes is that mine operators must comply
with the existing standards until the compliance dates in part 60.
5. Part 72--Health Standards for Coal Mines
a. Section 72.800--Single, Full-Shift Measurement of Respirable Coal
Mine Dust
Final Sec. 72.800, like the proposal, removes references to the
reduced RCMD standard. The section also replaces references to Tables
70-1, 71-1, and 90-1 with references to the new tables in Sec. Sec.
70.208, 70.209, 71.206, and 90.207. MSHA did not receive any comments
on the proposed changes.
b. Temporary Section Until Compliance Date
As described above, 60 days after publication of the final rule, a
new temporary section with the suffix ``T'' will be added for the
conforming amendments in part 72. Then, 360 days
[[Page 28351]]
after publication of the final rule, the existing section for the
conforming amendments in part 72 will be removed and the temporary
section will be redesignated without the ``T'' to replace the removed
section. The result of these technical changes is that mine operators
must comply with the existing standards until the compliance dates in
part 60.
6. Part 75--Mandatory Safety Standards--Underground Coal Mines
a. Section 75.350(b)(3)(i) and (ii)--Belt Air Course Ventilation
The final rule, like the proposal, updates Sec. 75.350 by revising
paragraph (b)(3)(i) and removing paragraphs (b)(3)(i)(A) and (B) and
(b)(3)(ii). Paragraph (b)(3)(i) is revised to ``[T]he average
concentration of respirable dust in the belt air course, when used as a
section intake air course, shall be maintained at or below 0.5 mg/
m\3\.'' Paragraph (b)(3)(i)(A) is removed because its provision has not
been in effect since August 1, 2016. Paragraph (b)(3)(i)(B) is removed
because the language has been incorporated in revised paragraph
(b)(3)(i), making (b)(3)(i)(B) redundant. Existing paragraph (b)(3)(ii)
is removed since it refers to a reduced RCMD standard under Sec.
70.101 that is also removed. Existing paragraph (b)(3)(iii) is
redesignated to (b)(3)(ii). MSHA did not receive any comments on the
proposed changes.
b. Temporary Section Until Compliance Date
As described above, 60 days after publication of the final rule, a
new temporary section with the suffix ``T'' will be added for the
conforming amendments in part 75. Then, 360 days after publication of
the final rule, the existing section for the conforming amendments in
part 75 will be removed and the temporary section will be redesignated
without the ``T'' to replace the removed section. The result of these
technical changes is that mine operators must comply with the existing
standards until the compliance dates in part 60.
7. Part 90--Mandatory Health Standards--Coal Miners Who Have Evidence
of the Development of Pneumoconiosis.
a. Section 90.2--Definitions
The final rule, like the proposal, removes the Quartz definition in
Sec. 90.2 because the Agency is removing the respirable dust standard
when quartz is present in Sec. 90.101. The term quartz no longer
appears in part 90.
In addition, MSHA is revising the definition of Part 90 miner to
remove ``the applicable standard'' (which referred to the reduced RCMD
standard). The revised definition just includes ``the standard'' (which
refers to the respirable dust standard specified in Sec. 90.100). MSHA
did not receive any comments on the proposed change.
b. Section 90.3--Part 90 Option; Notice of Eligibility; Exercise of
Option
The final rule, like the proposal, revises paragraph (a) in Sec.
90.3 to remove ``the applicable standard'' (which referred to the
reduced RCMD standard) and just include ``the standard'' (which refers
to the respirable dust standard specified in Sec. 90.100). MSHA did
not receive any comments on the proposed change.
c. Section 90.100--Respirable Dust Standard
In a change from the proposal, MSHA updates Sec. 90.100 by
removing paragraphs (a) and (b) and revising the section to, ``After
the 20th calendar day following receipt of notification from MSHA that
a part 90 miner is employed at the mine, the operator shall
continuously maintain the average concentration of respirable dust in
the mine atmosphere during each shift to which the part 90 miner in the
active workings of the mine is exposed, as measured with an approved
sampling device and expressed in terms of an equivalent concentration,
at or below 0.5 mg/m\3\.'' Paragraph (a) is removed because its
provision has not been in effect since August 1, 2016. Paragraph (b) is
removed because the language has been incorporated in the revised
language above, making it redundant. MSHA makes this change in the
final rule to match the change made in Sec. 75.350(b)(3)(i).
d. Section 90.101--Respirable Dust Standard When Quartz Is Present
The final rule, like the proposal, removes Sec. 90.101 in its
entirety and reserves the section number. The respirable coal mine dust
standard when quartz is present in Sec. 90.101 is no longer needed
because MSHA is adopting an independent respirable crystalline silica
standard in part 60.
As discussed in greater detail in Section VIII.B.3.b PEL in coal
mines, of this preamble, MSHA solicited comments on whether to
eliminate the reduced standard for total respirable dust when quartz is
present at coal mines and received feedback from stakeholders generally
agreeing with the Agency's proposal to establish a standard for
respirable crystalline silica that is independent from the respirable
coal mine dust standard. For example, the NMA, the Metallurgical Coal
Producers Association (MCPA) and the Pennsylvania Coal Alliance
supported the removal of the respirable dust standards when quartz is
present (i.e., Sec. Sec. 70.101 and 71.101, and 90.101), reasoning
that they are no longer needed since the rule proposes a standalone
standard for respirable crystalline silica (Document ID 1428; 1406;
1378).
In response to commenters, MSHA has concluded that establishing an
independent PEL of 50 [micro]g/m\3\ for a full-shift exposure,
calculated as an 8-hour TWA for respirable crystalline silica allows
more effective control of respirable crystalline silica than the
existing reduced standards, because the separate standard is more
transparent and protective. MSHA clarifies that the respirable coal
mine dust standard is not eliminated, only the sampling requirements
for when silica is present under Sec. Sec. 90.101. MSHA agrees with
the commenters supporting the removal of Sec. Sec. 90.101.
e. Section 90.102--Transfer; Notice
The final rule, like the proposal, amends Sec. 90.102 to remove
``the applicable standard'' (which referred to the reduced RCMD
standard) and just include ``the standard'' (which refers to the
respirable dust standard specified in Sec. 90.100). MSHA did not
receive any comments on the proposed change.
f. Section 90.104--Waiver of Rights; Re-Exercise of Option
The final rule, like the proposal, amends Sec. 90.104 to remove
``the applicable standard'' (which referred to the reduced RCMD
standard) and just include ``the standard'' (which refers to the
respirable dust standard specified in Sec. 90.100). MSHA did not
receive any comments on the proposed change.
g. Section 90.205--Approved Sampling Devices; Operation; Air Flowrate
The final rule, like the proposal, amends Sec. 90.205 to remove
``the applicable standard'' (which referred to the reduced RCMD
standard) and just include ``the standard'' (which refers to the
respirable dust standard specified in Sec. 90.100). MSHA did not
receive any comments on the proposed change.
h. Section 90.206--Exercise of Option or Transfer Sampling
The final rule, like the proposal, amends Sec. 90.206 to remove
``the applicable standard'' (which referred to the reduced RCMD
standard) and just include ``the standard'' (which refers to the
respirable dust standard specified in
[[Page 28352]]
Sec. 90.100). MSHA did not receive any comments on the proposed
change.
i. Section 90.207--Quarterly Sampling
The final rule, like the proposal, amends Sec. 90.207 to remove
``the applicable standard'' (which referred to the reduced RCMD
standard) and just include ``the standard'' (which refers to the
respirable dust standard specified in Sec. 90.100).
Paragraph (b) in Sec. 90.207 is removed and the paragraph
designation reserved. Conforming changes are made to paragraphs (c) and
(d)(1) and (2) to update the name of the table to table 1.
MSHA is amending paragraph (g) by removing Table 90-1 Excessive
Concentration Values (ECV) Based on Single, Full-Shift CMDPSU/CPDM
Concentration Measurements and Table 90-2 Excessive Concentration
Values (ECV) Based on the Average of 5 Full-Shift CMDPSU/CPDM
Concentration Measurements because Sec. 90.101 is removed. A new table
1 is added to paragraph (g) to replace the tables removed. The new
table contains the ECV for the section based on a single sample, two or
more samples, or the average of 5 full-shift CMDPSU/CPDM concentration
measurements. This table contains the remaining ECV after the removal
of the reduced standard in Sec. 90.101 and was generated from data
contained in Tables 90-1 and 90-2. MSHA did not receive any comments on
the proposed changes.
j. Section 90.300--Respirable Dust Control Plan; Filing Requirements
The final rule, like the proposal, amends Sec. 90.300 to remove
``the applicable standard'' (which referred to the reduced RCMD
standard) and just include ``the standard'' (which refers to the
respirable dust standard specified in Sec. 90.100). MSHA did not
receive any comments on the proposed change.
k. Section 90.301--Respirable Dust Control Plan; Approval by District
Manager; Copy to Part 90 Miner
The final rule, like the proposal, amends Sec. 90.301 to remove
``the applicable standard'' (which referred to the reduced RCMD
standard) and just include ``the standard'' (which refers to the
respirable dust standard specified in Sec. 90.100). MSHA did not
receive any comments on the proposed change.
l. Temporary Section Until Compliance Date
As described above, 60 days after publication of the final rule, a
new temporary section with the suffix ``T'' will be added for the
conforming amendments in part 90. Then, 360 days after publication of
the final rule, the existing section for the conforming amendments in
part 90 will be removed and the temporary section will be redesignated
without the ``T'' to replace the removed section. The result of these
technical changes is that mine operators must comply with the existing
standards until the compliance dates in part 60.
D. Updating MSHA Respiratory Protection Standards: Incorporation of
ASTM F3387-19 by Reference
MSHA is updating the Agency's existing respiratory protection
standard to help safeguard the life and health of all miners exposed to
respirable airborne contaminants at MNM and coal mines. The final rule
amends the Agency's existing respiratory protection standards to
incorporate by reference ASTM F3387-19, ``Standard Practice for
Respiratory Protection'', in Sec. Sec. 56.5005T and 57.5005T for MNM
mines and Sec. 72.710T for coal mines (which will become permanent
Sec. Sec. 56.5005 and 57.5005 720 days after publication and permanent
Sec. 72.710 360 days after publication). This change is consistent
with the incorporation by reference of ASTM F3387-19 in final Sec.
60.14(c)(2) making the standard's requirements applicable to respirable
crystalline silica, and other airborne hazards encountered by miners.
The ASTM F3387-19 standard includes provisions for selection, fitting,
use, and care of respirators used to remove airborne contaminants from
the air using filters, cartridges, or canisters, as well as respirators
that protect in oxygen-deficient or immediately dangerous to life or
health (IDLH) atmospheres. ASTM F3387-19 is the most recent consensus
standard developed by experts in government and professional
associations on the selection, use, and maintenance for respiratory
equipment. The ASTM Standard replaces American National Standards
Institute's ANSI Z88.2-1969, ``Practices for Respiratory Protection''
(ANSI Z88.2-1969), which was incorporated in the existing standards.
Incorporating this voluntary consensus standard complies with the
Federal mandate--as set forth in the National Technology Transfer and
Advancement Act of 1995 and OMB Circular A-119--that agencies use
voluntary consensus standards in their regulatory activities unless
doing so would be legally impermissible or impractical. This standard
also improves clarity because it is a consensus standard developed by
stakeholders.
Under existing standards, whenever respiratory protective equipment
is used, mine operators are required to have a respiratory protection
program that is consistent with the provisions of ANSI Z88.2-1969. At
the time of its publication, ANSI Z88.2-1969 reflected a consensus of
accepted practices for respiratory protection.
Respirator technology and knowledge on respiratory protection have
since advanced, and as a result, changes in respiratory protection
standards have occurred. For example, in 2006, OSHA revised its
respiratory protection standard to add definitions and requirements for
Assigned Protection Factors (APF) and Maximum Use Concentrations (MUCs)
(71 FR 50122, 50123). In addition to this rulemaking, OSHA updated
Appendix A to Sec. 1910.134: Fit Testing Procedures (69 FR 46986,
46993, Aug. 4, 2004).
After withdrawing the 1992 version of Z-88.2 in 2002, ANSI
published the American National Standard, ANSI/AIHA Z88.10-2010,
``Respirator Fit Testing Methods,'' approved in 2010. These rules and
standards addressed the topics of APFs and fit testing. APFs provide
employers with critical information to use when selecting respirators
for employees exposed to atmospheric contaminants found in industry.
Finally, in 2015, ANSI published ANSI/ASSE Z88.2-2015, ``Practices for
Respiratory Protection,'' which referenced OSHA regulations. These
updates included requirements for classification of considerations for
selection and use of respirators, establishment of cartridge/canister
change schedules, use of fit factor value for respirator fit testing,
calculation of effective protection factors, and compliance with
compressed air dew requirements, compressed breathing air equipment,
and systems and designation of positive pressure respirators. In July
2017, ANSI/ASSE transferred the responsibilities for developing
respiratory consensus standards to ASTM International.
The ASTM standard contains detailed guidance and provisions on
respirator selection that are based on NIOSH's extensive experience
with testing and approving respirators for occupational use and OSHA's
research and rulemaking on respiratory protection. ASTM F3387-19 also
addresses all aspects of establishing, implementing, and evaluating
respiratory protection programs and establishes minimum acceptable
respiratory protection program requirements in the areas of program
administration, standard operating procedures, medical evaluation,
respirator selection, training,
[[Page 28353]]
fit testing, respirator maintenance, inspection, and storage. ASTM
F3387-19 comprehensively covers numerous aspects of respiratory
protection and provides the most up-to-date provisions for current
respirator technology and effective respiratory protection. Therefore,
MSHA believes that ASTM F3387-19 will provide mine operators with
information and guidance on the proper selection, use, and maintenance
of respirators, which will protect the health and safety of miners.
1. Respiratory Protection Program Requirements
Under the final rule, MSHA requires that the respiratory protection
program be in writing and be consistent with the requirements of ASTM
3387-19, including program administration, standard operating
procedures, medical evaluation, respirator selection, training, fit
testing; and maintenance, inspection, and storage. The following
subsections discuss some of the requirements listed in ASTM F3387-19.
a. Program Administration
ASTM F3387-19 specifies several practices related to respiratory
protection program administration, including the qualifications and
responsibilities of a program administrator. For example, ASTM F3387-19
provides that responsibility and authority for the respirator program
be assigned to a single qualified person with sufficient knowledge of
respiratory protection. Qualifications may have been gained through
training or experience; however, the qualifications of a program
administrator must be commensurate with the respiratory hazards present
at a worksite.
This individual administering the program should have access to and
direct communication with the site manager about matters impacting
worker safety and health. ASTM F3387-19 notes a preference that the
administrator be in the company's industrial hygiene, environmental,
health physics, or safety engineering department; however, a third-
party entity meeting the provisions may also provide this service. ASTM
F3387-19 outlines the respiratory protection program administrator's
responsibilities, specifying that they should include: measuring,
estimating, or reviewing information on the concentration of airborne
contaminants; ensuring that medical evaluations, training, and fit
testing are performed; selecting the appropriate type or class of
respirator that will provide adequate protection for each contaminant;
maintaining records; evaluating the respirator program's effectiveness;
and revising the program, as necessary.
b. Standard Operating Procedures (SOP)
Written SOPs shall be established by the employer and shall cover a
complete respirator program for routine and emergency. ASTM F3387-19
also states that written SOPs for respirator programs are necessary
when respirators are used routinely or sporadically. Written SOPs
should cover hazard assessment; respirator selection; medical
evaluation; training; fit testing; issuance, maintenance, inspection,
and storage of respirators; schedule of air-purifying elements; hazard
re-evaluation; employer policies; and program evaluation and audit.
ASTM F3387-19 also provides that wearers of respirators be provided
with copies of the SOP and that written SOPs include special
consideration for respirators used for emergency situations. The
procedures are reviewed in conjunction with the annual respirator
program audit and are revised by the program administrator, as
necessary.
c. Medical Evaluation
Medical evaluations determine whether an employee has any medical
conditions that would preclude the use of respirators, limitation on
use, or other restrictions. ASTM F3387-19 provides that a program
administrator advise the PLHCP of the following conditions to aid in
determining the need for a medical evaluation: type and weight of the
respirator to be used; duration and frequency of respirator use
(including use for rescue and escape); typical work activities;
environmental conditions (e.g., temperature); hazards for which the
respirator will be worn, including potential exposure to reduced-oxygen
environments; and additional protective clothing and equipment to be
worn. ASTM F3387-19 also incorporates ANSI Z88.6 Respiratory
Protection--Respirator Use--Physical Qualifications for Personnel.
d. Respirator Selection
Proper respirator selection is an important component of an
effective respiratory protection program. ASTM F3387-19 provides that
proper respirator selection consider the following: the nature of the
hazard, worker activity and workplace factors, respirator use duration,
respirator limitations, and use of approved respirators. ASTM F3387-19
states that the respirator selection process for both routine and
emergency use should include hazard assessment, selection of respirator
type or class that can offer adequate protection, and maintenance of
written records of hazard assessment and respirator selection.
ASTM F3387-19 provides specific steps to establish the nature of
inhalation hazards, including determining the following: the types of
contaminants present in the workplace; the physical state and chemical
properties of airborne contaminants; the likely airborne concentration
of the contaminants (by measurement or by estimation); potential for an
oxygen-deficient environment; an occupational exposure limit for each
contaminant; existence of an IDLH atmosphere; and compliance with
applicable health standards for the contaminants.
ASTM F3387-19 includes other information to support the respirator
selection process, including information on operational
characteristics, capabilities, and performance limitations of various
types of respirators. These limitations must be considered during the
selection process. ASTM F3387-19 also describes types of respirators
and considerations for their use, including service life, worker
mobility, compatibility with other protective equipment, durability,
comfort factors, compatibility with the environment, and compatibility
with job and workforce performance. Finally, ASTM F3387-19 provides
other information that is essential for respirator selection, including
degree of oxygen deficiency, ambient noise, and need for communication.
e. Training
Employee training is essential for correct respirator use. ASTM
F3387-19 provides that all users be trained in their area of
responsibility by a qualified person to ensure the proper use of
respirators. A respirator trainer must be knowledgeable about the
application and use of the respirators and must understand the site's
work practices, respirator program, and applicable regulations.
Employees who should receive training under ASTM F3387-19 include the
workplace supervisor, the person issuing and maintaining respirators,
respirator wearers, and emergency teams. To ensure the proper and safe
use of a respirator, the standard also provides that the training for
each respirator wearer should cover, at a minimum: the need for
respiratory protection; the nature, extent, and effects of respiratory
hazards in the workplace; reasons for particular respirator selections;
reasons for engineering controls not being applied or reasons why they
are not adequate; types of efforts made to reduce or eliminate the need
for respirators; operation, capabilities, and limitations
[[Page 28354]]
of the respirators selected; instructions for inspecting, donning, and
doffing the respirator; the importance of proper respirator fit and
use; and maintenance and storage of respirators. The standard provides
for each respirator wearer to receive initial and annual training.
Workplace supervisors and persons issuing respirators are retrained as
determined by the program administrator. Training records for each
respirator wearer are maintained and include the date, type of training
received, performance results (as appropriate), and instructor's name.
f. Respirator Fit Testing
A serious hazard may occur if a respirator, even though properly
selected, is not properly fitted. For example, if a proper face seal is
not achieved, the respirator will provide a lower level of protection
than it is designed to provide because the respirator could allow
contaminants to leak into the breathing area. Proper fit testing
verifies that the selected make, model, and size of a respirator fits
adequately and ensures that the expected level of protection is
provided. ASTM F3387-19 includes provisions for qualitative and
quantitative fit testing to determine the ability of a respirator
wearer to obtain a satisfactory fit with a tight-fitting respirator and
incorporates ANSI/AIHA Z88.10, Respirator Fit Testing Methods, for
guidance on how to conduct fit testing of tight-fitting respirators and
on appropriate methods to be used. This includes information on the
application of fit factors and assigned protection factors, and how
these factors are used to ensure that a wearer is receiving the
necessary protection. ASTM F3387-19 provides for each respirator wearer
to be fit tested before being assigned a respirator; this fit testing
should happen at least once every 12 months or when a wearer expresses
concern about respirator fit or comfort or has a condition that may
interfere with the face piece seal.
g. Maintenance, Inspection, and Storage
Proper maintenance and storage of respirators are important in a
respiratory protection program. ASTM F3387-19 includes specific
provisions for decontaminating, cleaning, and sanitizing respirators,
inspecting respirators, replacing, and repairing parts, and storing and
disposing of respirators. For example, the decontamination provisions
state that respirators must be decontaminated after each use and
cleaned and sanitized regularly per manufacturer instructions.
Following cleaning and disinfection, reassembled respirators are
inspected to verify proper working condition. ASTM F3387-19 states that
employers consult manufacturer instructions to determine component
expiration dates or end-of-service life, inspect the rubber or other
elastomeric components of respirators for signs of deterioration that
would affect respirator performance, and repair or replace respirators
failing inspection. ASTM F3387-19 also provides that respirators are
stored according to manufacturer recommendations and in a manner that
will protect against hazards (e.g., physical, biological, chemical,
vibration, shock, temperature extremes, moisture). It also provides
that respirators are stored in a way that prevents distortion of rubber
or other parts.
2. Section-by-Section Analysis of Incorporation by Reference--ASTM
F3387-19
a. Part 56--Safety and Health Standards--Surface Metal and Nonmetal
Mines
Section 56.5005--Control of Exposure to Airborne Contaminants
Final Sec. 56.5005 is changed from the proposal. The final rule
requires a written respiratory protection program consistent with the
requirements of ASTM F3387-19. In the NPRM, MSHA proposed to revise
paragraph (b) to remove the incorporation by reference to ANSI Z88.2--
1969 and incorporate by reference ASTM F3387-19 to state that approved
respirators must be selected, fitted, cleaned, used, and maintained in
accordance with the requirements of ASTM F3387-19 ``as applicable.''
MSHA proposed to update the Agency's existing respiratory protection
standard to help safeguard the life and health of all miners when
exposed to respirable airborne contaminants at MNM mines while wearing
respirators. The ASTM F3387-19 standard includes, for example,
provisions for selection, fitting, use, and care of respirators used to
remove airborne contaminants from the air using filters, cartridges, or
canisters, as well as respirators that protect in oxygen-deficient or
immediately dangerous to life or health (IDLH) atmospheres. MSHA
proposed to incorporate by reference ASTM F3387-19 because it is the
most recent consensus standard developed by experts in government and
professional associations on the selection, use, and maintenance for
respiratory equipment.
AEMA stated that the final rule should clarify whether a specific
written respiratory protection program is required and under what
standards (Document ID 1424. MSHA's response to these comments is
discussed in detail in Section VIII.B.7. Section 60.14--Respiratory
protection. Also, the Agency provides a detailed description of some
requirements for the respiratory protection program in Section
VIII.D.1. Respiratory Protection Program Requirements.
In response to comments, MSHA has modified the language in
paragraph (b) in the final rule compared to the proposal. The
modifications include: the removal of ``as applicable''; clarification
that a respiratory protection program must be in writing, and one non-
substantive edit in the introductory clause. These changes clarify what
the requirements are for MNM mine operators' respiratory protection
programs.
MNM mine operators do not have to create a separate written
respiratory protection program under each of 30 CFR parts 56, 57, and
60 where ASTM F3387-19 is incorporated by reference. Operators may
create one single program that is applicable to respirable crystalline
silica hazards (part 60) and other airborne contaminants (parts 56 and
57). However, as required by ASTM F3387-19 and MSHA standards, the
respiratory protection program must assess the potential respiratory
hazard or hazards and the mine operator must then select approved
respirators which are appropriate for the airborne hazard(s)
encountered. MSHA believes the final rule provides MNM mine operators
with additional time which should be sufficient to allow them to
prepare and develop written respiratory protection programs, if
necessary, that are based on the finalrule's requirements.
Consistent with the proposal, MSHA is changing paragraph (c) to
require the presence of at least one other person with backup equipment
and rescue capability when respiratory protection is used in
atmospheres that are IDLH. This change is needed to conform to language
in the incorporation by reference of ASTM F3387-19, which defines IDLH
as ``any atmosphere that poses an immediate hazard to life or immediate
irreversible debilitating effects on health'' (ASTM International,
2019).
As described above in Section VIII.C. Conforming Amendments, 60
days after publication of the final rule, a new temporary section with
the suffix ``T'' will be added for the conforming amendments in part
56. Then, 720 days after publication of the final rule, the existing
section for the conforming amendments in part 56 will be removed and
the temporary section will be
[[Page 28355]]
redesignated without the ``T'' to replace the removed section. The
result of these technical changes is that mine operators must comply
with the existing standards until the compliance dates in part 60.
b. Part 57--Safety and Health Standards--Underground Metal and Nonmetal
Mines
Section 57.5005--Control of Exposure to Airborne Contaminants
Final Sec. 57.5005 is changed from the proposal for the same
reasons discussed in Sec. 56.5005. The final rule requires a written
respiratory protection program consistent with the requirements of ASTM
F3387-19. In the NPRM, MSHA proposed to revise paragraph (b) to remove
the incorporation by reference to ANSI Z88.2--1969 and incorporate by
reference ASTM F3387-19 to state that approved respirators must be
selected, fitted, cleaned, used, and maintained in accordance with the
requirements of ASTM F3387-19 ``as applicable.'' MSHA proposed to
update the Agency's existing respiratory protection standard to help
safeguard the life and health of all miners when exposed to respirable
airborne contaminants at MNM mines while wearing respirators. The ASTM
F3387-19 standard, for example, includes provisions for selection,
fitting, use, and care of respirators used to remove airborne
contaminants from the air using filters, cartridges, or canisters, as
well as respirators that protect in oxygen-deficient or immediately
dangerous to life or health (IDLH) atmospheres. MSHA proposed to
incorporate by reference ASTM F3387-19 because it is the most recent
consensus standard developed by experts in government and professional
associations on the selection, use, and maintenance for respiratory
equipment.
AEMA stated that the final rule should clarify whether a specific
written respiratory protection program is required and under what
standards (Document ID 1424). MSHA's response to these comments is
discussed in detail in Section VIII.B.7. Section 60.14--Respiratory
protection. Also, the Agency provides a detailed description of each of
the requirements for the respiratory protection program in Section
VIII.D.1. Respiratory Protection Program Requirements.
In response to comments, MSHA has modified the language in
paragraph (b) in the final rule compared to the proposal. The
modifications include: the removal of ``as applicable''; clarification
that a respiratory protection program must be in writing, and one non-
substantive edit in the introductory clause. These changes clarify what
the requirements are for MNM mine operators' respiratory protection
programs.
MNM mine operators do not have to create a written respiratory
protection program under each of 30 CFR parts 56, 57, and 60 where ASTM
F3387-19 is incorporated by reference. Operators may create one single
program that is applicable to respirable crystalline silica hazards
(part 60) and other airborne contaminants (parts 56 and 57). However,
as required by ASTM F3387-19 and MSHA standards, the respiratory
protection program must assess the potential respiratory hazard or
hazards and the mine operator must then select approved respirators
which are appropriate for the airborne hazard(s) encountered. The final
rule provides MNM mine operators additional time for compliance, which
MSHA believes should give them sufficient time to prepare and develop
written respiratory protection programs, if necessary, that are based
on the final rule's requirements.
Consistent with the proposal, MSHA is changing paragraph (c) to
require the presence of at least one other person with backup equipment
and rescue capability when respiratory protection is used in
atmospheres that are IDLH. This change is needed to conform to language
in the proposed incorporation by reference of ASTM F3387-19, which
defines the term IDLH as ``any atmosphere that poses an immediate
hazard to life or immediate irreversible debilitating effects on
health'' (ASTM International, 2019).
As described above in Section VIII.C. Conforming Amendments, 60
days after publication of the final rule, a new temporary section with
the suffix ``T'' will be added for the conforming amendments in part
57. Then, 720 days after publication of the final rule, the existing
section for the conforming amendments in part 57 will be removed and
the temporary section will be redesignated without the ``T'' to replace
the removed section. The result of these technical changes is that mine
operators must comply with the existing standards until the compliance
dates in part 60.
c. Part 72--Health Standards for Coal Mines
Section 72.710--Selection, Fit, Use, and Maintenance of Approved
Respirators
Final Sec. 72.710 includes two changes from the proposal. The
final rule requires that approved respirators be selected, fitted,
used, and maintained in accordance with the provisions of a written
respiratory protection program consistent with the requirements of ASTM
F3387-19. In the NPRM, MSHA proposed an editorial change to the
introductory statement to Sec. 72.710 and that approved respirators
must be selected, fitted, used, and maintained in accordance with the
requirements of ASTM F3387-19 ``as applicable.''
MSHA proposed to update the Agency's existing respiratory
protection standard to help safeguard the life and health of coal
miners when exposed to respirable airborne contaminants such as
respirable coal dust while wearing respirators. The ASTM F3387-19
standard includes provisions for selection, fitting, use, and care of
respirators used to remove airborne contaminants from the air using
filters, cartridges, or canisters, as well as respirators that protect
in oxygen-deficient or immediately dangerous to life or health (IDLH)
atmospheres. MSHA proposed to incorporate by reference ASTM F3387-19
because it is the most recent consensus standard developed by experts
in government and professional associations on the selection, use, and
maintenance for respiratory equipment.
AEMA stated that the final rule should clarify whether a specific
written respiratory protection program is required and under what
standards (Document ID 1424).
MSHA's response to these comments is discussed in detail in Section
VIII.B.7. Section 60.14--Respiratory protection. Also, the Agency
provides a detailed description of each of the requirements for the
respiratory protection program in Section VIII.D.1. Respiratory
Protection Program Requirements.
In response to comments, MSHA has modified the language to remove
as ``as applicable'' and to clarify that the respiratory protection
program must be in writing and must be consistent with ASTM F3387-19.
This change clarifies what the requirements are for coal mine
operators' respiratory protection programs.
Coal mine operators do not have to create a separate written
respiratory protection program under 30 CFR parts 60 and 72 part where
ASTM F3387-19 is incorporated by reference. Operators may create a
single program that is applicable to respirable crystalline silica
hazards (part 60) and other airborne contaminants (part 72). However,
as required by ASTM F3387-19 and MSHA standards, the respiratory
protection program must assess the potential respiratory hazard or
hazards and the mine operator must select approved respirators which
are
[[Page 28356]]
appropriate for the airborne hazard(s) encountered. MSHA believes the
final rule provides coal mine operators with sufficient time to prepare
and develop written respiratory protection programs that are based on
the rule's requirements.
As described above in Section VIII.C. Conforming Amendments, 60
days after publication of the final rule, a new temporary section with
the suffix ``T'' will be added for the conforming amendments in part
72. Then, 360 days after publication of the final rule, the existing
section for the conforming amendments in part 72 will be removed and
the temporary section will be redesignated without the ``T'' to replace
the removed section. The result of these technical changes is that mine
operators must comply with the existing standards until the compliance
dates in part 60.
IX. Summary of Final Regulatory Impact Analysis and Regulatory
Alternatives
A. Introduction
Executive Order (E.O.) 12866, as amended by E.O. 14094, and E.O.
13563 direct agencies to assess all costs and benefits of available
regulatory alternatives and, if regulation is necessary, to select
regulatory approaches that maximize net benefits (including potential
economic, environmental, public health and safety effects, distributive
impacts, and equity).\77\ E.O. 13563 emphasizes the importance of
quantifying both costs and benefits, of reducing costs, of harmonizing
rules, and of promoting flexibility. E.O.s 12866 and 13563 require that
regulatory agencies assess both the costs and benefits of regulations.
---------------------------------------------------------------------------
\77\ Executive Order 12866 of September 30, 1993: Regulatory
Planning and Review. 58 FR 51735. October 4, 1993. https://www.archives.gov/files/federal-register/executive-orders/pdf/12866.pdf (last accessed Jan. 10, 2024).
Executive Order 14094 of April 6, 2023: Modernizing Regulatory
Review. 88 FR 21879. April 11, 2023. https://www.federalregister.gov/documents/2023/04/11/2023-07760/modernizing-regulatory-review (last accessed Jan. 10, 2024).
Executive Order 13563 of January 18, 2011: Improving Regulation
and Regulatory Review. January 18, 2011. https://www.regulations.gov/document/EPA-HQ-OA-2018-0259-0005 (last accessed
Jan. 10, 2024).
---------------------------------------------------------------------------
Under E.O. 12866 (as amended by E.O. 14094), the Office of
Management and Budget (OMB)'s Office of Information and Regulatory
Affairs (OIRA) determines whether a regulatory action is significant
and, therefore, subject to the requirements of the E.O. and review by
OMB. 58 FR 51735, 51741 (1993). As amended by E.O. 14094, section 3(f)
of E.O. 12866 defines a ``significant regulatory action'' as a
regulatory action that is likely to result in a rule that may: (1) have
an annual effect on the economy of $200 million or more; or adversely
affect in a material way the economy, a sector of the economy,
productivity, competition, jobs, the environment, public health or
safety, or state, local, territorial, or tribal governments or
communities; (2) create a serious inconsistency or otherwise interfere
with an action taken or planned by another agency; (3) materially alter
the budgetary impact of entitlements, grants, user fees or loan
programs or the rights and obligations of recipients thereof; or (4)
raise legal or policy issues for which centralized review would
meaningfully further the President's priorities or the principles set
forth in the E.O. OIRA has determined that this final rule is a
significant regulatory action under section 3(f)(1) of E.O. 12866, and
accordingly it has been reviewed by OMB. Pursuant to Subtitle E of the
Small Business Regulatory Enforcement Fairness Act of 1996, also known
as the Congressional Review Act (5 U.S.C. 801 et seq.), OIRA has
determined that this rule meets the criteria set forth in 5 U.S.C.
804(2).
E.O. 13563 directs agencies to propose or adopt a regulation only
upon a reasoned determination that its benefits justify its costs; the
regulation is tailored to impose the least burden on society,
consistent with achieving the regulatory objectives; and in choosing
among alternative regulatory approaches, the agency has selected those
approaches that maximize net benefits. E.O. 13563 recognizes that some
benefits are difficult to quantify and provides that, where appropriate
and permitted by law, agencies may consider and discuss qualitative
values that are difficult or impossible to quantify, including equity,
human dignity, fairness, and distributive impacts.
To comply with E.O.s 12866 and 13563, MSHA has prepared a final
regulatory impact analysis (FRIA) for the final rule. The purpose of
the FRIA is to:
Profile the mining industry impacted by the final rule;
Estimate the monetized societal benefits attributable to
the new PEL resulting from reductions in fatal cases of lung cancer,
non-malignant respiratory disease, end-stage renal disease, and both
fatal and non-fatal cases of silicosis;
Identify additional non-quantified benefits expected from
the final rule;
Estimate the costs that the mining industry will incur to
achieve compliance with the final rule;
Assess the economic feasibility of the final rule for the
mining industry; and
Evaluate the principal regulatory alternatives to the
final rule that MSHA has considered.
MSHA estimates the final rule will have an annualized cost of $90.3
million in 2022 dollars at a discount rate of 3 percent. The breakdown
of this total cost value by compliance cost for each provision is as
follows: approximately 59 percent is attributable to exposure
monitoring; 21 percent to medical surveillance; 15 percent to exposure
controls (engineering, improved maintenance and repair, and
administrative controls); 5 percent to respiratory protection and
incorporating ASTM F3387-19. Of the annualized compliance cost of $90.3
million, the MNM sector will incur $82.1 million (approximately 91
percent) and the coal sector will incur $8.2 million (approximately 9
percent).
Under a discount rate of 3 percent, the total monetized benefits of
the new respirable crystalline silica final rule from avoided deaths
and morbidity cases, including the benefits of avoided morbidity
preceding mortality, are $246.9 million per year in 2022 dollars. The
net quantified benefits of the final rule are calculated as the
difference between the estimated benefits and costs. MSHA estimates
that the net annualized benefits of the final rule, using a discount
rate of 3 percent, is $156.6 million.
In addition to these quantified benefits, there are unquantified
benefits. MSHA believes that the medical surveillance program will help
miners to detect silica-related diseases early. Early detection of
illness often leads to early intervention and treatment, which may slow
disease progression and/or improve health outcomes. However, MSHA lacks
data to quantify these additional benefits. Furthermore, MSHA expects
that there will be additional benefits from replacing ANSI Z88.2-1969
with ASTM F3387-19. The ASTM standard reflects developments in
respiratory protection since the time in which MSHA issued its existing
standards. The updated standard will play a critical role in
safeguarding the health of miners, reducing their exposures to
respirable crystalline silica and other airborne contaminants. Again,
due to a lack of data, MSHA did not quantify the expected additional
benefits that would be realized by requiring respiratory protection
[[Page 28357]]
programs consistent with the ASTM F3387-19 standard.
The standalone FRIA contains detailed supporting data and
discussions for the summary materials presented here, including the
profile of the mining industry, estimated costs and benefits
attributable to the final rule, the assessment of the economic
feasibility of the final rule for the mining industry, and the
evaluation of regulatory alternatives. The standalone FRIA is placed in
the rulemaking docket at www.regulations.gov, docket number MSHA-2023-
0001. The summary of the standalone FRIA is presented below.
The FRIA includes several revisions made since the PRIA. In
response to public comments on the proposed rule and PRIA, MSHA revised
its cost and benefit estimates. The revisions increased both the
estimated costs and benefits.
Four types of changes were made to the cost and benefit estimates.
First, the final rule includes several changes from the proposed rule,
and these changes affected estimated costs. The changes include:
additional time provided by MSHA for mine operator compliance;
revisions to exposure monitoring requirements including removal of the
use of objective data and historical sample data to discontinue
sampling; the requirement for mine operators to immediately report all
exposures above the PEL from operator sampling to the MSHA District
Manager or other designated office; revisions to the requirement for
periodic evaluations to include additional evaluations whenever changes
are made; the requirement of respiratory protection for MNM mines when
engineering controls are being developed and implemented, or it is
necessary by the nature of the work performed; and changes to the
medical surveillance requirements for MNM operators related to the
compliance date and a new requirement for reporting miners' chest X-ray
results to NIOSH.
Second, MSHA revised the FRIA methodology to annualize compliance
costs over 60 years, which is the regulatory time horizon for this
analysis. The 60-year analysis period starts with the first day of
compliance for the coal sector (12 months after publication of the
final rule). Coal mine operators incur compliance costs beginning 12
months after publication of the final rule. MNM mine operators incur
compliance costs beginning 24 months after publication of the final
rule. The analysis period ends 60 years after the first day of
compliance for the coal sector, thus 60 years of compliance costs for
coal mine operators and 59 years of compliance costs for MNM mine
operators are included in the analysis. MSHA also updated both
compliance costs and benefits to reflect 2022 dollars using the GDP
implicit price deflator.
Third, MSHA made several changes to the PRIA cost estimation
methodology; for example, the Agency modified its assumption about the
proportion of the miner workforce that would be sampled in larger
mines, as well as its assumption about the number of corrective
actions, to account for circumstances in which multiple corrective
actions may be necessary to reduce miners' exposure to below the PEL.
MSHA also revised estimates of maintenance and repair and
administrative control costs each year.
Lastly, MSHA made some changes to the PRIA benefit estimation
methodology. Changes were also made to the benefit estimates. As
discussed in Section VI. Final Risk Analysis Summary, the PRA
underestimated benefits from the proposed rule by excluding future
retired miners from the number who would benefit. Both the FRA and the
FRIA are updated to account for benefits for working miners and future
retired miners. It is important to note that the FRIA only monetizes
benefits to future retired miners--i.e., retired individuals who were
employed as miners at least one year after the start of implementation.
The FRIA methodology does not attribute any health benefits to
individuals who retired before the start of implementation of the final
rule. The FRIA reflects the fact that the number of future retired
miners increases gradually after the start of implementation. For
example, in the first year after the start of implementation, there
will be no retired miners who benefit from the rule. In the second year
after the start of implementation, there will be one cohort of retired
miners who benefit from the rule (i.e., those in their final year of
mining when implementation began). In this way, the FRIA monetizes
benefits to future retired miners while accounting for the fact that
future retired miners who benefit from the rule increase in size
gradually during the 60-year analysis period.
B. Miners and Mining Industry
This section provides information on the characteristics of the MNM
and coal mining sectors, including their estimated revenues, number of
mines in each sector, commodities the industry produces, and employment
sizes. In addition, this section provides the respirable crystalline
silica exposure profiles for miners across different occupational
categories in the MNM and coal sectors. These data come from the U.S.
Department of the Interior (DOI), U.S. Geological Survey (USGS); U.S.
Department of Labor (DOL), Mine Safety and Health Administration
(MSHA), Educational Policy and Development and Program Evaluation and
Information Resources; DOL, Bureau of Labor Statistics (BLS),
Occupational Employment and Wage Statistics (OEWS); U.S. Census Bureau,
Statistics of U.S. Businesses (SUSB); and the Energy Information
Administration (EIA).
In general, economic profiles were developed using 2019 data
because this was the most recent year available that was not impacted
by temporary changes resulting from the COVID-19 pandemic. To estimate
the current number of miners, MSHA used the 2019 Quarterly Employment
Production Industry Profile (MSHA, 2019a) and the 2019 Quarterly
Contractor Employment Production Report (MSHA, 2019b). MSHA estimated
the number of and type of mines using 2019 data from the Mine Data
Retrieval System, including the Mines database, (MSHA, 2022d) and the
2019 employment data (MSHA, 2019a,b).
The size of the mining industry is difficult to forecast given the
uncertainties in future demand for various mined commodities, as well
as uncertainties about technological changes. MSHA assumed the current
mining workforce and the current number of mines would not change
during the 60 years following implementation of the final rule. If the
industry were to contract or expand in the future, the relative ratio
of benefits to costs would remain roughly the same because both the
benefits and costs of the final rule are in proportion to the size of
the industry.
1. Structure of the Mining Industry
The mining industry can be divided into two major sectors: (1) MNM
mines and (2) coal mines, with further distinction made regarding type
of operation (i.e., underground mines or surface mines) and commodity.
The MNM mining sector is made up of metal mines (e.g., copper, iron
ore, gold, silver, etc.) and nonmetal mines. Nonmetal mines can be
further categorized into four commodity groups: (1) nonmetal (mineral)
materials such as clays, potash, soda ash, salt, talc, and
pyrophyllite; (2) stone, including granite, limestone, dolomite,
sandstone, slate, and marble; (3) crushed limestone; and (4) sand and
gravel, including industrial sands.
MSHA categorizes mines by size based on employment. For purposes of
[[Page 28358]]
this industry profile and the FRIA analyses, MSHA categorized mines
into the following four size groups: \78\ (1) 1 to 20 miners; (2) 21 to
100 miners; (3) 101 to 500 miners; and (4) 501 or more miners.
---------------------------------------------------------------------------
\78\ Miner employment is based on the information submitted
quarterly through the MSHA Form 7000-2, excluding Subunit 99--Office
(professional and clerical employees at the mine or plant working in
an office); https://www.msha.gov/sites/default/files/Support_Resources/Forms/7000-2_0.pdf (last accessed Jan. 10, 2024).
---------------------------------------------------------------------------
MSHA tracks mine characteristics and maintains a database
containing the number of mines by mine type and size, number of
employees, and employee hours worked. MSHA also collects data on the
number of independent contractor firms who provide miners to the
industry, the number of contract miners they employ, and their employed
contract miners' hours worked. Contract miners may work at any mine.
Table IX-1 presents an overview of the mining industry, including
the number of MNM and coal mines, their employment (excluding contract
miners), and their estimated revenues by commodity and size. As
mentioned above, all data regarding the number of miners and mines are
current in reference to the year 2019 and are assumed to remain
constant during the 60 years following the implementation of the final
rule. Estimated revenues are also based on 2019 data but have been
inflated to 2022 dollars using the GDP implicit price deflator (U.S.
Bureau of Economic Analysis, 2023).
The MNM mining sector is comprised of an estimated 11,525 mines
which employ an estimated 169,070 individuals, of which 150,928 are
miners (excluding contract miners) and 18,142 are office workers. In
addition, contract miners work an estimated 71.3 million hours in MNM
mines each year.
The coal mining sector is comprised of an estimated 1,106 mines
that employ an estimated 52,966 individuals, of which 51,573 are miners
(excluding contract miners) and 1,393 are office workers. In addition,
contract miners work an estimated 28.0 million hours in coal mines each
year.
A further breakdown of MNM mines and coal mines by mine commodity
and mine size is provided below.
BILLING CODE 4520-43-P
[[Page 28359]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.156
BILLING CODE 4520-43-C
a. Metal Mining
There are 24 groups of metal commodities mined in the U.S. Metal
mines represent an estimated 2.4 percent (280/11,525) of all MNM mines
and employ an estimated 24.5 percent of all MNM miners (excluding
contract miners). Of these 280 estimated mines, 157 (56.1 percent)
employ 20 or fewer miners and 22 (7.9 percent) employ greater than 500
miners. Additionally, MSHA data show that there is an estimated total
of 13,792 contract miners in the metal mining industry with an
estimated 18.9 million reported production hours in a year.
b. Non-Metal (Mineral) Mining
There are 35 non-metal commodities mined in the U.S., not including
stone and sand and gravel. Non-metal mines represent an estimated 7.8
percent (897/
[[Page 28360]]
11,525) of all MNM mines and employ an estimated 15 percent of all MNM
miners (excluding contract miners). The majority of non-metal mines
(71.9 percent) employ fewer than 20 miners and less than 1 percent
employ more than 500 miners. According to MSHA data, there are an
estimated 11,346 contract miners in the non-metal mining industry with
an estimated 14.5 million reported production hours in a year.
c. Stone Mining
The stone mining subsector includes eight different stone
commodities. Of these eight, seven are further classified as either
dimension stone or crushed and broken stone. Stone mines make up an
estimated 20.9 percent (2,409/11,525) of all MNM mines and employ an
estimated 23.4 percent of all MNM miners (excluding contract miners).
The majority of these mines (83.1 percent) employ fewer than 20 miners
and one mine employs over 500 miners. According to MSHA data, there are
an estimated 18,559 contract miners in the stone mining industry with
an estimated total of 18.8 million reported production hours in a
single year.
d. Crushed Limestone
Crushed limestone mines make up an estimated 16.2 percent (1,862/
11,525) of all MNM mines and are estimated to employ about the same
percentage (16.0 percent) of all MNM miners (excluding contract
miners). Of the 1,862 crushed limestone mines, the vast majority (83.5
percent) employ fewer than 20 miners; none employ over 500 miners.
Additionally, MSHA data show that there are an estimated 9,065 contract
miners in the crushed limestone mining industry with an estimated total
of 10.2 million reported production hours in a single year.
e. Sand and Gravel Mining
Sand and gravel mines account for an estimated 52.7 percent (6,077/
11,525) of all MNM mines and employ an estimated 21.1 percent of all
MNM miners (excluding contract miners). Nearly all (96.7 percent)
employ fewer than 20 employees; none employ over 500 miners. MSHA data
show that there are an estimated 7,512 contract miners in the sand and
gravel mining industry with an estimated 8.9 million production hours
in a single year.
f. Coal
Of the estimated 1,106 total coal mines, an estimated 63.9 percent
(707/1,106) employ fewer than 20 miners and 1.1 percent employ more
than 500 miners. Overall coal mine employment is estimated to be
52,966, of which 51,573 are miners (excluding contract miners) and the
remaining 1,393 are office workers. Additionally, there are an
estimated total of 22,003 contract miners in the coal mining industry
with an estimated 28.0 million reported production hours in a single
year.
2. Economic Characteristics of the Mining Industry
The value of all MNM mining output in 2022 dollars was estimated at
$95.1 billion (U.S. Department of Interior, 2019). Metal mines, which
include iron, gold, copper, silver, nickel, lead, zinc, uranium,
radium, and vanadium mines, contributed $30.5 billion. In the USGS
Mineral Commodity Summaries, production values for nonmetals, stone,
sand and gravel, and crushed limestone are combined into one commodity
group titled ``industrial minerals.'' Therefore, MSHA estimated the
production value of each individual commodity by taking the proportion
of revenues for the commodity in question among all commodities in the
2017 SUSB and applying that proportion to the 2019 production value for
all industrial minerals reported by USGS. This approach yields the
following estimates: non-metal production is valued at an estimated
$22.3 billion, stone mining at $14.6 billion, crushed limestone at
$14.4 billion, and sand and gravel at $10.2 billion.
The U.S. coal mining sector is made up of three major commodity
groups: bituminous, anthracite, and lignite. According to MSHA data,
bituminous operations represent approximately 92.1 percent of total
coal production in short tons and employ 91.9 percent of all coal
miners (excluding contract miners). Anthracite operations represent 0.4
percent of coal production and employ 1.9 percent of coal miners
(excluding contract miners). Lignite operations represent roughly 7.5
percent of total coal production and employ 6.2 percent of coal miners
(excluding contract miners).
To estimate coal revenues in 2019, MSHA combined production
estimates with unit prices. Mine production data were taken from MSHA
quarterly data and the coal unit prices per ton were taken from the
2019 EIA Annual Coal Report. Estimated revenues were then inflated to
2022 dollar values using the GDP implicit price deflator. As shown in
Table IX-1, 2019 total coal revenues expressed in 2022 dollars totaled
an estimated $29.1 billion.
3. Respirable Crystalline Silica Exposure Profile of Miners
Using the quarterly employment data submitted by mines and the
Occupational Employment and Wage Statistics (OEWS) reported by the BLS,
MSHA estimated the distribution of miners (excluding contract miners)
across different occupational categories. For contract miners, MSHA
lacked information on occupational categories. However, based on MSHA's
program experience, MSHA assumed that the distribution of contract
miners across the different occupational categories mirrors that of the
miners (excluding contract miners) in each of the two sectors. For
example, MSHA assumed that, because 1.9 percent of MNM production
miners are drillers, 1.9 percent of contract miners working in MNM
mines are also drillers.
As discussed in Section VI. Final Risk Analysis Summary, full-time
equivalents (FTEs) are used to account for the fact that miners may
experience more or less than 2,000 hours of exposure to respirable
crystalline silica per year. MSHA calculates the number of miner FTEs
by dividing the estimated total number of hours worked across all mines
in a given sector by 2,000 hours. Based on these calculations, MSHA
estimates 184,615 FTEs in the MNM sector of which 148,966 (81 percent)
are miner FTEs (excluding contract miners) and the remaining 35,649 (19
percent) are contract miner FTEs (Table IX-2). For the coal sector,
MSHA estimates 72,768 FTEs of which 58,764 (81 percent) are miner FTEs
(excluding contract miners) and the remaining 14,004 (19 percent) are
contract miner FTEs.
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MSHA's exposure data is described in Section VI. Final Risk
Analysis Summary. In summary, MSHA used compliance data from 2005
through 2019 to estimate the current levels of exposure to respirable
crystalline silica among MNM miners (MSHA, 2022b). For the coal sector,
MSHA used data from 2016-2021 (MSHA, 2022a). For the coal sector, MSHA
only used exposure data since 2016, by which time all provisions of the
Coal Mine Dust Standard had gone into effect. MSHA did not use earlier
data so that the benefits in this FRIA are clearly attributable to this
final rule and not to the Coal Mine Dust Standard.
MSHA distributed the respirable dust samples in its MNM and coal
exposure datasets by occupational category and exposure interval.
Because exposure data associated with individual miners are not
available, MSHA derived the imputed exposure profile of miners and
miner FTEs stratified by occupational category and exposure interval.
Based on this imputation, MSHA found that, in the MNM sector, an
estimated 13,242 miners (6 percent), including contract miners,
currently have respirable crystalline silica exposures above the
existing PEL of 100 [micro]g/m\3\, an estimated 37,966 (18 percent)
have exposures above the new PEL of 50 [micro]g/m\3\, and an estimated
77,736 (37 percent) have exposures at or above the action level of 25
[micro]g/m\3\. On an FTE basis, an estimated 11,579 miner FTEs (6
percent), including contract miner FTEs, have respirable crystalline
silica exposures above the existing PEL of 100 [micro]g/m\3\, an
estimated 33,146 (18 percent) have exposures above the new PEL of 50
[micro]g/m\3\, and an estimated 67,946 (37 percent) have exposures at
or above the action level of 25 [micro]g/m\3\.
In the coal sector, an estimated 1,406 miners (2 percent),
including contract miners, currently have respirable crystalline silica
exposures above the existing PEL of 85.7 [micro]g/m\3\, an estimated
4,080 (6 percent) have exposures above the new PEL of 50 [micro]g/m\3\,
and an estimated 13,971 (19 percent) have exposures at or above the
action level of 25 [micro]g/m\3\. On an FTE basis, the figures are
similar with an estimated 1,391 miner FTEs (2 percent), including
contract miner FTEs, having respirable crystalline silica exposures
above the existing PEL of 85.7 [micro]g/m\3\, an estimated 4,035 (6
percent) having exposures above the new PEL of 50 [micro]g/m\3\, and an
estimated 13,818 (19 percent) having exposures at or above the action
level of 25 [micro]g/m\3\.
C. Cost Analysis
The FRIA assesses the costs in the MNM and coal sectors of reducing
miners' exposures to silica to 50 [mu]g/m\3\ for a full-shift exposure,
calculated as an 8-hour TWA and the costs of complying with the final
rule's other requirements.
Under the final rule, mine operators are required to: implement
exposure controls (Sec. 60.11); conduct exposure monitoring and report
all samples over the PEL to MSHA (Sec. 60.12); take immediate
corrective actions and provide miners with respirators when a sampling
result indicates that miner exposure exceeds the PEL (Sec. 60.13);
respiratory protection is required as a temporary measure for all MNM
miners when MNM miner exposure exceeds the PEL while engineering
controls are being developed and implemented or when it is necessary by
the nature of work involved (for example, occasional entry to hazardous
atmospheres to perform maintenance or investigation) (Sec. 60.14)(a);
make periodic medical examinations available to MNM miners and ensure
certain medical results are reported to NIOSH (Sec. 60.15); develop or
revise existing respiratory protection programs and practices in
accordance with the ASTM F3387-19 (Sec. Sec. 56.5005, 57.5005, and
72.710); and retain records for the specified durations (Sec. 60.16).
MSHA estimates the annualized costs of the final rule range from
$88.8 million to $92.4 million, depending on the discount rate used
(Table IX-3). Of this total, about 91 percent will be incurred by mine
operators in the MNM sector and 9 percent by mine operators in the Coal
sector. The difference in cost between the MNM and coal sectors is
driven by the much larger number of MNM mines, as well as differences
in mine size and the extent to which current exposures are already
below 50 [mu]g/m\3\. In addition, MNM mine operators will incur costs
to meet the medical surveillance requirements which further drives the
difference in total costs between the MNM and coal sectors.
[[Page 28362]]
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For the PRIA, MSHA estimated annualized costs would range from
$56.2 million (0 percent discount rate) to $60.0 million (7 percent
discount rate). However, the estimated compliance costs for the PRIA
were calculated in 2021 dollars. To compare PRIA and FRIA costs on an
equivalent basis, MSHA inflated estimated PRIA compliance costs from
2021 dollars to 2022 dollars, which increases PRIA costs by about 7
percent. In 2022 dollars, estimated PRIA costs range from $60.1 million
(0 percent discount rate) to $64.2 million (7 percent discount rate).
Annualized estimated FRIA compliance costs exceed PRIA costs by about
$28.2 to $28.7 million per year.
After accounting for the inflation to 2022 dollars, the remaining
difference in estimated compliance costs between the PRIA and FRIA are
attributable to several changes to the proposed rule, including:
A longer phase-in implementation is provided for both coal
and MNM mines.
Objective data and historical sample data may no longer be
used to demonstrate compliance with exposure monitoring requirements.
Sample results exceeding the PEL must be reported to the
MSHA district manager or other designated office.
Periodic evaluations must be conducted at least every 6
months or whenever there is a change in: production; processes;
installation or maintenance of engineering controls; installation or
maintenance of equipment; administrative controls; or geological
conditions.
Limited temporary use of respirators is permitted in MNM
mines only.
For medical surveillance, the first medical examination
offered to all MNM miners must be within 12 months of the compliance
date. Also, chest X-ray results must be reported to NIOSH.
Under the FRIA, annualized costs are attributable to the following
provisions of the final rule:
Exposure Monitoring ($53.2 million, 59 percent of total)
Exposure Controls ($13.7 million, 15 percent of total)
Respiratory Protection ($3.3 million, 4 percent of total)
Medical Surveillance ($18.8 million, 21 percent of total),
and
ASTM Update ($1.2 million, 1 percent of total).
Nearly two-thirds of the increase in estimated compliance costs
($19.0 million) is attributable to the exposure monitoring requirements
under the final rule. The remainder is largely attributable to
increased estimates for exposure controls ($7.5 million) and
respiratory protection ($2.2 million). MSHA expects that the amount of
sampling performed by mine operators will increase because the final
rule does not allow mine operators to use objective data and historical
sample data (operator and MSHA sample data from prior 12 months) to
demonstrate compliance with exposure monitoring requirements. Below the
estimate of each cost component is discussed in more detail.
1. Costs for Exposure Monitoring
There are five types of exposure monitoring required under the
final rule:
First-time sampling and second-time sampling based on a
representative fraction of miners (Sec. 60.12(a)). First-time sampling
occurs starting by the rule's respective compliance dates for coal
mines and MNM mines. Second-time sampling occurs within three months of
first-time sampling.
Above-action-level sampling of a representative fraction
of miners. If the most recent sampling results are at or above the
action level (Sec. 60.12(a)), above-action-level sampling starts three
months after the most recent sampling and continues until two
consecutive samples demonstrate that miners' exposures are below the
action level.
Corrective actions must be performed for samples over the
PEL. The mine operator must take corrective actions to reduce exposure
and conduct corrective actions sampling until sample results are at or
below the PEL (Sec. 60.12(b)). All corrective actions sample results
exceeding the PEL must be immediately reported to the MSHA District
Manager or other office designated by the District Manager.
Periodic evaluations (qualitative monitoring) must be
performed at least every 6 months, or whenever there is a change in
production, processes, engineering or administrative controls, or
geological conditions that may reasonably be expected to result in new
or increased respirable crystalline silica exposures to ensure that any
change will not have increased miners' exposures (Sec. 60.12(c)).
If the periodic evaluations conducted under Sec. 60.12(c)
determine that increased exposures are likely, post-evaluation sampling
must be conducted to ensure exposures remain at or above the action
level (Sec. 60.12(d)).
For quantitative monitoring, MSHA estimates total sampling costs as
a function of several factors: the unit cost of sampling, made up of
labor costs (miners' and external consultants' time and hourly wage),
laboratory costs for analyzing the samples, and clerical costs for
recording the results; the number of samples that constitutes the
required representative fraction each time the operator conducts
sampling; and the frequency with which operators are assumed to carry
out different types of monitoring (samplings and evaluation). MSHA
assumes that regardless of the type of sampling, the unit cost of
sampling does not vary, since the process of collecting a dust sample
and
[[Page 28363]]
analyzing for respirable crystalline silica is relatively similar at
different mines. For the qualitative monitoring, MSHA estimates
periodic evaluation costs as a function of labor costs and the
frequency of evaluation. The calculation of each of these factors is
discussed below.
Labor Costs of Exposure Monitoring
The most important component of sampling and evaluation cost is the
time required to conduct the activities. For sampling, this includes
the time needed to prepare for sampling, take the samples, and perform
recordkeeping tasks on the results. Sampling takes time, which is
valued at the hourly wage of the person wearing the sampling equipment
and the person conducting the sampling. To err on the side of
overestimates, MSHA assumed that in MNM mines, sample preparation and
collection is performed by an industrial hygienist (IH).\79\ The IH may
be an in-house specialist or an external consultant. For coal mines,
miners certified to perform sampling under 30 CFR 70.202, 71.202, and
90.202 can conduct the sampling required under the final rule.
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\79\ In reality, some MNM mines may train their miners or other
in-house employees to conduct sampling. In such scenarios, an IH
would not be used and the labor cost of sampling would be based on
the loaded hourly wage for the participating employee.
---------------------------------------------------------------------------
In addition, MSHA assumed the personnel conducting sampling can
collect 2, 3, and 4 samples per day at small, medium, and large mines,
respectively. This determines the number labor hours needed to complete
sampling at a mine, and therefore directly affects labor costs.
Sampling labor costs: For coal mines, MSHA estimates sampling labor
cost at $398 per sample at mines with 20 or fewer employes; $264 per
sample at mines with 21 to 500 employees; and $248 per sample at mines
with more than 500 employees. For metal mines, MSHA estimates sampling
labor cost at $747 per sample for mines with 20 or fewer employes; $380
per sample at mines with 21 to 500 employees; and $334 per sample for
mines with more than 500 employees. For nonmetal mines, MSHA estimates
sampling labor cost at $772 per sample at mines with 20 or fewer
employees; $366 per sample at mines with 21 to 500 employees; and $322
per sample at mines with more than 500 employees. These figures include
the recordkeeping costs specified below.
Evaluation labor costs: MSHA estimates that a periodic evaluation
will typically require two hours of time for an IH. Thus, the cost
ranges from $131 to $162 per evaluation.
Laboratory Analysis Costs of Sampling
MSHA estimates that laboratory analysis will cost the mine operator
$150 per sample. This includes the cost of packing and shipping the
sample to the lab, the laboratory analysis, and reporting sample
results to the operator.
Recordkeeping Cost of Sampling
The labor time required for recording results of sampling is
estimated at 17 minutes and is valued at the loaded hourly wage of an
industrial hygienist. Thus, costs for recordkeeping time due to
sampling range from $19 to $23 per sample.
Number of Samples--Representative Sampling
While the cost of labor time and laboratory analysis are the
primary components of cost per sample, a second major determinant of
sampling cost at any mine is the number of samples required each time
sampling occurs. Where several miners perform the same tasks on the
same shift and in the same work area, the mine operator may sample a
representative fraction (i.e., at least two) of these miners to meet
the sampling requirements. The final rule requires that mine operators
sample a representative fraction of miners who are expected to have the
highest exposure to respirable crystalline silica. MSHA estimated the
number of miners considered a representative sample based on the size
of the mine. In small mines that employ 20 or fewer miners (including
contract miners), MSHA assumes that a sample comprising at least 50
percent of miners will be necessary to collect a representative sample.
In medium-sized mines with 20 to 100 miners, the assumption is that a
minimum 25 percent of miners will need to be sampled for the sample to
be representative. In large mines with 100 or more miners, the Agency
assumes that a minimum 15 percent of miners will need to be sampled for
the sample to be representative.
Frequency of Exposure Monitoring--Number of Samples and Evaluations
The third component of sampling cost is the frequency with which it
must be performed. Sampling frequency depends on sample results, as
specified by MSHA's exposure monitoring requirements.
First-time and second-time sampling. First-time and second-time
sampling is performed by all mine operators. First-time sampling occurs
by the relevant compliance date for existing mines. Second-time
sampling occurs within 3 months following first-time sampling. First-
time and second-time sampling is representative sampling. The number of
samples taken at a mine will depend on the size of the mine. After the
first-time sampling is completed, each operator will determine the next
action based on the first sample result. If that result is below the
action level, the mine operator will have to conduct the second
sampling. If the results from both samplings are below the action
level, no further sampling is required, unless there are changes
identified by periodic evaluations that may reasonably be expected to
result in new or increased respirable crystalline silica exposures.
(Periodic evaluations are further discussed below.) The second-time
sampling must be taken after the operator receives the results of the
first-time sampling but no sooner than 7 days after the prior sampling
was conducted.
Above-action-level sampling. Sampling above the action level is
also representative. Unlike first- and second-time sampling, this type
of sampling will not be required of all mines, but only of those mines
showing exposure levels at or above the action level of 25 [mu]g/m\3\.
This sampling continues as long as the most recent sample results
demonstrate exposure at a mine is at or above the action level of 25
[mu]g/m\3\ but below the new PEL of 50 [mu]g/m\3\.
MSHA estimated the percent of samples exceeding the action level in
Year 1 based on its exposure profile developed using the Agency's
compliance sampling data. MSHA assumed that mine operators will reduce
the percentage of samples exceeding the action level from their current
level of 31 percent to about 15 percent of samples by Year 7.
Corrective Actions Sampling. Corrective actions sampling is
required when a sample result exceeds the new PEL. A sample result
above the PEL requires the mine operator to take corrective actions and
conduct corrective actions sampling to determine if the actions reduced
exposures to the PEL. MSHA uses the estimated number of samples
exceeding 50 [mu]g/m\3\ to estimate the number of corrective actions
taken. Each sample result above the PEL requires a corrective action
and an additional sample to ensure that the corrective action was
effective. Not all corrective actions may be effective in reducing
exposures below the PEL. Therefore, MSHA increased the number of
samples exceeding the new PEL by 25 percent to account for situations
requiring more
[[Page 28364]]
than one corrective action taken by mine operators.
Periodic Evaluation. MSHA assumed that mines operating only two
quarters or less per year will conduct this evaluation once per year,
while mines operating more than two quarters per year will perform this
evaluation twice per year.
However, because the rule requires periodic evaluation whenever
factors change that may affect exposures, some mines, such as portable
mines, will likely have to conduct evaluations more frequently than
semi-annually. Therefore, MSHA increased its estimate of the number of
periodic evaluations by 20 percent (i.e., annual periodic evaluations
are equal to 2.4 times the number of mines) to account for mines that
will need to perform evaluations more than twice per year.
Post-Evaluation Sampling. Periodic evaluation may lead to sampling
performed for purposes of evaluating whether exposure levels might have
changed or if they remain below the action level. MSHA assumed that
post-evaluation sampling comprises 2.5 percent of miners. This
percentage is relatively small because mine operators are already
collecting sample data which can be used for these purposes. However,
MSHA estimated that some additional sampling might be needed and
included additional post-evaluation sampling costs.
Table IX-4 summarizes how the costs of each type of monitoring
measures are estimated.
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[[Page 28365]]
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Table IX-5 below presents the estimated number of samples by
sampling type and by commodity sector in the first 7 years of the
analysis because MSHA expects a long-run average to be reached in Year
7. MSHA projects that in the first 2 years (following the coal and MNM
compliance dates), 259,059 samples will be taken compared to 92,663 per
year in Years 7 through 60. This is a result of: (a) declines in first-
time and second-time sampling after the first year of compliance, and
(b) declines in above-action-level and corrective actions sampling as
mine operators become more experienced in developing and implementing
new controls.
[[Page 28366]]
First-time and second-time sampling. Of the 259,059 samples
expected to be taken in the first 2 years following the coal and MNM
compliance dates, MSHA projects that approximately 60 percent (154,680/
259,059) will be from first-time and second-time sampling. After Year 1
for Coal, and Year 2 for MNM, all first-time and second-time sampling
will only be performed by new mines. MSHA projects that about 2 percent
of mines in any given year will be new entrants to the mining industry,
although the total number of mines in each year remains roughly
constant.
[GRAPHIC] [TIFF OMITTED] TR18AP24.160
[[Page 28367]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.161
[[Page 28368]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.162
Above-action-level sampling. MSHA projects that the number of
above-action-level samples will increase from 5,423 in Year 1 to 48,275
in Year 2 and to 79,062 in Year 3 as more mines start their above-
action-level sampling. This type of sampling is projected to decline
starting from Year 4, due to the implementation of engineering
controls, maintenance and repair of controls, and implementation of
administrative controls, all of which will result in fewer miners and
contract miners with exposure levels at or above the action level. MSHA
projects that by Year 7, about 45,000 samples per year will be taken.
Corrective actions sampling. MSHA also projects that the number of
corrective actions samples--those taken after corrective actions, to
ensure exposures have been reduced to below the new PEL--will be 46,912
in Year 3. This figure is also projected to decline over time, to
27,743 by Year 7.
Evaluations. MSHA projects that starting with Year 2 following
implementation, 12,631 mines will take about 28,308 evaluations per
year.
Post-evaluation sampling. Similarly, post-evaluation sampling
remains constant at approximately 16,953 samples per year since these
samples are independent of the above-action-level sampling.
Total Annualized Exposure Monitoring Costs
Table IX-6 below presents estimated total annualized exposure
monitoring costs by type of monitoring and mining sector. The five
types of exposure monitoring (samplings and evaluation) are projected
to cost mine operators an average of about $53.2 million (3 percent
discount rate) per year over 60 years. The first-time and second-time
sampling ($4.2 million per year) account for about 8 percent of
exposure monitoring costs; above-action-level sampling ($23.5 million)
accounts for 44 percent; corrective actions sampling ($14.9 million)
accounts for 28 percent; and periodic evaluations and post-evaluation
sampling ($10.7 million) together account for about 20 percent. Of the
total exposure monitoring costs, about 89 percent are expected to be
incurred by MNM mines and the remaining 11 percent by coal mines.
[[Page 28369]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.163
BILLING CODE 4520-43-C
Several commenters disagreed with MSHA's estimates for sampling
costs (Document ID 1419; 1441; 1442; 1448) in the PRIA. For example, a
mining trade association NSSGA provided estimates from several mine
operators that exposure monitoring costs would be substantially higher
than those reported in MSHA's PRIA (Document ID 1448). This commenter
provided sampling costs ranging from a low of $139 to a maximum of
$1,800 per sample, with a median of $650 per sample, that would
increase costs by $34 million to $162 million for 250,000 MNM miners.
This commenter further stated that sampling costs vary according to the
number of miners sampled: $2,866 for one miner, but $3,247 for 3 miners
(approximately $1,082 per miner). A second commenter, a MNM mine
operator/owner Vanderbilt Minerals, LLC, listed costs in excess of
$11,000 for a single 3-day sampling event (Document ID 1419). A third
commenter, an industry trade association EMA, stated that 400 of its
446 employees would require 1,200 individual samples over the course of
one year to meet the sampling requirements (Document ID 1442). A fourth
commenter, NVMA, stated that one of its members estimated sampling
costs would increase by $1.2 million for its 7,000 employees (Document
ID 1441).
MSHA acknowledges that the range of costs per sample provided by
commenters likely exceeds MSHA's own estimates. As explained earlier,
and in greater detail in Section 4 of the standalone FRIA document,
MSHA's calculations of the average unit costs of sampling, sample
analysis, and evaluation take into account the labor cost of time spent
sampling, laboratory fees for sample analysis, lost work time due to
sampling, recordkeeping time, plus the cost of performing periodic
evaluations. MSHA assumes that the labor cost of sampling varies by
commodity and mine size. MSHA estimates that mine operators will take
5.76 million samples at a cost of $3.09 billion over the 60-year
analysis period. MSHA estimated the weighted average (mean) cost at
$500 per sample, with costs ranging from $250 per sample (for coal
mines with more than 500 employees) to $750 per sample (for metal mines
with 20 or fewer employees). A direct comparison with the cost
estimates provided by the above commenter (NSSGA) is not possible
because NSSGA presents the median but not the mean cost per sample from
the organization's members who provided data. Because the distribution
of costs provided by this commenter is skewed towards higher values,
the mean cost is likely to exceed the median value. Thus, these data
suggest the sampling costs provided by the commenter are probably
falling within the range of MSHA's estimates.
[[Page 28370]]
However, MSHA estimates sampling costs of a ``typical'' mine for
the purpose of this analysis.\80\ NSSGA presented costs of $1,800 per
sample, $2,866 for sampling one miner, and $3,247 for sampling 3 miners
are not necessarily inconsistent with MSHA's cost estimates. For
example, the operator who lists costs exceeding $11,000 for a 3-day
sampling episode did not provide the number of miners sampled or the
number of samples taken in that sampling episode. Using MSHA's lowest
estimate of $330 per sample for a mine with more than 500 miners, this
estimate is equivalent to about 33 samples, which is not unreasonable
for three, 10-hour days of sampling. The commenter's cost estimate of
$11,000 over 3 days is consistent with MSHA's estimate.
---------------------------------------------------------------------------
\80\ Industry-wide, a ``typical'' mine is considered as a small
surface mine, most likely to produce MNM commodity. Such a mine:
would likely have a small number of buildings, such as a maintenance
shop, an office, and a couple of storage; might employ up to 50
miners plus managerial and office staff; and would likely have a
crusher and screening plant, a conveyor, and several pieces of heavy
equipment and haulage vehicles.
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MSHA acknowledges that some mine operators will incur higher
sampling costs than the operator of a ``typical'' mine. MSHA believes
that some small mine operators may experience higher sampling costs
than MSHA estimates due to operating in remote areas where it may be
more difficult to procure sampling services, and to the size of the
mine. MSHA estimates the labor cost per sample at a small MNM mine will
be nearly twice the cost per sample at larger MNM mines. Under MSHA
estimates, the percentage of miners needed to achieve representative
sampling (50 percent) is twice as large as the percentage at larger
mines (25 percent or less).
MSHA was unable to determine from the information provided by
commenters, how they determined a representative sample and the
frequency of samples taken. For example, the range of values provided
by the NSSGA was based on ``more than 20 companies.'' However, there
are more than 6,000 sand and gravel mines affected by the rule, and it
is unclear whether this cost data represents the whole sector.
MSHA's estimated cost per sample is largely influenced by a mine's
need to hire a sampling professional. Some mines might perform their
own sampling, others may hire a sampling professional (e.g., industrial
hygienist); and others may use a combination of the two, based on
sample timing, numbers of samples, and mine location. In estimating
sampling costs, MSHA assumed half of the MNM samples would be collected
in house and half collected by a sampling professional. MSHA considers
that mine operators (or controllers) will evaluate the costs of options
and make the most cost-effective decision. The Agency's estimated
average cost per sample collected by a contracted industrial hygienist
is nearly equivalent to the high-end cost examples provided by some
commenters. Differences are attributable assumptions made on travel
time and expense, numbers of samples collected per day, numbers of days
per trip (over which travel time and expense are averaged). To the
extent that more remote mines are able to coordinate through a local,
state, or national industry association, insurance carrier, their
common mine controller, or other affiliation, these costs can be
reduced by coordinating sampling dates. In addition, organizations and
associations provide training on conducting air sampling. A trained
technician working under an experienced industrial hygienist can reduce
sampling costs.
Estimated total sampling costs from some commenters are much higher
than MSHA's estimates because they assume more miners would have to be
sampled than MSHA estimated under the proposed rule. For example, NSSGA
estimated that at a cost per sample of $139 per sample, industry costs
will increase by $34 million, while its median cost of $650 per sample
will increase industry cost by $162 million (Document ID 1448). This
commenter appears to have multiplied the cost per sample by its
estimated number of affected miners, 250,000. Similarly, EMA mentioned
an operator who assumes that 400 of 446 employees would be sampled
(Document ID 1442), while a member mentioned by the NVMA appears to
assume that all, or at least the vast majority of its 7,000 employees
would be sampled (Document ID 1441).
In response to public comments, MSHA increased its estimate of the
number of samples operators would need to take to meet the sampling
requirements of the final rule by increasing the number of samples that
constitutes the required representative fraction (or sampling
representativeness) and frequency of sampling and evaluation. For
example, over the first six years starting from the start of
implementation, MSHA now estimates 758,000 samples of all types will be
taken (Table IX-5), compared to 499,000 under the proposed rule.
Based on exposure profiles for the MNM and coal mining industries
and MSHA's experience and knowledge of the mining industry, MSHA
expects that on average the ratio of samples to miners sampled will be
smaller than estimated by commenters. The final rule allows mine
operators to sample a representative fraction of miners to meet the
rule requirement. That is, a mine operator would be required to sample
a minimum of two miners where several miners perform the same tasks on
the same shift and in the same work area, so not all miners working in
the same mine need to be sampled. Additionally, this sampling will stop
when sampling results demonstrate exposure at a mine is below the
action level. In Section 8.2.2 of the standalone FRIA document, MSHA
provides two examples of how representative sampling will reduce the
number of samples required based on MSHA experience in exposure
sampling at mines and occupation categories.
MSHA has determined that exposure monitoring requirements in the
final rule are necessary to maintain exposure levels at a safe level to
ensure miners' health. The exposure monitoring requirements are also
consistent with the Mine Act's statutory purpose to provide improved
health protection for miners. Section 8.2.2 of the standalone FRIA
document outlines a number of steps mine operators can take to reduce
their monitoring cost.
2. Costs for Exposure Controls
To estimate the installation cost and to determine which mines will
likely incur exposure control costs to reach compliance with the new
PEL, MSHA analyzed the most recent 5 years of data on silica exposure
(2015-2019 for MNM and August 2016-July 2021 for coal). As a starting
point, it assumed that a mine will incur costs to meet the new PEL if
it had a single sample result that exceeded the new PEL from the most
recent day for which sample results were available. Analysis of the
data yielded an initial estimate that 9.7 percent of all mines would
incur costs, as reported in the PRIA. In response to public comments,
MSHA updated this estimate to reflect the likelihood that more mines
would incur additional costs of exposure controls. Based on its
analysis and experience, MSHA projects in this FRIA that each year,
about 20 percent of mines will incur some type of exposure control
costs under the final rule.
MSHA estimated three types of exposure control costs, as described
in the following sections:
Installation costs, consisting of the costs of purchasing
new engineering control equipment and installing it or
[[Page 28371]]
purchasing new services to clean or ventilate dust from work areas.
Maintenance and repair costs, to ensure proper use of
existing engineering controls with increased frequency of dust control
maintenance and repair.
Costs of administrative controls to reduce dust exposure
(for example, the costs of training or posting signage regarding new
policies).
Breaking down the total by type of cost, each year 5 percent of
mines are expected to incur additional amortized installation costs,
while 20 percent (that 5 percent plus an additional 15 percent) are
expected to incur additional maintenance and repair costs and costs for
administrative controls.
Costs for New Engineering Controls
Some affected mines will incur installation costs because they will
need to implement additional engineering control measures to reduce
exposure levels. Using historical data and institutional knowledge,
MSHA estimates the number of mines, by size, that will require
additional engineering controls to meet the new PEL and the estimated
level of capital investment (i.e., minimal, moderate, and large)
needed. It projects that 580 mines--or a little under half of those
with exposures above the new PEL at the time of their most recent
sampling--will require these additional engineering controls, with a
large majority requiring minimal capital expenditure. (Table IX-7).
[GRAPHIC] [TIFF OMITTED] TR18AP24.164
MSHA estimates an average cost for engineering controls based on
NIOSH evaluation of the dust controls used in the mining industry. MSHA
assumed operating and maintenance (O&M) costs to be 35 percent of
initial capital expenditure and assumed that installation cost, when
appropriate, will be equal to initial capital expenditure. MSHA assumed
most controls will have a 10-year service life, with exceptions for
some equipment. For example, heavy haulage and excavating machinery are
assumed to have a 15-year service life, and new or substantially
renovated structural ventilation systems are assumed to have a 30-year
service life. Within each category of capital expenditures, MSHA takes
an average of the engineering control costs, inclusive of installation,
maintenance, capital, and replacements costs over the 60-year analysis
period and annualized the costs. Each affected mine is assigned the
average value for its capital expenditure category. At a 3 percent
discount rate, annualized costs range from $556 per mine for the lowest
cost tier of capital equipment to $24,345 per mine for the highest cost
tier. The annualized cost is $2,573 per mine per year when averaged
across all mines.
Table IX-8 presents total annualized engineering costs calculated
at $1.43 million (0 percent) to $1.58 million (7 percent) over 60
years.
[[Page 28372]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.165
Costs for Maintenance & Repair of Engineering Controls
Beyond adopting more advanced engineering control infrastructure,
an integral method of reducing respirable crystalline silica exposure
is by increasing the frequency of maintenance and repairs for dust
control systems. In MSHA experience, when there are overexposures,
often engineering controls are in place but the operator has neglected
maintenance and repair. MSHA has determined that, when the appropriate
dust control systems are used, effective and regular maintenance and
repair of such systems can help reduce respirable crystalline silica
exposure below the new PEL. Maintenance and repair activities are
usually conducted at the beginning of each shift (or as frequently as
necessary) and can be a part of existing safety and operational checks
performed on most equipment.
MSHA estimates, on average, that mine operators would spend 16
hours per quarter on additional inspection and maintenance (i.e., 64
hours per year). To account for additional maintenance and repair costs
that would result from using inspection checklists to cover maintenance
and repair of dust suppression and control equipment, MSHA added 25
percent to the costs for maintenance and repairs. These maintenance and
repair costs will be incurred every year over a 60-year analysis
period, resulting annual cost of $3,389 per mine for MNM and $4,789 per
mine for coal.
MSHA anticipates that additional mines will incur increased
maintenance and repair costs each year to reduce exposure below the
action level to avoid exposure monitoring costs. MSHA assumes that in
total, these maintenance and repair costs will be incurred by 19.7
percent of mines, or 2,489 mines (2,249 MNM mines and 241 coal mines).
These mines include the 4.7 percent that will incur new installation
costs, plus an additional 15 percent that will incur only maintenance
and repair costs and costs of administrative controls. MSHA assumes
that this is the share of mines industrywide that will incur costs in
each year, even as the specific mines incurring those costs may vary
from year to year. Multiplying the average maintenance and repair cost
per mine by the estimated 2,489 mines that will incur costs ranging
from $8.65 million (0 percent discount rate) to $8.27 million (7
percent discount rate) for increased maintenance and repair (Table IX-
9).
[[Page 28373]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.166
Costs for Administrative Controls
Administrative controls comprise a variety of methods to reduce
exposure to respirable crystalline silica dust. In general, mine
operators evaluate situations in which exposure can be reduced through
changes in policies and work practices, and implements those changes by
informing miners through training, published announcements, procedures,
instructions, and signage. Examples of administrative controls include
enclosing cabs to work with doors and windows shut and setting speed
limits and minimum distances for equipment operated on dusty haul
roads.
While many of these examples are applications of common-sense
policies, they can be circumvented either accidently or deliberately.
Administrative controls are not always effective, or as effective as
they could be, because unlike engineering controls, administrative
controls depend on miners' adherence to the policies and work
practices. Administrative controls rank lower than engineering controls
in the hierarchy of effectiveness.
The cost of administrative controls is composed of labor hours.
MSHA believes that 2,489 mines will spend, on average, 16 labor hours
on administrative controls starting in Year 1 for coal and Year 2 for
MNM of the 60-year analysis period. As with the estimates of additional
maintenance and repair costs, this figure for number of affected mines
is based on MSHA's assumption that, beyond those mines with exposures
currently above the new PEL, an additional 10 percent of mines might
incur increased administrative costs each year to reduce exposure to
below the action level.
In addition to the time spent identifying administrative controls,
mine staff need to prepare and publish training and instructional
materials, and post signage and/or other informational materials to
implement such controls; to account for this, MSHA increases the value
of labor hours by a factor of 2.0. MSHA estimates that the additional
labor costs spent on administrative controls as an average of the
loaded hourly wage rate weighted by the relative employment of these
occupations in the mining industry. The estimated average cost is
$1,439 per affected MNM mine (Year 2--60) and $2,222 per coal mine
(Year 1--60).
Table IX-10 shows the estimated number of mines and annual costs
expected to be incurred in Year 1 and Years 2 through 60 for
administrative controls. Additionally, Table IX-11 shows that total
annualized costs range from $3.7 million (0 percent discount rate) to
$3.6 million (7 percent discount rate) based on the discount rate used.
The higher totals for the MNM sector are attributable to the much
larger number of affected mines than the coal sector.
[GRAPHIC] [TIFF OMITTED] TR18AP24.167
[[Page 28374]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.168
Several commenters did not agree with MSHA's exposure control
estimates as applied to their mines, stating that MSHA underestimated
the costs of implementing exposure controls (Document ID 1419; 1441;
1448; 1455), and/or asserted that most mine operators who meet the
current PEL will need to install significant new engineering controls
to meet the new PEL. For example, Nevada Mining Association, stated
that estimated compliance costs for one of their members was $22.7
million for the first year and $13.6 million for each following year to
retrofit mobile equipment with filtered pressurized air as well as
medical surveillance and exposure sampling costs (Document ID 1441).
NSSGA stated that ``[b]ased on communications with 13 member companies,
costs for exposure controls will vary widely, but on average are
$920,000 annually, with a median of $225,000 (Document ID 1448).''
Neither the types of controls nor the number of mines installing the
controls was included with the commenter's estimate. One of NSSGA's
members also stated that its 2023 budget for exposure controls is
approximately equal to the MSHA annual estimate for all of MNM. Another
commenter, US Silica, stated that in 2023 alone, it incurred $3.6
million in capital costs on two automated projects and multiple other
projects exceeding MSHA's estimate for the industry (Document ID 1455).
A fifth commenter, Vanderbilt Minerals, LLC provided expected costs of
$7 million for a list of renovations to existing facilities and new
equipment purchases (Document ID 1419).
Based on its analysis of the Agency's sampling database, MSHA
believes roughly 90 percent of mines will be able to meet the PEL
without incurring additional costs. In Section 4 of the standalone FRIA
document, MSHA estimates that about 1,230 mines are expected to incur
exposure control costs to meet the new PEL. Of these, a little more
than 50 percent (650 mines) should be able to meet the new PEL using
controls such as additional maintenance and repair, and administrative
controls. The remaining 47 percent of mines (580 mines) expected to
incur costs will also implement engineering controls--in addition to
increased maintenance, repair, and administrative costs--to meet the
new PEL.\81\ The distinction between the two types of mines is related
to sample data that shows compliance with the existing PEL.
Additionally, MSHA includes an extra 10 percent of total mines (111
coal mines and 1,153 MNM mines) that will incur exposure control costs,
including enhanced administrative controls and frequent maintenance and
repair. MSHA's analysis is described in more detail in the standalone
FRIA. Twenty operators commented that MSHA underestimated exposure
control costs. A couple of these commenters did not provide specific
evidence to support their position that many operators will incur
substantial engineering control costs.
---------------------------------------------------------------------------
\81\ The maintenance, repair, and administrative costed for the
additional 1,260 mines are not to meet the new PEL but to reduce
exposures below the action level to reduce monitoring costs.
---------------------------------------------------------------------------
MSHA assumes that all mines are currently in compliance with the
existing PEL when estimating compliance costs. Costs incurred by
operators are attributed to lowering exposures from the existing PEL to
the new PEL. Some mine operators have found it difficult to
consistently control exposures to meet the existing PEL; any additional
costs incurred by them will be more appropriately attributed to
maintaining compliance with the existing PEL.
The estimated costs presented in the standalone FRIA represent the
average estimated compliance costs for a typical mine. MSHA
acknowledges that the exposure control costs will differ depending on
the size of the mine, the current level of exposure to respirable
crystalline silica, existing engineering and administrative controls,
the mine layout, work practices, and other variables. MSHA's price and
cost estimations are based on a variety of sources including market
research and MSHA's experience and sample data. The evidence provided
by the commenters was collected from members of trade organizations. It
appears that at least some of the cost estimates are from either very
large mines--far larger than the ``typical'' mine used for MSHA cost
estimates--or may reflect an estimate for all mines controlled by an
operator. For example, the comment that the ``total amount to retrofit
all underground and surface mobile equipment with filtered pressurized
air, medical surveys and increased sampling is $22.7 million for the
first year, and $13.6 million each year after'' is from an MNM operator
with 7,000 employees. If this represents a single mine, only 26 MNM
mines (0.2 percent) employed more than 500 miners in 2019 (Table IX-1),
if this represents multiple mines, then the anticipated compliance
costs per mine would be smaller. Because the number of mines is
unknown, and because the commenter includes sampling costs (provided
separately as $1.2 million per year) and medical surveillance costs in
the total, it is impossible to meaningfully compare this estimate with
MSHA's estimates.
Similarly, US Silica presented costs exceeding $3.6 million in
capital expenditures on two automated projects; totaling all projects,
US Silica states it exceeded MSHA's estimate for the entire industry
(Document ID 1455). However, it is unclear how many mines owned by US
Silica incurred the costs. In addition, US Silica installed two
automated systems. Generally, an automated bagging operation is more
costly to purchase and install than a manual bagging system. The higher
capital cost of an automated system also likely results in offsetting
cost savings (e.g., labor costs), and thus US Silica's estimated
compliance costs likely include decisions made for other business
reasons, not just the cost of reducing worker exposure.
Vanderbilt Minerals LLC provided expected costs of $7 million for
renovations to existing facilities and new equipment purchases at a
single site, including ``the purchase/installation of such items as a
new
[[Page 28375]]
bagging system for 50-pound bags, new dust collectors for drying/
milling equipment, renovation of a laboratory, office, break room, mill
control office, and crusher operator booth, purchase of larger water
trucks and an increase in paved haul roads (Document ID 1419).'' In
this case, the costs by the commenter are clearly higher than MSHA's
estimated compliance costs for a single typical mine. However, the site
in question appears to be highly atypical of most of MNM mining and
therefore not appropriate for extrapolating industry costs. More
details are provided in Section 8 of the standalone FRIA document.
A further difficulty in evaluating commenters' estimates of
engineering costs is that MSHA presents annualized costs; that is,
compliance costs with initial capital and one-time costs amortized over
the service life of the control. Many commenters provided first-year
costs (without identifying capital, one-time, or recurring (operation
and maintenance) cost components) to show that MSHA underestimated
exposure control costs. The comparison of commenters' first-year costs
with MSHA's annualized cost estimates is inappropriate. For example, a
MNM mine operator provided $3.6 million as the first-year cost estimate
without offering information about the actual service lives of these
automation projects (Document ID 1455). If those costs are amortized at
a 3 percent discount rate using an assumed 10-year service life
(implying the system will be replaced 6 times over the course of the
60-year analysis period), the annualized capital component of their
cost is about $410,000; if the expected service life is 30 years
(replaced twice over 60 years), the annualized cost is about $178,000.
Similarly, when amortized using a 3 percent rate, a $7 million in
initial capital cost is equivalent to less than $800,000 annualized
cost per year if the system has a 10-year service life, and less than
$400,000 if the service life is 30 years. Thus, it is difficult to
directly compare MSHA's annualized costs with first-year costs provided
by commenters without service life information.
Small mine operators specifically questioned MSHA's estimates of
the cost of controlling exposure to respirable silica crystalline
silica dust (Document ID 1411; 1415; 1427; 1435; 1436). Water based
dust suppression, especially if combined with magnesium chloride, is
likely to be more expensive at some remote mines in arid regions due to
the cost of obtaining and transporting water. However, these commenters
did not discuss the applicability of other methods of reducing
exposures presented in the FRIA and Technological Feasibility
discussions. For example, operating vehicles with windows closed,
reduced vehicle speed, and wider vehicle spacing have all been shown to
decrease operator exposure to dust. These commenters provided the cost
of cabin air filters and their preference to not use air conditioning,
but it should be noted that there may be trade-offs in the choices mine
operators make to reduce exposure to dust. For example, the use of air
conditioning by vehicle operators will increase costs (filters, fuel
use), but will decrease exposures. These increased operating costs
should be offset by reduced sampling costs.
3. Costs for Respiratory Protection
The new PEL may result in an increased use of respirators by miners
when compared with usage under the existing PEL. This additional usage
will result from provisions Sec. 60.13: Corrective actions and Sec.
60.14 (a): Respiratory protection. Under Sec. 60.13, if sampling
results indicate miners' exposure exceeds the new PEL, mine operators
must make approved respirators available to affected miners; ensure
that miners wear respirators properly during the period of
overexposure; and take corrective actions to lower the concentration of
respirable crystalline silica to at or below the PEL. Section 60.14 (a)
requires the temporary use of respirators by MNM miners when
engineering controls are developed and implement or when necessary due
to the nature of work involved (e.g., entry into a hazardous atmosphere
to perform maintenance). MSHA expects that additional use of
respiratory protection will occur because exposure levels that were
below the existing PEL will now be above the new PEL. MSHA believes
that most respirator use will occur during the first few years after
implementation of the rule until mine operators can consistently
control sources of respirable crystalline silica dust exposure at the
new PEL using engineering controls, but that the respirator use will
decline as mines implement and improve additional controls. However,
with little data to support an assumption concerning how quickly
incremental respirator use might decline, MSHA chose to model
respirator use as remaining constant over the 60-year analysis period.
Under Sec. 60.13 MSHA believes that miners who are most likely to
need incremental respirator use to perform corrective actions work in
the following occupations:
Kiln, Mill, and Concentrator Workers (MNM mines)
Mobile Workers & Jackhammer Operators (MNM mines)
Miners in Other Occupations (MNM mines)
Underground Miners (Coal mines)
Surface Miners (Coal mines)
To estimate the number of miners who might be required to use
respirators under Sec. 60.13, MSHA first uses sample data to estimate
the number of miners in these occupations with respirable crystalline
silica exposures between the new PEL and the existing standards (50
[mu]g/m\3\ to 100 [mu]g/m\3\ range for MNM and 50 [mu]g/m\3\ to 85.7
[mu]g/m\3\ for coal) to identify the miners most likely to increase
their use of respirators as a result of the rule. MSHA then assumes
that 20 percent of that total, about 2,109 miners would these miners
end up using respirators as a result of the rule. MSHA thus estimates
that mine operators will incur costs for increased respiratory
protection by 1,984 MNM miners and 125 coal miners per year to meet the
requirements of Sec. 60.13.
Under Sec. 60.14, MSHA uses sample data to estimate the number of
MNM miners that might need to increase their use of respirators due to
the rule. MSHA assumes that MNM mine operators will need to provide
additional respiratory protection for 20 percent of MNM miners in all
occupations with exposures between the new PEL and the existing PEL.
MSHA estimates MNM operators will need to provide respiratory
protection to 4,945 MNM miners to meet the requirements of Sec. 60.14.
Under sections 60.13 and 60.14 together, mine operators are
expected to increase respirator protection for approximately 7,054
miners and contract miners (6,928 MNM miners and 125 coal miners).
MSHA estimates two types of respiratory protection costs: the
purchase of new respirators to be issued and the incremental cost of
additional temporary respirator use. MSHA believes that given the
existing respiratory protection standards, most miners have already
been issued respirators to deal with intermittent, temporary
circumstances where exposures exceed the existing standards. However,
some mine operators with miners at low risk of exceeding the existing
standard may need to purchase respirators to account for possible
temporary exposures in the range between the new PEL and existing
standards. It is likely that some miners newly at risk for exposure in
this range will not have respirators. In addition,
[[Page 28376]]
because respirators will be used more under the new PEL, respirators
will deteriorate more quickly and need replacement. In addition to
miners who did not need to wear a respirator under the existing
standards but might have occasional temporary need for respiratory
protection under the new PEL, some mine operators will need to replace
respirators for miners more frequently due to a small increase in the
need for temporary respiratory protection.
MSHA assumes that in Year 1, coal mine operators will incur costs
for new respirators for 50 percent of their coal miners who are
expected to increase respirator use (i.e., a total of 63 new
respirators) under Sec. 60.13. In Year 2, MNM mine operators will
similarly incur costs for new respirators for 50 percent of the total
MNM coal miners who are expected to increase their respirator use
(i.e., 3,464 new respirators under Sec. 60.13 and Sec. 60.14
combined). In Years 2 through 60 (for coal) and Years 3 through 60 (for
MNM), mine operators will incur replacement costs for 50 percent of the
total number of new respirators purchased in Year 1 (for coal) and Year
2 (for MNM). Therefore, in Year 3 and onwards, coal and MNM mine
operators will purchase a total of 1,763 new respirators per year.
Furthermore, MSHA assumed that all new respirator purchases in any year
throughout the analysis period will require fit testing and training.
MSHA assumed that mine operators will purchase tight-fitting, re-
useable half-mask elastomeric respirators at a cost of $39.57 each plus
$17.29 for filters.\82\ In addition, MSHA assumed respirators are
assigned to individuals, not shared equipment. Furthermore, miners
issued new respirators will require an additional 2 hours of labor time
for fit testing and training which is valued at the weighted average
loaded wage of all mine workers in the given sector ($50.60 for Metal
miners, $40.47 for Nonmetal miners, and $49.97 for coal
miners).83 84 The resulting annual cost per miner requiring
a new respirator is estimated to be $145 for MNM miners and $157 for
coal miners.
---------------------------------------------------------------------------
\82\ Based on online (non-discount) prices: websites for
Northern Safety, 2022: $29.14/each 3MSeries 6500 half mask
respirator, $10.25/pair for P100 pancake filters; and Grainger,
2022: $50.00 for MSA 420 series half mask respirator, $24.32 for
P100 filter cartridges (package of 2). Prices are higher end of
potential range, supplier bulk discounts available from numerous
other sources.
\83\ OSHA APF rulemaking (update to 29 CFR 1910.134) Unit Costs:
1 hour employee training, 1 hour employee qualitative fit testing.
Alternatively, 2 hours for quantitative fit testing (from costs
estimated in 2001-2006; may be reduced due to efficiency of more
modern quantitative fit testing equipment currently available and
widely used). MSHA assumed that worker fit testing is conducted in
small groups; two to four miners are fit tested during the hour, but
all remain part of the group for the full hour.
\84\ MSHA assumed there will be no additional labor costs for
personnel conducting fit testing or training because current
respiratory protection programs already require these steps.
---------------------------------------------------------------------------
Table IX-12 presents the estimated annual costs of purchasing new
respirators for respiratory protection under the new PEL for miners who
did not require respiratory protection under the existing PEL. In Year
1 of compliance for coal mines, 63 coal miners (including contract
miners), who occasionally perform corrective actions where they would
likely be exposed to respirable crystalline silica in the range between
the new PEL and the existing standards are expected to be provided with
new respirators by mine operators t a cost of $9,821. In Year 1 of
compliance for MNM mines (Year 2 following publication of the final
rule), 3,464 MNM miners will also be provided with new respirators for
corrective actions and temporary use at a cost to mine operators of
$502,282. New respirator purchase costs in Year 1 of compliance for
coal and MNM mine operators are estimated to total $512,103 across both
sectors. In subsequent years (Years 2 through 60 for coal mines; Years
3 through 60 for MNM mines), annual costs are expected to be about half
of first year costs ($256,052).
[GRAPHIC] [TIFF OMITTED] TR18AP24.169
Table IX-13 summarizes the total annualized cost of new respirator
purchases by sector. Overall, the new PEL is expected to lead mine
operators to purchase new respirators costing an average of $256,134
(at a 0 percent discount rate) to $255,285 (at a 7 percent discount
rate) per year over the 60-year analysis period.
[[Page 28377]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.170
MSHA estimates the cost of additional respirator use under the new
PEL for miners who did not need it under the existing standards. MSHA
assumes the cost of additional respirator use starts in Year 1 (for
coal mines) and Year 2 (for MNM mines) will remain constant over the
60-year analysis period. On average, MSHA believes additional
respirator use will be necessary for 4 hours per week per miner, or an
additional 208 hours per year (4 hours per week x 52 weeks per year).
For estimating costs, if an elastomeric respirator uses two filters at
a time, and the filters last eight hours before requiring replacement,
then these miners will need an additional 26 pairs of filters per year
(208 hours per year/8 hours per filter pair). At an average price of
$17.29 per pair of filters, mine operators will spend an additional
$450 per miner per year ($17.29 x 26 filter pairs) for respirator
filters.
Table IX-14 and Table IX-15 present the estimated total annual and
annualized cost of additional respirator usage by sector. The annual
cost of additional temporary respirator use is expected to be $450 per
miner per year over the 60-year analysis period (Table IX-14) and total
annualized cost is expected to range from $3.12 million (0 percent
discount rate) to $2.96 million (7 percent discount rate) per year
(Table IX-15).
[GRAPHIC] [TIFF OMITTED] TR18AP24.171
[GRAPHIC] [TIFF OMITTED] TR18AP24.172
The estimate presented in Table IX-15 may be an overestimate of the
cost of respirator use. MSHA assumed respiratory use would remain
constant over the 60-year analysis period, it is likely that need for
additional respirator use will decline as mines implement and improve
engineering and administrative controls. However, with little data to
support an assumption concerning how quickly the need for additional
respirators might decline, MSHA chose to model it as constant. Second,
while most mines operate year-round, some mines may operate for as
little as 3 months per year. This will also decrease the need for
respirators use.
[[Page 28378]]
Some commenters provided unit cost data for respirators and filters
that were greater than the unit cost estimates that used in the PRIA
(Document ID 1411; 1415; 1427; 1435; 1436). First, based on their data,
the replacement filter cartridges last much longer than those costed by
MSHA, so that the cost of one year's use will be lower than MSHA's cost
estimate due to the long life span of replacement filters used by
commenters. Second, the commenters assumed all employees would require
new respirators and did not account for baseline use (or availability)
of respirators at the mine. The final rule requires MNM mine operator
to use respiratory protection as a temporary measure when miners must
work in concentrations of respirable crystalline silica above the PEL
when engineering control measures are being developed and implemented
or necessitated by the nature of work involved. MSHA determined that
its cost assumption is more comprehensive and likely overestimates
respirator protection costs.
4. Cost for Medical Surveillance
Under the final rule, MSHA will require each MNM mine operator to
provide mandatory medical examinations to miners who are new to the
mining industry and voluntary periodic examinations to all currently
employed miners. These new medical surveillance standards extend to MNM
miners the opportunity for medical surveillance that is already
available to coal miners under the existing rules.
The medical examinations will be provided by a physician or other
licensed health care professional (PLHCP), or by a specialist. The
medical examination will include a miner's medical and work history, a
physical examination, a chest X-ray, and a pulmonary function test. For
those miners new to the mining industry, the first mandatory
examination must take place within 60 days after beginning employment.
This must be followed by a mandatory follow-up examination at 3 years.
Should the follow-up examination indicate any medical issues related to
lung disease, a second mandatory follow-up examination must take place
in 2 years. In addition to these mandatory examinations, mine operators
must also offer voluntary periodic medical examinations to all MNM
miners at least every 5 years. The first periodic medical examination
for existing MNM miners must be provided within 12 months of the final
rule's MNM compliance date, or if a MNM mine commences operation after
the compliance date, within 12 months of the mine beginning operations.
All of the medical examinations must be provided at no cost to the
miner.
Additionally, the MNM mine operator must ensure that, within 30
days of the medical examination, the PLHCP or specialist provides the
results of chest X-ray classifications to NIOSH, once NIOSH establishes
a reporting system. The cost of the x-ray includes the cost of
preparing the report and transmitting those results to NIOSH.
To estimate the costs of compliance with the medical surveillance
requirement, MSHA first estimated the ``unit cost'' of a single medical
examination. MSHA then estimated how many examinations would occur in
each year over the 60-year analysis period and multiplied the numbers
of examinations by the unit cost to determine total costs in each year.
MSHA summed the costs in each year to estimate a total cost over the
full 60-year period.
Unit Costs
MSHA assumed that all examinations entail the same cost elements
(in decreasing order of cost): the physical examination, chest X-ray,
spirometry test, lost work time while being examined, lost travel time,
symptom assessment and occupational history, transportation cost, and
recordkeeping of the mine operator. Table IX-16 displays estimated
components in 2022 dollars, which sum to a unit cost of $628.58 per
examination.
[GRAPHIC] [TIFF OMITTED] TR18AP24.173
To estimate the number of examinations expected per year, MSHA used
the estimated number of full-time equivalent (FTE) employees in MNM
mining, which is 184,615 FTE workers. MSHA assumed that the MNM
employment will remain constant over the 60-year analysis period
following compliance of the medical surveillance requirement.\85\ MSHA
estimates that the average length of employment as an MNM miner (before
leaving the mining occupation) is 22 years, which is derived from a
NIOSH survey that found the average mining experience of MNM miners is
approximately 11 years.\86\
[[Page 28379]]
Based on this estimate, MSHA assumed that each year 8,392 miners (i.e.,
about 1/22, or 4.55 percent, of 184,615 FTE MNM miners) would leave the
industry, and be replaced by the same number of new entering workers.
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\85\ MSHA chose to express mine employment in FTEs for the
benefits analysis because health impacts would differ between part-
time miners, who would experience less exposure to respirable
crystalline silica dust and thus would be less likely to experience
the same negative health effects in the same amount of time as
miners who worked full-time or more. A similar logic applies to
miners deciding whether to accept medical examinations, thus medical
surveillance costs are also estimated based on FTE miners.
\86\ The 2012 report by NIOSH, entitled, ``National Survey of
the Mining Population: Part 1: Employees,'' includes the findings of
its 2008 survey on mine operators and miners in the U.S. https://www.cdc.gov/niosh/mining/works/coversheet776.html (last accessed
Jan. 10, 2024). Details on the survey methodology and results are
available in the link. The NIOSH survey found the following mine
experiences for different types of MNM mines, which average to about
11 years (11.375 to be precise): metal mines, 10.7 years; nonmetal,
12.0 years; stone, 12.5 years, and sand and gravel 10.3 years. For
comparison, the same survey found the average mining experience for
coal miners was 16.0 years. These averages reflected the average
number of years that respondent miners had worked at mines at the
time the survey was conducted. MSHA considered these average mine
experiences to represent approximately one half of the mining tenure
these miners would have (the years in mining when they leave).
Conversely, MSHA estimated miners' total expected tenure to be twice
these average mining experiences.
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MSHA estimates total medical surveillance costs over the 60-year
analysis period under two different scenarios due to the uncertainty of
how many currently employed miners will participate in voluntary
medical surveillance programs. Assuming a participation rate of 25
percent (Scenario 1), annualized costs range from $14.6 million (with a
0 percent discount) to $14.0 million (with a 7 percent discount rate)
and the annualized cost per MNM miner ranges from $79 (with 0 percent
discount rate) to $76 (with a 7 percent discount rate).
In scenario 2, MSHA assumed that the participation rate is 75
percent. Annualized costs range from $23.7 million (0 percent discount
rate) to $23.1 million (7 percent discount rate). The annualized cost
per MNM miner range from $128 (7 percent discount rate) to $125 (0
percent discount rate). A summary of estimated medical surveillance
costs under the two scenarios is presented in Table IX-17.
[GRAPHIC] [TIFF OMITTED] TR18AP24.174
Vanderbilt Minerals LLC stated that MSHA underestimated the cost of
medical surveillance and stated its program cost approximately $9,400
per site per year, plus an additional $4,000 per site per year in
employee time at 3 hours per employee (Document ID 1419). Assuming an
average loaded wage of a nonmetal sector extraction worker at $40.47
per hour, $4,000 in employee time would cover 33 employees. This
suggests that average medical surveillance costs would be about $406
per employee by dividing total costs of $13,400 (= $9,400 + $4,000) per
site by 33 employees.\87\ This is significantly lower than MSHA's
estimated unit cost for medical surveillance of $629 per examination in
2022 dollars (Table IX-16).
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\87\ The commenter does not state whether employee time is
valued at a loaded hourly rate (including benefits and overhead) or
the raw hourly rate. If the latter rate is used ($24.34 per hour),
then the commenter's program would cover 55 employees at a cost of
$244 per employee.
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Another commenter, National Mining Association, stated that the
proposed medical surveillance requirements would impose significant
costs on its members, due to the expansion to cover potentially 200,000
MNM miners at more than 11,000 mines (Document ID 1428). As mentioned
above, MSHA assumes that under the final rule, operators are required
to conduct medical surveillance on currently employed miners and new
miners (those who start to work on the mining industry for the first
time). For currently employed miners, MSHA assumes two participation
rates (25 percent and 75 percent) for medical surveillance and
estimates the number of tests per year as 6,700 under 25 percent
participation rate and 20,200 under 75 percent participation rate tests
per year at an average cost of $4.24 million to $12.7 million each year
(undiscounted). Average over the two participation rates, MSHA
estimates that operators will conduct an average of 13,500 tests per
year on the new miners at an average cost of $8.5 million each year
(undiscounted).
Commenters also shared concerns on medical surveillance costs for
small mine operators (Document ID 1408; 1411; 1415; 1427; 1435; 1436).
The specific issue raised by these commenters concerned the cost of
hourly wages and travel expenses from remote mine locations to obtain
medical examinations. Thus, their costs will be larger than estimated
by MSHA. MSHA acknowledges these concerns but notes that commenters
provided no specific data in support of their position.
At least two commenters, NSSGA and Illinois Association of
Aggregate Producers, stated that, under the proposed rule, companies
would incur millions of dollars in costs that do not benefit miners'
health and safety, using as examples requiring sampling every 3 months
indefinitely for exposures between 25 [mu]g/m\3\ and 50 [mu]g/m\3\,
requiring that medical surveillance be offered to miners with less than
30 days a year of exposure to respirable silica at
[[Page 28380]]
or above the action level and requiring initial sampling even for
facilities that have had exposure monitoring for decades (Document ID
1448; 1456). MSHA has determined that on-going sampling and periodic
evaluations are necessary to ensure that exposures to respirable
crystalline silica meet the new PEL and that miners' health is
protected. Exposure monitoring, that includes an action level, provides
mine operators and miners with necessary information to take actions to
prevent miners' overexposures. Allowing mine operators to cease
monitoring once exposure is maintained below the action level provides
operators with the incentive to reduce and maintain exposures below the
PEL. For medical surveillance, MSHA believes it is important for MNM
operators to provide medical surveillance so that MNM miners will have
information about their health to take necessary action early to
prevent any further progression of disease.
5. Cost for ASTM Update
Under the final rule, mine operators are required to have a written
respiratory protection program in accordance with the 2019 ASTM F3387-
19 standard. A written respiratory protection program must include:
program administration; written standard operating procedures; medical
evaluations; respirator selection; training; fit testing; and
maintenance, inspection, and storage. Mine operators will compare the
ASTM standard to their existing respiratory protection program or
practices and identify the elements of their existing respiratory
protection program or practices that need to be revised. MSHA evaluated
the components of the 2019 ASTM standard that have the potential to
impose additional costs on mine operators.
MSHA assumes that 20 percent of MNM mines will incur costs to meet
the 2019 ASTM standard each year. MSHA assumes that all coal mines are
affected by the update to the 2019 ASTM standard because 30 CFR
72.700(a) requires coal mine operators to make respirators available to
their miners. This should be an overestimate because it is likely that
many coal mines already meet the 2019 ASTM standard. MSHA assumes that
only a small subset of miners uses respirators each year. MSHA assumes
about 10 percent of MNM miners and 3.7 percent of coal miners are
expected to be required to use respirators each year.
Table X-18 presents the total number of mines compared to the total
number of mines expected to incur compliance costs to update their
respiratory protection program and practices. In Year 1, MSHA assumes
that 1,106 coal mines will incur costs to update their respiratory
protection program and practices to the 2019 ASTM standard, and 2,722
coal miners and contract miners are expected to wear respirators.
Starting in Year 2, MSHA estimates that 3,411 mines (i.e., 20 percent
of the 11,525 MNM mines and 100 percent of the 1,106 coal mines) are
expected to incur costs. In addition, MSHA estimates 6,946 miners and
contract miners wear respirators each year, which represents less than
2.5 percent of all miners including contract miners (6,946/284,778).
Respirators are worn to protect miners from airborne contaminants
(including respirable crystalline silica and coal dust) at a small
percentage of mines each year and only a small fraction of the miners
at those mines wear respirators.
[GRAPHIC] [TIFF OMITTED] TR18AP24.175
MSHA evaluates the components of the 2019 ASTM standard that may
impose additional costs on mine operators, and the assumptions in
estimating those costs.
Approved Respirators. Mine operators are familiar with MSHA's
existing requirements for using NIOSH-approved respirators, and this
analysis assumed that mine operators will not incur additional costs
for these requirements. MSHA assumed recordkeeping primarily results in
labor costs.
Program Audit. Program costs for an annual review and written
report by the program administrator are included with the annual labor
time. A program administrator will perform the review and prepare the
report. A second review in the form of an outside audit is conducted by
a person not involved in the respirator program. The audit is to be
repeated at a frequency determined by the complexity of the program.
Written Standard Operating Procedures. MSHA assumes that most mines
have established written Standard Operating Procedures (SOPs) that
comply with the ASTM standard. MSHA assumed that 50 percent of affected
mine operators will prepare new or updated SOPs at the start of
implementation. Following this initial period, these costs will be
incurred only by new mines.
Medical Evaluations. Under this provision, mine operators would
update the information provided to the PLHCP concerning each miner's
work area, type and weight of respirator, duration and frequency of
respirator use, work activities and environmental conditions, hazards,
and other PPE worn. This information is assumed to be part of the
miner's job description and personnel records (e.g., fit-test results)
and is likely available electronically at most mines. As a result, the
cost of this provision is associated with the requirement to document
this information in the miner's records and transmit it to the PLHCP.
Respirator Selection. The provisions for respirator selection in
the 2019 ASTM standard reflect the current standard of care for
respirator use in the U.S. In this analysis, MSHA assumed
[[Page 28381]]
that mine operators are already using these criteria for selecting
respiratory protection. MSHA assumed that mine operators will not incur
additional costs for this provision.
Mine Operator Responsibilities. The 2019 ASTM standard provides
that mine operators allow miners wearing respirators to leave a
hazardous atmosphere for any reason related to the respirator. The mine
operator will also investigate the cause of respirator failures and
communicate with the respirator manufacturer and government agencies
about defects. Respirator failures or defects are considered rare
events. To account for the potential time involved should defective
respirators be encountered, this analysis adds a minimal amount of
labor time.
Training the ``Respirator Trainer''. Under the 2019 ASTM standard,
the respirator trainer will provide training to others with
responsibilities for implementing the mine operator's respirator
program, and therefore, this person must have an appropriate training
or experience. For existing mines, this cost is unlikely to recur
except when a respirator trainer leaves the mine operator's employment.
However, it is likely to be incurred by the 2 percent of new mines
entering the market in any given year.
Training for the Mine Operator/Supervisor and the Person Issuing
Respirators. The mine operator or supervisor of any miner who must wear
a respirator must receive training on the elements of the respiratory
protection program in the SOPs and related topics. The cost in the
first year of compliance will also be incurred in subsequent years by--
at a minimum--new mines entering the market.
Miner Training. Miners required to use respirators already receive
training each year under the 1969 ANSI standard and under 30 CFR part
46 and Part 48. Most mines incorporate this into their existing annual
health and training plan, and therefore MSHA estimates that there are
no incremental costs attributable to this provision.
Fit Testing Frequency. The 2019 ASTM standard provides for annual
respirator fit testing to ensure that the make, model, and size of the
respirator issued to the miner are appropriate and the miner is still
able to achieve a good face seal. MSHA assumed that, on average, miners
receive annual fit testing under existing training standards. A
provision under the 2019 ASTM standard is that the fit testing must be
overseen by a trained technician or supervisor. The time of the trained
supervisor is an additional cost incurred under this provision.
Maintenance, Inspection, and Storage. The provisions for respirator
selection in the 2019 ASTM standard reflect the current standard of
care for respirator use in the U.S. In this analysis, MSHA assumed that
mine operators are already using these criteria for maintaining,
inspecting, and storing respirators. Therefore, MSHA assumed that mine
operators will not incur additional costs for this provision.
Table IX-19 presents average compliance costs per mine by sector.
In Year 1, compliance costs average about $1,700 for coal mines. In
Year 2, compliance costs average about $1,200 for MNM mines and $500
for coal mines. In Years 3 and following, average compliance costs per
mine are smaller, ranging from $262 for MNM mines to $479 for coal
mines, with an overall average of $332 per mine.
MSHA assumes that all mines are affected by the requirement to have
a written respiratory protection program that meets the ASTM standard
but not all mines are expected to incur costs for this requirement.
MSHA estimates, in Year 1 (for coal mines) and Year 2 (for MNM mines),
only 50 percent of affected mines are expected to incur costs under
provision 2 (SOPs) because many mines already have SOPs that comply
with the ASTM. In Years 2 through 60 (for coal) and Years 3 through 60
(for MNM), the number of affected mines that would incur costs is
smaller than in Years 1 and 2 because following Year 1 (for coal) and
Year 2 (for MNM), additional compliance costs are expected to be
incurred primarily by new mines entering the industry. For example,
provisions related to written SOPs, Training for the Respirator
Trainer, and Training for the Mine Operator and Person Responsible for
Issuing Respirators are initial costs incurred in the first year of
compliance. In subsequent years, those costs would generally be
incurred only by the 2 percent of new mines entering the industry.
[GRAPHIC] [TIFF OMITTED] TR18AP24.176
[[Page 28382]]
Below in Table IX-20 are the annualized costs associated with the
ASTM requirement. The total annualized cost to the mining industry
ranges from $1.18 million (0 percent discount rate) to $1.32 million (7
percent discount rate), with 53 percent of those costs attributable to
MNM mines and 47 percent attributable to coal mines.
[GRAPHIC] [TIFF OMITTED] TR18AP24.177
6. Cost Summary
MSHA estimates that the annualized cost of the final rule will
range from $88.8 million to $92.4 million in 2022 dollars. At a
discount rate of 3 percent,\88\ 59.0 percent is attributable to
exposure monitoring; 20.9 percent to medical surveillance; 15.1 percent
to engineering, improved maintenance and repair, and administrative
controls; 3.7 percent to additional respiratory protection (e.g., when
miners need temporary respiratory protection from exposure at the new
PEL when it would not have been necessary at the existing PEL); and 1.4
percent related to the selection, use, and maintenance of approved
respirators in accordance with ASTM F3387-19, respiratory protection
practices (see Table IX-21).
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\88\ In its analysis, MSHA annualizes all costs using 3 percent
and 7 percent real discount rates as recommended by OMB. Using a 7
percent discount rate, the annualized cost of the rule is estimated
at $75.4 million in 2022 dollars.
[GRAPHIC] [TIFF OMITTED] TR18AP24.178
Given the larger size of the MNM sector and the higher proportion
of samples in the MNM sector that are above 50 [mu]g/m\3\, most costs
are attributable to MNM mines (see Table IX-1 and Table IX-2). Of the
$90.3 million total, MSHA estimates that the MNM sector will incur
$82.1 million (91 percent) and the coal sector will incur $8.2 million
(9 percent) in annualized compliance costs (see Table IX-22).
[[Page 28383]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.179
To estimate compliance costs, MSHA determined the expected measures
necessary for mines to comply with each provision of the final rule
then estimated the costs incurred by a typical mine to comply with each
provision. These include one-time costs, such as those to purchase and
install an engineering control, provide equipment expected to last
multiple years (e.g., respirators), or devise and implement an
administrative control. They also include recurring costs, such as the
operating and maintenance (O&M) costs of using an engineering control
or the value of the labor hours and supplies used to perform periodic
exposure monitoring. To aggregate costs for each provision, MSHA
multiplies the average cost per mine by the number of mines expected to
incur that cost or the average cost per miner by the number of miners
expected to be affected by the given provision. These costs are summed
across all provisions for each of the two major mining sectors to
estimate total industry costs. For purposes of the cost analysis, MSHA
assumes employment is constant over this period.
MSHA annualizes all costs using 3 percent and 7 percent discount
rates as recommended by OMB.\89\ All costs and benefits are annualized
over a 60-year analysis period. MSHA annualized benefits to reach the
long-run steady state values projected in MSHA's FRA.\90\ Costs are
also estimated and annualized over a 60-year period. This means that
costs for durable equipment, for example, are estimated based on their
expected service life. If the expected service life of a building
ventilation system is 30 years, MSHA assumes that a mine operator would
purchase the system in year 1 and again in year 31 to estimate 60 years
of capital costs. This is the major change in costing methodology for
the final rule. Under the proposed rule, MSHA annualized costs over
shorter periods. Given the types of controls appropriate for meeting
the requirements of the proposed rule, this approach was reasonable.
Because MSHA set a 1-year difference between the compliance dates for
the coal and MNM sectors under the final rule, that method is no longer
accurate. MSHA's analysis of this final rule is based on a timeframe of
60 years (which is enough time to analyze 45 years of working life and
15 years of retirement for new miners who only experience exposures
under the new PEL).
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\89\ Discount rates throughout this section refer to real
discount rates. Real discount rates are distinct from nominal
discount rates because they do not include inflation.
\90\ Technically, MNM benefits would not reach their long-run
average values until 61 years following the compliance date for the
coal sector since the compliance deadline for MNM is 1 year after
the compliance deadline for coal.
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For both MNM and coal mines, the estimated costs to comply with the
new PEL (50 [mu]g/m\3\) assumes that all mines are compliant with the
existing PEL of 100 [mu]g/m\3\ for MNM mines (for a full shift,
calculated as an 8-hour TWA) and 85.7 [mu]g/m\3\ for coal mines (for a
full shift, calculated as an 8-hour TWA).
Two mining trade organizations, American Exploration and Mining
Association and Nevada Mining Association, stated that MSHA's cost
projections were inaccurate because they predicted fixed costs based on
gross proceeds (instead of net proceeds) (Document ID 1424; 1441).
These commenters also noted that, because the cost model for each
commodity differs, compliance costs for each commodity will differ.
MSHA did not estimate compliance costs based on either gross or net
proceeds. MSHA has determined that its approach better identifies
likely costs than the approach recommended by the commenters. The
Agency estimated compliance costs based on a wide range of quantitative
and qualitative data including: sampling data on miner exposure, MSHA
program experience, and MSHA's knowledge of typical controls,
maintenance, and work practices at mines of different types and size.
MSHA estimates compliance costs using mine size, labor cost, and other
factors at commodity level, which is more flexible and accurate than
the estimation of proceeds.
One commenter, a mining-related business, stated that MSHA's cost
estimates were based on flawed sampling data, that ``used samples taken
by MSHA inspectors and then weighted these based on the number of
samples plus exposures to the current standard (Document ID 1392). The
commenter stated that powered haulage operators account for the bulk of
samples, while conveyor operators account for the fewest samples,
resulting in a ratio of about 1 conveyor operator to 79 powered haulage
operators. The commenter stated that in its experience, the ratio is
about 1 conveyor operator to 4 haulage operators. Because conveyor
operators are underrepresented in the analysis, this would affect
MSHA's cost estimates.
As described in Part B--Miners and Mining Industry, MSHA used 2019
OEWS data to estimate the number of miners in each occupational
group.\91\ The OEWS is a nationally representative dataset and MSHA
uses it to examine labor force in the mining industry. While BLS
reported the number of workers under powered haulage operators, it did
not report any employment in the OCC Code 53-7011 (Conveyor Operators
and Tenders) due to an insufficient number of respondents identified as
Conveyor Operators and Tenders.
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\91\ OEWS data available at https://www.bls.gov/oes/ (last
accessed Jan. 10, 2024).
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The samples taken by MSHA inspectors were not weighted based on
[[Page 28384]]
the ``number of samples plus exposures to the current standard,'' as
the commenter suggested, but rather by the estimated number of workers
in each occupational group (Document ID 1392). MSHA took this approach
because the samples taken by inspectors are not representative of all
jobs at a mine, rather they are concentrated in areas where miners are
at the greatest risk for dust exposure. The FRIA analysis is based on
sample and employment data to provide an overview of all occupational
groups and their associated risks for the mining industry.
One commenter, N-Compliance Safety Services, Inc., stated that
large mining company costs under the proposed rule would be in the
millions of dollars annually, a figure that does not include the cost
of citations, downtime, and contesting violations (Document ID 1383).
Stating that the proposed rule's costs would drive up the costs of
commodities and impact transportation needs and expenses, the commenter
said that the proposed 25 [mu]g/m\3\ action level would place most
mines in violation, as it is four times less than the current PEL and
would require four times the actions to maintain compliance below it.
Downtime to maintain controls is included in the cost of the final
rule. In response to the comment from mine operators that the action
level would place most mines in violation, MSHA clarifies that mine
operators are not required to maintain exposures below the action
level. The purpose of the action level is to alert mine operators and
miners when exposures are approaching the PEL. Mine operators will be
in violation if exposures exceed the new PEL. Mine operators who
maintain exposures at or above the action and at or below the new PEL
will incur sampling costs but will not be in violation of the final
rule and will not be faced with citations, downtime, or contesting
violations. MSHA notes that the commenter has provided no data to
support their statement that the rule will cost large mining companies
millions of dollars in compliance costs.
D. Benefit Analysis
In the FRIA, MSHA estimates that, during the 60 years following the
compliance date for the coal sector (i.e., the start of the timeframe
for the cost analysis), annual benefits will gradually increase, as the
share of miners' working lives under the new PEL (rather than the
existing standards) increases.\92\ In the FRA, MSHA estimated the
avoided cases attributable to the new PEL using a comparison of a
population of miners exposed only under the new PEL to one exposed only
under the existing standards throughout their working and retired
lives. These benefits included reductions to excess cases of fatal
silicosis, fatal non-malignant respiratory diseases (NMRD), fatal end-
stage renal disease, fatal lung cancer, and non-fatal silicosis. These
five health outcomes were chosen based on their well-established
exposure-response relationships with occupational respirable
crystalline silica exposure.\93\
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\92\ Throughout this document, the term ``long-run'' refers to
the period of time when all surviving working and retired miners
will have only been exposed under the new PEL.
\93\ The standalone Health Effects document and the FRA discuss
the evidence for these relationships in depth, as well as the
exposure-response models used for analysis in the FRA.
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In the FRIA, MSHA estimates and monetizes the excess morbidity and
mortality cases avoided during the same 60-year analysis timeframe as
considered by the cost analysis so that benefits can be directly
compared with the costs of the final rule. The number of avoided cases
presented in the FRIA during the 60-year analysis period is less than
the number of lifetime cases avoided estimated in the FRA, since miners
with exposure under the current limits are gradually replaced by miners
with exposure under the new PEL during the 60 years following the start
of implementation.
In the PRA, MSHA underestimated the number of miners who would
benefit from this rule. Based on the 2019 Quarterly Employment
Production Industry Profile (MSHA, 2019a) and the 2019 Quarterly
Contractor Employment Production Report (MSHA, 2019b), the current
number of working miners full-time equivalents (FTEs) is assumed to be
184,615 for MNM and 72,768 for coal.\94\ In the PRA, MSHA assumed
excess cases of disease would be reduced only among these working
miners. However, once the current mining workforce is replaced with new
entrants to the mining industry so that the entire workforce has worked
only under the new PEL for their 45-years of working life (i.e., 60
years after the start of implementation), the future mining workforce
will experience fewer excess deaths and illnesses from excess exposure
to respirable crystalline silica. The PRA's methodology did not include
the number of future retired miners who experienced lower exposures for
their working lives under the final rule and will continue to benefit
during their retirement, and therefore, the PRA underestimated the
benefits attributable to the final rule.
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\94\ The analysis of this FRIA assumes the mining workforce will
not change size during the 60 years following compliance with the
rule to simplify estimation of health benefits. The current and
long-term size of the mining workforce was estimated using 2019
data, since the COVID-19 pandemic may have led to temporary changes
in the mining workforce that will be reversed in coming years.
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Both the FRA and the FRIA are updated to account for benefits among
both working miners and future retired miners. It is important to note
that the FRIA only monetizes benefits to future retired miners--i.e.,
retired individuals who were employed as miners after the start of
implementation. The FRIA methodology does not attribute any health
benefits to individuals who retired before the start of implementation
of the final rule. The FRIA is updated to reflect the number of future
retired miners, which increases gradually after the start of
implementation. For example, in the first year after the start of
implementation, there will be no retired miners who benefit from the
rule. In the second year after the start of implementation, there will
be one cohort of retired miners (i.e., those in their final year of
mining when implementation began). In this way, the FRIA monetizes
benefits to future retired miners while accounting for the fact that
future retired miners who benefit from the rule increase in size
gradually during the 60-year analysis period.
MSHA estimates that:
For a population of working and retired miners exposed
only under the new PEL, the final respirable crystalline silica rule
will result in a total of 1,067 lifetime avoided deaths (982 in MNM
mines and 85 in coal mines) and 3,746 lifetime avoided morbidity cases
(3,421 in MNM mines and 325 in coal mines). These avoided cases will be
achieved once all miners, working and retired, have been exposed
exclusively under the new PEL (see Table IX-23).
Over the first 60 years immediately following the start of
implementation, fewer cases will be avoided than are shown in Table IX-
23. This is because the annual number of cases avoided will increase
gradually to the long-run steady-state values, which ultimately will be
achieved only when all miners have been exposed only under the new PEL.
Table IX-24 shows that, in the first 60 years following the start of
implementation, the final rule will result in a total of 531 avoided
deaths (487 in MNM and 44 in coal) and 1,836 avoided morbidity cases
(1,673 in MNM and 162 in coal), which are the benefits MSHA monetized
in its FRIA. In general, the actual number of cases that will be
avoided in the 60 years
[[Page 28385]]
following the start of implementation is approximately half the number
of avoided cases once benefits reach their long-run average annual
values (see Table IX-24).
Under a discount rate of 3 percent, the total benefits of
the new respirable crystalline silica rule from these avoided deaths
and morbidity cases, including the benefits of avoided morbidity
preceding mortality, are $246.9 million per year in 2022 dollars (see
Table IX-25).
Because a higher monetary value is placed on avoided death
as compared to an avoided morbidity case, the majority (62.5 percent;
$154.3 million) of these benefits is attributable to avoided mortality
due to non-malignant respiratory disease (NMRD) ($75.4 million),
silicosis ($40.3 million), and end-stage renal disease (ESRD) ($28.4
million), and lung cancer ($10.2 million) (see Table IX-25).
[cir] Benefits from avoided morbidity due to non-fatal silicosis
are $72.8 million per year. Of this, $66.3 million are due to cases
avoided in MNM mines and $6.5 million are due to cases avoided in coal
mines (see Table IX-25).
[cir] Benefits from avoided morbidity that precedes fatal cases of
NMRD, silicosis, renal disease, and lung cancer, are $19.8 million. Of
this, $18.2 million are due to cases avoided in MNM mines and $1.6
million are due to cases avoided in coal mines (see Table IX-25).
BILLING CODE 4520-43-P
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[[Page 28386]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.182
BILLING CODE 4520-43-C
MSHA acknowledges that its benefit estimates are influenced by
underlying assumptions and that the long timeframe of this analysis
(i.e., 60 years) is a source of uncertainty. The main assumptions
underlying these estimates of avoided mortality and morbidity include
the following:
Employment is held constant over the 60 years (i.e., the
analysis period of the final rule).\95\
---------------------------------------------------------------------------
\95\ MSHA recognizes that it is very challenging to predict
economic factors over such a long period with high degrees of
confidence. Given known information and forecast limitations, MSHA
believes assuming constant employment is reasonable.
---------------------------------------------------------------------------
For analyses under the ``Baseline'' scenario, any
exposures to respirable crystalline silica above the existing standards
(i.e., 100 [mu]g/m\3\ for MNM miners and 85.7 [mu]g/m\3\ for coal
miners) were capped at 100 [mu]g/m\3\ and 85.7 [mu]g/m\3\ for MNM and
coal exposures, respectively.
For analyses under the ``New PEL 50'' scenario, any
exposures to respirable crystalline above the new PEL are capped at the
new PEL (i.e., 50 [mu]g/m\3\).
Miners have identical employment and hence identical
exposure tenures (i.e., 45 years).
In addition to the above-mentioned quantified health benefits, MSHA
expects that there will be additional benefits from requiring approved
respirators be selected, fitted, used, and maintained in accordance
with ASTM F3387-19. The ASTM standard reflects improved developments in
respiratory protection since the time in which MSHA issued its existing
standards. ASTM F3387-19 also includes respiratory protection program
elements such as program administration; standard operating procedures
(SOPs); medical evaluation; respirator selection; training; fit
testing; and respirator maintenance, inspection, and storage.
This provision of the final rule will ensure that, in circumstances
where respirator use is required, mine operators will provide miners
with respiratory protection that incorporates advances in technology
and changes in respiratory protection practices. This respiratory
protection will play a critical role in safeguarding the health of
miners and reducing their exposures to respirable crystalline silica
and other airborne contaminants. As demonstrated in the FRA, reductions
in occupational exposure to respirable crystalline silica are expected
to reduce adverse health outcomes. However, given the uncertainty about
the current state of mine operator respiratory protection practices,
MSHA did not quantify the expected additional benefits that would be
realized by requiring approved respirators to be selected, fitted,
used, and maintained in accordance with the requirements of ASTM F3387-
19.
MSHA believes that reductions in coal miners' exposure to
respirable crystalline silica may also lead to lower levels of coal
mine dust inhalation. MSHA expects that adverse health outcomes
attributable to respirable coal mine dust exposure, such as simple and
complex coal workers' pneumoconiosis (CWP), will also be reduced. MSHA
has not estimated the reduction in risk associated with CWP among coal
miners because the literature does not contain an exposure-response
model that quantifies the impact of respirable crystalline silica on
CWP mortality risk, and because MSHA is not making any assumptions
about whether levels of coal mine dust will be reduced due to the final
rule. MSHA anticipates that there will be additional unquantified
benefits from the reduction in CWP provided by the final rule. Within
the avoided silicosis and NMRD deaths, however, MSHA includes benefits
from avoided mortality due to progressive massive fibrosis (PMF)--
including mortality due to complicated CWP and complicated silicosis.
Finally, MSHA also expects that the final rule's medical
surveillance provisions will reduce mortality and morbidity from
respirable crystalline silica exposure among MNM miners. The initial
mandatory examination that assesses a new miner's baseline pulmonary
status, coupled with periodic examinations, will assist in the early
detection of respirable crystalline silica-related illnesses. Early
detection of illness often leads to early intervention and treatment,
which may slow disease progression and/or improve health outcomes. This
may also result in less miner time-off and less miner turnover.
However, MSHA lacks data to quantify these additional benefits.
[[Page 28387]]
National Coalition of Black Lung and Respiratory Disease Clinics
was concerned that the projected benefits of the proposed rule for coal
miners were significantly lower than the projected benefits for MNM
miners and suggested that MSHA correct for this by including dust
samples from coal mines taken prior to August 1, 2016 (Document ID
1410). Similarly, the Appalachian Citizens' Law Center asserted that
the benefits estimated in the PRA are low and urged MSHA to include a
longer history of coal dust sampling data (Document ID 1445). MSHA
believes that samples from before August 1, 2016, may not accurately
reflect the current conditions in coal mines and therefore should not
be used in analyzing the impact of this final rule. As discussed in
Appendix A of the preamble, on August 1, 2016, Phase III of the 2014
RCMD Standard went into effect, and this lowered the PEL for RCMD in
coal mines. The controls put in place to achieve that new PEL impacted
both RCMD with and without respirable crystalline silica dust in coal
mines, and as such, these controls likely lowered concentrations of
respirable crystalline silica. Using data from after the coal mine dust
rule went into effect helps to ensure that benefits attributable to
that rule are not attributed to this rule incorrectly. More details
about the respirable crystalline silica sample dataset, including the
time coverage and brief statistics, are described in ``Description of
MSHA Respirable Crystalline Silica Samples'' (Appendix A of the
preamble of Proposed Rule). In addition to the prior effects of the
2014 RCMD Standard on respirable crystalline silica exposure in the
coal sector, there will also be greater benefits to MNM miners owing to
the medical surveillance requirements which are already existing for
coal miners. However, these benefits are unquantified in the FRA and
FRIA analyses and therefore, do not specifically contribute to the
discrepancy mentioned by these commenters.
Further, the benefits quantified here may underestimate the true
benefits to coal miners. MSHA believes this final rule will likely
lower not only respirable crystalline silica concentrations, but also
RCMD levels. As a result, MSHA believes this final rule will provide
additional reductions in CWP, NMRD, and PMF beyond those conferred by
the 2014 RCMD Standard. In the 2014 Coal Dust Rule, NIOSH emphasized
the important role respirable crystalline silica plays in causing these
diseases, stating that, ``in concentrating on this particular exposure-
response relationship with coal mine dust, we must not forget that
[coal] miners today are being exposed to excess silica levels,
particularly in thinner seam and small mines, and that this situation
could well get worse as the thicker seams are mined out. Hence, since
silica is more toxic than mixed coal dust, tomorrow's [coal] miners
could well be at greater risk, despite a reduction in the mixed coal
mine dust standard.'' While additional reductions in total RCMD would
be expected due to this final rule, these reductions cannot be
quantified as the reductions depend on the particular control measures
that mine operators implement. Additionally, exposure-response models
for respirable crystalline silica exposure and resultant CWP are not
available. Thus, the benefits quantified in this FRIA may underestimate
the true benefits to coal miners, as MSHA does not account for expected
reductions in CWP or in other diseases due to reduced RCMD.
E. Benefit-Cost Analysis
The net benefits of the final rule are the differences between the
estimated benefits and costs. Table IX-26 shows estimated net benefits
using alternative discount rates of 0, 3, and 7 percent. The choice of
discount rate has an effect on annualized costs, benefits, and net
benefits. While the net benefits of the final respirable crystalline
silica rule vary depending on the choice of discount rate used to
annualize costs and benefits, total benefits exceed total costs under
all discount rate considered. MSHA's estimate of the net annualized
benefits of the final rule, using a discount rate of 3 percent, is
$156.6 million a year, with the majority ($143.9 million; 91.9 percent)
attributable to the MNM sector.
[[Page 28388]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.183
F. Sensitivity Analysis on the Tenure of Miners
As mentioned in Part E. Benefit-Cost Analysis, in performing the
benefit analysis, MSHA assumed that all miners have a working tenure of
45 years, from the start of age 21 to the end of age 65. MSHA also
assumed that each miner's level of exposure remains the same in each
day of each year. MSHA also performed a sensitivity analysis to see how
benefits would differ under three scenarios with alternative tenures,
though with all three sharing the same simplifying assumption that
exposure remains constant for each miner across all of their working
years. These alternative scenarios involved: (1) a tenure of 35 working
years (rather than 45), between the ages of 26 and 60; (2) a tenure of
25 working years, between the ages of 31 and 55; and a tenure of 15
years, between the ages of 36 and 50. These age ranges were selected to
maintain the same midpoint miner age of 43.
Under the assumption that the same number of miners (257,383) are
working at any given time the lower the tenure, the more turnover there
would be among miners, the greater the number of new miners who would
enter each year to replace those who are retiring or changing jobs. For
example, when the scenario changes from a 45-year tenure (which was
used in the benefit analysis) to a 15-year tenure, the analysis would
require a single miner who would work for 45 years to be effectively
replaced by three miners who would each be working for 15 years (one
after another) during those same 45 years. This means that, in these
lower-tenure scenarios, each miner would have accumulated less exposure
by the time they retire, but there would be more miners retiring with
that level of exposure.
From analyzing the alternative scenarios with different tenures,
using its risk model, MSHA found that lower tenures tended to result in
more avoided cases of mortality. This is because, while the risk of
mortality increases for any miner who works more years, at lower tenure
rates, many more miners are exposed and are put at risk of dying from
the disease. According to the models, the increased number of exposed
miners, when tenure is short, leads to a greater increase in overall
mortality than does the increased likelihood of mortality occurring for
each miner, when the tenure is long. As a result, this sensitivity
analysis found that the rule would have greater benefits, in terms of
reducing mortality, under scenarios with shorter tenure than under the
45-year tenure assumption used in the benefits analysis. The assumption
of a 45-year tenure may be seen as effectively leading to an
underestimate the benefits of the rule in terms of reduced mortality,
relative to assumptions involving lower tenures.
From the way the risk model is designed, however, the opposite
effect was observed with regard to morbidity cases, where there were
more cases of morbidity under longer tenure rates. Under longer tenure
rates, there are estimated to be more cases of morbidity overall, and
therefore the rule has a greater estimated effect on reducing cases of
morbidity under the assumption of a 45-year tenure than under the
alternative scenarios. Nevertheless, because the benefits of reduced
mortality cases count much more than the benefits of reduced morbidity
cases, it may be concluded that under the shorter tenures of the
alternative scenarios, the benefits of the rule would be greater. In
other words, if the tenures of miners are, in fact, shorter than 45
years, the assumption of a 45-year tenure has the net effect of
underestimating the benefits of the rule.
[[Page 28389]]
G. Regulatory Alternatives
In developing the final rule, MSHA considered three regulatory
alternatives. The first two alternatives contain less stringent
exposure monitoring provisions than the final rule, which comparatively
presents a comprehensive approach for lowering miners' exposure to
respirable crystalline silica and improving respiratory protection for
all airborne contaminants. The first alternative includes no change to
the final rule's PEL and action level, whereas the second alternative
includes a more stringent PEL. The second alternative combines less
stringent exposure monitoring with a more stringent PEL. The third
alternative examines a different methodology for calculating miners'
exposures and assessing compliance. MSHA discusses the regulatory
options in the sections below.
1. Regulatory Alternative 1: Changes in Sampling and Evaluation
Requirements
Under this alternative, the new PEL would remain unchanged at 50
[mu]g/m\3\ and the action level would remain unchanged at 25 [mu]g/
m\3\. Further, mine operators would conduct: (1) first-time and second-
time sampling for miners who may be exposed to respirable crystalline
silica at or above the action level of 25 [mu]g/m\3\, (2) above-action-
level sampling twice per year for miners who are at or above the action
level of 25 [mu]g/m\3\ but at or below the PEL of 50 [mu]g/m\3\, and
(3) annual evaluation of changing mining processes or conditions that
would reasonably be expected to result in new or increased exposures.
Mine operators would still be required to conduct sampling under
this Regulatory Alternative and would thus incur compliance costs.
However, exposure monitoring requirements under this alternative are
less stringent than the requirements under the final rule because the
frequency of above-action-level sampling and periodic evaluations are
set at half the frequency of the final exposure monitoring
requirements. Therefore, the cost of compliance would be lower under
this alternative. MSHA estimates that annualized exposure monitoring
costs would total $29.3 million for this alternative (at a 3 percent
discount rate), compared to $53.2 million for the final exposure
monitoring requirements, resulting in an estimated difference of $24.0
million in compliance costs per year (Table IX-27).
Although this alternative does not eliminate exposure monitoring,
the requirements are minimal relative to the monitoring requirements
under the final rule. However, MSHA believes it is necessary for mine
operators to establish an initial baseline for any miner who may be
reasonably expected to be exposed to respirable crystalline silica. In
addition, above-action-level sampling helps mine operators correlate
mine conditions to miner exposure levels and see exposure trends more
rapidly than would result from semi-annual or annual sampling. This
will enable mine operators to take necessary measures to ensure
continued compliance with the new PEL. Further, more frequent
monitoring will enable mine operators to ensure the adequacy of
controls at their mines and better protect miners' health. These
benefits cannot be quantified, but they are nevertheless material
benefits that increase the likelihood of compliance.
[GRAPHIC] [TIFF OMITTED] TR18AP24.184
MSHA also believes that requiring more frequent above-action-level
sampling will provide mine operators with greater confidence that they
are in compliance with the new PEL. Because of the variable nature of
miner exposures to airborne concentrations of respirable crystalline
silica, maintaining exposures below the action level
[[Page 28390]]
provides mine operators with reasonable assurance that miners would not
be exposed to respirable crystalline silica at levels above the PEL on
days when sampling is not conducted. MSHA believes that the benefits of
the final sampling requirements justify the additional costs relative
to Regulatory Alternative 1.
Two mining trade associations, American Exploration and Mining
Association and National Mining Association, expressed support for
Regulatory Alternative #1 (Changes in Sampling and Evaluation
Requirements) as a more appropriate approach than the one in the
proposed rule, with one clarifying that its support for Regulatory
Alternative #1 is only secondary to its primary recommendation that
MSHA adopt OSHA's risk-based approach to sampling and evaluation
requirements (Document ID 1424; 1428). Specifically, these commenters
supported the Regulatory Alternative #1 requirement for baseline
sampling for miners whose exposure is at or above the proposed action
level of 25 [micro]g/m\3\ in lieu of the requirement for baseline
sampling of each miner who is or may reasonably be expected to be
exposed to respirable crystalline silica of any level. Further, these
commenters supported the Regulatory Alternative #1 periodic sampling
requirement of twice per year for miners between the action level and
the PEL, which they said was more in line with established industrial
hygiene guidelines and would allow mine operators to allocate
industrial hygiene resources to those areas where they are better used,
including areas where there is higher risk of exposure above the PEL.
Finally, these commenters supported the Regulatory Alternative #1
requirement for annual evaluation of mine processes or conditions,
instead of the proposed rule's semi-annual review, stating that it
would provide an equal amount of protection to miners (given that
mining processes and conditions are relatively stable and non-
changing), while lowering operator compliance costs.
MSHA believes it is necessary for mine operators to establish a
solid baseline for any miner who is reasonably expected to be exposed
to respirable crystalline silica. In addition, frequent, regular
sampling and evaluation help mine operators correlate mine conditions
to mine exposure levels and see exposure trends more rapidly than would
result from semi-annual sampling and annual evaluation. This will
enable mine operators to take measures necessary to ensure continued
compliance with the PEL. Further, more frequent monitoring will enable
mine operators to ensure the adequacy of controls at their miners and
better protect miners' health. These benefits cannot be quantified, but
they are nevertheless material benefits that increase the likelihood of
compliance. MSHA believes that the benefits of the sampling and
evaluation requirements justify the additional costs for the final rule
relative to Regulatory Alternative 1. Therefore, MSHA did not select
Regulatory Alternative 1.
2. Regulatory Alternative 2: Changes in Sampling and Evaluation
Requirements and the PEL
Under this Regulatory Alternative, the PEL would be set at 25
[mu]g/m\3\, mine operators would install whatever controls were
necessary to meet the PEL, and no action level would be designated.
Further, under this Regulatory Alternative, mine operators would not be
required to conduct first-time and second time sampling, above-action-
level sampling, and corrective actions sampling. However, mine
operators would be required to perform periodic evaluations of changing
conditions and to sample as frequently as necessary to determine the
adequacy of controls. Additionally, mine operators would be required to
perform post-evaluation sampling when the operators determine as a
result of the periodic evaluation that miners may be exposed to
respirable crystalline silica at or above the action level of 25 [mu]g/
m\3\.
When estimating the cost of monitoring requirements under the final
rule, MSHA assumed that the number of samples for post-evaluation
sampling are relatively small (2.5 percent of miners) because mine
operators are already collecting information which can be used for
these purposes through the significant amount of above-action-level
sampling. Since Regulatory Alternative 2 does not require above-action-
level sampling given the lack of an action level under this
alternative, MSHA increases the share of samples after each evaluation
to 10 percent of miners to ensure the monitoring requirements can be
met.
In addition, to meet the PEL of 25 [mu]g/m\3\, mine operators would
incur greater engineering control costs as compared to the estimated
cost of compliance for reaching a PEL of 50 [mu]g/m\3\. To estimate
these additional engineering control costs, MSHA largely uses the same
methodology as for mines affected at the new PEL of 50 [mu]g/m\3\.
a. Number of Mines Affected Under Regulatory Alternative 2
MSHA first estimated the number of mines expected to incur the cost
of implementing engineering controls to reach the more stringent PEL.
After excluding mines that are affected at the new PEL of 50 [mu]g/m\3\
(to avoid double-counting), MSHA finds that 3,477 mines (2,991 MNM
mines and 486 coal mines) operating in 2019 had at least one sample at
or above 25 [mu]g/m\3\ but below 50 [mu]g/m\3\.\96\
---------------------------------------------------------------------------
\96\ About 8,053 of mines active in 2019 either had neither a
sample >25 [mu]g/m\3\ nor a sample in the last 5 years.
---------------------------------------------------------------------------
In addition, MSHA also includes the 1,226 affected mines expected
to incur costs to reach the new PEL of 50 [mu]g/m\3\. Based on its
experience and knowledge, MSHA does not expect the mines that install
engineering controls to meet the PEL of 50 [mu]g/m\3\ would also be
able to comply with a PEL of 25 [mu]g/m\3\. For example, to comply with
the PEL of 50 [mu]g/m\3\, a mine might need to add the engineering
controls necessary to achieve an additional 10 air changes per hour
over that achieved by existing controls, which are included in the
costs presented in Table IX-21. However, such a mine facility would
then need to add an additional 10 air changes per hour to meet the more
stringent PEL of 25 [mu]g/m\3\, which is not included in the costs
presented in Table IX-21. Thus, MSHA expects that the 1,226 affected
mines will incur additional costs to meet the PEL of 25 [mu]g/m\3\
specified under this alternative.
MSHA estimates a total of 4,703 mines will incur costs to purchase,
install, and operate engineering controls to meet the more stringent
PEL of 25 [mu]g/m\3\ under this alternative. MNM mines account for
4,087 (87 percent) and coal accounts for the remaining 616 mines (13
percent).
b. Estimated Engineering Control Costs Under Regulatory Alternative 2
MSHA identified potential engineering controls that would enable
mines with respirable crystalline silica dust exposures at or above 25
[mu]g/m\3\ but below 50 [mu]g/m\3\ categories to meet the more
stringent PEL of 25 [mu]g/m\3\ for this alternative. While MSHA assumed
that mine operators will base such decisions on site-specific
conditions such as mine layout and existing infrastructure, MSHA cannot
make further assumptions about the specific controls that might be
adopted and instead assumed the expected value of purchased
technologies should equal the simple average of the technologies listed
in each control category.
Where more precise information is unavailable, MSHA assumed
operating and maintenance (O&M) costs to be 35 percent of initial
capital expenditure
[[Page 28391]]
and installation cost to be equal to the initial capital expenditure
(Table IX-28). MSHA also assumed the larger capital expenditure
controls will have a 30-year service life.
[GRAPHIC] [TIFF OMITTED] TR18AP24.185
However, the difficulty of meeting a PEL of 25 [mu]g/m\3\ is such
that MSHA's experience suggests a single control from Table IX-29 would
not be sufficient. For example, respirable crystalline silica dust
exposure at such a stringent limit is likely to occur in more than one
area of the mine; in addition to increasing ventilation to a crusher/
grinder, enclosing and ventilating the belt conveyor would likely be
necessary to reduce concentrations below a PEL of 25 [mu]g/m\3\.
Similarly, increasing facility ventilation from 20 to 30 air changes
per hour may not be adequate to meet the PEL. Rather, 40 air changes
per might be necessary. Therefore, MSHA assumes mine operators will
purchase and install at least two of the engineering controls listed in
Table IX-28 under this Regulatory Alternative. This assumption was made
to err on the side of overestimation.
Table IX-29 presents the annualized engineering control costs per
mine and total annualized engineering control costs by mine sector. At
a 3 percent discount rate, the annualized engineering control costs are
about $98,124 per mine, resulting in an additional cost of $461.5
million if the PEL were set at 25 [mu]g/m\3\ instead of 50 [mu]g/m\3\.
[GRAPHIC] [TIFF OMITTED] TR18AP24.186
[[Page 28392]]
Table IX-30 summarizes the estimated annualized cost of this
Regulatory Alternative under consideration. At a 3 percent discount
rate, exposure monitoring costs less than it does for the final rule.
However, this lower monitoring cost is more than offset by the
increased control costs necessitated by the requirement that mines
maintain respirable crystalline silica exposure levels below 25 [mu]g/
m\3\. At an estimated annualized cost of $520.7 million, this
alternative would cost nearly six times more than the final
requirements.
[GRAPHIC] [TIFF OMITTED] TR18AP24.187
c. Avoided Mortality and Morbidity Under Regulatory Alternative 2
Regulatory Alternative 2 increases miner protection by establishing
the PEL at 25 [mu]g/m\3\, resulting in measurable increases in avoided
mortality cases and other health benefits. Table IX-31 presents the
avoided morbidity and mortality cases over the 60-year regulatory
analysis time horizon under this alternative. Under this alternative,
1,271 mortality cases are expected to be avoided, which is 2.4 times
higher than the 531 mortality cases expected to be avoided under the
new PEL (50 [mu]g/m\3\). Additionally, 2,521 morbidity cases are
expected to be avoided under this alternative, which is 1.4 times
higher than the 1,836 morbidity cases expected to be avoided under the
new PEL (50 [mu]g/m\3\).
[[Page 28393]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.188
d. Monetized Benefits Under Regulatory Alternative 2
Table IX-32 presents the monetized benefits associated with this
avoided morbidity and mortality. The expected total benefits,
discounted at 3 percent, are $516.3 million, which is more than twice
the expected total benefits of $246.9 million under the new PEL (50
[mu]g/m\3\).
Under this Regulatory Alternative, these benefits are made up of
$369.0 million due to avoided mortality, $47.3 million due to avoided
morbidity preceding mortality, and $100.0 million due to avoided
morbidity not preceding mortality. However, when compared to the
annualized costs of $520.7 million (3 percent) and $662.2 million (7
percent) for the Part 60 requirements, the net benefits of this
alternative are negative at a 3 percent and 7 percent discount rate.
[[Page 28394]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.189
A professional association, American Industrial Hygiene
Association, expressed support for Regulatory Alternative 2 (Changes in
Sampling and Evaluation Requirements and the Proposed PEL) (Document ID
1351). However, the commenter recommended that mine operators be
required to (1) conduct baseline sampling and periodic sampling, (2)
conduct semi-annual or more frequent evaluations of changing
conditions, and (3) sample as frequently as necessary to determine the
adequacy of controls. In addition, the commenter stated that, under
this alternative, mine operators should be required to perform post-
evaluation sampling when the operators determine from the semi-annual
evaluation that miners are exposed at the 95-percent confidence level
to respirable crystalline silica above the PEL of 50 [mu]g/m\3\,
referencing a NIOSH Occupational Sampling Strategy Manual.
e. Net Benefits Under Regulatory Alternative 2
Although the benefits associated with this avoided morbidity and
mortality under Regulatory Alternative 2 (Table IX-31 and Table IX-32)
are greater than those for the final rule, the net benefits of this
alternative are negative at both a 3 percent and 7 percent real
discount rate owing to the much higher compliance costs for this
alternative as compared to those for the final rule (Table IX-31).
Further, MSHA determines that meeting a PEL of 25 [mu]g/m\3\ is not
achievable for all mines and therefore, Regulatory Alternative 2 is not
chosen.
3. Regulatory Alternative 3: Changes in the Calculation of Exposure
Concentrations
Regulatory Alternative 3 calculates exposure concentrations as an
entire-shift time-weighted average, called a ``full shift TWA''. Under
this Regulatory Alternative, a different methodology is used for
calculating exposures and assessing compliance. Elsewhere in the final
rule, the costs and benefits are based on calculating exposure for a
full shift, calculated as an 8-hour TWA. In this Regulatory
Alternative, MSHA calculates exposure as a full shift TWA and re-
analyzes the costs and benefits of the rule. No other changes, such as
changes to the rule requirements, are included under this Regulatory
Alternative.
a. Number of Mines Affected Under Regulatory Alternative 3
MSHA expects a change in the number of affected mines. MSHA has
estimated the number of mines expected to incur costs when baseline
exposure concentrations are re-calculated as full shift TWAs. Based on
the use of a full shift TWA, MSHA finds that 1,053 mines operating in
2019 would incur costs to purchase, install, and operate exposure
controls under the final rule. Of this total, 955 are MNM mines and 98
are coal mines. This total is 173 fewer mines than what would incur new
compliance costs under an 8-hour TWA (1,226 affected mines).
b. Estimated Costs Under Regulatory Alternative 3
Aside from the change to the calculation of exposure concentrations
and the number of affected mines at those concentrations, MSHA does not
make any additional changes in assumptions or calculations under this
Regulatory Alternative. Therefore, the cost estimates of this
Regulatory Alternative are calculated using the same methodology as
described in Section 4 of the FRIA. The changes in cost estimates are
completely attributable to changes in the estimated baseline exposure
conditions and the total number of affected mines, as described in
Section 7.3.1 of the FRIA.
Table IX-33 below presents the estimated annualized compliance
costs of part 60 if exposure concentrations were calculated using a
full shift TWA instead of a full shift, 8-hour TWA.
[[Page 28395]]
Total part 60 annualized compliance costs are estimated at $86.4
million (at a 3 percent discount rate), with 92.3 percent of costs
attributable to MNM mines and 7.7 percent attributable to coal mines.
This is $2.7 million (3.0 percent) less than the total part 60
annualized compliance costs when using an 8-hour TWA ($89.1 million).
The difference is explained by the decreased number of mines and miners
who are affected by the rule under this Regulatory Alternative as
compared to the main analysis.
[GRAPHIC] [TIFF OMITTED] TR18AP24.190
c. Avoided Mortality and Morbidity Under Regulatory Alternative 3
While the compliance costs decrease when a full shift TWA is used,
the estimated benefits of the rule are also expected to decrease. When
miners work shifts that are longer than 8 hours (which commonly occurs,
as seen both in the exposure data and in the employment data), the full
shift, 8-hour TWA will result in a higher calculated exposure level
than the full shift TWA.
Table IX-34 presents the estimated number of avoided deaths and
illnesses during the 60 years following the start of implementation of
the new rule, under the Regulatory Alternative. The total number of
avoided morbidity cases over the 60-year analysis period is 1,500,
which is 18 percent lower under the Regulatory Alternative than the
estimate of 1,836 avoided morbidity cases in the main analysis (see
Table IX-24). The total number of avoided mortality cases over the 60-
year analysis period is 434, which is 18 percent lower under the
Regulatory Alternative than the estimate of 531 avoided mortality cases
in the main analysis (see Table IX-24).
[[Page 28396]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.191
d. Monetized Benefits Under Regulatory Alternative 3
Table IX-35 presents the annualized benefits of the final rule
under this Regulatory Alternative. The undiscounted annualized benefits
under the Regulatory Alternative are estimated at $312.8 million, with
$291.5 million attributable to MNM mines and $21.3 million attributable
to coal mines. The discounted annualized benefits under the Regulatory
Alternative are estimated at $201.9 million at a 3 percent discount
rate and $107.9 million at a 7 percent discount rate. At a 3 percent
discount rate, the annualized benefits are $45.0 million (18 percent)
less under the Regulatory Alternative than when using an 8-hour TWA
($246.9 million). The annualized benefits under the Regulatory
Alternative are also 18 percent lower both at the 0 percent discount
and 7 percent discount rates.
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[[Page 28397]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.192
BILLING CODE 4520-43-C
e. Net Benefits Under Regulatory Alternative 3
The net annualized benefits under the Regulatory Alternative are
$226.5 million (undiscounted), $114.3 million (3 percent discount
rate), and $18.6 million (7 percent discount rate). The net benefits
under the Regulatory Alternative are lower than those in the main
analysis by 23 percent (0 percent discount rate), 27 percent (3 percent
discount rate), and 53 percent (7 percent discount rate).\97\
---------------------------------------------------------------------------
\97\ There are limitations in how the risk calculations can be
performed because of limitations in the underlying exposure-response
models from the literature. The exposure-response models were not
designed to detect the impact of longer work shifts, nor were they
based on longitudinal data that could track individuals' work shifts
over their careers. These calculations presented in this Alternative
analysis provide new estimates of avoided cases when calculating
exposure as a full shift TWA and when accounting for the fact that
fewer samples would meet the threshold of the new PEL or the new
action level under a full shift TWA.
---------------------------------------------------------------------------
MSHA received comments both in agreement with the Agency's proposed
``full-shift, 8-hour TWA'' calculation method and against it.
Commenters in favor stated that the proposed calculation method of
collecting a sample for a full-shift and calculating the exposure level
over an 8-hour period (i.e., normalizing a longer work shift to an 8-
hour shift) capture the total cumulative exposure to silica dust
properly. Those against the proposal preferred the use of the entire
duration of the miner's extended work shift without any adjustment, and
stated that normalizing the extended shift sampling result to an 8-hour
period inaccurately skews the results. For more details on the comments
received, please see section VIII.B.3 of this preamble.
The Agency does not choose Regulatory Alternative 3, that uses full
shift TWA as an alternate calculation of exposure concentration.
Regulatory Alternative 3 yields much smaller net benefits than the
final rule. Importantly, Regulatory Alternative 3 would provide miners
less health protection. Cumulative exposure to respirable crystalline
silica is an important risk factor in the development of silica-related
disease, as discussed in the standalone FRA document and section
VIII.B.3.c of this preamble. However, the full shift TWA methodology
does not account for the increased health risks associated with the
higher cumulative exposures that can occur during longer work shifts.
The full shift TWA calculation does not differentiate between the
impacts of working 8-hour shifts and working extended shifts.
Regulatory Alternative 3 would provide less protection for miners
working longer shifts.
[[Page 28398]]
X. Final Regulatory Flexibility Analysis
A. The Regulatory Flexibility Act
The Regulatory Flexibility Act of 1980 as amended by the Small
Business Regulatory Enforcement Fairness Act of 1996, hereafter jointly
referred to as the RFA, requires that an agency consider the economic
impact that a final rulemaking will have on small entities. The RFA
provides that, ``[w]hen an agency promulgates a final rule under
section 553 of this title, after being required by that section or any
other law to publish a general notice of proposed rulemaking . . . the
agency shall prepare a final regulatory flexibility analysis.'' 5
U.S.C. 604(a). However, under section 605(b), in lieu of an initial
regulatory flexibility analysis (IRFA) or final regulatory flexibility
analysis (FRFA), the head of an agency may certify that the final rule
``will not, if promulgated, have a significant economic impact on a
substantial number of small entities.'' 5 U.S.C. 605(b). That
certification must be supported by a factual basis.
As part of its notice of proposed rulemaking, MSHA prepared an IRFA
that analyzed the potential impact of the proposed rule on small
entities. See 5 U.S.C. 603(a). After considering public comments on the
IRFA, MSHA believes that the final rule will not have a significant
economic impact on a substantial number of small entities. However, in
the furtherance of good governance principles and consistent with
guidance from the Small Business Administration (SBA), the Agency has
prepared a FRFA. Under section 604(a), the FRFA analysis must contain:
(1) a statement of the need for, and objectives of, the rule;
(2) a statement of the significant issues raised by the public
comments in response to the initial regulatory flexibility analysis, a
statement of the assessment of the agency of such issues, and a
statement of any changes made in the proposed rule as a result of such
comments;
(3) the response of the agency to any comments filed by the Chief
Counsel for Advocacy of the Small Business Administration in response
to the proposed rule, and a detailed statement of any change made to
the proposed rule in the final rule as a result of the comments;
(4) a description of and an estimate of the number of small
entities to which the rule will apply or an explanation of why no such
estimate is available;
(5) a description of the projected reporting, recordkeeping and
other compliance requirements of the rule, including an estimate of the
classes of small entities which will be subject to the requirement and
the type of professional skills necessary for preparation of the report
or record; and
(6) a description of the steps the agency has taken to minimize the
significant economic impact on small entities consistent with the
stated objectives of applicable statutes, including a statement of the
factual, policy, and legal reasons for selecting the alternative
adopted in the final rule and why each one of the other significant
alternatives to the rule considered by the agency which affect the
impact on small entities was rejected; and for a covered agency, as
defined in section 609(d)(2), a description of the steps the agency has
taken to minimize any additional cost of credit for small entities. 5
U.S.C. 604(a).
While a full understanding of MSHA's analysis and conclusions with
respect to costs and economic impacts on small entities requires a
reading of the standalone FRIA document, this FRFA summarizes the key
aspects of MSHA's analysis as they affect small entities.
B. Initial Assessment
As part of the proposed rule, MSHA published an IRFA. MSHA's
proposed rule would affect MNM and coal mining operations. The IRFA
identified which mine controllers were small entities, estimated the
direct compliance costs for those small entities, and compared the
compliance costs to the revenues of the small entities. Results from
the IRFA are summarized below.
1. Definition of Small Entities
In its IRFA analysis, MSHA relied on the Small Business
Administration (SBA)'s 2017 Table of Size Standards to define the size
thresholds for small entities. MSHA identified small-entity controllers
in each North American Industry Classification System (NAICS) code,
after determining that a ``controller,'' the entity that owns and
controls one or more mines, is the appropriate unit of the IRFA
analysis, based on SBA guidance.\98\ (SBA, 2017).\99\ The IRFA detailed
how SBA's size standards vary by North American Industry Classification
System (NAICS) code, which NAICS codes were used in the IRFA, and which
controllers were small entities according to these standards.
---------------------------------------------------------------------------
\98\ Small Business Administration, Office of Advocacy, How to
Comply with the Regulatory Flexibility Act, August 2017.
\99\ A controller is a parent company owning or controlling one
or more mines, whereas a mine is an establishment of a parent
company. Small entities subject to the requirements of the
Regulatory Flexibility Act are entities that are parent companies
only and not establishments. See Small Business Administration,
Office of Advocacy, How to Comply with the Regulatory Flexibility
Act, August 2017. Sec. 3(d) of the Mine Act defines ``operator'' as
``any owner, lessee, or other person who operates, controls, or
supervises a coal or other mine.'' 30 U.S.C. 802(d). Under 30 CFR
part 41, an operator must file a legal identity report with MSHA,
and with this report, MSHA identifies a controller for each mine. 30
U.S.C. 819(d) (each operator shall file the name and address of the
``person who controls or operates the mine''). In the FRFA,
consistent with SBA guidance and the Mine Act, MSHA determines
whether the controller is a small entity.
---------------------------------------------------------------------------
2. Number of Affected Small Entities
MSHA estimated that in 2021, there were a total of 11,791 mines and
a total of 5,879 controllers. Of the controllers, 5,007 were small-
entity controllers; these small-entity controllers owned 8,240 mines.
Many controllers owned one or two mines, while some controllers owned
hundreds of mines nationwide (or worldwide).
3. Results of the Initial Regulatory Flexibility Analysis
MSHA estimated the regulatory compliance costs and revenues for
each of the 5,007 small-entity controllers identified in 2021. In
estimating compliance costs for small-entity controllers, MSHA factored
in the types of commodities that controllers produced and their
employment size, which were gathered from the MSHA Standardized
Information System (MSIS). MSHA estimated the revenues of the small-
entity controllers based on data from the Statistics of U.S. Businesses
published by the U.S. Census Bureau, using NAICS codes and each
controller's employment size.\100\ MSHA then calculated the compliance
costs as a proportion of revenues and used that as an indicator of the
relative burden of the compliance costs for small-entity controllers.
---------------------------------------------------------------------------
\100\ U.S. Census Bureau, ``Statistics of U.S. Businesses,''
released May 2021. https://www.census.gov/data/tables/2017/econ/susb/2017-susb-annual.html (last accessed Jan. 10, 2024). Data in
the report were in reference to the year 2017, which MSHA adjusted
to 2021 dollars. Data on revenues are presented in the report under
the equivalent term ``receipts.'' MSHA converted the 2017 revenues
to 2021 dollars using the GDP Implicit Price Deflator published by
the Bureau of Economic Analysis October 26, 2022, Table 1.1.9
Implicit Price Deflators for Gross Domestic Product, Series A191RD.
https://apps.bea.gov/histdata/fileStructDisplay.cfm?HMI=7&DY=2022&DQ=Q3&DV=Advance&dNRD=October-28-2022 (last accessed Jan. 10, 2024). The index was 107.749 for
2017 and 118.895 for 2021, creating an adjustment factor (from 2017
to 2021 dollars) of 118.895/107.749 or 1.103.
---------------------------------------------------------------------------
From these two sets of estimates, MSHA generated estimates of the
ratios of regulatory compliance cost to revenue for each controller.
Table X-1 shows the number of controllers, average annual regulatory
costs, average annual
[[Page 28399]]
revenues, and average cost as a percent of revenue presented in the
IFRA. As shown in Table X-1, for every $1 million in revenue earned by
a small-entity controller, the average compliance cost was estimated to
be $1,220.
[GRAPHIC] [TIFF OMITTED] TR18AP24.193
C. MSHA Compliance With RFA Requirements
1. Outreach and Small Business Advocacy Review
On July 13, 2023, MSHA published its notice of proposed rulemaking
in the Federal Register. The proposed rule was also posted on
Regulations.gov and on MSHA's website to ensure that members of the
public, including small businesses, had more than one way to access the
proposal. Prior to publication, MSHA made an informal copy of the
proposed rule available on the Agency's website to provide small
businesses and other stakeholders with additional time to become
familiar with the proposal. MSHA also reached out to mining labor and
industry stakeholders, public interest groups, and trade associations,
notifying them of the upcoming publication of the proposed rule. Some
of these stakeholders represented small businesses.
During the public comment period, MSHA held three public hearings
(virtual and in-person)--in Arlington, Virginia (on August 3, 2023),
Beckley, West Virginia (on August 10, 2023), and Denver, Colorado (on
August 21, 2023)--to facilitate the participation of the public, small
businesses and organizations that represent them, and all other
stakeholders.
On August 30, 2023, MSHA attended a Small Business Labor Safety
Roundtable organized by the SBA's Office of Advocacy to discuss the
proposal. The Roundtable was also attended by the small business
community and representatives from industry and labor. MSHA provided
education about the NPRM's content at this roundtable.\101\
---------------------------------------------------------------------------
\101\ MSHA considered the testimonies from the public hearings
and written comments submitted to the docket for its development of
the final rule, but not the discussion at the Roundtable. For
transparency, however, MSHA makes the materials presented at the
Roundtable available in the docket at Regulations.gov.
---------------------------------------------------------------------------
2. Final Regulatory Flexibility Analysis
a. Objectives of, and Need for, the Final Rule
Based on its review of the health effects literature, MSHA
determined that occupational exposure to respirable crystalline silica
causes silicosis and other diseases. In its FRA, MSHA also determined
that, under existing standards, miners face a risk of material
impairment of health or functional capacity from exposures to
respirable crystalline silica.
Following these determinations, MSHA is issuing a final rule to
better protect miners against occupational exposure to respirable
crystalline silica, a carcinogen, and to improve respiratory protection
for airborne contaminants. The final rule will affect both MNM and coal
mining operations.
The final rule establishes, for mines of all sizes, a PEL of 50
[micro]g/m\3\ for a full-shift exposure, calculated as an 8-hour TWA,
and an action level of 25 [micro]g/m\3\ for a full-shift exposure,
calculated as an 8-hour TWA. In addition to the PEL and
[[Page 28400]]
action level, the rule includes provisions for methods of compliance,
exposure monitoring, corrective actions, respiratory protection,
medical surveillance for MNM mines, and recordkeeping. MSHA also amends
existing standards for other airborne contaminants to replace
requirements for respiratory protection and incorporates by reference
ASTM F3387-19 Standard Practice for Respiratory Protection to update
existing respiratory protection standards. The final rule will
significantly improve health protections for all miners over the course
of their working lives.
b. The Agency's Response to Public Comments
MSHA received written comments from trade associations representing
small businesses or small mines (Document ID 1406; 1408; 1411; 1413;
1415; 1422; 1424; 1427; 1430; 1435; 1436; 1441; 1448; 1453; 1456; 1300;
1302; 1303; 1349; 1368; 1369; 1378; 1383; 1392; 1398). The Agency also
received a letter from the Deputy Chief Counsel and Assistant Chief
Counsel for Advocacy of the SBA requesting a 60-day extension of the
public comment period to give small businesses more time to comment and
provide small business representatives time to consult their membership
about their operations and how the proposed rule would impact them.
On August 14, 2023, MSHA published a notice in the Federal Register
extending the comment period by changing the closing date from August
28, 2023, to September 11, 2023 (88 FR 54961).
Commenters raised concerns about MSHA's estimates of the proposed
rule's costs and impacts. MNM operators, mining and industry trade
associations, and a mining related business stated that MSHA had
underestimated the costs of the proposal for small mines (Document ID
1427; 1430; 1435; 1436 1448; 1456; 1392). Commenters, including mining
related businesses, MNM operators, and mining trade associations, also
stated that, for some mines, there would be high costs of initial
compliance or high costs of annual compliance thereafter (Document ID
1408; 1411; 1415; 1427; 1430; 1435; 1436; 1448; 1453; 1456; 1383;
1392). Commenters including mining trade associations and MNM operators
cited the cost of obtaining equipment and services needed to establish
sampling and medical surveillance programs, as well as the cost of
implementing engineering controls (Document ID 1408; 1411; 1415; 1427;
1435; 1436; 1441; 1448; 1392). MNM operators, mining trade
associations, and other mine organizations commented on the costs of
lab fees, respirators, and travel to undergo medical examinations for
medial surveillance (Document ID 1408; 1411; 1415; 1435; 1436; 1448;
1453; 1378; 1392). Several MNM operators and a mining-related business
stated that compliance with the proposal would substantially increase
their water costs (Document ID 1411; 1415; 1427; 1435; 1436; 1392).
Some commenters including a mining-related business, mining trade
associations, MNM operators, and other mine industry organizations
noted that the costs of compliance would be higher for small mines
operating in remote locations (Document ID 1408; 1411; 1415; 1422;
1424; 1453; 1378; 1392). A mining trade association and a mining-
related business stated that MSHA failed to consider that some small
mines might go out of business due to being unable to afford to comply
with the new rule, which would result in losses to local economies
(Document ID 1429; 1368; 1392).
Taking these comments into consideration, MSHA changed its
compliance dates and other requirements, which resulted in revisions to
some of previous cost estimates. MSHA's cost estimates are detailed in
Section 4 of the standalone FRIA document. MSHA believes its cost
estimates for sampling, exposure controls, laboratory fees, and medical
surveillance are accurate for small-entity controllers. As explained in
Section 8 of the standalone FRIA document, MSHA adjusted some
compliance costs upwards in response to commenters; in particular,
sampling and exposure control costs. MSHA incorporated these adjusted
costs in the cost estimates for small entities. In the FRFA
methodology, the compliance costs that were derived in the FRIA, per
mine employee, were estimated for specific size categories of mines,
and for the type of commodity produced in the mine.\102\ Based on these
costs, and the number of employees at mines, MSHA estimated the
average, expected compliance cost for each small-entity controller in
2021. These are average costs, which will vary among small-entity
controllers. However, overall, MSHA believes that these estimates
support the conclusion that the compliance costs incurred by small-
entity controllers, on average, will be a small fraction of the revenue
that small controllers earn from their operations. MSHA found that,
among small-entity controllers, the compliance costs of the final rule
represent, on average, about 0.318 percent of the revenues that small
entities earn. MSHA concluded that these compliance costs are generally
unlikely to have significantly negative economic impacts on small-
entity controllers or on local economies.
---------------------------------------------------------------------------
\102\ These size categories were mines with 20 or fewer
employees, 21-100 employees, 101-500 employees, and over 500
employees.
---------------------------------------------------------------------------
MSHA understands that some small-entity controllers might have high
initial capital investments for the installation of new engineering
controls. However, high initial capital expenses, in general, are not
uncommon in mining operations, especially with regard to the purchase
of major units of equipment for engineering controls. Because these new
engineering controls will last for many years, their purchase is
comparable to any other type of investment in physical capital, for
mining operations, that will be either paid directly or financed
through periodic payments. If they are paid directly, this would be a
one-time payment to cover several years, resulting in a lower cost per
year. If the payment is financed, the annual (or monthly) costs will be
much lower as well. Because these costs, on an annual basis, as
determined by the useful life of the engineering controls, will be much
lower than the initial investment, and these annual costs will be a
small fraction of the revenues earned in those years, MSHA believes
these new engineering controls will not, on average, be significantly
burdensome to small-entity controllers. Moreover, MSHA expects that
many of the mines that implement new engineering controls will be able
to discontinue sampling once exposure levels are reduced below the
action level. Thus, even mines with higher initial expenditures are
unlikely to also have high annual costs thereafter.
MSHA acknowledges the concerns from small mine operators in rural
and remote areas. Because of the nature of mining, many mine operators,
including small-entity operators, operate in rural and remote areas.
MSHA believes that this final rule will not present major logistical
challenges for small mine operators. As MSHA has stated in Section
VIII.A. General Issues, once the final rule is implemented, the Agency
will provide compliance assistance, including training and best
practice materials, to all mine operators, with an emphasis on small
operators.
A mining-related business noted that the IRFA included no estimates
of indirect costs of the rule (Document ID 1392). Examples of such
costs cited by the commenter included lost
[[Page 28401]]
production, the expenses of employees traveling to medical
examinations, and impacts on local communities of reductions in
charitable donations by operators.
MSHA considered the comment that the rule might lead to lost
production. MSHA is providing additional compliance time for mine
operators, including small-entity controllers, to prepare for the final
rule's requirements. The extended compliance period under the final
rule (24 months after the publication date for MNM operators and 12
months after the publication date for coal operators) provides
additional time for mine operators to comply with the requirements,
such as implementing engineering controls and finding appropriate
resources (industrial hygienists, medical facilities, laboratories,
sampling devices, etc.). This extended compliance period is intended to
provide industry additional time for planning. For example, a MNM small
entity mine operator could use the increased time to identify and
implement engineering controls to reduce miners' exposures.
As in the IRFA, the FRFA includes the travel expenses related to
miners' time lost due to travelling to medical examinations and their
transportation costs. Regarding the costs of travel time to medical
examinations, MSHA believes its estimates of the average travel time
spent to and from medical examinations and the related cost are
reliable, though it should be recognized that these are averages and
that travel times could be different for different mines.
MSHA considered the comment that the rule could incur ``costs to
communities'' by making it harder for mine operators to make charitable
donations to those communities. MSHA has not included charitable
donations from operators in its analysis, as charitable donations are
voluntary. MSHA believes that the final rule will benefit communities
because the health and safety of miners is greatly improved. In this
regard, MSHA's final rule is expected to have a net beneficial effect
on mining communities through the improved health of miners, which
should reduce the need for charitable support. Details on the revised
estimates are provided in Section X.D. Analysis of Small Business
Impacts.
c. Description of the Number of Small Entities to Which the Final Rule
Will Apply
The final rule, like the proposed rule, will affect MNM and coal
mining operations. As in its IRFA, MSHA considered a controller (parent
company) that owns and operates one or more mines as the appropriate
unit of this FRFA.
To determine the number of small entities subject to the final
rule, MSHA used SBA's 2023 Size Standards and other guidance from the
Office of Advocacy such as how to determine if a government entity is a
small entity, NAICS codes, and MSIS, which identifies mines and their
numbers of employees working at mines.
MSHA estimated that the number of small-entity controllers in 2021
was 5,462 out of the total number of controllers (5,879). The 5,462
small-entity controllers owned a total of 9,395 mines out of a total of
12,529 mines owned by all controllers in 2021.\103\ The estimated
number of small-entity controllers reflects an increase from 5,007 in
the IRFA; this revision is due to the use of more current NAICS codes
and more current SBA size standards. In addition, MSHA performed a more
thorough analysis of potential enterprises that might be small but had
not been estimated as small in the IFRA, such as small local
governments that owned mines.
---------------------------------------------------------------------------
\103\ The total number of mines (12,529) was updated in the FRFA
based on additional analysis of the data.
---------------------------------------------------------------------------
In analyzing controllers of mines, MSHA determined that mining
operations subject to the final rule would fall under 19 NAICS codes.
These industry categories and their accompanying six-digit NAICS codes
are shown in Table X-2.\104\ MSHA then matched the NAICS codes with SBA
small-entity size standards (based on the number of employees) to
determine the number of small entities within each of the respective
NAICS codes. MSHA then counted the number of small-entity controllers
in each NAICS code, after determining which controllers owned which
mines. Many controllers owned one or two mines, while some controllers
owned hundreds of mines nationwide (or worldwide).105 106
Table X-2 shows the count of all controllers and a count of small-
entity controllers in each NAICS code.
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\104\ The NAICS classifications used in this analysis are drawn
from the latest version of the NAICS, which was effective in July
2022. MSHA also used, in the analysis, an earlier version of NAICS
categories that was effective in August 2019. MSHA had begun
developing this analysis prior to the most current NAICS being
effective. The older NAICS categories were still used in the part of
the current analysis that estimated revenues. This is because the
older categories were still needed in order for MSHA to cross-
tabulate (or crosswalk) its data on mines and controllers with
Bureau of Census data on revenues by NAICS codes, where these Census
data were organized by the same NAICS codes that were in the earlier
version. No comparable revenue data, at this writing, had yet been
revised to the most recent NAICS categories.
\105\ The number of controllers and mines examined in this
regulatory flexibility analysis are those specifically known to
operate in 2021. The year 2021 is the most current year for which
complete information was available. Such information about
controllers as parent companies might include, for example,
knowledge of whether the parent company is a large, multinational
corporation, which would then have bearing on this regulatory
flexibility analysis.
\106\ Each mine is assigned only one NAICS code, reflecting the
commodity that mine primarily produces. There are several cases in
which more than one mine, owned by the same controller, have
different NAICS codes, so that there are different NAICS codes for
that one controller. In particular, of the 5,879 unique controllers
identified in 2021, 608 of them each had mines that had different
NAICS codes. In theory, this could present an ambiguity as to
whether a controller with more than one NAICS code should be
considered a small entity or not. Since NAICS codes vary by their
small-entity thresholds, it is theoretically possible for a
controller with more than one NAICS code to be a small entity
according to the threshold for one of its NAICS codes, while not
being a small entity according to a lower threshold for a different
one of its NAICS codes. However, this situation was not found to
occur for any of the mine controllers; all controllers that were
determined to be small entities met the conditions for a small
entity for each of their NAICS codes.
---------------------------------------------------------------------------
Table X-2 presents the distribution of controllers by the one NAICS
code for which they have the most employees, because some controllers
are in more than one mining NAICS code.
BILLING CODE 4520-43-P
[[Page 28402]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.194
BILLING CODE 4520-43-C
d. Reporting, Recordkeeping, and Other Compliance Requirements of the
Final Rule
The final rule not only establishes a PEL of 50 [micro]g/m\3\ and
an action level of 25 [micro]g/m\3\ for respirable crystalline silica,
but also includes provisions for methods of compliance, exposure
monitoring, corrective actions, respiratory protection, and medical
surveillance for MNM mines. Under the
[[Page 28403]]
final rule, mine operators are required to install, use, and maintain
feasible engineering and administrative controls to keep each miner's
exposure to respirable crystalline silica at or below the PEL. Mine
operators are required to conduct sampling to assess miners' exposure
to respirable crystalline silica. MNM operators are required to provide
to all miners, including those who are new to the mining industry,
periodic medical examinations performed by a PLHCP or specialist, at no
cost to the miner. This requirement will ensure that MNM miners, like
coal miners, are able to monitor their health and detect early signs of
respiratory illness.
In addition, the final rule creates new information collection
requirements for mine operators. As described in greater detail in
Section XI. Paperwork Reduction Act, operators are required to collect
information involving: (1) exposure monitoring, (2) corrective actions,
(3) respiratory protection, and (4) medical surveillance for MNM mines.
(Table XI-1 in that section displays an estimate of the annualized
information collection burden for the whole mining industry.)
e. Steps the Agency Has Taken To Minimize the Economic Impact on Small
Entities
In response to commenters who expressed concerns that the rule
would lead to excessive demand and backlogs for sampling devices,
industrial hygienists, labs, medical facilities, and NIOSH B Readers,
MSHA adjusted the requirements in the final rule to provide additional
time for small-entity controllers and other controllers, to prepare for
compliance (24 months after publication of the final rule for MNM mines
and 12 months after publication of the final rule for coal mines). MSHA
is allowing this longer period for compliance because MNM operators,
particularly small-entity controllers, may have less experience with
sampling and may also need time to prepare for compliance with medical
surveillance. For coal mines, the delayed compliance period gives
operators sufficient time to plan and prepare for effective compliance
with the new standards, while also ensuring that improved protections
for miners from the hazards of respirable crystalline silica take
effect as soon as practically possible. For additional details on the
compliance dates, see Section VIII.B. Section-by-Section Analysis.
MSHA will also provide compliance assistance to small-entity
controllers and the mining community overall (including industry and
labor) after publication of the final rule. This assistance will
include guidance to assist mine operators in developing and
implementing appropriate controls; outreach seminars (onsite and
virtual, dates and locations will be posted on MSHA's website); dust
control workshops at the National Mine Health and Safety Academy;
support from the Educational Field and Small Mine Services staff;
support from MSHA's Technical Support staff; silica training and best
practice materials; and information on MSHA's enforcement efforts.
MSHA examined three possible regulatory alternatives to this final
rule and considered how they could affect small-entity controllers.
Under Regulatory Alternative 1, the PEL would remain unchanged at
50 [mu]g/m3 and the action level would remain unchanged at 25 [mu]g/m3.
Further, mine operators would conduct: (1) first-time and second-time
sampling for miners who may be exposed to respirable crystalline silica
at or above the action level of 25 [mu]g/m3, (2) periodic sampling
twice per year, and (3) an annual evaluation of changing mining
processes or conditions that would reasonably be expected to result in
new or increased respirable crystalline silica exposures. Under
Regulatory Alternative 2, the PEL would be set at 25 [mu]g/m3; mine
operators would install whatever controls are necessary to meet the
PEL; and there would not be an action level. Further, mine operators
would (1) not be required to conduct any sampling, but they would be
required to (2) conduct periodic evaluations of changing conditions and
(3) sample as frequently as necessary to determine the adequacy of
controls.
MSHA determined that the final rule will provide improved health
protections for miners and will be achievable for all mines, including
those that are owned and operated by small entities. MSHA has made the
following determinations regarding the three alternatives considered:
Regulatory Alternative 1, ``Changes in Sampling and
Evaluation Requirements,'' would reduce overall costs to the mining
industry by 26.9 percent for costs calculated at a 3 percent, and by
26.4 percent for costs calculated at a 7 percent discount rate. These
reduced costs would be proportionally experienced by small entities.
The average costs as a percent of revenues for small entities would
then be reduced (relative to the final rule) from 0.318 percent to
0.232 percent based on a 3 percent discount rate, or to 0.234 percent
based on a 7 percent discount rate.
Regulatory Alternative 2, ``Changes in Sampling and
Evaluation Requirements and the Proposed PEL,'' would increase overall
costs to the mining industry by 484.8 percent for costs calculated at a
3 percent discount rate, and by 627.1 percent for costs calculated at a
7 percent discount rate. The average costs as a percent of revenues for
small entities would then rise (relative to the final rule) from 0.318
percent to 1.859 percent based on a 3 percent discount rate, and from
0.318 percent to 2.31 percent based on a 7 percent discount rate.
Regulatory Alternative 3, ``Changes in the Calculation of
Exposure Concentrations,'' would change the methodology used for
calculating exposures and assessing compliance to a full shift TWA,
rather than a full-shift exposure, calculated as an 8-hour TWA. MSHA
estimated that this alternative would decrease overall costs to the
mining industry by 3.02 percent for costs calculated at a 3 percent
discount rate, and by 3.41 percent for costs calculated at a 7 percent
discount rate. The average costs as a percent of revenues for small
entities would then fall from 0.318 percent to 0.308 percent based on a
3 percent discount rate, and to 0.307 percent based on a 7 percent
discount rate.
Regulatory Alternative 1 would reduce the costs to small entities.
However, the final rule will better protect miners from exposures to
respirable crystalline silica. The final rule's exposure monitoring
requirements are necessary to ensure that miners' health is adequately
protected. MSHA determined that Regulatory Alternative 1 would not
protect miners' health. The final rule's exposure monitoring
requirements, including monitoring on a more frequent basis, will
provide mine operators with greater confidence that they are in
compliance with the final rule.
Regulatory Alternative 2 would increase costs to small entities,
making it an unsuitable choice for small mines. Additionally, this
alternative would not be achievable for all mines because a PEL of 25
[micro]g/m\3\, while technically feasible, is not practical for all
mines.
Regulatory Alternative 3 would reduce the costs to small entities.
However, the final rule will better protect miners by using an exposure
calculation method that recognizes the importance of cumulative
exposure to respirable crystalline silica being an important risk
factor in the development of silica-related disease. Regulatory
Alternative 3 does not take into account the increased health risks
associated
[[Page 28404]]
with the higher cumulative exposures that can occur during longer work
shifts, and, therefore, is less protective for those miners who work
longer shifts. A more in-depth discussion of the costs associated with
each regulatory alternative is presented in Section IX. Summary of
Final Regulatory Impact Analysis and Regulatory Alternatives and the
standalone FRIA document.
D. Analysis of Small Business Impacts
1. Data and Methodology
a. Average Annual Cost per Small-Entity Controller
Because the controllers vary in the scale of their mining
operations, MSHA first estimated regulatory costs on a per-miner basis.
MSHA anticipated that the regulatory costs per miner would vary across
the six major commodity categories: coal, metal, nonmetal, stone,
crushed limestone, and sand and gravel.\107\ The differences in
regulatory costs by commodity reflect the varying levels of expected
exposure to silica, as calculated in the FRIA.
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\107\ MSHA also anticipated that regulatory costs would vary by
the size of the mine in terms of the number of miners, with the size
categories of: (1) 20 or fewer miners, (2) 21-100 miners, (3) 101-
500 miners, and (4) over 500 miners.
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MSHA examined employment data for each controller. By combining
this information with per-mine compliance cost information, MSHA
derived estimates of the regulatory costs for each of the 5,462 small-
entity controllers identified in 2021. See the average annual
regulatory cost per controller in Table X-3.
The compliance burden on the controllers, large and small, consists
primarily of the costs of additional dust control measures, exposure
monitoring, medical surveillance for MNM mines, and other program
activities needed to comply with the rule. For costs estimates by
component, by commodity, and by mine size, please see Section 4 of the
standalone FRIA document.
b. Average Annual Revenue per Small-Entity Controller
MSHA estimated revenues for each small-entity controller. The
Agency estimated revenues per employee, by mine, and by controller,
using data published by the U.S. Bureau of Census in their report,
``Statistics of U.S. Businesses'' (SUSB).\108\ The SUSB data provided
revenue estimates for enterprises (mines) in each NAICS code and for
each ``size category'' (based on number of employees) within each NAICS
code.\109\
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\108\ U.S. Census Bureau, ``Statistics of U.S. Businesses,''
released May 2021. https://www.census.gov/data/tables/2017/econ/susb/2017-susb-annual.html (last accessed Jan. 10, 2024). Data in
the report were in reference to the year 2017, which MSHA adjusted
to 2021 dollars. Data on revenues are presented in the report under
the equivalent term ``receipts.'' MSHA converted the 2017 revenues
to 2022 dollars using Price Indexes for Gross Domestic Product,
Bureau of Economic Analysis, Table 1.1.4. https://apps.bea.gov/iTable/?reqid=19&step=3&isuri=1&1910=x&0=-99&1921=survey&1903=4&1904=2009&1905=2018&1906=a&1911=0 (last
accessed Jan. 10, 2024). The index was 100 for 2017 and 117 for
2021, creating an adjustment factor (from 2017 to 2022 dollars) of
1.118.
\109\ In a small number of cases (in terms of NAICS codes and
size categories) the SUSB data were incomplete. In these cases, MSHA
imputed revenue/employee ratios based on closely related data for
comparable NAICS-size categories. MSHA then used these imputed
revenue/employee ratios to estimate the revenues of some small-
entity controllers, by the methodology just described.
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Some of the small-entity controllers have operations in non-mining
industries. Non-mining revenues are not accounted for in this analysis,
as the data was not available. If non-mining revenues were accounted
for, the ratio of regulatory costs to revenues shown in the summary
table would be even smaller.
MSHA calculated the number of mining employees for each small-
entity controller, and for each NAICS category (for mining NAICS)
within each controller's activities. MSHA then combined these data with
SUSB data on revenues by NAICS category and size category to generate
estimated revenues for each small-entity controller. See the estimated
average annual revenue per controller in Table X-3.
c. Average of Cost as a Percent of Revenue (Among Small-Entity
Controllers)
MSHA estimated the average annual regulatory cost per small-entity
controller, as well as the average annual revenue per small-entity
controller. MSHA estimated, for each controller, the annual compliance
cost of the final rule as a proportion of that controller's annual
revenue.
2. Economic Analysis Results
Based on the methodology described above, MSHA generated estimates
of the ratios of regulatory compliance cost to revenue for each
controller. Table X-3 shows the number of controllers, average annual
regulatory costs, average annual revenues, and average cost as a
percent of revenue.
BILLING CODE 4520-43-P
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[GRAPHIC] [TIFF OMITTED] TR18AP24.195
BILLING CODE 4520-43-C
MSHA estimated that the final rule would have an average cost, per
small-entity controller, of $11,026 per year in 2022 dollars. The
estimated costs for the final rule represent the costs necessary for
small-entity mine operators to achieve full compliance with the final
rule.\110\
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\110\ MSHA estimated the costs of the rule for small-entity
controllers by summing the costs for each of these controller's
mines. The estimated cost for each mine was based on the number of
miners and the mine's industry category. A controller's estimated
cost was the sum of costs for each of its mines. Similarly, the
estimated revenues of a controller was the sum of the revenues of
each of its mines.
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From the cost and revenue estimates described above, MSHA estimated
the ratio of annual regulatory cost to annual revenue for each small-
entity controller. As shown in Table X-3, the average of these
proportions (weighting controllers equally) was 0.318 percent. In other
words, for every $1 million in revenue earned by a small-entity
controller, the average compliance cost was estimated to be
approximately $3,000. This compliance cost-to-revenue ratio is slightly
lower for controllers with five or fewer employees (0.299), implying
that the low compliance cost-to-revenue ratios are generally applicable
for the smallest of the small-entity controllers. The low cost-to-
revenue ratio of these controllers with five or fewer employees is due
largely to the estimated annual revenues of these controllers averaging
above $1 million in 2022 dollars, in comparison to their estimated
compliance costs averaging approximately $3,000 per year.
MSHA believes that the Agency could certify the economic impact of
this final rule on small entities, however, in the interest of public
disclosure and transparency, the Agency prepared a full analysis to
inform the public of its decision-making process.
XI. Paperwork Reduction Act
The Paperwork Reduction Act of 1995 (44 U.S.C. 3501-3521) provides
for the Federal Government's collection, use, and dissemination of
information. The goals of the Paperwork Reduction Act include
minimizing paperwork and reporting burdens and ensuring the maximum
possible utility from the information that is collected under 5 CFR
part 1320. The Paperwork Reduction Act requires Federal agencies to
obtain approval from the Office of Management and Budget (OMB) before
requesting or requiring ``a collection of information'' from the
public.
As part of the Paperwork Reduction Act process, agencies are
generally required to provide a notice in the Federal Register
concerning each proposed collection of information to solicit, among
other things, comment on the necessity of the information collection
and its estimated burden, as required in 44 U.S.C. 3506(c)(2)(A). To
[[Page 28406]]
comply with this requirement, MSHA published a notice of proposed
collection of information in the Agency's notice of proposed rulemaking
on July 13, 2023 (88 FR 44852). MSHA solicited comment on the proposed
information collection requirements and provided an opportunity for
comments to be sent directly to OMB. MSHA also prepared and submitted
an information collection request (ICR) to OMB for the collection of
information requirements identified in the proposal for OMB's review in
accordance with 44 U.S.C. 3507(d).
MSHA has made several additions and changes to the proposed rule
and methodology that have paperwork burden implications. Key additions
include the immediate reporting of samples over the PEL to MSHA,
reporting chest X-ray classification results to NIOSH, as well as a
written respiratory protection program consistent with the requirements
of ASTM F3387-19. Key changes include certain compliance dates,
sampling requirements, medical examination dates for current miners, as
well as the frequency of periodic evaluations and post-evaluation
recordkeeping. Each addition and change and reasons for each are
discussed in detail in Section VIII.B. Section-by-Section Analysis. The
Agency has also changed the compliance dates from the proposed rule to
provide mine operators adequate preparation time to comply effectively
with the final rule's requirements.
A. Responses to Comments
MSHA sought comment on the utility of the recordkeeping
requirements in part 60. MSHA received multiple comments on the
proposed recordkeeping requirements, with several commenters supporting
MSHA's proposed recordkeeping provisions or recommending that records
have a longer retention period than proposed. None of the comments
addressed the methodology, assumptions, or calculations made in the
Paperwork Reduction Act portion of the proposal.
This section presents a summary of the comments received and the
Agency's responses. Section VIII.B.9. Section 60.16--Recordkeeping
Requirements provides a more detailed summary of the comments related
to recordkeeping and MSHA's responses.
The NSSGA stated that MSHA should adopt the same rule as the
Occupational Safety and Health Administration's (OSHA) 2016 Silica Rule
since some companies have OSHA and MSHA regulated facilities (Document
ID 1448). This commenter stated that MSHA's silica rule with different
requirements than OSHA creates excessive, unnecessary paperwork for
these companies.
The Agency clarifies that the Mine Act gives MSHA jurisdiction over
each MNM or coal mine and each operator of such mine. The mining
industry is different from the industries that are subject to OSHA's
standards. MSHA did consider and adopt, as appropriate, some of OSHA's
regulatory approach to controlling workers' exposures to respirable
crystalline silica in developing its final rule. This final rule will
better protect miners against occupational exposure to respirable
crystalline silica, a carcinogenic hazard, and improve respiratory
protection for airborne contaminants miners encounter. Nonetheless, the
Agency has developed the rule's paperwork requirements to minimize
burden on mine operators.
For records retained under proposed paragraphs 60.16(a)(1) through
(3)--evaluation records, sampling records, and corrective action
records, respectively--many commenters, including labor organizations,
advocacy organizations, and a MNM mine operator, recommended that
record retention periods should be extended beyond the proposed
requirements, especially for MNM mines (Document ID 1416; 1417; 1425;
1439; 1447; 1449). A miner health advocate recommended that sampling
records under Sec. 60.16(a)(2) be preserved for as long as the mine is
in operation instead of the 2-year proposed requirement (Document ID
1372). Additionally, Appalachian Voices recommended that the records
under Sec. 60.16(a)(2) should be retained for longer than the life of
the mine operation (Document ID 1425).
In response to comments requesting an increase in the record
retention period, in the final rule, MSHA increases the record
retention period for evaluation, sampling, and corrective actions
records in paragraphs (a)(1) to (3) to at least 5 years. The 5-year
record retention period for evaluation, sampling, and corrective
actions records is consistent with the 5-year record retention period
for operator samples collected while monitoring for airborne exposure
to diesel particulate matter in underground metal and nonmetal mines
(Sec. 57.5071(d)(2)) and other injury and illness reports required
under section 50.40. MSHA concludes in this final rule that a 5-year
retention period for the records retained under paragraphs Sec.
60.16(a)(1) through (3) is effective in providing information for the
protection of miners. This is because the evaluation, Sec.
60.16(a)(1), and sampling, Sec. 60.16(a)(2), records can identify a
change in operation that might lead to increased exposures to
respirable crystalline silica. Similarly, the 5-year recordkeeping
requirement for corrective action records under Sec. 60.16(a)(3) is
intended to help the operator and MSHA identify the effectiveness of
existing controls, or the need for maintenance or additional control
measures. In MSHA's experience, recent records can more effectively
assist MSHA and mine operators in achieving these goals. MSHA believes
the 5-year retention period achieves the proper balance between the
operator's burden to maintain records and the effective utility of
older records to mine operators, miners, and MSHA.
For records retained under proposed paragraphs Sec. 60.16(a)(4)
and (5)--written determination and medical opinion records,
respectively, received from a PLHCP or specialist--some commenters such
as a medical professional organization, a public health advocacy
organization, and labor unions also suggested an increased retention
period to help miners diagnosed with silica-related health conditions
request workers' compensation claims (Document ID 1416; 1425; 1373;
1437; 1412; 1398; 1447). A labor union recommended that medical
surveillance data collected by mine operators should be kept for the
duration of a miner's employment plus 20 or 30 years and for the
records to be provided to the miner upon termination of employment
(Document ID 1398). MSHA concludes in this final rule that it is
appropriate to retain determination and medical opinion records, which
have very limited medical information only relevant to the miner's
ability to wear a respirator, for the duration of the miner's
employment plus 6 months because the miner may need to wear a
respirator at some point without notice. The requirement to retain
records for an additional 6 months beyond the miner's employment gives
miners more time to request records once they terminate their
employment at the mine.
A commenter (NVMA) asked for clarification on the medical
surveillance recordkeeping requirements, stating that the rule does not
include provisions requiring tracking of miners' silica exposure
throughout their careers and noting that miners often change companies
over the course of their careers (Document ID 1441). MSHA clarifies
that mine operators do not have access to a miner's medical information
and, therefore, do not maintain a record of such information. Instead,
the mine operator will retain a record of the date of the medical
examination, a statement
[[Page 28407]]
that the examination has met the requirements of this section, and any
recommended limitations on the miner's use of respirators. Each miner,
or the miner's physician or other designee at the request of the miner,
will have access to all medical examination results.
Two commenters including a labor union also suggested that
corrective action records and cumulative exposure records be submitted
to MSHA, miner representatives, or miners (Document ID 1447; 1439).
After considering the comments, MSHA determined that it is not
necessary to change the requirement of providing all the listed records
promptly upon request to miners, authorized representatives of miners,
and authorized representatives of the Secretary of Labor. This is
because the requirement to provide all the listed records promptly upon
request ensures that miners and MSHA will have access to records as
needed can facilitate enforcement and transparency. Because miners,
miners' representatives, and MSHA can request the records at any time
for their own recordkeeping purposes, MSHA does not believe it is
necessary to have operators submit the records to miners and MSHA
without request. However, in response to comments, the final rule
requires mine operators to immediately report all exposures above the
PEL from operator sampling to the MSHA District Manager or to any other
MSHA office designated by the District Manager. This modification will
allow the Agency to promptly address overexposures as appropriate. As
discussed below, this change from the proposal presents a modest
increase in the estimated paperwork burden.
The final rule requires a new information collection as well as
modifications to existing collections. As required by the Paperwork
Reduction Act, the Department has submitted information collections,
including a new information collection and revisions of two existing
collections, to OMB for review to reflect new burdens and changes to
existing burdens. Once OMB completes its review, the Agency will
publish a notice on the new information collection under OMB Control
Number 1219-0156. (The regulated community is not required to respond
to any collection of information unless it displays a current, valid,
OMB Control Number.)
B. New Information Collection Under Part 60, Respirable Crystalline
Silica
Under final part 60, certain new burdens apply to all mine
operators, and other burdens apply to only some mine operators. Section
60.16 lists all the recordkeeping requirements related to part 60. Each
of the requirements are discussed below:
Section 60.12 requires mine operators to make a record for each
sampling and each periodic evaluation conducted pursuant to the
section. The samplings identified in Sec. 60.12(a) include: sampling
by the compliance date (Sec. 60.12(a)(1)), an additional sampling
(Sec. 60.12(a)(2)), above-action-level-sampling (Sec. 60.12(a)(3)),
corrective actions sampling (Sec. 60.12(b)), and post-evaluation
sampling (Sec. 60.12(d)). The sampling record consists of the sampling
date, the occupations sampled, and the concentrations of respirable
crystalline silica and respirable dust, and the mine operator must also
retain laboratory reports on sampling results under Sec. 60.12(g).
In a change from the proposal, under final Sec. 60.12(c), the
periodic evaluations must be conducted at least every 6 months or
whenever there is a change in: production; processes; installation and
maintenance of engineering controls; installation and maintenance of
equipment; administrative controls; or geological conditions; mine
operators shall evaluate whether the change may reasonably be expected
to result in new or increased respirable crystalline silica exposures.
The periodic evaluation record includes the evaluated change, the
impact on respirable crystalline silica exposure, and the date of the
evaluation under Sec. 60.12(c)(1). In addition, the mine operator is
required to post the sampling and evaluation records and the laboratory
report on the mine bulletin board and, if applicable, by electronic
means, for 31 days, upon receipt under Sec. 60.12(c)(2).
The mine operator must immediately report all exposures above the
PEL to the MSHA District Manager or to any other MSHA office designated
by the District Manager under Sec. 60.12(b). A corrective action must
be taken immediately to lower the concentration of respirable
crystalline silica to at or below the PEL, once a sample reporting
exposure above the PEL is recorded. The corrective actions record must
include the corrective actions taken, including any related respirator
use by affected miners, and the dates of the corrective actions under
Sec. 60.13(c). All records must be retained for at least 5 years from
the date of each sampling, evaluation, or corrective action.
Section 60.14(b) requires mine operators to temporarily transfer a
miner either to work in a separate area of the same mine or to an
occupation at the same mine where respiratory protection is not
required if the miner has a written determination from the PLHCP that
the miner is unable to wear a respirator. Section 60.16(a)(4) requires
the written determination record to be retained for the duration of a
miner's employment plus 6 months. In a change from the proposal, final
Sec. 60.14(c)(2) requires mine operators to have a written respiratory
protection program that meets the following requirements in accordance
with ASTM F3387-19: program administration; written standard operating
procedures; medical evaluation; respirator selection; training; fit
testing; maintenance, inspection, and storage.
Section 60.15 requires MNM mine operators to provide miners
periodic medical examinations at no cost to the miner. Section
60.15(d)(1) requires the mine operator to ensure that the results of
medical examinations or tests are provided from the PLHCP or specialist
to the miner within 30 days of the medical examination, and, at the
request of the miner, to the miner's designated physician or another
designee identified by the miner. Section 60.15(d)(2) requires MNM mine
operators to ensure that, within 30 days of the medical examination,
the PLHCP or specialist provides the results of chest X-ray
classifications to the National Institute for Occupational Safety and
Health (NIOSH), once NIOSH establishes a reporting system. Mine
operators are required to obtain a written medical opinion from the
PLHCP or specialist within 30 days of a miner's medical examination.
The written medical opinion must contain only the date of the medical
examination, a statement that the examination has met the requirements
of the section, and any recommended limitations on the miner's use of
respirators under Sec. 60.15(e). The written medical opinion record
must be retained by MNM mine operators for the duration of a miner's
employment plus 6 months under Sec. 60.15(f).
C. Existing Information Collections
The final rule results in changes to two existing information
collection packages: a non-substantive change to information collection
package under OMB Control Number 1219-0011, Respirable Coal Mine Dust
Sampling; and a substantive change to information collection package
under OMB Control Number 1219-0048, Respirator Program Records. This is
a change from the proposal, which only contained non-substantive
changes to existing information collections.
Non-substantive changes to OMB Control Number 1219-0011 involve
references to respirable dust when
[[Page 28408]]
quartz is present in the respirable coal mine dust standard. OMB
Control Number 1219-0011 involves records for quarterly sampling of
respirable dust in coal mines. MSHA's standards require that coal mine
operators sample respirable coal mine dust quarterly and submit these
samples to MSHA for analysis to determine if the mine is complying with
the respirable coal mine dust standards. The supporting statement
references quartz and a reduced standard for respirable dust when
quartz is present. Since the final rule eliminates the reduced standard
and establishes a separate standard for respirable crystalline silica,
MSHA will make a non-substantive change to the supporting statement by
removing such references. However, there will be no changes from the
proposal in paperwork burden and costs in this information collection
because the change only contains non-substantive changes to existing
information collections.
OMB Control Number 1219-0048 involves recordkeeping requirements
under 30 CFR parts 56 and 57 for MNM mines when respiratory protection
is used. Under the final rule, MSHA updates the existing respiratory
protection standard and requires a written respiratory protection
program that meets the following requirements in accordance with ASTM
F3387-19: program administration; written standard operating
procedures; medical evaluation; respirator selection; training; fit
testing; maintenance, inspection, and storage. This substantive change
will result in an increase in the paperwork burden and costs associated
with respiratory protection in the existing information collection.
D. Information Collection Requirements
1. New Information Collection 1219-0156
Type of Review: New Collection.
OMB Control Number: 1219-0156.
Title: Respirable Crystalline Silica Standard.
Description of the ICR: The final rule on respirable crystalline
silica contains information collection requirements on sampling,
periodic evaluations, medical examinations, and respirator protection
practices. The collected information will assist miners and mine
operators in tracking actual and potential miners' occupational
exposure to respirable crystalline silica, and identifying possible
actions taken to control such exposure.
There are provisions of this rule that will take effect at
different times after the date of publication of this rule, and there
are information collection provisions that will have different
respondents, responses, burden hours, and costs in each year.
Therefore, this ICR estimates the first 3 years of compliance.
There were changes in this ICR between the proposed and final rule
based on changes in methodology and the rule text. Based on changes to
Sec. 60.1 in the final rule, MNM mines are not expected to begin
implementing the rule until year 2. This change decreases the
recordkeeping burden for all cost items in the final rule. In the
proposed rule, operators were allowed to use historical and objective
data instead of a second-time sampling. In the final rule, every mine
is required to conduct a first-time and second-time sampling, thereby
increasing the related time burden. The methodology for calculating
corrective actions samples and post-evaluation samples was also
changed, leading to an increased time burden for both. Additionally,
based on changes to Sec. 60.12(b) in the final rule, operators are now
required to notify MSHA after every overexposure.
The inclusion of ASTM F3387-19 costs in this ICR was a result of a
change in the rule text between the proposed rule and final rule. In
the proposed rule, operators could choose which ASTM F3387-19 elements
to adopt. In the final rule, mine operators must have a written
respiratory protection program that meets an explicit set of
requirements in accordance with ASTM F3387-19. This change leads to a
substantial increase in the recordkeeping burden for this ICR. Lastly,
the addition of Sec. 60.15(d)(2) in the final rule, which requires the
mine operator to ensure that a miner's PLHCP or specialist provides the
results of chest X-ray classifications to the National Institute for
Occupational Safety and Health (NIOSH), created a new recordkeeper
cost.
Summary of the Collection of Information
Highlighted below are the key assumptions, by provision, used in
the burden estimates in Table XI-1:
a. Section 60.12--Exposure Monitoring
ICR. Section 60.12 requires mine operators to make a record for
each sampling, corrective actions sampling, periodic evaluation, and
post-evaluation sampling. Per Sec. 60.1, the compliance date for MNM
mines begins one year after the compliance date for coal mines.
Number of respondents. For Sec. 60.12, the respondents consist of
all active mines, because operators of active mines are assumed to
perform sampling and conduct periodic evaluations. MSHA counts the
number of active mines in 2019, defining an active mine as one that had
at least 520 employment hours (equivalent to 1 person working full time
for a quarter of a year) in at least one quarter of 2019. Using this
definition, MSHA estimates that a total of 12,631 mines (11,525 MNM
mines and 1,106 coal mines) will generate sampling and evaluation
records.
Annual number of responses. Annual responses are summed from
several separate activities including: all types of sampling (e.g., the
first-time/second-time sampling, above-action-level sampling,
corrective actions sampling, and post-evaluation sampling), and
periodic evaluations. The estimated average annual number of responses
is 199,817, including 52,587 first-time and second-time samples (the
first sample is taken by the compliance date or within 6 months after
beginning operations and the second-time sample is taken within 3
months after the first sample), 44,253 above-action-level samples,
50,834 corrective action samples and MSHA notifications, 12,766 post-
evaluation samples, and 39,377 periodic evaluation recordings and
postings. Details of each type of sampling and periodic evaluations are
discussed below.
First-time sampling and second-time sampling apply to every coal
and MNM mine. However, a certain number of mines are predicted to be
able to discontinue sampling if the results of these samples are below
the action level. Furthermore, subsequent to Year 1 for Coal, and Year
2 for MNM, all first-time and second-time sampling will only be
performed by new mines. MSHA projects that about 2 percent of mines in
any given year will be new entrants to the mining industry. MSHA
assumes that all active coal mines (1,106 mines) will conduct first-
time and second-time sampling in year 1 of compliance (producing 29,796
samples). In years 2 and 3, an estimated 22 new coal mines will conduct
first-time and second-time sampling (producing 596 samples each year).
Similarly, MSHA assumes that all 11,525 MNM mines will conduct first-
time and second-time sampling in year 2 of compliance (producing
124,288 samples). In year 3, 231 new MNM mines will conduct first-time
and second-time sampling (producing 2,486 samples). MSHA estimates that
an annual average of 52,587 first-time and second-time samples will be
collected in the first 3 years of compliance.
The estimated number of above-action-level sampling is calculated
based on the following factors: the number of miners with sampling
results at or above the action level (25 [mu]g/m\3\) but at or below
the permissible exposure
[[Page 28409]]
limit (PEL) (50 [mu]g/m\3\), the percent of miners needed for
representative samples, and the number of quarters in a year that mines
will be in operation. Estimation of above-action-level sampling does
not include costs related to first-time sampling and second-time
sampling. MSHA has revised its methodology from the proposal,
increasing the number of corrective actions samples to account for some
operators needing multiple corrective actions samples before obtaining
a sample below the PEL. The estimated number of samples is based only
on previous operator samples, not ones from MSHA inspectors. MSHA does
not expect above-action-level sampling to begin until the second half
of year 1 for coal mines. MSHA estimates there will be 5,423 above-
action-level coal samples in the second half of year 1. Due to the
projected decrease in the share of samples over the action level for
coal mine compliance due to more mines engaging in increased
administrative controls and frequent maintenance and repair, the number
of above-action-level coal samples is projected to decrease to 10,556
in year 2 and 10,170 in year 3. A more detailed discussion is provided
in Section 4.2 of the standalone FRIA document. MSHA expects above-
action-level sampling to begin in the second half of year 2 for MNM
mines, resulting in the number of above-action-leveling samples
increasing from 37,719 in the second half of year 2 to 68,892 in all of
year 3. Consequently, MSHA estimates that an annual average of 44,253
above-action-level samples will be collected from coal and MNM mines in
the first 3 years of compliance.
MSHA estimates that an annual average of 731 active mines (604 MNM
and 127 coal) will carry out an annual average of 25,417 corrective
actions (22,152 MNM and 3,265 coal) due to overexposure, and these
mines will then conduct corrective actions sampling for each corrective
action. Miner operators will have to immediately notify MSHA about each
overexposure. MSHA estimates that an annual average of 25,417
corrective action notifications will be sent to MSHA.
Next, MSHA assumes that all 1,106 coal mines will record periodic
evaluation results approximately 2.4 times, on average, per year, and
then post those results on a mine bulletin board, or if applicable, by
electronic means. In a change from the proposal, MSHA increased its
estimate for the number of periodic evaluations from about 2 per year
to about 2.4 per year, a 20 percent increase. This was done for two
reasons. First, Sec. 60.12(c) now requires periodic evaluations at
least every 6 months after commencing sampling or whenever there is a
change in production; processes; installation or maintenance of
engineering controls; installation or maintenance of equipment;
administrative controls; or geological conditions. Second, MSHA now
accounts for portable mines, which move frequently and are therefore
more likely to experience one of the changes noted in Sec. 60.12(c). A
more thorough explanation for this calculation can be found in Section
4.2 of the standalone FRIA document.
The number of records for periodic evaluation in coal mines is
2,449 each year. All 11,525 MNM mines will record periodic evaluation
results approximately 2.4 times, on average, a year, and then post
those results on a mine bulletin board, or if applicable, by electronic
means, starting in year 2. The number of records for periodic
evaluation in MNM mines is 0 for year 1, and 25,859 for years 2 and 3.
Mine operators will also post results of each periodic evaluation on
mine bulletin boards, creating an annual average of 19,688 records
(2,449 in year 1, 28,308 in year 2, and 28,308 in year 3).
Additionally, MSHA estimates mines will conduct post-evaluation
sampling as a result of their periodic evaluations, resulting in an
annual average of 12,766 sampling records (8,376 for MNM mines and
4,390 for coal mines). MSHA estimates an annual average of 39,377
periodic evaluation recordings and postings and 12,766 post-evaluation
samples.
The assumption for calculating corrective actions samples and post-
evaluation samples was changed from the proposal. In the proposed rule,
the number of corrective actions samples was combined with the number
of post-evaluation samples and their sum was assumed to be equivalent
to a constant 2.5 percent of all miners per periodic evaluation. In the
final rule, the number of corrective actions samples is based on the
projected share of samples over the PEL, increased by 25 percent to
account for some operators needing multiple samples before obtaining a
sample below the PEL, while the number of post-evaluation samples alone
is now equivalent to 2.5 percent of miners per periodic evaluation. The
change in methodology is intended to made estimates more consistent
with existing sampling data. In year 1 for coal mines and year 2 for
MNM mines, they will sample for only half a year. See Section 4.2 of
the standalone FRIA document for more details.
Estimated annual burden. The estimated average annual burden is
41,781 hours, including 13,147 hours for first-time and second-time
sampling, 11,063 hours for above-action-level sampling, 8,472 for
corrective actions sampling, 5,907 hours for periodic evaluations
recording and posting, and 3,192 hours for post-evaluation sampling.
MSHA estimates that it takes 15 minutes to record the sampling
results, 15 minutes to record the results of a periodic evaluation, 5
minutes to notify MSHA after an overexposure, and 3 minutes to post
each of the evaluation results on the mine bulletin board, and, if
applicable, by electronic means.
b. Section 60.13--Corrective Actions
ICR. Section 60.13 requires mine operators to make approved
respirators available to affected miners and immediately take
corrective actions to lower the concentration of respirable crystalline
silica to at or below the PEL if any sampling indicates overexposure.
Once corrective actions are taken, the mine operator is expected to
make a record of corrective actions. As per Sec. 60.1, the compliance
date for MNM mines begins one year after the compliance date for coal
mines. Based on changes to MSHA's methodology, there is no longer a
separate paperwork burden related to respirator records. In the
proposal, MSHA estimated an annual average of 5,685 records of miners
who are provided respirator until corrective actions are complete. In
the final rule, MSHA does not treat the paperwork burden of respirator
records as a separate cost. Instead, it is assumed to be part of the
corrective action records. Hence, the paperwork burden of respirator
records is not a separate cost.
Number of respondents. For Sec. 60.13, only those mines with at
least one miner exposure above the PEL are assumed to carry out the
requirement. MSHA estimates that an annual average of 731 active mines
(604 MNM mines and 127 coal mines) will require corrective actions,
starting in the second half of year 1 for coal mines and second half of
year 2 for MNM mines. This change from the proposed rule is based on
MSHA's new methodology for calculating corrective actions samples,
which required updating corrective actions calculations to be
consistent with that methodology. In the proposal, corrective actions
samples were combined with post-evaluation samples, accounting for 2.5
percent of all miners per periodic evaluation. The number of
respondents was assumed to be one-fourth of the number of responses for
each full year of sampling. In the final rule, the overexposure rate is
expected to decrease linearly in the first several
[[Page 28410]]
years after the start of implementation of the rule. As a result, the
number of corrective actions respondents is assumed to start with the
current number of operators with an overexposure in their last sampling
event from an MSHA inspector (as of 2019 for MNM mines and 2021 for
coal mines) and falls each year based on the decreasing overexposure
rate in each year. Additionally, some operators are expected to need
multiple corrective actions before they carry out a sample below the
PEL, thereby increasing the number of corrective actions by 25 percent.
Annual number of responses. The estimated average annual number of
responses is 25,417 (22,152 MNM and 3,265 coal). MSHA assumes that each
corrective actions sample, whose calculations are described above and
in Section 4.2 of the standalone FRIA document, will be preceded by a
corrective action, resulting in 25,417 corrective action records.
Estimated annual burden. The estimated average annual burden is
2,118 hours. MSHA estimates that on average it takes 5 minutes to
record a corrective action and the date.
c. Section 60.14--Respiratory Protection
ICR. Section 60.14(b) requires mine operators to temporarily
transfer a miner when the miner has a written determination from the
PLHCP that the miner is unable to wear a respirator. Section 60.14(a)
requires the temporary use of respirators in MNM mines under conditions
specified in Sec. Sec. 60.14(a)(1) and 60.14(a)(2). The written
determination record must be retained for the duration of a miner's
employment plus 6 months under Sec. 60.16(a)(4). Section 60.14(c)(2)
requires mine operators to have a written respiratory protection
program that meets the following requirements in accordance with ASTM
F3387-19: program administration; written standard operating
procedures; medical evaluation; respirator selection; training; fit
testing; maintenance, inspection, and storage, which is incorporated by
reference in the final rule. As per Sec. 60.1, the compliance date for
MNM mines is one year after the compliance date for coal mines.
Number of respondents. For Sec. 60.14(b), MSHA assumes that each
mine taking a corrective action (an annual average of 604 MNM mines and
127 coal mines) will have one miner unable to wear a respirator. MSHA
estimates that an additional 10 percent of MNM mines, which temporarily
use respirators, will also have one miner unable to wear a respirator
in years 2 and 3 (an annual average of 769 mines). Consequently, MSHA
estimates that an annual average of 1,500 (1,373 MNM and 127 coal)
mines will have a miner unable to wear a respirator.
This is a change from the proposal, where MSHA assumed that \1/3\
of mine operators affected by respiratory protection requirements would
have their miners wear respiratory protection in year 1 and 10 percent
of the same mine operators would have their miners wear respiratory
protection in years 2 and 3. This change is a result of MSHA updating
its methodology to be consistent with the final rule requirements.
For the ASTM F3387-19 incorporation by reference under Sec.
60.14(c)(2), MSHA assumes, to err on the side of overestimation, that a
total of 3,411 mine respondents (2,305 MNM mines and 1,106 coal mines)
would have respiratory protection programs. MSHA assumes that a half of
the coal mines (553 mines) would write new standard operating
procedures (SOPs) relating to the respiratory protection program and
the remaining half (533 mines) would revise existing SOPs in year 1.
New coal mines, estimated at 2 percent (22 mines), are assumed to write
respiratory protection SOPs in years 2 and 3. Similarly, for MNM mines,
MSHA assumes that: a half of them (1,153 mines) would write new SOPs
relating to the respiratory protection program; the remaining half
(1,152 mines) would revise existing SOPs in year 2; and approximately
46 new MNM mines to write respiratory protection SOPs in year 3.
The inclusion of ASTM F3387-19 costs in this ICR is a result of a
change between the proposed rule and final rule. In the proposed rule,
operators could choose which ASTM F3387-19 elements to adopt. In the
final rule, mine operators must have a written respiratory protection
program that meets the following requirements in accordance with ASTM
F3387-19: program administration; written standard operating
procedures; medical evaluation; respirator selection; training; fit
testing; maintenance, inspection, and storage. MSHA estimates that
3,411 mines will be affected by respiratory protection requirements, an
annual average of 599 existing mines will have to write new respiratory
protection SOPs, and an annual average of 569 mines will have to revise
existing SOPs each year.
Annual number of responses. The estimated average annual number of
responses is 5,310, including 1,500 for records relating to miners'
inability to wear respirators (Sec. 60.14(b)) and 3,810 for
respiratory protection requirements of writing and updating SOPs (Sec.
60.14 (c)(2)). MSHA estimates that the annual average of 1,500 mines
that will need records of miners' inability to wear respirators will
each have one miner requiring such record, totaling 1,500 records per
year (Sec. 60.14(b)). The annual 3,810 responses concerning Sec.
60.14 (c)(2) are estimated in the following. First, MSHA assumes that
approximately half of the 3,411 existing mine operators affected by
respiratory protection requirements, as well as all new mines affected
by these requirements, will have to write new respiratory protection
SOPs, resulting an annual average of 599 new written SOPs (553 in year
1, 1,175 in year 2, and 68 in year 3). Second, MSHA makes a similar
assumption that the other half of mines affected by respiratory
protection requirements will have to revise existing ones, generating
an annual average of 569 revised SOPs. Together, there will be a total
of 1,168 records of new (599) and revised (569) SOPs per year. Finally,
based on ASTM F3387-19 guidelines adopted in Sec. 60.14(c)(2) of this
rule, MSHA determines that existing and new mine operators will keep
records of the new and revised SOPs, which results in an annual average
of 2,642 records in total.
Estimated annual burden. The estimated annual burden is 11,333
hours, including 750 for records relating to miners' inability to wear
respirators and 10,583 for the ASTM F3387-19 incorporation by
reference. MSHA assumes it takes 30 minutes to determine and record
where a miner unable to wear a respirator can be temporarily
transferred either to work in a separate area of the same mine or to an
occupation at the same mine where respiratory protection is not
required. This will impact one miner in each of the 1,500 affected
mines. MSHA estimates that, on average, it takes 4 hours for mine
operators to write respiratory protection program SOPs and 1 hour to
revise existing respiratory protection program SOPs. For coal mines,
MSHA estimates that it takes 4 hours in year 1 and 2 hours in years 2
and 3 to carry out recordkeeping relating to the respiratory protection
program SOPs. For MNM mines, MSHA estimates that it takes 4 hours in
year 2 and 2 hours in year 3 to perform the same tasks.
d. Section 60.15--Medical Surveillance for Metal and Nonmetal Mines
ICR. Section 60.15 requires MNM mine operators to ensure that the
results of medical examinations or tests will be provided from the
PLHCP or specialist
[[Page 28411]]
within 30 days of the medical examination to the miner, and at the
request of the miner, to the miner's designated physician or another
designee identified by the miner. MNM mine operators also must ensure
that within 30 days of the medical examination, the PLHCP or specialist
provides the results of chest X-ray classifications to NIOSH, once
NIOSH establishes a reporting system [Sec. 60.15(d)(2)].
Also, MNM mine operators must obtain a written medical opinion from
a PLHCP or specialist regarding any recommended limitations on a
miner's use of respirators under Sec. 60.15(e). The written medical
opinion must contain the date of the medical examination, a statement
that the examination has met the requirements of the section, and any
recommended limitations on the miner's use of respirators. The written
medical opinion record must be retained by MNM mine operators for the
duration of a miner's employment plus 6 months under Sec. 60.16(a)(5).
As per Sec. 60.1, the compliance date for MNM mines begins one
year after the compliance date for coal mines.
Number of respondents. Due to uncertainty regarding participation
of currently employed miners, including contract workers, in medical
surveillance programs, MSHA considered two rates (25 percent and 75
percent) when estimating medical surveillance costs. To be consistent
with FRIA estimates, the values presented here are the average number
of MNM miners between the assumed participation rates of 25 percent and
75 percent. Furthermore, MSHA expects that 50 percent of current miners
will obtain their voluntary medical examinations in year 2, as that is
when the compliance period begins for MNM mines. Given that the
examinations for current miners do not need to be repeated until 5
years later there is no cost burden associated with this cost item in
year 3. As a result, an average of 29,371 current MNM miners are
estimated to receive voluntary medical examinations per year (0 in year
1, 88,112 in year 2, 0 in year 3).
MSHA further estimates that 8,392 miners each year, including
contract workers, are new miners and contractors working in MNM mines
and receive mandatory medical examinations. MSHA estimates that the
turnover of MNM miners will be 8,392 miners per year, starting from
year 2 (1/22 of the estimated total of 184,615 MNM workers, with an
average number of 22 years on the job before leaving the mining
industry). This results in an annual average of 5,595 MNM miners
receiving mandatory medical examinations (0 in year 1, 8,392 in years 2
and 3). The estimated total respondents per year therefore will be
34,965 (= 29,371 current miners x 5,595 new miners).
Annual number of responses. The estimated annual number of
responses is 34,965, including 5,595 medical opinion records for new
miners and 29,371 records for current miners.
Estimated annual burden. The estimated annual burden is 8,741
hours, including 1,399 hours for new MNM miners and 7,343 hours for
current MNM miners. MSHA estimates it will take 15 minutes to record
the medical examination results for each of the 34,965 miners.
Total Recordkeeping Burden for Part 60
Total recordkeeping burden for Part 60 is summarized in Table XI-1.
[GRAPHIC] [TIFF OMITTED] TR18AP24.196
The total annual number of respondents is 47,596; the total annual
number of responses will be 265,509; and the estimated annual burden
will be 63,972 hours.
The following estimates of information collection burden are
summarized in Table XI-2.
Affected Public: Businesses or For-Profit.
Estimated Number of Respondents: 1,106 respondents in year 1;
109,135 respondents in the year 2; and 21,023 respondents in year 3.
Frequency: On Occasion.
Estimated Number of Responses: 52,821 responses in year 1; 433,240
responses in year 2; and 310,467 responses in year 3.
Estimated Number of Burden Hours: 18,720 hours in year 1; 109,983
hours in year 2; and 63,215 hours in year 3.
Estimated Hour Burden Costs: $1,260,819 in year 1; $7,704,098 in
year 2; and $4,238,135 in year 3.
[[Page 28412]]
Estimated Capital Costs to Respondents: $27,044 in year 1;
$2,093,280 in year 2; and $206,725 in year 3.
[GRAPHIC] [TIFF OMITTED] TR18AP24.197
The number of responses and burden hours decreased from year 2 to
year 3 mainly as a result of decreases in sampling in current MNM
mines. In year 2, MNM mines will conduct first-time and second-time
sampling, while only a small number of new mines starting operations in
year 3 are required to conduct this type of sampling. The increase in
capital costs in year 2 is a result of all medical examinations for
current miners taking place in that year.
For a detailed summary of the burden hours and related costs by
provision, see the FRIA accompanying the final rule. The FRIA includes
the estimated costs and assumptions related to the paperwork
requirements under this final rule.
2. Existing Information Collection 1219-0011
Type of Review: Non-substantive change to currently approved
information collection.
OMB Control Number: 1219-0011.
Title: Respirable Coal Mine Dust Sampling.
Description of the ICR
Background
In October 2022, MSHA received OMB approval for the reauthorization
of Respirable Coal Mine Dust Sampling under OMB Control Number 1219-
0011. This information collection request outlines the legal authority,
procedures, burden, and costs associated with recordkeeping and
reporting requirements for coal mine operators. MSHA's standards
require that coal mine operators sample respirable coal mine dust
quarterly and make records of such samples.
Summary of Changes
This non-substantive change request revises the supporting
statement for this information collection request due to the
establishment of a PEL for respirable crystalline silica separate from
coal mine dust in this final rule. These revisions remove any reference
in the information collection request to quartz or the reduction of the
respirable coal mine dust standard due the presence of quartz. This
change does not modify the authority, affected mine operators, or
paperwork burden in this information collection request.
Summary of the Collection of Information
Changes in Burden
The calculated burden including respondents and responses remain
the same.
Affected Public: Businesses or For-Profit.
Estimated Number of Respondents: 676 (0 from this rule).
Frequency: On occasion.
Estimated Number of Responses: 995,102 (0 from this rule).
Estimated Number of Burden Hours: 58,259 (0 from this rule).
Estimated Hour Burden Costs: $3,271,611 ($0 from this rule).
Estimated Capital Costs to Respondents: $29,835 ($0 from this
rule).
3. Existing Information Collection 1219-0048
Type of Review: Substantive change to currently approved
information collection.
OMB Control Number: 1219-0048.
Title: Respirator Program Records.
Description of the ICR
Background
Title 30 CFR parts 56 and 57 incorporate by reference requirements
of ANSI Z88.2-1969, ``Practices for Respiratory Protection.'' Under
this standard, certain records are required to be kept in connection
with respirators in MNM mines. The final rule incorporates by reference
ASTM F3387-19, ``Standard Practice for Respiratory Protection,'' in 30
CFR parts 56 and 57 to replace the Agency's existing respiratory
protection standard. The final rule requires respiratory protection
programs to be in writing and to meet the following requirements in
accordance with ASTM F3387-19: program administration; written standard
operating procedures; medical evaluation; respirator selection;
training; fit testing; maintenance, inspection, and storage.
Summary of Changes
This substantive change request is to revise the supporting
statement for this information collection request due to a modification
of respiratory protection standard from ANSI Z88.2-1969 to ASTM F3387-
19 in the final rule. These revisions require mine operators to update
their respiratory protection standard and increase recordkeeping costs.
The change does not modify the authority or affected mine operators but
increases the paperwork burden and costs associated with respiratory
protection in this information collection request.
[[Page 28413]]
Summary of the Collection of Information
Changes in Burden
The calculated burden including respondents and responses
increases.
Affected Public: Businesses or For-Profit.
Estimated Number of Respondents: 2,305 (1,955 from this rule).
Frequency: On occasion.
Estimated Number of Responses: 43,795 (37,495 from this rule).
Estimated Number of Burden Hours: 23,626 (20,038 from this rule).
Estimated Hour Burden Costs: $1,459,309 ($1,175,211 from this
rule).
Estimated Capital Costs to Respondents: $140,000 ($0 from this
rule).
XII. Other Regulatory Considerations
A. National Environmental Policy Act
The National Environmental Policy Act (NEPA) of 1969 (42 U.S.C.
4321 et seq.), requires each Federal agency to consider the
environmental effects of final actions and to prepare an Environmental
Impact Statement on major actions significantly affecting the quality
of the environment. MSHA has reviewed the final standard in accordance
with NEPA requirements, the regulations of the Council on Environmental
Quality (40 CFR part 1500), and the Department of Labor's NEPA
procedures (29 CFR part 11). As a result of this review, MSHA has
determined that this final rule will not have a significant
environmental impact. Accordingly, MSHA has not conducted an
environmental assessment nor provided an environmental impact
statement.
B. The Unfunded Mandates Reform Act of 1995
MSHA reviewed this rule according to the Unfunded Mandates Reform
Act of 1995 (UMRA) (2 U.S.C. 1501 et seq.). Under section 202(a) of the
UMRA, 2 U.S.C. 1532(a), an agency must prepare a written qualitative
and quantitative assessment of any regulation that may result in the
expenditure by State, local, or tribal governments, in the aggregate,
or by the private sector, of $100 million (adjusted annually for
inflation) or more in any one year. That threshold is $196 million as
of 2023.
The statutory authority for the final rule is provided by the Mine
Act under sections 101(a), 103(h), and 508. 30 U.S.C. 811(a), 813(h),
and 957. MSHA implements the provisions of the Mine Act to prevent
death, illness, and injury from mining and promote safe and healthful
workplaces for miners. The Mine Act requires the Secretary of Labor
(Secretary) to develop and promulgate improved mandatory health and
safety standards to prevent hazardous and unhealthy conditions and
protect the health and safety of the nation's miners. 30 U.S.C. 811(a).
MSHA concludes that the final rule would impose a federal mandate
on the private sector in excess of $196 million in expenditures in one
of the 60-year implementation years, as documented in the standalone
FRIA document (see Table C-2, Appendix C). The expenditure burden on
the private sector will be borne by mine operators. Such expenditures
may include conducting exposure monitoring; selecting, improving, and
implementing exposure controls; providing respiratory protection;
updating respiratory protection practices in accordance with the 2019
ASTM standard; and, for MNM mine operators, making specified medical
examinations available for all their miners. However, the rule will not
require State, local, or tribal governments to expend, in the
aggregate, $196 million or more in any one year for their commercial
activities. Accordingly, the rule does not trigger the requirements of
the UMRA based on its impact on State, local, or tribal governments.
Section 202(c) of the UMRA, 2 U.S.C. 1532(c), authorizes a Federal
agency to prepare any written statement required under section 202(a)
of the UMRA in conjunction with or as a part of any other statement or
analysis that accompanies the final rule. The FRIA constitutes the
written statement containing a qualitative and quantitative assessment
of these anticipated costs and benefits required under Section 202(a)
of the UMRA.
In addition, section 205(a) of UMRA, 2 U.S.C. 1535(a), requires
MSHA to identify and consider a reasonable number of regulatory
alternatives before promulgating a rule for which a written statement
under section 202 is required. MSHA is required to select from those
alternatives the most cost-effective and least burdensome alternative
that achieves the objectives of the rule unless the Agency publishes an
explanation for doing otherwise, or the selection of such an
alternative is inconsistent with law. After considering three
regulatory alternatives, this final rule presents a comprehensive
approach for lowering miners' exposure to respirable crystalline silica
and MSHA has determined the rule is both technologically feasible and
economically justified as described in Section VII. Feasibility. A full
discussion of the alternatives considered is presented in Section IX.
Summary of the Final Regulatory Impact Analysis and Regulatory
Alternatives and the standalone FRIA document.
C. The Treasury and General Government Appropriations Act of 1999:
Assessment of Federal Regulations and Policies on Families
Section 654 of the Treasury and General Government Appropriations
Act of 1999 (5 U.S.C. 601 note) requires agencies to assess the impact
of Agency action on family well-being. MSHA has determined that the
final rule will have no effect on family stability or safety, marital
commitment, parental rights and authority, or income or poverty of
families and children, as defined in the Act. The final rule impacts
the mining industry and does not impose requirements on states or
families. Accordingly, MSHA certifies that this final rule will not
impact family well-being, as defined in the Act.
D. Executive Order 12630: Government Actions and Interference With
Constitutionally Protected Property Rights
Section 5 of E.O. 12630 requires Federal agencies to ``identify the
takings implications of proposed regulatory actions . . .'' MSHA has
determined that the final rule does not implement a taking of private
property or otherwise have takings implications. Accordingly, E.O.
12630 requires no further Agency action or analysis.
E. Executive Order 12988: Civil Justice Reform
The final rule was written to provide a clear legal standard for
affected conduct and was carefully reviewed to eliminate drafting
errors and ambiguities to minimize litigation and avoid undue burden on
the Federal court system. Accordingly, the final rule meets the
applicable standards provided in section 3 of E.O. 12988, Civil Justice
Reform.
F. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
E.O. 13045 requires Federal agencies submitting covered regulatory
actions to OMB's Office of Information and Regulatory Affairs (OIRA)
for review, pursuant to E.O. 12866, to provide OIRA with (1) an
evaluation of the environmental health or safety effects that the
planned regulation may have on children, and (2) an explanation of why
the planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the agency. In E.O.
13045,
[[Page 28414]]
``covered regulatory action'' is defined as rules that may (1) be
significant under Executive Order 12866 Section 3(f)(1) (i.e., a
rulemaking that has an annual effect on the economy of $200 million or
more or would adversely affect in a material way the economy, a sector
of the economy, productivity, competition, jobs, the environment,
public health or safety, or State, local, territorial, or tribal
governments or communities), and (2) concern an environmental health
risk or safety risk that an agency has reason to believe may
disproportionately affect children. Environmental health risks and
safety risks refer to risks to health or to safety that are
attributable to products or substances that the child is likely to come
in to contact with or ingest through air, food, water, soil, or product
use or exposure.
MSHA has determined that, in accordance with E.O. 13045, while the
final rule is considered significant under E.O. 12866 Section 3(f)(1),
it does not concern an environmental health or safety risk that may
have a disproportionate impact on children. MSHA's final rule would
lower the occupational exposure limit to respirable crystalline silica
for all miners, including pregnant miners, take other actions to
protect miners from adverse health risks associated with exposure to
respirable crystalline silica, and require updated respiratory
standards to better protect miners from airborne contaminants.
MSHA is aware of studies which have characterized and assessed the
risks posed by ``take-home'' exposure pathways for hazardous dust
particles. However, the final rule's primary reliance on engineering
and administrative controls to protect miners from respirable
crystalline silica exposures helps minimize risks associated with
``take-home'' exposures by reducing or eliminating silica that is in
the mine atmosphere or the miner's personal breathing zone. The risks
of take-home exposures are further minimized by MSHA's existing
standards, mine operators' policies and procedures, and mine operators'
use of clothing cleaning systems.
MSHA's existing standards limit miners' exposures to respirable
crystalline silica. MSHA also requires coal mine operators to provide
miners with bathing facilities and change rooms. Miners have access to
these facilities to shower and change their work clothes at the end of
each shift. In addition, some mine operators provide miners with clean
company clothing for each shift, have policies and procedures for
cleaning or disposing of contaminated clothing, and provide a boot wash
for miners to clean work boots during and after each shift. Moreover,
some mine operators use clothing cleaning systems that can remove dust
from a miner's clothing. Many of these systems include NIOSH-designed
dust removal booths that use compressed air to remove dust, which is
then vacuumed through a filter to remove airborne contaminants.
Overall, the Agency's standards, mine operators' policies and
procedures, and other safety and health practices including the use of
clothing cleaning systems help to reduce or eliminate the amount of
take-home exposure, therefore protecting other persons in a miner's
household or persons who come into contact with the miner outside of
the mine site.
MSHA identified one epidemiological study (Onyije et al., 2022)
that suggests a possible association between paternal exposure to
respirable crystalline silica and childhood leukemia. However, this
study does not provide dose-response data which would be needed to
establish the dose of respirable crystalline silica which results in a
no-adverse-effect-level (NOAEL) for childhood leukemia. This potential
association has not been independently confirmed by another study.
MSHA has no evidence that the environmental health or safety risks
posed by respirable crystalline silica, including ``take-home''
exposure to respirable crystalline silica, disproportionately affect
children. Therefore, MSHA concludes no further analysis or action is
needed, in accordance with E.O. 13045.
G. Executive Order 13132: Federalism
MSHA has determined that the final rule does not have ``federalism
implications'' because it will not ``have substantial direct effects on
the States, on the relationship between the national government and the
States, or on the distribution of power and responsibilities among the
various levels of government.'' Accordingly, under E.O. 13132, no
further Agency action or analysis is required.
H. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
MSHA has determined the final rule does not have ``tribal
implications'' because it will not ``have substantial direct effects on
one or more Indian tribes, on the relationship between the Federal
Government and Indian tribes, or on the distribution of power and
responsibilities between the Federal Government and Indian tribes.''
Accordingly, under E.O. 13175, no further Agency action or analysis is
required.
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
E.O. 13211 requires agencies to publish a Statement of Energy
Effects for ``significant energy actions,'' which are agency actions
that are ``likely to have a significant adverse effect on the supply,
distribution, or use of energy'' including a ``shortfall in supply,
price increases, and increased use of foreign supplies.'' MSHA has
reviewed the final rule for its impact on the supply, distribution, and
use of energy because it applies to the mining industry. The final rule
would result in annualized compliance costs of $8.2 million using a 3
percent discount rate and $8.6 million using a 7 percent discount rate
for the coal industry relative to annual revenue of $29.1 billion. The
final rule would also result in annualized compliance costs of $81.9
million using a 3 percent discount rate and $83.6 million using a 7
percent discount rate for the metal/nonmetal mine industry relative to
annual revenue of $95.1 billion. Because it is not ``likely to have a
significant adverse effect on the supply, distribution, or use of
energy'' including a ``shortfall in supply, price increases, and
increased use of foreign supplies,'' it is not a ``significant energy
action.'' Accordingly, E.O. 13211 requires no further agency action or
analysis.
J. Executive Order 13272: Proper Consideration of Small Entities in
Agency Rulemaking
MSHA has thoroughly reviewed the final rule to assess and take
appropriate account of its potential impact on small businesses, small
governmental jurisdictions, and small organizations. MSHA's analysis is
presented in Section X. Final Regulatory Flexibility Analysis.
K. Executive Order 13985: Advancing Racial Equity and Support for
Underserved Communities Through the Federal Government
E.O. 13985 provides ``that the Federal Government should pursue a
comprehensive approach to advancing equity for all, including people of
color and others who have been historically underserved, marginalized,
and adversely affected by persistent poverty and inequality.'' E.O.
13985 defines ``equity'' as ``consistent and systematic fair, just, and
impartial treatment of all individuals, including individuals who
belong to underserved communities that have been denied such treatment,
such
[[Page 28415]]
as Black, Latino, and Indigenous and Native American persons, Asian
Americans and Pacific Islanders and other persons of color; members of
religious minorities; lesbian, gay, bisexual, transgender, and queer
(LGBTQ+) persons; persons with disabilities; persons who live in rural
areas; and persons otherwise adversely affected by persistent poverty
or inequality.'' To assess the impact of the final rule on equity, MSHA
considered two factors: (1) the racial/ethnic distribution in mining in
NAICS 212 (which does not include oil and gas extraction) compared to
the racial/ethnic distribution of the U.S. workforce (Table XII-1), and
(2) the extent to which mining may be concentrated within general
mining communities (Table XII-2).
In 2008, NIOSH conducted a survey of mines, which entailed sending
a survey packet to 2,321 mining operations to collect a wide range of
information, including demographic information on miners. NIOSH's 2012
report, entitled ``National Survey of the Mining Population: Part I:
Employees'' reported the findings of this survey (NIOSH, 2012a). Race
and ethnicity information about U.S. mine workers is presented in Table
XII-1. Of all mine workers, including miners as well as administrative
employees at mines, 93.4 percent of mine workers were white, compared
to 80.6 percent of all U.S workers.\111\ There were larger percentages
of American Indian or Alaska Native and Native Hawaiian or Other
Pacific Islander people in the mining industry compared to all U.S.
workers, while there were smaller percentages of Asian, Black or
African American, and Hispanic/Latino people in the mining industry
compared to all U.S. workers.
---------------------------------------------------------------------------
\111\ National data on workers by race were not available for
the year 2008; comparable data for 2012 are provided for comparison
under the assumption that there would not be major differences in
distributions between these two years.
---------------------------------------------------------------------------
Table XII-2 shows that there are 22 mining communities, defined as
counties where at least 2 percent of the population is working in the
mining industry.\112\ Although the total population in this table
represents only 0.15 percent of the U.S. population, it represents 12.0
percent of all mine workers. The average per capita income in these
communities in 2020, $47,977,\113\ was lower than the U.S. average,
$59,510, representing 80.6 percent of the U.S. average. However, each
county's average per capita income varies substantially, ranging from
56.4 percent of the U.S. average to 146.8 percent.
---------------------------------------------------------------------------
\112\ Although 2 percent may appear to be a small number for
identifying a mining community, one might consider that if the
average household with one parent working as a miner has five
members in total, then approximately 10 percent of households in the
area would be directly associated with mining. While 10 percent may
also appear small, this refers to the county. There are likely
particular areas that have a heavier concentration of mining
households.
\113\ This is a simple average rather than a weighted average by
population.
---------------------------------------------------------------------------
The final rule would lower exposure to respirable crystalline
silica and improve respiratory protection for all mine workers. MSHA
determined that the final rule is consistent with the goals of E.O.
13985 and would support the advancement of equity for all workers at
mines, including those who are historically underserved and
marginalized.
BILLING CODE 4520-43-P
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BILLING CODE 4520-43-C
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[GRAPHIC] [TIFF OMITTED] TR18AP24.199
L. Incorporation by Reference
The Office of the Federal Register (OFR) has regulations concerning
incorporation by reference. 5 U.S.C. 552(a); 1 CFR part 51. These
regulations require that information that is incorporated by reference
in a rule be ``reasonably available'' to the public. They also require
discussion in the preamble to the rule of the ways in which materials
are reasonably available to interested parties or how the Agency worked
to make those materials reasonably available to interested parties.
Additionally, the preamble to the rule must summarize the material. 1
CFR 51.5(b).
[[Page 28418]]
In accordance with the OFR's requirements, MSHA provides the
following: (a) summaries of the materials to be incorporated by
reference and (b) information on the public availability of the
materials and on how interested parties can access the materials.
ASTM F3387-19, ``Standard Practice for Respiratory Protection''
ASTM F3387-19 is a voluntary consensus standard that represents up-
to-date advancements in respiratory protection technologies, practices,
and techniques. The standard includes provisions for selection,
fitting, use, and care of respirators designed to remove airborne
contaminants from the air using filters, cartridges, or canisters, as
well as respirators that protect miners in oxygen-deficient or
immediately dangerous to life or health atmospheres. These provisions
are based on NIOSH's long-standing experience of testing and approving
respirators for occupational use and OSHA's respiratory protection
standards on assigned protection factors and fit testing. This final
rule incorporates by reference ASTM F3387-19 in Sec. Sec. 56.5005T,
57.5005T, and 72.710T (which will become permanent Sec. Sec. 56.5005
and 57.5005 720 days after publication and permanent Sec. 72.710 360
days after publication) and in Sec. 60.14(c)(2) to better protect all
miners from airborne contaminants. MSHA believes that incorporating by
reference ASTM F3387-19 provides mine operators with up-to-date
requirements for respirator technology, reflecting an improved
understanding of effective respiratory protection and therefore better
protecting the health and safety of miners. For further details on
MSHA's update to the Agency's existing respiratory protection standard,
please see Section VIII.D. Updating MSHA Respiratory Protection
Standards: Incorporation of ASTM F3387-19 by Reference.
A paper copy or printable version of ASTM F3387-19 may be purchased
by mine operators or any member of the public at any time from ASTM
International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken,
PA 19428-2959; www.astm.org. ASTM International makes read-only
versions of its standards that have been referenced or incorporated
into Federal regulation or laws available free of charge at its online
Reading Room, www.astm.org/products-services/reading-room.html.
In addition, upon finalization of this rule, ASTM F3387-19 will be
available for review free of charge at MSHA headquarters at 201 12th
Street South, Arlington, VA 22202-5450 (202-693-9440) and at Mine
Safety Health Enforcement District and Field Offices.
ISO 7708:1995(E): Air quality--Particle Size Fraction Definitions for
Health-Related Sampling
ISO 7708:1995 is an international consensus standard that defines
sampling conventions for particle size fractions used in assessing
possible health effects of airborne particles in the workplace and
ambient environment. It defines conventions for the inhalable,
thoracic, and respirable fractions. The final rule incorporates by
reference ISO 7708:1995 in Sec. 60.12(e)(4) to ensure consistent
sampling collection by mine operators through the utilization of
samplers conforming to ISO 7708:1995. For further details on MSHA's
incorporation by reference of ISO 7708:1995, please see Section
VIII.B.5.d. Sampling Devices: Incorporation of ISO 7708:1995 by
Reference.
A paper copy or printable version of ISO 7708:1995 may be purchased
by mine operators or any member of the public at any time from ISO, CP
56, CH-1211 Geneva 20, Switzerland; phone: + 41 22 749 01 11; fax: + 41
22 733 34 30; website: www.iso.org/. ISO makes read-only versions of
its standards that have been incorporated by reference in the CFR
available free of charge at its online Incorporation by Reference
Portal, http://ibr.ansi.org/Default.aspx.
In addition, upon finalization of this rule, ISO 7708:1995 will be
available for review free of charge at MSHA headquarters at 201 12th
Street South, Arlington, VA 22202-5450 (202-693-9440) and at Mine
Safety Health Enforcement District and Field Offices.
TLVs[supreg] Threshold Limit Values for Chemical Substances in Workroom
Air Adopted by ACGIH for 1973
ACGIH's publication entitled ``TLVs[supreg] Threshold Limit Values
for Chemical Substances in Workroom Air Adopted by ACGIH for 1973''
presents Threshold Limit Value (TLV[supreg]) guidelines for hundreds of
chemical substances found in the work environment (particulates, gases,
and vapors). TLVs[supreg] are airborne concentrations of chemical
substances that represent conditions under which it is believed that
nearly all workers may be repeatedly exposed, day after day, over a
working lifetime, without adverse effects. TLVs[supreg] generally refer
to time-weighted average concentrations (TWAs) for a 7 or 8-hour
workday and 40-hour workweek that are applied as guidelines in the
control of health hazards.
TLVs[supreg], which appears the amendatory text of this rule, was
previously approved for use in Sec. Sec. 56.5001 and 57.5001.
Copies of the document may be purchased from the American
Conference of Governmental Industrial Hygienists, 3640 Park 42 Drive,
Cincinnati, OH 45241; 513-742-2020; http://www.acgih.org. This
publication is also available for examination free of charge at MSHA's
Office of Standards, Regulations, and Variances, 201 12th Street South,
Arlington, VA 22202-5452; 202-693-9440; and at Mine Safety and Health
Enforcement District and Field Offices.
American National Standards Practices for Respiratory Protection ANSI
Z88.2-1969.
ANSI Z88.2-1969, which appears the amendatory text of this rule,
was previously approved for use in Sec. 72.710.
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XIV. Appendix
Appendix A--Description of MSHA Respirable Crystalline Silica Samples
This document describes the respirable crystalline silica
samples used in this rule. The Mine Safety and Health Administration
(MSHA) collected these samples from metal/nonmetal (MNM) and coal
mines, then analyzed the data to support this rulemaking. Technical
details are discussed in the attachments that follow.
MNM Respirable Dust Sample Dataset, 2005-2019
From January 1, 2005, to December 31, 2019, 104,354 valid MNM
respirable dust samples were entered into the MSHA Technical Support
Laboratory Information Management System (LIMS) database.\114\ The
dataset includes MNM mine respirable dust personal exposure samples
collected by MSHA inspectors. A total of 57,824 samples contained a
respirable dust mass of 0.100 mg or greater (referred as
``sufficient-mass dust samples''), while a total of 46,530 samples
contained a respirable dust mass of less than 0.100 mg (referred as
``insufficient-mass dust samples'').\115\
---------------------------------------------------------------------------
\114\ Only valid (non-void) MNM respirable dust samples were
included in the LIMS dataset. Voided samples include any samples
with a documented reason which occurred during the sampling and/or
the MSHA's laboratory analysis for invalidating the results.
\115\ Sufficient-mass dust samples are analyzed for their quartz
content, whereas insufficient-mass dust samples are not. This is
because even if the insufficient-mass dust samples contained only
quartz they would not have exceeded the permissible exposure limit
(PEL) at that time.
---------------------------------------------------------------------------
Respirable dust samples collected by MSHA inspectors are
assigned a three-digit ``contaminant code'' based on the contaminant
in the sample. MSHA's contaminant codes group contaminants based on
their health effects \116\ and are assigned by the MSHA Laboratory
based on sample type and analysis results. The codes link
information to the sample, such as contaminant description,
permissible exposure limit (PEL), and the units of measure for each
contaminant sampled.
---------------------------------------------------------------------------
\116\ For example, contaminant code 523 indicates that dust from
that sample contained 1 percent or more respirable crystalline
silica (quartz). Exposure to respirable crystalline silica has been
linked to the following health outcomes: silicosis, non-malignant
respiratory disease, lung cancer, and renal disease.
---------------------------------------------------------------------------
The MNM respirable crystalline silica dataset includes five
contaminant codes.
MNM Respirable Dust Sample Contaminant Codes
Contaminant code 521--MNM respirable dust samples that
were not analyzed for respirable crystalline silica.
Contaminant code 523--MNM respirable dust samples
containing 1 percent or more quartz.
Contaminant code 525--MNM respirable dust samples
containing cristobalite.
Contaminant code 121--MNM respirable dust samples
containing less than 1 percent quartz where the commodity is listed
as a ``nuisance particulate'' in Appendix E of the TLVs[supreg]
Threshold Limit Values for Chemical Substances in Workroom Air
Adopted by ACGIH for 1973 (reproduced in Table A-1).
Contaminant code 131--MNM respirable dust samples
containing less than 1 percent quartz where the commodity is not
listed as a ``nuisance particulate'' in Appendix E of the 1973 ACGIH
TLV[supreg] Handbook (reproduced below).
[[Page 28432]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.130
MNM Respirable Dust Samples With a Mass of at Least 0.100 Milligram
(mg) (Sufficient-Mass Dust Samples)
The 57,824 samples that contained at least 0.100 mg of
respirable dust were analyzed to quantify their respirable
crystalline silica content--mostly respirable quartz but also
respirable cristobalite. The respirable crystalline silica
concentrations were entered into the MSHA Standardized Information
System (MSIS) database (internal facing) and Mine Data Retrieval
System (MDRS) database (public facing). MSIS and MDRS differ from
LIMS in that some of the fields associated with a sample can be
modified or corrected by the inspector who conducted the sampling.
These correctable fields include Mine ID, Location Code, and Job
Code. Inspectors cannot access or modify the fields in the LIMS
database.
Fifty-five samples \117\ were removed from the dataset because
they were erroneous, had an incorrect flow rate, had insufficient
sampling time, or were duplicates. This resulted in a final dataset
consisting of 57,769 MNM samples that contained a mass of at least
0.100 mg of respirable dust. The dataset containing the analyzed
samples that MSHA retained can be found in the rulemaking docket
MSHA-2023-0001.
---------------------------------------------------------------------------
\117\ There were 55 samples removed: 7 samples had no detected
mass gain (denoted as ``0 mg''); 1 sample was a partial shift that
was not originally marked correctly; 1 sample was removed at the
request of the district; 44 samples had flow rates outside the
acceptable range of 1.616-1.785 L/min; and 2 samples were duplicates
of samples that were already in the dataset. This resulted in the
final sample size of 57,769 = 57,824-(7 + 1 + 1 + 44 + 2).
---------------------------------------------------------------------------
MNM Respirable Dust Samples With a Mass of Less Than 0.100 mg
(Insufficient-Mass Dust Samples)
The LIMS database also included 46,530 MNM respirable dust
samples that contained less than 0.100 mg of respirable dust. These
samples did not meet the minimum dust mass criterion of 0.100 mg and
were not analyzed for respirable crystalline silica by MSHA's
Laboratory.
From these 46,530 samples, 167 samples \118\ were removed
because they were erroneous, had an incorrect flow rate, or had
insufficient sampling time. This resulted in 46,363 remaining MNM
samples containing less than 0.100 mg of respirable dust. These
samples were assigned to contaminant code 521, indicating that the
samples were not analyzed for quartz. The dataset containing the
unanalyzed samples that MSHA retained can be found in the rulemaking
docket MSHA-2023-0001.
---------------------------------------------------------------------------
\118\ There were 167 samples removed: 75 samples had a cassette
mass less than -0.03 mg (based on instrument tolerances, samples
that report a cassette mass between -0.03 mg and 0 mg were treated
as having a mass of 0 mg, samples with masses below that threshold
of -0.03 mg were excluded); 52 samples had Mine IDs that did not
report employment in any year from 2005-2019; 31 samples had flow
rates outside the acceptable range of 1.615-1.785 L/min ; six
samples had sampling times of less than 30 minutes; and three
samples had invalid Job Codes. This resulted in the final sample
size of 46,363 = 46,530-(75 + 52 + 31 + 6 + 3).
---------------------------------------------------------------------------
All MNM Respirable Dust Samples
After removing the 222 samples mentioned above (55 sufficient-
mass and 167 insufficient-mass), the dataset consisted of 104,132
MNM respirable dust samples: 57,769 sufficient-mass samples and
46,363 insufficient-mass samples. A breakdown of the MNM respirable
dust samples is included in Table A-2.
[[Page 28433]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.200
Coal Respirable Dust Sample Dataset, 2016-2021
From August 1, 2016, to July 31, 2021, 113,607 valid respirable
dust samples from coal mines were collected by MSHA inspectors and
entered in the LIMS database.\119\ For coal mines, the reason the
analysis is based on samples collected by inspectors beginning on
August 1, 2016, is that this is when Phase III of MSHA's 2014 RCMD
Standard went into effect. Samples taken prior to implementation of
the RCMD standard would not be representative of current respirable
crystalline silica exposure levels in coal mines.
---------------------------------------------------------------------------
\119\ Only valid (non-void) coal respirable dust samples were
included in the LIMS dataset. Voided samples include any samples
with a documented reason which occurred during the sampling and/or
the MSHA's Laboratory analysis for invalidating the results.
---------------------------------------------------------------------------
Of these samples collected by MSHA inspectors, 67,963 samples
were analyzed for respirable crystalline silica; 45,644 samples were
not. The record of a respirable dust sample from coal mines contains
a record of the sample type and the occupation of the miner sampled.
A coal sample's type is based on the location within the mine as
well as the occupation of the miner sampled. Below is a list of coal
sample types and descriptions, as well as the mass of respirable
dust required for that type of sample to be analyzed for respirable
crystalline silica.
Type 1--Designated occupation (DO). The occupation on a
mechanized mining unit (MMU) that has been determined by results of
respirable dust samples to have the greatest respirable dust
concentration. Designated occupation samples must contain at least
0.100 mg of respirable dust to be analyzed for respirable
crystalline silica.
Type 2--Other designated occupation (ODO). Occupations
other than the DO on an MMU that are also designated for sampling,
required by 30 CFR part 70. These samples must contain at least
0.100 mg of respirable dust to be analyzed for respirable
crystalline silica.
Type 3--Designated area (DA). Designated area samples
are from specific locations in the mine identified by the operator
in the mine ventilation plan under 30 CFR 75.371(t), where samples
will be collected to measure respirable dust generation sources in
the active workings. These samples must contain at least 0.100 mg of
respirable dust to be analyzed for respirable crystalline silica.
Type 4--Designated work position (DWP). A designated
work position in a surface coal mine or surface work area of an
underground coal mine that is designated for sampling in order to
measure respirable dust generation sources in the active workings.
Designated work position samples must contain at least 0.200 mg of
respirable dust to be analyzed for respirable crystalline silica.
There are exceptions for certain occupations: bulldozer operator
(MSIS general occupation code 368), high wall drill operator (code
384), high wall drill helper (code 383), blaster/shotfirer (code
307), refuse/backfill truck driver (code 386), or high lift
operator/front end loader (code 382). Samples from these occupations
must have at least 0.100 mg of respirable dust to be analyzed for
respirable crystalline silica.
Type 5--Part 90 miner. A Part 90 miner is employed at a
coal mine and has exercised the option under the old section 203(b)
program (36 FR 20601, Oct. 27, 1971) or under 30 CFR 90.3 to work in
an area of a mine where the average concentration of respirable dust
in the mine atmosphere during each shift to which a miner is exposed
is continuously maintained at or below the applicable standard and
has not waived these rights. A sample from a Part 90 miner must
contain at least 0.100 mg of respirable dust to be analyzed for
respirable crystalline silica.
Type 6--Non-designated area (NDA). Non-designated area
samples are taken from locations in the mine that are not identified
by the operator in the mine ventilation plan under 30 CFR 75.371(t)
as areas where samples will be collected to measure respirable dust
generation sources in the active workings. These samples are not
analyzed for respirable crystalline silica.
Type 7--Intake air samples are taken from air that has
not yet ventilated the last working place on any split of any
working section or any worked-out area, whether pillared or non-
pillared, as per 30 CFR 75.301. These samples are not analyzed for
respirable crystalline silica.
[[Page 28434]]
Type 8--Non-designated work position (NDWP). A work
position in a surface coal mine or a surface work area of an
underground coal mine that is sampled during a regular health
inspection to measure respirable dust generation sources in the
active workings but has not been designated for mandatory sampling.
For the analysis of respirable crystalline silica, these samples
must have at least 0.200 mg of respirable dust. There are exceptions
for certain occupations: bulldozer operator (MSIS general occupation
code 368), high wall drill operator (code 384), high wall drill
helper (code 383), blaster/shotfirer (code 307), refuse/backfill
truck driver (code 386), or high lift operator/front end loader
(code 382). Samples taken from these occupations must contain at
least 0.100 mg respirable dust to be analyzed for respirable
crystalline silica.
Coal Respirable Dust Samples Analyzed for Respirable Crystalline Silica
There were 67,963 samples from coal mines collected by MSHA
inspectors from underground and surface coal mining operations that
were analyzed for respirable crystalline silica. These results were
entered first into LIMS, and then into MSIS and MDRS. Results from
MSIS were used as they may be updated by the inspectors at later
dates.\120\ From those 67,963 samples, 4,836 samples were removed as
they were environmental samples, voided in MSIS, or had other
errors.\121\ This resulted in a dataset of 63,127 samples from coal
mines that were analyzed for respirable crystalline silica. The
dataset containing the analyzed samples that MSHA retained can be
found in the rulemaking docket MSHA-2023-0001.
---------------------------------------------------------------------------
\120\ As mentioned in the section concerning samples for MNM
mines, MSIS and MDRS differ from LIMS in that some data fields can
be modified or corrected by the inspector. These correctable fields
include market.
\121\ There were 4,836 samples removed: 4,199 samples were
environmental and not personal samples (see Sample Type explanation
for more detail); 631 samples had been voided after they had been
entered into MSIS; and 6 had invalid Job Codes. This resulted in the
final sample size of 63,127 = 67,963-(4,199 + 631 + 6).
---------------------------------------------------------------------------
Coal Respirable Dust Samples Not Analyzed for Respirable Crystalline
Silica
Similar to MNM respirable dust samples, the LIMS database
includes 45,644 coal samples that did not meet the criteria for
analysis and were thus not analyzed for respirable crystalline
silica content.\122\ After removing 13,243 \123\ samples that were
environmental samples, erroneous, or had voided controls, there were
32,401 samples that were not analyzed for respirable crystalline
silica. The dataset containing the unanalyzed samples that MSHA
retained can be found in the rulemaking docket MSHA-2023-0001.
---------------------------------------------------------------------------
\122\ In addition to the criteria listed above, samples from
Shop Welders (code 319) are not analyzed for respirable crystalline
silica as they are instead analyzed for welding fumes.
\123\ There were 13,243 samples removed: 6 samples had
typographical errors; 14 samples had a cassette mass less than -0.03
mg (based on instrument tolerances, samples that report a cassette
mass between -0.03 mg and 0 mg were treated as having a mass of 0
mg); 92 samples had invalid Job Codes; 12,724 were environmental
samples; 44 samples had an occupation code of 000 despite having a
personal sample `Sample Type'; 271 samples had controls that were
voided; and 92 came from Job Code 319--Welder (see Footnote 119).
This resulted in the final sample size of 32,401 = 50,545-(6 + 14 +
92 + 12,724 + 44 + 271 + 92).
---------------------------------------------------------------------------
All Coal Respirable Dust Samples
In total, 18,079 respirable dust samples from coal mines were
removed from the original datasets: 4,836 samples that were analyzed
for respirable crystalline silica and 13,243 samples that were not.
This created a final dataset of 95,528 samples: 63,127 analyzed
samples and 32,401 samples that were not analyzed.\124\ A breakdown
of respirable dust samples from coal mines is included in Table A-3.
---------------------------------------------------------------------------
\124\ This dataset did not include any other coal mine
respirable dust sample types collected by MSHA inspectors--i.e.,
sample types 3 (designated area samples), types 6 (Non-face
occupations) and 7 (Intake air), samples taken on the surface mine
shop welder (n=319), and all voided samples. Voided samples are any
samples that have a documented reason which occurred during the
sampling and/or laboratory analysis for invalidating the results.
[GRAPHIC] [TIFF OMITTED] TR18AP24.201
[[Page 28435]]
Attachment 1. MNM Samples Analyzed for Cristobalite
Cristobalite is one of the three polymorphs of respirable
crystalline silica. At the request of the inspector, MNM \125\
respirable dust samples that contain at least 0.050 mg of respirable
dust are analyzed for cristobalite. Of the 57,769 retained MNM
samples that contained at least 0.050 mg of respirable dust, 0.6
percent (or 359 samples) were analyzed for cristobalite. Coal
respirable dust samples are not analyzed for cristobalite.\126\
---------------------------------------------------------------------------
\125\ See Attachment 2. Technical Background about Measuring
Respirable Crystalline Silica, for more information.
\126\ See Attachment 2. Technical Background about Measuring
Respirable Crystalline Silica, for more information.
[GRAPHIC] [TIFF OMITTED] TR18AP24.202
While the samples that were analyzed for cristobalite were
assigned to all four contaminant codes seen in this dataset, the
majority were assigned contaminant code 523.
[GRAPHIC] [TIFF OMITTED] TR18AP24.203
The distribution of the 359 samples by cristobalite mass can be
seen in Table A1-3.\127\
---------------------------------------------------------------------------
\127\ Of the 369 samples that were analyzed for cristobalite,
334 had a value for cristobalite mass that was less than the limit
of detection (LOD) for cristobalite, 10[mu]g. As such these samples
were assigned a value of 5[mu]g of cristobalite, one half the LOD.
See Attachment 2. Technical Background about Measuring Respirable
Crystalline Silica, for more information.
[GRAPHIC] [TIFF OMITTED] TR18AP24.204
[[Page 28436]]
The mass of each sample was then used to calculate a
cristobalite concentration by dividing the mass of cristobalite by
the volume of air sampled (0.816 m\3\). The calculated
concentrations ranged from 6[mu]g/m\3\ to 53[mu]g/m\3\.\128\
---------------------------------------------------------------------------
\128\ One sample had a cristobalite concentration of 53[mu]g/
m\3\. It was sampled in July of 2011 at Mine ID 4405407 and cassette
number 610892. The commodity being mined was Stone: Crushed, Broken
Quartzite. The occupation of the miner being sampled was Miners in
Other Occupations: Job Code 513--Building and Maintenance.
[GRAPHIC] [TIFF OMITTED] TR18AP24.205
Attachment 2. Technical Background About Measuring Respirable
Crystalline Silica
In the proposed rule, respirable crystalline silica refers to
three polymorphs: quartz, cristobalite, and tridymite. MSHA's
Laboratory uses two methods to analyze respirable crystalline silica
content in respirable dust samples. The first method, X-ray
diffraction (XRD), separately analyzes quartz, cristobalite, and
tridymite contents in respirable dust samples that mine inspectors
obtain at MNM mine sites (MSHA Method P-2, 2018a). The second
method, Fourier transform infrared spectroscopy (FTIR), is used to
analyze quartz in respirable dust samples obtained at coal mines
(MSHA Method P-7, 2018b and 2020b). Although the XRD method can be
expanded from MNM to coal dust samples, MSHA chooses to use the FTIR
method for coal dust samples because it is a faster and less
expensive method. However, the current MSHA P-7 FTIR method cannot
quantify quartz if cristobalite and/or tridymite are present in the
sample. The method also corrects the quartz result for the presence
of kaolinite, an interfering mineral for quartz analysis when found
in coal dust.
Limits of Detection and Limits of Quantification for Silica Sample Data
The Limits of Detection (LOD) and Limits of Quantification (LOQ)
are the two terms used to describe a method's capability. The LOD
refers to the smallest amount of the target analyte (respirable
crystalline silica) that can be detected in the sample and
distinguished from zero with an acceptable confidence level that the
analyte is actually present. It can also be described as the
instrument signal that is needed to report with a specified
confidence that the analyte is present. The LOQ refers to the
smallest amount of the target analyte that can be repeatedly and
accurately quantified in the sample with a specified precision. The
LOQ is higher than the LOD. The values of the LOD and LOQ are
specific to MSHA's Laboratory as well as the instrumentation and
analytical method used to perform the analysis. These values do not
change from one batch to another when samples are analyzed on the
same equipment using the same method. However, their levels may
change over time due to updated analytical methods and technological
advances. The values of the LOD and LOQ for the methods (XRD and
FTIR) used in analyzing respirable crystalline silica samples are
explained in MSHA documents for MNM samples and coal samples (MSHA
Method P-2, 2018a; MSHA Method P-7, 2018b and 2020b). MSHA
periodically updates these values to reflect progress in its
analytical methods. The values of LOD and LOQ were last updated in
2022 for MNM samples and in 2020 for coal samples.
The values of LODs and LOQs for respirable crystalline silica in
samples from MSHA inspectors depend on several factors, including
the analytical method used (XRD or FTIR) and the silica polymorph
analyzed (quartz, cristobalite, or tridymite), as presented in Table
A2-1.
For a sample with respirable crystalline silica content less
than the method LOD, the maximum concentration is calculated as the
respirable crystalline silica mass equivalent to LOD divided by the
volume of air sampled. For example, the XRD analysis as performed
for a MNM sample, as a method LOD of 5[mu]g. If a such a sample is
analyzed using that method and no quartz is detected and that sample
is collected at 1.7 L/min air flow rate for 480 minutes (i.e., 8
hours), the air sample volume would be 816 L (= 1.7 L/min * 480
minutes), or 0.816 m\3\. The calculated maximum concentration
associated with such sample having respirable crystalline silica
mass below the method LOD would be 6[mu]g/m\3\ (= 5[mu]g/0.816
m\3\). The ``half maximum concentration'' is the midpoint between 0
and the calculated maximum respirable crystalline silica
concentration, which is 3[mu]g/m\3\ (= \1/2\ * 6[mu]g/m\3\) in this
example.
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[[Page 28437]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.206
BILLING CODE 4520-43-C
The air volume is treated differently for MNM and coal samples
under the existing standards. In the case of MNM samples, 8-hour
equivalent time weighted averages (TWAs) are calculated using 480
minutes (8 hours) and a flow rate of 1.7 L/min, even if samples are
collected for a longer duration. In contrast, coal TWAs are
calculated using the full duration of the shift and a flow rate of
2.0 L/min and converted to an MRE equivalent concentration under
existing standards.
Assumptions for Analyzed Samples
Samples from MNM mines that contain at least 0.100 mg of dust
mass are analyzed for the presence of quartz and/or cristobalite.
For samples from coal mines, the minimum amount of respirable dust
for a sample to be analyzed for respirable crystalline silica is
determined by sample type and the occupation of the miner sampled.
For Sample Types 1, 2, and 5, the sample must contain at least 0.100
mg of respirable dust. For Sample Types 4 and 8, the sample must
contain at least 0.200 mg of respirable dust unless it comes from
one of the following occupations: bulldozer operator (MSIS general
occupation code 368), high wall drill operator (code 384), high wall
drill helper (code 383), blaster/shotfirer (code 307), refuse/
backfill truck driver (code 386), and high lift operator/front end
loader (code 382). Samples taken from these occupations must contain
at least 0.100 mg respirable dust to be analyzed for respirable
crystalline silica.
MSHA makes separate assumptions based on the mass of respirable
crystalline silica for a sample, whether it is above or below the
method LOD. For all samples reporting a mass of respirable
crystalline silica greater or equal to the method LOD, MSHA used the
reported values to calculate the respirable crystalline silica
concentration for the sample. For samples with values below the
method LOD, including samples reported as containing 0 [mu]g of
silica, MSHA used \1/2\ of the LOD to calculate the respirable
crystalline silica concentration of the sample. MSHA understands
that its assumptions regarding samples with respirable crystalline
silica mass below the method LOD will have a minimal impact on the
assessment.\129\
---------------------------------------------------------------------------
\129\ In its Final Regulatory Economic Analysis (FREA) for its
2016 silica rule, OSHA observed: `` . . . that XRD analysis of
quartz from samples prepared from reference materials can achieve
LODs and LOQs between 5 and 10 [mu]g was not disputed in the
[rulemaking] record.'' (OSHA, 2016).
---------------------------------------------------------------------------
[[Page 28438]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.207
The reported value of respirable crystalline silica mass from an
MNM or coal sample can fall under one of four groups: (1) at or
above the method LOQ, (2) at or above the method LOD but below the
LOQ, (3) greater than 0 [mu]g but less than the method LOD, or (4)
equal to 0 [micro]g. MSHA treats these samples differently based on
their respirable crystalline silica mass.
Quartz Mass at or Above the Method LOQ
For MNM and coal samples reporting quartz mass at or above the
method LOQs, MSHA uses the values reported by the MSHA's Laboratory.
Quartz Mass Between Method LOD and LOQ
For MNM and coal samples reporting quartz mass at or above the
method LOD but below the LOQ, MSHA uses the values reported by the
MSHA's Laboratory.
Quartz Mass Between the Method LOD and 0 [mu]g
A review of respirable crystalline silica samples in LIMS
reveals that some samples had a respirable crystalline silica mass
below the LOD of the analytical methods but greater than 0 [mu]g.
Values in this range (i.e., below the method LOD but greater than 0
[mu]g) cannot reliably indicate the presence of respirable
crystalline silica. The mass of silica in these is too small to
reliably detect, but the concentration of silica could be up to the
calculated maximum concentration based on the method LOD. For
example, consider a sample from an MNM mine that was analyzed for
quartz and had a reported quartz mass of 4 [mu]g. This falls below
the LOD of 5 [mu]g but above 0 [mu]g, and as such the sample could
actually contain anywhere from 0 [mu]g of quartz up to the LOD value
of 5 [mu]g of quartz.
In these cases, MSHA used \1/2\ the LOD value to calculate
respirable crystalline silica concentration. MSHA explored other
options to treat these samples such as treating the reported silica
mass as 0 [mu]g/m\3\ (lower bound) as well as assuming the sample
silica mass is just below the LOD and assigning each sample a value
of the method LOD (upper bound). The use of the \1/2\ LOD value is
considered a reasonable assumption since using either the lower
bound of 0 [mu]g/m\3\ or the upper bound of the associated method's
LOD could under or overestimate exposures, respectively. The
assumption is not expected to impact the assessment of silica
concentration because any sample results with respirable crystalline
silica mass below the method LODs (between 3-10 [mu]g/m\3\) would
also have been well below the lowest exposure profile range (<25
[mu]g/m\3\).
Quartz Mass of 0 [mu]g
A portion of the MNM and coal samples below the LOD are listed
as having respirable crystalline silica (specifically quartz) mass
levels of 0 [mu]g. For these samples, instead of treating the mass
of silica in the sample as a true zero, MSHA replaced the value with
\1/2\ the LOD of the associated method. Although the respirable
crystalline silica mass of these samples is less than the LOD, it is
likely that the sample still contains a small amount of respirable
crystalline silica. Hence, MSHA assumes a value of \1/2\ LOD in its
calculation of respirable crystalline silica concentration for these
samples. This assumption is considered to be reasonable because
using the lower bound of 0 [mu]g/m\3\ for these samples could
underestimate the respirable crystalline silica concentration while
using the upper bound of method LODs could overestimate the
respirable crystalline silica concentration.
Table A2-3 presents an example for quartz, one of the respirable
crystalline silica polymorphs. This table shows the LOD of quartz
mass and the possible range of quartz concentrations for samples
reporting a quartz mass of 0 [mu]g. These adjusted concentrations
are expected to have a limited impact of the assessment of
respirable crystalline silica concentration, as supported by MSHA's
sensitivity analyses.
[[Page 28439]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.208
Cristobalite Measurement
Respirable dust samples from MNM mines are rarely analyzed for
cristobalite by MSHA, and respirable coal dust samples are not
analyzed for the presence of cristobalite. MNM samples are analyzed
for the presence of cristobalite only when requested by MSHA
inspectors because the geological or work conditions indicate this
specific polymorph may be present. The LIMS database includes
samples for which cristobalite was analyzed, either with or without
quartz analysis. MSHA uses similar assumptions for cristobalite and
quartz.
The cristobalite LOD for these samples is 10 [mu]g. The MSHA
Laboratory-reported values are used for analyzed dust samples with
cristobalite mass values equal to or above the method LODs. Samples
that were analyzed for cristobalite and had a cristobalite mass
value below the method LOD were assigned values of \1/2\ LOD, or 5
[mu]g. For example, 267 samples, or 74.4 percent of the 359 samples
that were analyzed for cristobalite, reported a value of 0 [mu]g of
cristobalite; these were assigned a value of 5 [mu]g.
When a sample is analyzed for two polymorphs (i.e., both quartz
and cristobalite), detectable quartz and cristobalite are summed to
generate the total respirable crystalline silica. If only one of
these polymorphs is detected, the sample concentration is based on
the detected polymorph. If the concentrations of both polymorphs
(quartz and cristobalite) are reported as 0 [mu]g/m\3\, \1/2\ the
LOD mass is assumed in calculating the concentrations and the
resulting concentrations are summed.
Unanalyzed Samples
There are also samples whose dust mass fell below their
associated mass threshold, and as such, they were not analyzed for
the presence of quartz and/or cristobalite. The respirable dust mass
for a sample was considered to be 0 [mu]g when the net mass gain of
dust was 0 [mu]g or less.
References
MSHA. 2018. P-2: X-Ray Diffraction Determination of Quartz and
Cristobalite in Respirable Metal/Nonmetal Mine Dust.
MSHA. 2018a. P-7: Infrared Determination of Quartz in Respirable
Coal Mine Dust.
MSHA. 2020b. P-7: Determination of Quartz in Respirable Coal Mine
Dust by Fourier Transform Infrared Spectroscopy.
OSHA, 2016. Final Regulatory Economic Analysis (FEA) for OSHA's
Final Rule on Respirable Crystalline Silica, Chapter IV.3.2.3--
Sensitivity of Sampling and Analytical Methods.
Appendix B--Mining Commodity Groups
For this final rule, the mining industries are grouped into six
commodities--Coal, Metal, Nonmetal, Stone, Crushed Limestone, and
Sand and Gravel. The table below shows the six commodity groupings
based on the Standard Industrial Classification (SIC) codes and the
2022 North American Industry Classification System (NAICS) codes.
The SIC system is a predecessor of NAICS using industry titles to
standardize industry classification. The NAICS is widely used by
Federal statistical agencies, including the Small Business
Administration (SBA), for classifying business establishments for
the purpose of collecting, analyzing, and publishing statistical
data related to the U.S. business economy.
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[[Page 28440]]
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[[Page 28441]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.210
[[Page 28442]]
BILLING CODE 4520-43-C
Appendix C--Occupational Categories for Respirable Crystalline Silica
Sample Collection
This Appendix explains how MSHA categorized MNM and coal samples
in constructing respirable crystalline silica exposure profile
tables for the final rule. MSHA developed respirable crystalline
silica exposure profile tables using its inspectors' sampling
results. One set of exposure profile tables displays the analysis of
15 years of respirable crystalline silica sampling data collected
from MNM mines (Attachment 1), and the other set displays the
analysis of 5 years of respirable crystalline silica samples
collected from coal mines (Attachment 2).\130\ In the MNM tables,
the respirable crystalline silica concentration information is
broken out by 5 commodities (e.g., ``Metal,'' ``Crushed Limestone,''
etc.) and then by 11 occupational categories (e.g., ``Drillers,''
``Stone Cutting Operators,'' etc.). The data for coal mining is
disaggregated by 2 locations (``Underground'' and ``Surface'') and
then by 9 occupational categories (e.g., ``Crusher Operators,''
``Continuous Mining Machine Operators,'' etc.).
---------------------------------------------------------------------------
\130\ For coal mines, the analysis is based on samples collected
by inspectors beginning on August 1, 2016, when Phase III of MSHA's
2014 RCMD standard went into effect. Samples taken prior to
implementation of the RCMD standard would not be representative of
current respirable crystalline silica exposure levels in coal mines.
---------------------------------------------------------------------------
Job Codes and Respirable Dust Sampling
MSHA inspectors use job codes to label samples of respirable
dust when they conduct health inspections.\131\ Following the
sampling strategy outlined in the most recent MSHA Health Inspection
Procedures Handbook (December 2020; PH20-V-4), the inspectors
determine potential airborne contaminants to which miners may be
exposed, including respirable dust, and then take samples from the
appropriate miners or working areas at a mine. Using gravimetric
samplers, the inspectors collect respirable dust samples at MNM and
coal mines. When submitting the collected samples to MSHA's
Laboratory for analysis, the inspectors label their samples with the
three-digit job code that best describes the duties that each miner
was performing during the sampling period.
---------------------------------------------------------------------------
\131\ The job codes have been referred to as both job codes and
occupation codes by MSHA. For example, in the Mine Data Retrieval
System, they are called job codes; in other materials, including
MSHA's Inspection Application System (IAS), they are called
occupational codes. For the purposes of this document, the term job
code has been used to clearly differentiate the job codes from the
occupational categories.
---------------------------------------------------------------------------
The three-digit job codes are taken from MSHA's Inspection
Application System (IAS), which includes 220 job codes for coal
mines and 121 job codes for MNM mines. Attachments 3 and 4 list the
complete list of IAS job codes for coal and MNM operations,
respectively.
Coal Job Codes: The coal job codes have generally been
consistent over time, with new codes added when needed. In the
three-digit coal job code, the first digit generally identifies
where the work is taking place in the mine: 0 (Underground Section
Workers--Face); 1 (General Underground--Non-Face); 2 (Underground
Transportation--Non-Face); 3 (Surface); 4 (Supervisory and Staff); 5
(MSHA--State); and 6 (Shaft and Slope Sinking). The coal codes
starting with 6 were added in 2020 to better delineate the samples
for miners conducting shaft and slope sinking activities. An example
is presented below in Table C-1. IAS has the same job code for the
duties of a coal ``supervisor/foreman'' as two predecessor
documents--the ``Job Code Pocket Cards'' for coal mining, used by
MSHA's predecessor, the Mining Enforcement and Safety Administration
(MESA) (see Attachment 5), and a Fall 1983 Mine Safety and Health
publication.
[GRAPHIC] [TIFF OMITTED] TR18AP24.211
MNM Job Codes: Many of the 121 MNM job codes are similar to the
coal job codes, as noted in Attachment 4. One major difference is
that unlike the coal job codes, MNM job codes are not based on the
location of the work/job. The first digit of the three-digit MNM job
code does not indicate whether a job is located at an underground or
surface area of the mine. For example, a ``MNM Diamond Drill
Operator'' (Job Code 034) could be working on the surface or
underground, whereas a ``Coal Drill Operator'' would have a
different job code based on the miner's location within a mine (Job
Code 034--underground at the face; Job Code 334--at the surface).
Occupational Categories for the Respirable Crystalline Silica
Rulemaking
Some of the original work to group the MNM job codes into
occupational categories was completed in 2010 in support of earlier
rulemaking efforts. The MNM occupational categories were developed
first and were later updated with additional sampling data as it
became available. The coal occupational categories were developed
several years later and were generally modeled after the MNM tables;
however, coal occupational categories are first divided based on
surface and underground locations because occupational activities at
different locations of a mine can have differing impacts on coal
miners' exposures to respirable crystalline silica. Originally, MSHA
used 9 coal and 14 MNM occupational categories for its respirable
crystalline silica data analyses.
For the respirable crystalline silica exposure profile tables in
the proposed
[[Page 28443]]
respirable crystalline silica rule, MSHA made no change to the 9
coal occupational categories, but condensed the 14 MNM occupational
categories to 11. These occupational categories are meant to
reasonably group multiple job codes with similar occupational
activities/tasks and engineering controls. The grouping of job codes
into occupational categories purposely focused on the occupational
activities/tasks and exposure risk of the miner performing a
particular job rather than the type of mining equipment utilized by
the miner. The creation of occupational categories based on the
types of equipment utilized by miners would have failed to
accurately characterize the risk of individual miners.
Coal Occupational Categories
There are 220 job codes for coal miners in IAS.\132\ Overall,
209 job codes are included in the 9 occupational categories. Some
job codes were excluded, primarily because sampling data were not
available for those job codes. The codes that have been excluded
are:
---------------------------------------------------------------------------
\132\ IAS also contains 272 coal job codes that are used to fill
out a Mine Accident, Injury and Illness Report (MSHA Form 7000-1).
These codes were not included in the respirable crystalline silica
exposure profile tables and are not discussed further in this
document.
---------------------------------------------------------------------------
Job code 0 ``Area,'' because area samples are not
specific to any one occupation.
Job code 398 ``Groundman,'' because there were no
sample data for this code in the respirable crystalline silica
sampling dataset.
Job codes 590 ``Education Specialist,'' 591 ``Mineral
Industrial Safety Officer,'' 592 ``Mine Safety Instructor,'' and 594
``Training Specialist,'' because there were no coal respirable
crystalline silica (quartz) data for these codes for the timeframe
selected.
Job codes 602 ``Electrician,'' 604 ``Mechanic,'' 609
``Supply Person,'' 632 ``Ventilation Worker,'' and 635 ``Continuous
Miner Operator Helper,'' because there were no sample data for these
codes in the respirable crystalline silica sampling dataset.
The remaining 209 coal job codes are first divided by the job
location--underground or surface--because potential respirable
crystalline silica exposures at coal mines can vary depending on
where a miner works at a given mine. (Three job codes are used in
both underground and surface locations: job codes 402 ``Master
Electrician,'' 404 ``Master Mechanic,'' and 497 ``Clerk/
Timekeeper.'') The underground and surface job codes are further
grouped on the basis of the types of tasks and typical engineering
controls. For example, as shown in Figure C-1, the underground
``Continuous Mining Machine Operators'' occupational category
includes 14 different occupations that involve drilling activities--
occupations such as ``Coal Drill Helper,'' ``Coal Drill Operator,''
and ``Rock Driller.'' The underground ``Operators of Large Powered
Haulage Equipment'' occupational category has 12 similar occupations
including ``Loading Machine Operator,'' ``Shuttle Car Operator,''
and ``Motorman.''
Figure C-1: Examples of the Grouping of Coal Job Codes Into Coal
Occupational Categories
[GRAPHIC] [TIFF OMITTED] TR18AP24.085
There are five categories of underground occupations and four
categories of surface occupations.
The five underground occupational categories include:
(1) Continuous Mining Machine Operators (e.g., Coal Drill Helper
and Coal Drill Operator);
(2) Operators of Large Powered Haulage Equipment (e.g., Shuttle
Car, Tractor, Scoop Car);
(3) Longwall Workers (e.g., Headgate Operator and Jack Setter
(Longwall));
(4) Roof Bolters (e.g., Roof Bolter and Roof Bolter Helper); and
(5) Underground Miners (e.g., Electrician, Mechanic, Belt Man/
Conveyor Man, and Laborer, etc.).
The four surface occupational categories include:
(1) Drillers (e.g., Coal Drill Operator, Coal Drill Helper, and
Auger Operator);
(2) Operators of Large Powered Haulage Equipment (e.g., Backhoe,
Forklift, and Shuttle Car);
(3) Crusher Operators (e.g., Crusher Attendant, Washer Operator,
and Scalper-Screen Operator); and
(4) Mobile Workers (e.g., Electrician, Mechanic, Blaster,
Cleanup Man, Mine Foreman, etc.).
Attachments 1 and 3 provide the full lists of occupational
categories and coal job codes.
MNM Occupational Categories
From the 121 MNM job codes in IAS, 120 job codes are included in
the occupational categories and 1 job code is excluded. The code
that has been excluded is:
Job code 413 ``Janitor,'' because there were no sample
data for this code in the respirable crystalline silica sampling
dataset.
Of the 120 job codes included, 1 job code was listed in both the
``Crushing Equipment and Plant Operators'' occupational category and
the ``Kiln, Mill and Concentrator Workers'' category. The code that
was used twice is:
Job Code 388 ``Screen/Scalper Operators,'' because MNM
job codes do not indicate the location where the work is taking
place and this work can be conducted either in a plant or on the
surface of the mine.
The final 121 MNM job codes (with job code 388 included twice)
were first grouped into 14 occupational categories based on the
types of tasks and typical engineering controls used. For example,
as seen in Figure C-2, the ``Drillers'' occupational category
includes the 20 different occupations that involve drilling
activities, such as ``Diamond Drill Operator,'' ``Drill Operator
Churn,'' and ``Continuous Miner Operator.'' ``Belt Cleaner,'' ``Belt
Crew,'' and ``Belt Vulcanizer'' are included in the occupational
category, ``Conveyor Operators.'' Similar tasks were grouped
together because the work activities and respirable crystalline
silica exposures were anticipated to be comparable.
Figure C-2: Examples of the Grouping of MNM Job Codes Into MNM
Occupational Categories
[[Page 28444]]
[GRAPHIC] [TIFF OMITTED] TR18AP24.086
The 14 occupational categories were:
(1) Bagging Machines;
(2) Stone Saws;
(3) Stone Trimmers, Splitters;
(4) Truck Loading Stations;
(5) Mobile Workers (e.g., Laborers, Electricians, Mechanics, and
Supervisors);
(6) Conveyors;
(7) Crushers;
(8) Dry Screening Plants;
(9) Kilns/Dryers, Rotary Mills, Ball Mills, and Flotation/
Concentrators;
(10) Large Powered Haulage Equipment (e.g., Trucks, FELs,
Bulldozers, and Scalers);
(11) Small Powered Haulage Equipment (e.g., Bobcats and
Forklifts);
(12) Jackhammers;
(13) Drills; and
(14) Other Occupations.
After additional consideration, it was determined that the
original 14 categories could be further condensed into the final 11
categories since some of the occupational categories contained job
codes where the types of tasks and engineering and administrative
controls were similar enough to be combined.
The final 11 occupational categories include:
(1) Drillers (e.g., Diamond Drill Operator, Wagon Drill
Operator, and Drill Helper);
(2) Stone Cutting Operators (e.g., Jackhammer Operator, Cutting
Machine Operator, and Cutting Machine Helper);
(3) Operators of Large Powered Haulage Equipment (e.g., Trucks,
Bulldozers, and Scalers);
(4) Conveyor Operators (e.g., Belt Cleaner, Belt Crew, and Belt
Vulcanizer);
(5) Crushing Equipment and Plant Operators (Crusher Operator/
Worker, Scalper Screen Operator, and Dry Screen Plant Operator);
(6) Kiln, Mill, and Concentrator Workers (e.g., Ball Mill
Operator, Leaching Operator, and Pelletizer Operator);
(7) Operators of Small Powered Haulage Equipment (e.g., Bobcats,
Shuttle Car, and Forklifts);
(8) Packaging Equipment Operators (e.g., Bagging Operator and
Packaging Operations Worker);
(9) Truck Loading Station Tenders (e.g., Dump Operator and Truck
Loader);
(10) Mobile Workers (Laborers, Electricians, Mechanics, and
Supervisors, etc.); and
(11) Miners in Other Occupations (Welder, Dragline Operator,
Shotcrete/Gunite Man, and Dredge/Barge Operator, etc.).
The sampling data for each of the 11 occupational categories
were then summarized by commodity group (``Metal,'' ``Nonmetal,''
``Stone,'' ``Crushed Limestone,'' and ``Sand and Gravel'') based on
the material being extracted.\133\ The available sampling data were
then collated for each occupation and commodity and summarized by
concentration ranges in the exposure profile tables for MNM mines.
---------------------------------------------------------------------------
\133\ Crushed Limestone and Sand and Gravel were considered
separately because these commodities make up a large percentage of
inspection samples. Watts et al. (2012). Respirable crystalline
silica [Quartz] Concentration Trends in Metal and Nonmetal Mining, J
Occ Environ Hyg 9:12, 720-732.
---------------------------------------------------------------------------
BILLING CODE 4520-43-P
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BILLING CODE 4520-43-C
List of Subjects
30 CFR Part 56
Chemicals, Electric power, Explosives, Fire prevention, Hazardous
substances, Incorporation by reference, Metal and nonmetal mining, Mine
safety and health, Noise control, Reporting and recordkeeping
requirements, Surface mining.
30 CFR Part 57
Chemicals, Electric power, Explosives, Fire prevention, Gases,
Hazardous substances, Incorporation by reference, Metal and nonmetal
mining, Mine safety and health, Noise control, Radiation protection,
Reporting and recordkeeping requirements, Underground mining.
30 CFR Part 60
Coal, Incorporation by reference, Metal and nonmetal mining,
Medical surveillance, Mine safety and health, Respirable crystalline
silica, Reporting and recordkeeping requirements, Surface mining,
Underground mining.
30 CFR Part 70
Coal, Mine safety and health, Reporting and recordkeeping
requirements, Respirable dust, Underground coal mines.
30 CFR Part 71
Coal, Mine safety and health, Reporting and recordkeeping
requirements, Surface coal mines, Underground coal mines.
30 CFR Part 72
Coal, Health standards, Incorporation by reference, Mine safety and
health, Training, Underground mining.
30 CFR Part 75
Coal, Mine safety and health, Reporting and recordkeeping
requirements, Underground coal mines, Ventilation.
30 CFR Part 90
Coal, Mine safety and health, Reporting and recordkeeping
requirements, Respirable dust.
Christopher J. Williamson,
Assistant Secretary of Labor for Mine Safety and Health.
For the reasons discussed in the preamble, the Mine Safety and
Health Administration is amending 30 CFR subchapters K, M, and O as
follows:
Subchapter K--Metal and Nonmetal Mine Safety and Health
PART 56--SAFETY AND HEALTH STANDARDS--SURFACE METAL AND NONMETAL
MINES
0
1. The authority citation for part 56 continues to read as follows:
Authority: 30 U.S.C. 811.
Subpart D--Air Quality and Physical Agents
0
2. Amend Sec. 56.5001 by revising the introductory text to read as
follows:
Sec. 56.5001 Exposure limits for airborne contaminants.
The following is required until April 7, 2026. Except as permitted
by Sec. 56.5005--
* * * * *
0
3. Add Sec. 56.5001T to read as follows:
Sec. 56.5001T Exposure limits for airborne contaminants.
As of April 8, 2026 the following is required, except as permitted
by Sec. 56.5005--
(a) TLVs standard. Except as provided in paragraph (b) of this
section and in part 60 of this chapter, the exposure to airborne
contaminants shall not exceed, on the basis of a time weighted average,
the threshold limit values adopted by the American Conference of
Governmental Industrial Hygienists, as set forth and explained in the
1973 edition of the Conference's publication, entitled TLV's Threshold
Limit Values for Chemical Substances in Workroom Air Adopted by ACGIH
for 1973, pages 1 through 54. This publication is incorporated by
reference into this section with the approval of the Director of the
Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. This
incorporation by reference (IBR) material is available for inspection
at the Mine Safety and Health Administration (MSHA) and at the National
Archives and Records Administration (NARA). Contact MSHA at: MSHA's
Office of Standards, Regulations, and Variances, 201 12th Street South,
Arlington, VA 22202-5450; (202) 693-9440; or at any Mine Safety and
Health Enforcement District Office. For information on the availability
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected]. The material may be
obtained from American Conference of Governmental Industrial
Hygienists, 1330 Kemper Meadow Drive, Attn: Customer Service,
Cincinnati, OH 45240; www.acgih.org.
(b) Asbestos standard--(1) Definitions. Asbestos is a generic term
for a number of asbestiform hydrated silicates that, when crushed or
processed, separate into flexible fibers made up of fibrils.
Asbestos means chrysotile, cummingtonite-grunerite asbestos
(amosite), crocidolite, anthophylite
[[Page 28469]]
asbestos, tremolite asbestos, and actinolite asbestos.
Asbestos fiber means a fiber of asbestos that meets the criteria of
a fiber.
Fiber means a particle longer than 5 micrometers ([micro]m) with a
length-to-diameter ratio of at least 3-to-1.
(2) Permissible Exposure Limits (PELs)--(i) Full-shift limit. A
miner's personal exposure to asbestos shall not exceed an 8-hour time-
weighted average full-shift airborne concentration of 0.1 fiber per
cubic centimeter of air (f/cc).
(ii) Excursion limit. No miner shall be exposed at any time to
airborne concentrations of asbestos in excess of 1 fiber per cubic
centimeter of air (f/cc) as averaged over a sampling period of 30
minutes.
(3) Measurement of airborne asbestos fiber concentration. Potential
asbestos fiber concentration shall be determined by phase contrast
microscopy (PCM) using the OSHA Reference Method in OSHA's asbestos
standard found in 29 CFR 1910.1001, Appendix A, or a method at least
equivalent to that method in identifying a potential asbestos exposure
exceeding the 0.1 f/cc full-shift limit or the 1 f/cc excursion limit.
When PCM results indicate a potential exposure exceeding the 0.1 f/cc
full-shift limit or the 1 f/cc excursion limit, samples shall be
further analyzed using transmission electron microscopy according to
NIOSH Method 7402 or a method at least equivalent to that method.
(c) Required action. Employees shall be withdrawn from areas where
there is present an airborne contaminant given a ``C'' designation by
the Conference and the concentration exceeds the threshold limit value
listed for that contaminant.
Sec. 56.5001 [Removed]
0
4. Effective April 8, 2026, remove Sec. 56.5001.
Sec. 56.5001T [Redesignated as Sec. 56.5001]
0
5. Effective April 8, 2026, redesignate Sec. 56.5001T as Sec.
56.5001.
0
6. Amend Sec. 56.5005 by revising the introductory text to read as
follows:
Sec. 56.5005 Control of exposure to airborne contaminants.
The following is required until April 7, 2026. Control of employee
exposure to harmful airborne contaminants shall be, insofar as
feasible, by prevention of contamination, removal by exhaust
ventilation, or by dilution with uncontaminated air. However, where
accepted, engineering control measures have not been developed or when
necessary by the nature of work involved (for example, while
establishing controls or occasional entry into hazardous atmospheres to
perform maintenance or investigation), employees may work for
reasonable periods of time in concentrations of airborne contaminants
exceeding permissible levels if they are protected by appropriate
respiratory protective equipment. Whenever respiratory protective
equipment is used a program for selection, maintenance, training,
fitting, supervision, cleaning, and use shall meet the following
minimum requirements:
* * * * *
0
7. Add Sec. 56.5005T to read as follows:
Sec. 56.5005T Control of exposure to airborne contaminants.
As of April 8, 2026, the following is required. Control of employee
exposure to harmful airborne contaminants shall be, insofar as
feasible, by prevention of contamination, removal by exhaust
ventilation, or by dilution with uncontaminated air. However, where
accepted engineering control measures have not been developed or when
necessary by the nature of work involved (for example, while
establishing controls or occasional entry into hazardous atmospheres to
perform maintenance or investigation), employees may work for
reasonable periods of time in concentrations of airborne contaminants
exceeding permissible levels if they are protected by appropriate
respiratory protective equipment. Whenever respiratory protective
equipment is used, its selection, fitting, maintenance, cleaning,
training, supervision, and use shall meet the following minimum
requirements:
(a) Respirators approved by NIOSH under 42 CFR part 84 which are
applicable and suitable for the purpose intended shall be furnished and
miners shall use the protective equipment in accordance with training
and instruction.
(b) A written respiratory protection program consistent with the
requirements of ASTM F3387-19, Standard Practice for Respiratory
Protection, approved August 1, 2019, which is incorporated by reference
into this section with the approval of the Director of the Federal
Register under 5 U.S.C. 552(a) and 1 CFR part 51. This incorporation by
reference (IBR) material is available for inspection at the Mine Safety
and Health Administration (MSHA) and at the National Archives and
Records Administration (NARA). Contact MSHA at: MSHA's Office of
Standards, Regulations, and Variances, 201 12th Street South,
Arlington, VA 22202-5450; (202) 693-9440; or any Mine Safety and Health
Enforcement District Office. For information on the availability of
this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected]. The material may be obtained
from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428-2959; www.astm.org.
(c) When respiratory protection is used in atmospheres immediately
dangerous to life or health (IDLH), the presence of at least one other
person with backup equipment and rescue capability shall be required in
the event of failure of the respiratory equipment.
Sec. 56.5005 [Removed]
0
8. Effective April 8, 2026, remove Sec. 56.5005.
Sec. 56.5005T [Redesignated as Sec. 56.5005]
0
9. Effective April 8, 2026, redesignate Sec. 56.5005T as Sec.
56.5005.
PART 57--SAFETY AND HEALTH STANDARDS--UNDERGROUND METAL AND
NONMETAL MINES
0
10. The authority citation for part 57 continues to read as follows:
Authority: 30 U.S.C. 811.
Subpart D--Air Quality, Radiation, Physical Agents, and Diesel
Particulate Matter
0
11. Amend Sec. 57.5001 by revising the introductory text to read as
follows:
Sec. 57.5001 Exposure limits for airborne contaminants.
The following is required until April 7, 2026. Except as permitted
by Sec. 57.5005--
* * * * *
0
12. Add Sec. 57.5001T to read as follows:
Sec. 57.5001T Exposure limits for airborne contaminants.
As of April 8, 2026, except as permitted by Sec. 57.5005--
(a) TLVs standard. Except as provided in paragraph (b) of this
section and in part 60 of this chapter, the exposure to airborne
contaminants shall not exceed, on the basis of a time weighted average,
the threshold limit values adopted by the American Conference of
Governmental Industrial Hygienists, as set forth and explained in the
1973 edition of the Conference's publication, entitled TLV's Threshold
Limit Values for Chemical Substances in Workroom Air Adopted by ACGIH
for 1973, pages 1 through 54. This publication is incorporated by
reference into this section with the approval of the Director of the
Federal Register under 5 U.S.C.
[[Page 28470]]
552(a) and 1 CFR part 51. This incorporation by reference (IBR)
material is available for inspection at the Mine Safety and Health
Administration (MSHA) and at the National Archives and Records
Administration (NARA). Contact MSHA at: MSHA's Office of Standards,
Regulations, and Variances, 201 12th Street South, Arlington, VA 22202-
5450; (202) 693-9440; or at any Mine Safety and Health Enforcement
District Office. For information on the availability of this material
at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or
email [email protected]. The material may be obtained from
American Conference of Governmental Industrial Hygienists, 1330 Kemper
Meadow Drive, Attn: Customer Service, Cincinnati, OH 45240;
www.acgih.org.
(b) Asbestos standard--(1) Definitions. Asbestos is a generic term
for a number of asbestiform hydrated silicates that, when crushed or
processed, separate into flexible fibers made up of fibrils.
Asbestos means chrysotile, cummingtonite-grunerite asbestos
(amosite), crocidolite, anthophylite asbestos, tremolite asbestos, and
actinolite asbestos.
Asbestos fiber means a fiber of asbestos that meets the criteria of
a fiber.
Fiber means a particle longer than 5 micrometers ([micro]m) with a
length-to-diameter ratio of at least 3-to-1.
(2) Permissible Exposure Limits (PELs)--(i) Full-shift limit. A
miner's personal exposure to asbestos shall not exceed an 8-hour time-
weighted average full-shift airborne concentration of 0.1 fiber per
cubic centimeter of air (f/cc).
(ii) Excursion limit. No miner shall be exposed at any time to
airborne concentrations of asbestos in excess of 1 fiber per cubic
centimeter of air (f/cc) as averaged over a sampling period of 30
minutes.
(3) Measurement of airborne asbestos fiber concentration. Potential
asbestos fiber concentration shall be determined by phase contrast
microscopy (PCM) using the OSHA Reference Method in OSHA's asbestos
standard found in 29 CFR 1910.1001, Appendix A, or a method at least
equivalent to that method in identifying a potential asbestos exposure
exceeding the 0.1 f/cc full-shift limit or the 1 f/cc excursion limit.
When PCM results indicate a potential exposure exceeding the 0.1 f/cc
full-shift limit or the 1 f/cc excursion limit, samples shall be
further analyzed using transmission electron microscopy according to
NIOSH Method 7402 or a method at least equivalent to that method.
(c) Required action. Employees shall be withdrawn from areas where
there is present an airborne contaminant given a ``C'' designation by
the Conference and the concentration exceeds the threshold limit value
listed for that contaminant.
Sec. 57.5001 [Removed]
0
13. April 8, 2026, remove Sec. 57.5001.
Sec. 57.5001T [Redesignated as Sec. 57.5001]
0
14. Effective April 8, 2026, redesignate Sec. 57.5001T as Sec.
57.5001.
0
15. Amend Sec. 57.5005 by revising the introductory text to read as
follows:
Sec. 57.5005 Control of exposure to for airborne contaminants.
The following is required until April 7, 2026. Control of employee
exposure to harmful airborne contaminants shall be, insofar as
feasible, by prevention of contamination, removal by exhaust
ventilation, or by dilution with uncontaminated air. However, where
accepted engineering control measures have not been developed or when
necessary by the nature of work involved (for example, while
establishing controls or occasional entry into hazardous atmospheres to
perform maintenance or investigation), employees may work for
reasonable periods of time in concentrations of airborne contaminants
exceeding permissible levels if they are protected by appropriate
respiratory protective equipment. Whenever respiratory protective
equipment is used a program for selection, maintenance, training,
fitting, supervision, cleaning, and use shall meet the following
minimum requirements:
* * * * *
0
16. Add Sec. 57.5005T to read as follows:
Sec. 57.5005T Control of exposure to airborne contaminants.
As of April 8, 2026, the following is required. Control of employee
exposure to harmful airborne contaminants shall be, insofar as
feasible, by prevention of contamination, removal by exhaust
ventilation, or by dilution with uncontaminated air. However, where
accepted engineering control measures have not been developed or when
necessary by the nature of work involved (for example, while
establishing controls or occasional entry into hazardous atmospheres to
perform maintenance or investigation), employees may work for
reasonable periods of time in concentrations of airborne contaminants
exceeding permissible levels if they are protected by appropriate
respiratory protective equipment. Whenever respiratory protective
equipment is used, its selection, fitting, maintenance, cleaning,
training, supervision, and use shall meet the following minimum
requirements:
(a) Respirators approved by NIOSH under 42 CFR part 84 which are
applicable and suitable for the purpose intended shall be furnished and
miners shall use the protective equipment in accordance with training
and instruction.
(b) A written respiratory protection program consistent with the
requirements of ASTM F3387-19, Standard Practice for Respiratory
Protection, approved August 1, 2019, which is incorporated by reference
into this section with the approval of the Director of the Federal
Register under 5 U.S.C. 552(a) and 1 CFR part 51. This incorporation by
reference (IBR) material is available for inspection at the Mine Safety
and Health Administration (MSHA) and at the National Archives and
Records Administration (NARA). Contact MSHA at: MSHA's Office of
Standards, Regulations, and Variances, 201 12th Street South,
Arlington, VA 22202-5450; (202) 693-9440; or any Mine Safety and Health
Enforcement District Office. For information on the availability of
this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected]. The material may be obtained
from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428-2959; www.astm.org.
(c) When respiratory protection is used in atmospheres immediately
dangerous to life or health (IDLH), the presence of at least one other
person with backup equipment and rescue capability shall be required in
the event of failure of the respiratory equipment.
Sec. 57.5005 [Removed]
0
17. Effective April 8, 2026, remove Sec. 57.5005.
Sec. 57.5005T [Redesignated as Sec. 57.5005]
0
18. Effective April 8, 2026, redesignate Sec. 57.5005T as Sec.
57.5005.
Subchapter M--Uniform Mine Health Regulations
0
19. Add part 60 to subchapter M to read as follows:
PART 60--RESPIRABLE CRYSTALLINE SILICA
Sec.
60.1 Scope; compliance dates.
60.2 Definitions.
60.10 Permissible exposure limit (PEL).
60.11 Methods of compliance.
60.12 Exposure monitoring.
60.13 Corrective actions.
[[Page 28471]]
60.14 Respiratory protection.
60.15 Medical surveillance for metal and nonmetal mines.
60.16 Recordkeeping requirements.
60.17 Severability.
Authority: 30 U.S.C. 811, 813(h) and 957.
Sec. 60.1 Scope; compliance dates.
(a) This part sets forth mandatory health standards for each
surface and underground metal, nonmetal, and coal mine subject to the
Federal Mine Safety and Health Act of 1977, as amended. Requirements
regarding medical surveillance for metal and nonmetal mines are also
included.
(b) The compliance dates for the provisions of this part are as
follows:
(1) For coal mine operators, April 14, 2025.
(2) For metal and nonmetal mine operators, April 8, 2026.
Sec. 60.2 Definitions.
The following definitions apply in this part:
Action level means an airborne concentration of respirable
crystalline silica of 25 micrograms per cubic meter of air ([mu]g/m\3\)
for a full-shift exposure, calculated as an 8-hour time-weighted
average (TWA).
Respirable crystalline silica means quartz, cristobalite, and/or
tridymite contained in airborne particles that are determined to be
respirable by a sampling device designed to meet the characteristics
for respirable-particle-size-selective samplers that conform to the
International Organization for Standardization (ISO) 7708:1995: Air
Quality--Particle Size Fraction Definitions for Health-Related
Sampling.
Specialist means an American Board-Certified Specialist in
Pulmonary Disease or an American Board-Certified Specialist in
Occupational Medicine.
Sec. 60.10 Permissible exposure limit (PEL).
The mine operator shall ensure that no miner is exposed to an
airborne concentration of respirable crystalline silica in excess of 50
[mu]g/m\3\ for a full-shift exposure, calculated as an 8-hour TWA.
Sec. 60.11 Methods of compliance.
(a) The mine operator shall install, use, and maintain feasible
engineering controls, supplemented by administrative controls when
necessary, to keep each miner's exposure at or below the PEL, except as
specified in Sec. 60.14.
(b) Rotation of miners shall not be considered an acceptable
administrative control used for compliance with this part.
Sec. 60.12 Exposure monitoring.
(a) Sampling. (1) Mine operators shall commence sampling by the
compliance date in Sec. 60.1 to assess the full shift, 8-hour TWA
exposure of respirable crystalline silica for each miner who is or may
reasonably be expected to be exposed to respirable crystalline silica.
(2) If the sampling under paragraph (a)(1) of this section is:
(i) Below the action level, the mine operator shall take at least
one additional sampling within 3 months.
(ii) At or above the action level but at or below the PEL, the mine
operator shall take another sampling within 3 months.
(iii) Above the PEL, the mine operator shall take corrective
actions and sample pursuant to Sec. 60.12(b).
(3) Where the most recent sampling indicates that miner exposures
are at or above the action level but at or below the PEL, the mine
operator shall continue to sample within 3 months of the previous
sampling.
(4) The mine operator may discontinue sampling when two consecutive
samplings indicate that miner exposures are below the action level. The
second of these samplings must be taken after the operator receives the
results of the prior sampling but no sooner than 7 days after the prior
sampling was conducted.
(b) Corrective actions sampling. Where the most recent sampling
indicates that miner exposures are above the PEL, the mine operator
shall sample after corrective actions are taken pursuant to Sec. 60.13
until the sampling indicates that miner exposures are at or below the
PEL. The mine operator shall immediately report all operator samples
above the PEL to the MSHA District Manager or to any other MSHA office
designated by the District Manager.
(c) Periodic evaluation. At least every 6 months after commencing
sampling under 60.12(a)(1) or whenever there is a change in:
production; processes; installation or maintenance of engineering
controls; installation or maintenance of equipment; administrative
controls; or geological conditions; mine operators shall evaluate
whether the change may reasonably be expected to result in new or
increased respirable crystalline silica exposures. Once the evaluation
is completed, the mine operator shall:
(1) Make a record of the evaluation, including the evaluated
change, the impact on respirable crystalline silica exposure, and the
date of the evaluation; and
(2) Post the record on the mine bulletin board and, if applicable,
by electronic means, for the next 31 days.
(d) Post-evaluation sampling. If the mine operator determines as a
result of the periodic evaluation under paragraph (c) of this section
that miners may be exposed to respirable crystalline silica at or above
the action level, the mine operator shall perform sampling to assess
the full shift, 8-hour TWA exposure of respirable crystalline silica
for each miner who is or may reasonably be expected to be at or above
the action level.
(e) Sampling requirements. (1) Sampling shall be performed for the
duration of a miner's regular full shift and during typical mining
activities, including shaft and slope sinking, construction, and
removal of overburden.
(2) The full-shift, 8-hour TWA exposure for such miners shall be
measured based on:
(i) Personal breathing-zone air samples for metal and nonmetal
operations; or
(ii) Occupational environmental samples collected in accordance
with Sec. 70.201(c), Sec. 71.201(b), or Sec. 90.201(b) of this
chapter for coal operations.
(3) Where several miners perform the same tasks on the same shift
and in the same work area, the mine operator may sample a
representative fraction (at least two) of these miners to meet the
requirements in paragraphs (a) through (e) of this section. In sampling
a representative fraction of miners, the mine operator shall select the
miners who are expected to have the highest exposure to respirable
crystalline silica.
(4) The mine operator shall use respirable-particle-size-selective
samplers that conform to ISO 7708:1995(E) to determine compliance with
the PEL. ISO 7708:1995(E), Air quality--Particle size fraction
definitions for health-related sampling, First Edition, 1995-04-01, is
incorporated by reference into this section with the approval of the
Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part
51. This incorporation by reference (IBR) material is available for
inspection at the Mine Safety and Health Administration (MSHA) and at
the National Archives and Records Administration (NARA). Contact MSHA
at: MSHA's Office of Standards, Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202-5450; (202) 693-9440; or any Mine
Safety and Health Enforcement District Office. For information on the
availability of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected]. The
material may be obtained from the International Organization for
[[Page 28472]]
Standardization (ISO), CP 56, CH-1211 Geneva 20, Switzerland; phone: +
41 22 749 01 11; fax: + 41 22 733 34 30; website: www.iso.org.
(f) Methods of sample analysis. (1) The mine operator shall use a
laboratory that is accredited to ISO/IEC 17025 ``General requirements
for the competence of testing and calibration laboratories'' with
respect to respirable crystalline silica analyses, where the
accreditation has been issued by a body that is compliant with ISO/IEC
17011 ``Conformity assessment--Requirements for accreditation bodies
accrediting conformity assessment bodies.''
(2) The mine operator shall ensure that the laboratory evaluates
all samples using respirable crystalline silica analytical methods
specified by MSHA, the National Institute for Occupational Safety and
Health (NIOSH), or the Occupational Safety and Health Administration
(OSHA).
(g) Sampling records. For each sample taken pursuant to paragraphs
(a) through (e) of this section, the mine operator shall make a record
of the sample date, the occupations sampled, and the concentrations of
respirable crystalline silica and respirable dust and post the record
and the laboratory report on the mine bulletin board and, if
applicable, by electronic means, for the next 31 days, upon receipt.
Sec. 60.13 Corrective actions.
(a) If any sampling indicates that a miner's exposure exceeds the
PEL, the mine operator shall:
(1) Make approved respirators available to affected miners before
the start of the next work shift in accordance with Sec. 60.14(b) and
(c);
(2) Ensure that affected miners wear respirators properly for the
full shift or during the period of overexposure until miner exposures
are at or below the PEL; and
(3) Immediately take corrective actions to lower the concentration
of respirable crystalline silica to at or below the PEL.
(b) Once corrective actions have been taken, the mine operator
shall:
(1) Conduct sampling pursuant to Sec. 60.12(b); and
(2) Take additional or new corrective actions until sampling
indicates miner exposures are at or below the PEL.
(c) The mine operator shall make a record of corrective actions and
the dates of the corrective actions under paragraph (a) of this
section.
Sec. 60.14 Respiratory protection.
(a) Temporary use of respirators at metal and nonmetal mines. The
metal and nonmetal mine operator shall use respiratory protection as a
temporary measure in accordance with paragraph (c) of this section when
miners must work in concentrations of respirable crystalline silica
above the PEL while:
(1) Engineering control measures are being developed and
implemented; or
(2) It is necessary by the nature of work involved (for example,
occasional entry into hazardous atmospheres to perform maintenance or
investigation).
(b) Miners unable to wear respirators at all mines. Upon written
determination by a physician or other licensed health care professional
(PLHCP) that an affected miner is unable to wear a respirator, the
miner shall be temporarily transferred either to work in a separate
area of the same mine or to an occupation at the same mine where
respiratory protection is not required.
(1) The affected miner shall continue to receive compensation at no
less than the regular rate of pay in the occupation held by that miner
immediately prior to the transfer.
(2) The affected miner may be transferred back to the miner's
initial work area or occupation when temporary use of respirators under
paragraph (a) of this section or section 60.13 is no longer required.
(c) Respiratory protection requirements at all mines. (1) Affected
miners shall be provided with a NIOSH-approved atmosphere-supplying
respirator or NIOSH-approved air-purifying respirator equipped with the
following:
(i) Particulate protection classified as 100 series under 42 CFR
part 84; or
(ii) Particulate protection classified as High Efficiency ``HE''
under 42 CFR part 84.
(2) When approved respirators are used, the mine operator must have
a written respiratory protection program that meets the following
requirements in accordance with ASTM F3387-19: program administration;
written standard operating procedures; medical evaluation; respirator
selection; training; fit testing; maintenance, inspection, and storage.
ASTM F3387-19, Standard Practice for Respiratory Protection, approved
August 1, 2019, is incorporated by reference into this section with the
approval of the Director of the Federal Register under 5 U.S.C. 552(a)
and 1 CFR part 51. This incorporation by reference (IBR) material is
available for inspection at the Mine Safety and Health Administration
(MSHA) and at the National Archives and Records Administration (NARA).
Contact MSHA at: MSHA's Office of Standards, Regulations, and
Variances, 201 12th Street South, Arlington, VA 22202-5450; (202) 693-
9440; or any Mine Safety and Health Enforcement District Office. For
information on the availability of this material at NARA, visit
www.archives.gov/federal-register/cfr/ibr-locations or email
[email protected]. The material may be obtained from ASTM
International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken,
PA 19428-2959; www.astm.org.
Sec. 60.15 Medical surveillance for metal and nonmetal mines.
(a) Medical surveillance. Each operator of a metal and nonmetal
mine shall provide to each miner periodic medical examinations
performed by a physician or other licensed health care professional
(PLHCP) or specialist, as defined in Sec. 60.2, at no cost to the
miner.
(1) Medical examinations shall be provided at frequencies specified
in this section.
(2) Medical examinations shall include:
(i) A medical and work history, with emphasis on: past and present
exposure to respirable crystalline silica, dust, and other agents
affecting the respiratory system; any history of respiratory system
dysfunction, including diagnoses and symptoms of respiratory disease
(e.g., shortness of breath, cough, wheezing); history of tuberculosis;
and smoking status and history;
(ii) A physical examination with special emphasis on the
respiratory system;
(iii) A chest X-ray (a single posteroanterior radiographic
projection or radiograph of the chest at full inspiration recorded on
either film (no less than 14 x 17 inches and no more than 16 x 17
inches) or digital radiography systems), classified according to the
International Labour Office (ILO) International Classification of
Radiographs of Pneumoconioses by a NIOSH-certified B Reader; and
(iv) A pulmonary function test to include forced vital capacity
(FVC) and forced expiratory volume in one second (FEV1) and
FEV1/FVC ratio, administered by a spirometry technician with
a current certificate from a NIOSH-approved Spirometry Program Sponsor
or by a pulmonary function technologist with a current credential from
the National Board for Respiratory Care.
(b) Voluntary medical examinations. Each mine operator shall
provide the opportunity to all miners employed at the mine to have the
medical examinations specified in paragraph (a) of this section as
follows:
[[Page 28473]]
(1) During an initial 12-month period; and
(2) At least every 5 years after the end of the period in paragraph
(b)(1). The medical examinations shall be available during a 6-month
period that begins no less than 3.5 years and not more than 4.5 years
from the end of the last 6-month period.
(c) Mandatory medical examinations. For each miner who begins work
in the mining industry for the first time, the mine operator shall
provide medical examinations specified in paragraph (a) of this section
as follows:
(1) An initial medical examination no later than 60 days after
beginning employment;
(2) A follow-up medical examination no later than 3 years after the
initial examination in paragraph (c)(1) of this section; and
(3) A follow-up medical examination conducted by a specialist no
later than 2 years after the examinations in paragraph (c)(2) of this
section if the chest X-ray shows evidence of pneumoconiosis or the
spirometry examination indicates evidence of decreased lung function.
(d) Medical examinations results. (1) The mine operator shall
ensure that the results of medical examinations or tests made pursuant
to this section shall be provided from the PLHCP or specialist within
30 days of the medical examination to the miner, and at the request of
the miner, to the miner's designated physician or another designee
identified by the miner.
(2) The mine operator shall ensure that, within 30 days of the
medical examination, the PLHCP or specialist provides the results of
chest X-ray classifications to the National Institute for Occupational
Safety and Health (NIOSH), once NIOSH establishes a reporting system.
(e) Written medical opinion. The mine operator shall obtain a
written medical opinion from the PLHCP or specialist within 30 days of
the medical examination. The written opinion shall contain only the
following:
(1) The date of the medical examination;
(2) A statement that the examination has met the requirements of
this section; and
(3) Any recommended limitations on the miner's use of respirators.
(f) Written medical opinion records. The mine operator shall
maintain a record of the written medical opinions received from the
PLHCP or specialist under paragraph (e) of this section.
Sec. 60.16 Recordkeeping requirements.
(a) Table 1 to this paragraph (a) lists the records the mine
operator shall retain and their retention period.
(1) Evaluation records made under Sec. 60.12(c) shall be retained
for at least 5 years from the date of each evaluation.
(2) Sampling records made under Sec. 60.12(g) shall be retained
for at least 5 years from the sample date.
(3) Corrective actions records made under Sec. 60.13(c) shall be
retained for at least 5 years from the date of each corrective action.
These records must be stored with the records of related sampling under
Sec. 60.12(g).
(4) Written determination records received from a PLHCP under Sec.
60.14(b) shall be retained for the duration of the miner's employment
plus 6 months.
(5) Written medical opinion records received from a PLHCP or
specialist under Sec. 60.15(f) shall be retained for the duration of
the miner's employment plus 6 months.
Table 1 to Paragraph (a)--Recordkeeping Requirements
------------------------------------------------------------------------
Section
Record references Retention period
------------------------------------------------------------------------
1. Evaluation records.......... Sec. At least 5 years from
60.12(c) date of each
evaluation.
2. Sampling records............ Sec. At least 5 years from
60.12(g) sample date.
3. Corrective actions records.. Sec. At least 5 years from
60.13(c) date of each
corrective action.
4. Written determination Sec. Duration of miner's
records received from a PLHCP. 60.14(b) employment plus 6
months.
5. Written medical opinion Sec. Duration of miner's
records received from a PLHCP 60.15(f) employment plus 6
or specialist. months.
------------------------------------------------------------------------
(b) Upon request from an authorized representative of the
Secretary, from an authorized representative of miners, or from miners,
mine operators shall promptly provide access to any record listed in
this section.
Sec. 60.17 Severability.
Each section of this part, as well as sections in 30 CFR parts 56,
57, 70, 71, 72, 75, and 90 that address respirable crystalline silica
or respiratory protection, is separate and severable from the other
sections and provisions. If any provision of this subpart is held to be
invalid or unenforceable by its terms, or as applied to any person,
entity, or circumstance, or is stayed or enjoined, that provision shall
be construed so as to continue to give the maximum effect to the
provision permitted by law, unless such holding shall be one of utter
invalidity or unenforceability, in which event the provision shall be
severable from these sections and shall not affect the remainder
thereof.
Subchapter O--Coal Mine Safety and Health
PART 70--MANDATORY HEALTH STANDARDS--UNDERGROUND COAL MINES
0
20. The authority citation for part 70 continues to read as follows:
Authority: 30 U.S.C. 811, 813(h), 957.
Subpart A--General
Sec. 70.2 [Amended]
0
21. Effective April 14, 2025, amend Sec. 70.2 by removing the
definition of ``Quartz''.
Subpart B--Dust Standards
Sec. 70.101 [Removed and Reserved]
0
22. Effective April 14, 2025, remove and reserve Sec. 70.101.
Subpart C--Sampling Procedures
0
23. Amend Sec. 70.205 by adding introductory text to read as follows:
Sec. 70.205 Approved sampling devices; operation; air flowrate.
The following is required until April 14, 2025:
* * * * *
0
24. Add Sec. 70.205T to read as follows:
Sec. 70.205T Approved sampling devices; operation; air flowrate.
As of April 14, 2025:
(a) Approved sampling devices shall be operated at the flowrate of
2.0 L/min if using a CMDPSU; at 2.2 L/min if
[[Page 28474]]
using a CPDM; or at a different flowrate recommended by the
manufacturer.
(b) If using a CMDPSU, each approved sampling device shall be
examined each shift by a person certified in sampling during:
(1) The second hour after being put into operation to assure it is
in the proper location, operating properly, and at the proper flowrate.
If the proper flowrate is not maintained, necessary adjustments shall
be made by the certified person. This examination is not required if
the sampling device is being operated in an anthracite coal mine using
the full box, open breast, or slant breast mining method.
(2) The last hour of operation to assure that the sampling device
is operating properly and at the proper flowrate. If the proper
flowrate is not maintained, the respirable dust sample shall be
transmitted to MSHA with a notation by the certified person on the back
of the dust data card stating that the proper flowrate was not
maintained. Other events occurring during the collection of respirable
dust samples that may affect the validity of the sample, such as
dropping of the sampling head assembly onto the mine floor, shall be
noted on the back of the dust data card.
(c) If using a CPDM, the person certified in sampling shall monitor
the dust concentrations and the sampling status conditions being
reported by the sampling device at mid-shift or more frequently as
specified in the approved mine ventilation plan to assure: The sampling
device is in the proper location and operating properly; and the work
environment of the occupation or DA being sampled remains in compliance
with the standard at the end of the shift. This monitoring is not
required if the sampling device is being operated in an anthracite coal
mine using the full box, open breast, or slant breast mining method.
Sec. 70.205 [Removed]
0
25. Effective April 14, 2025, remove Sec. 70.205.
Sec. 70.205T [Redesignated as Sec. 70.205]
0
26. Effective April 14, 2025, redesignate Sec. 70.205T as Sec.
70.205.
Sec. Sec. 70.206 and 70.207 [Removed and Reserved]
0
27. Effective April 14, 2025, remove and reserve Sec. Sec. 70.206 and
70.207.
0
28. Amend Sec. 70.208 by revising the introductory text to read as
follows:
Sec. 70.208 Quarterly sampling; mechanized mining units.
The following is required from February 1, 2016, until April 14,
2025:
* * * * *
0
29. Add Sec. 70.208T to read as follows:
Sec. 70.208T Quarterly sampling; mechanized mining units.
As of April 14, 2025:
(a) The operator shall sample each calendar quarter:
(1) The designated occupation (DO) in each MMU on consecutive
normal production shifts until 15 valid representative samples are
taken. The District Manager may require additional groups of 15 valid
representative samples when information indicates the operator has not
followed the approved ventilation plan for any MMU.
(2) Each other designated occupation (ODO) specified in paragraphs
(b)(1) through (10) of this section in each MMU or specified by the
District Manager and identified in the approved mine ventilation plan
on consecutive normal production shifts until 15 valid representative
samples are taken. Sampling of each ODO type shall begin after
fulfilling the sampling requirements of paragraph (a)(1) of this
section. When required to sample more than one ODO type, each ODO type
must be sampled over separate time periods during the calendar quarter.
(3) The quarterly periods are:
(i) January 1-March 31
(ii) April 1-June 30
(iii) July 1-September 30
(iv) October 1-December 31.
(b) Unless otherwise directed by the District Manager, the approved
sampling device shall be worn by the miner assigned to perform the
duties of the DO or ODO specified in paragraphs (b)(1) through (10) of
this section or by the District Manager for each type of MMU.
(1) Conventional section using cutting machine. DO--The cutting
machine operator;
(2) Conventional section blasting off the solid. DO--The loading
machine operator;
(3) Continuous mining section other than auger-type. DO--The
continuous mining (CM) machine operator or mobile bridge operator when
using continuous haulage; ODO--The roof bolting machine operator who
works nearest the working face on the return air side of the continuous
mining machine; the face haulage operators on MMUs using blowing face
ventilation; the face haulage operators on MMUs ventilated by split
intake air (``fishtail ventilation'') as part of a super-section; and
face haulage operators where two continuous mining machines are
operated on an MMU.
(4) Continuous mining section using auger-type machine. DO--The
jacksetter who works nearest the working face on the return air side of
the continuous mining machine;
(5) Scoop section using cutting machine. DO--The cutting machine
operator;
(6) Scoop section, blasting off the solid. DO--The coal drill
operator;
(7) Longwall section. DO--The longwall operator working on the
tailgate side of the longwall mining machine; ODO--The jacksetter who
works nearest the return air side of the longwall working face, and the
mechanic;
(8) Hand loading section with a cutting machine. DO--The cutting
machine operator;
(9) Hand loading section blasting off the solid. DO--The hand
loader exposed to the greatest dust concentration; and
(10) Anthracite mine sections. DO--The hand loader exposed to the
greatest dust concentration.
I [Reserved]
(d) If a normal production shift is not achieved, the DO or ODO
sample for that shift may be voided by MSHA. However, any sample,
regardless of production, that exceeds the standard by at least 0.1 mg/
m\3\ shall be used in the determination of the equivalent concentration
for that occupatioI(e) When a valid representative sample taken in
accordance with this section meets or exceeds the ECV in table 1 to
this section that corresponds to the particular sampling device used,
the operator shall:
(1) Make approved respiratory equipment available to affected
miners in accordance with Sec. 72.700 of this chapter;
(2) Immediately take corrective action to lower the concentration
of respirable dust to at or below the respirable dust standard; and
(3) Make a record of the corrective actions taken. The record shall
be certified by the mine foreman or equivalent mine official, no later
than the end of the mine f'reman's or equivalent of'icial's next
regularly scheduled working shift. The record shall be made in a secure
book that is not susceptible to alteration or electronically in a
computer system so as to be secure and not susceptible to alteration.
Such records shall be retained at a surface location at the mine for at
least 1 year and shall be made available for inspection by authorized
representatives of the Secretary and the representative of miners.
[[Page 28475]]
(f) Noncompliance with the standard is demonstrated during the
sampling period when:
(1) Three or more valid representative samples meet or exceed the
ECV in table 1 to this section that corresponds to the particular
sampling device used; or
(2) The average for all valid representative samples meets or
exceeds the ECV in table 1 to this section that corresponds to the
particular sampling device used.
(g)(1) Unless otherwise directed by the District Manager, upon
issuance of a citation for a violation of the standard involving a DO
in an MMU, paragraph (a)(1) of this section shall not apply to the DO
in that MMU until the violation is abated and the citation is
terminated in accordance with paragraphs (h) and (i) of this section.
(2) Unless otherwise directed by the District Manager, upon
issuance of a citation for a violation of the standard involving a type
of ODO in an MMU, paragraph (a)(2) of this section shall not apply to
that ODO type in that MMU until the violation is abated and the
citation is terminated in accordance with paragraphs (g) and (h) of
this section.
(h) Upon issuance of a citation for violation of the standard, the
operator shall take the following actions sequentially:
(1) Make approved respiratory equipment available to affected
miners in accordance with Sec. 72.700 of this chapter;
(2) Immediately take corrective action to lower the concentration
of respirable coal mine dust to at or below the standard; and
(3) Make a record of the corrective actions taken. The record shall
be certified by the mine foreman or equivalent mine official, no later
than the end of the mine f'reman's or equivalent of'icial's next
regularly scheduled working shift. The record shall be made in a secure
book that is not susceptible to alteration or electronically in a
computer system so as to be secure and not susceptible to alteration.
Such records shall be retained at a surface location at the mine for at
least 1 year and shall be made available for inspection by authorized
representatives of the Secretary and the representative of miners.
(4) Begin sampling, within 8 calendar days after the date the
citation is issued, the environment of the affected occupation in the
MMU on consecutive normal production shifts until five valid
representative samples are taken.
(i) A citation for a violation of the standard shall be terminated
by MSHA when:
(1) Each of the five valid representative samples is at or below
the standard; and
(2) The operator has submitted to the District Manager revised dust
control parameters as part of the mine ventilation plan applicable to
the MMU in the citation and the changes have been approved by the
District Manager. The revised parameters shall reflect the control
measures used by the operator to abate the violation.
Table 1 to Sec. 70.208T--Excessive Concentration Values (ECV) Based on a Single Sample, Three Samples, or the
Average of Five or Fifteen Full-Shift CMDPSU/CPDM Concentration Measurements
----------------------------------------------------------------------------------------------------------------
ECV (mg/m\3\)
Section Samples -------------------------------
CMDPSU CPDM
----------------------------------------------------------------------------------------------------------------
70.208 (e)................................. 70.1-0(a)--Single sample........... 1.79 1.70
70.1-0(b)--Single sample........... 0.74 0.57
70.208(f)(1)............................... 70.1-0(a)--3 or more samples....... 1.79 1.70
70.1-0(b)--3 or more samples....... 0.74 0.57
70.208(f)(2)............................... 70.1-0(a)--5 sample average........ 1.63 1.59
70.1-0(b)--5 sample average........ 0.61 0.53
70.208(f)(2)............................... 70.1-0(a)--15 sample average....... 1.58 1.56
70.1-0(b)--15 sample average....... 0.57 0.52
70.208(i)(1)............................... 70.1-0(a)--Each of 5 samples....... 1.79 1.70
70.1-0(b)--Each of 5 samples....... 0.74 0.57
----------------------------------------------------------------------------------------------------------------
Sec. 70.208 [Removed]
0
30. Effective April 14, 2025, remove Sec. 70.208.
Sec. 70.208T [Redesignated as Sec. 70.208]
0
31. Effective April 14, 2025, redesignate Sec. 70.208T as Sec. 70.208
and redesignate table 1 to Sec. 70.208T as table 1 to Sec. 70.208.
0
32. Amend Sec. 70.209 by revising the introductory text to read as
follows:
Sec. 70.209 Quarterly sampling; designated areas.
The following is required until April 14, 2025:
* * * * *
0
33. Add Sec. 70.209T to read as follows:
Sec. 70.209T Quarterly sampling; designated areas.
As of April 14, 2025:
(a) The operator shall sample quarterly each designated area (DA)
on consecutive production shifts until five valid representative
samples are taken. The quarterly periods are:
(1) January 1-March 31
(2) April 1-June 30
(3) July 1-September 30
(4) October 1-December 31.
(b) [Reserved].
(c) When a valid representative sample taken in accordance with
this section meets or exceeds the ECV in table 1 to this section that
corresponds to the particular sampling device used, the operator shall:
(1) Make approved respiratory equipment available to affected
miners in accordance with Sec. 72.700 of this chapter;
(2) Immediately take corrective action to lower the concentration
of respirable dust to at or below the respirable dust standard; and
(3) Make a record of the corrective actions taken. The record shall
be certified by the mine foreman or equivalent mine official, no later
than the end of the mine foreman's or equivalent official's next
regularly scheduled working shift. The record shall be made in a secure
book that is not susceptible to alteration or electronically in a
computer system so as to be secure and not susceptible to alteration.
Such records shall be retained at a surface location at the mine for at
least 1 year and shall be made available for inspection by authorized
representatives of the Secretary and the representative of miners.
(d) Noncompliance with the standard is demonstrated during the
sampling period when:
[[Page 28476]]
(1) Two or more valid representative samples meet or exceed the ECV
in table 1 to this section that corresponds to the particular sampling
device used; or
(2) The average for all valid representative samples meets or
exceeds the ECV in table 1 to this section that corresponds to the
particular sampling device used.
(e) Unless otherwise directed by the District Manager, upon
issuance of a citation for a violation of the standard, paragraph (a)
of this section shall not apply to that DA until the violation is
abated and the citation is terminated in accordance with paragraphs (e)
and (f) of this section.
(f) Upon issuance of a citation for a violation of the standard,
the operator shall take the following actions sequentially:
(1) Make approved respiratory equipment available to affected
miners in accordance with Sec. 72.700 of this chapter;
(2) Immediately take corrective action to lower the concentration
of respirable coal mine dust to at or below the standard; and
(3) Make a record of the corrective actions taken. The record shall
be certified by the mine foreman or equivalent mine official, no later
than the end of the mine foreman's or equivalent official's next
regularly scheduled working shift. The record shall be made in a secure
book that is not susceptible to alteration or electronically in a
computer system so as to be secure and not susceptible to alteration.
Such records shall be retained at a surface location at the mine for at
least 1 year and shall be made available for inspection by authorized
representatives of the Secretary and the representative of miners.
(4) Begin sampling, within 8 calendar days after the date the
citation is issued, the environment of the affected DA on consecutive
normal production shifts until five valid representative samples are
taken.
(g) A citation for a violation of the standard shall be terminated
by MSHA when:
(1) Each of the five valid representative samples is at or below
the standard; and
(2) The operator has submitted to the District Manager revised dust
control parameters as part of the mine ventilation plan applicable to
the DA in the citation, and the changes have been approved by the
District Manager. The revised parameters shall reflect the control
measures used by the operator to abate the violation.
Table 1 to Sec. 70.209T--Excessive Concentration Values (ECV) Based on a Single Sample, Two Samples, or the
Average of Five or Fifteen Full-Shift CMDPSU/CPDM Concentration Measurements
----------------------------------------------------------------------------------------------------------------
ECV (mg/m\3\)
Section Samples -------------------------------
CMDPSU CPDM
----------------------------------------------------------------------------------------------------------------
70.209 (c)................................. 70.100(a)--Single sample........... 1.79 1.70
70.100(b)--Single sample........... 0.74 0.57
70.209(d)(1)............................... 70.100(a)--2 or more samples....... 1.79 1.70
70.100(b)--2 or more samples....... 0.74 0.57
70.209(d)(2)............................... 70.100(a)--5 sample average........ 1.63 1.59
70.100(b)--5 sample average........ 0.61 0.53
70.209(d)(2)............................... 70.100(a)--15 sample average....... 1.58 1.56
70.100(b)--15 sample average....... 0.57 0.52
70.209(g)(1)............................... 70.100(a)--Each of 5 samples....... 1.79 1.70
70.100(b)--Each of 5 samples....... 0.74 0.57
----------------------------------------------------------------------------------------------------------------
Sec. 70.209 [Removed]
0
34. Effective April 14, 2025, remove Sec. 70.209.
Sec. 70.209T [Redesignated as Sec. 70.209]
0
35. Effective April 14, 2025, redesignate Sec. 70.209T as Sec. 70.209
and redesignate table 1 to Sec. 70.209T as table 1 to Sec. 70.209.
Tables 70-1 and 70-2 to Subpart C of Part 70 [Removed]
0
36. Effective April 14, 2025, remove tables 70-1 and 70-2 to subpart C
of part 70.
PART 71--MANDATORY HEALTH STANDARDS--SURFACE COAL MINES AND SURFACE
WORK AREAS OF UNDERGROUND COAL MINES
0
37. The authority citation for part 71 continues to read as follows:
Authority: 30 U.S.C. 811, 813(h), 957.
Subpart A--General
Sec. 71.2 [Amended]
0
38. Effective April 14, 2025, amend Sec. 71.2 by removing the
definition of ``Quartz''.
Subpart B--Dust Standards
Sec. 71.101 [Removed and Reserved]
0
39. Effective April 14, 2025, remove and reserve Sec. 71.101.
Subpart C--Sampling Procedures
0
40. Amend Sec. 71.205 by adding introductory text to read as follows:
Sec. 71.205 Approved sampling devices; operation; air flowrate.
The following is required until April 14, 2025:
* * * * *
0
41. Add Sec. 71.205T to read as follows:
Sec. 71.205T Approved sampling devices; operation; air flowrate.
As of April 14, 2025:
(a) Approved sampling devices shall be operated at the flowrate of
2.0 L/min, if using a CMDPSU; at 2.2 L/min, if using a CPDM; or at a
different flowrate recommended by the manufacturer.
(b) If using a CMDPSU, each sampling device shall be examined each
shift by a person certified in sampling during:
(1) The second hour after being put into operation to assure it is
in the proper location, operating properly, and at the proper flowrate.
If the proper flowrate is not maintained, necessary adjustments shall
be made by the certified person.
(2) The last hour of operation to assure that it is operating
properly and at the proper flowrate. If the proper flowrate is not
maintained, the respirable dust sample shall be transmitted to MSHA
with a notation by the certified person on the back of the dust data
card stating that the proper flowrate was not maintained. Other events
occurring during the collection of respirable dust samples that may
affect the validity of the sample, such as
[[Page 28477]]
dropping of the sampling head assembly onto the mine floor, shall be
noted on the back of the dust data card.
(c) If using a CPDM, the person certified in sampling shall monitor
the dust concentrations and the sampling status conditions being
reported by the sampling device at mid-shift or more frequently as
specified in the approved respirable dust control plan, if applicable,
to assure: The sampling device is in the proper location and operating
properly; and the work environment of the occupation being sampled
remains in compliance with the standard at the end of the shift.
Sec. 71.205 [Removed]
0
42. Effective April 14, 2025, remove Sec. 71.205.
Sec. 71.205T [Redesignated as Sec. 71.205]
0
43. Effective April 14, 2025, redesignate Sec. 71.205T as Sec.
71.205.
0
44. Amend Sec. 71.206 by adding introductory text to read as follows:
Sec. 71.206 Quarterly sampling; designated work positions.
The following is required until April 14, 2025:
* * * * *
0
45. Add Sec. 71.206T to read as follows:
Sec. 71.206T Quarterly sampling; designated work positions.
As of April 14, 2025:
(a) Each operator shall take one valid representative sample from
the DWP during each quarterly period. The quarterly periods are:
(1) January 1-March 31
(2) April 1-June 30
(3) July 1-September 30
(4) October 1-December 31.
(b) [Reserved].
(c) Designated work position samples shall be collected at
locations to measure respirable dust generation sources in the active
workings. The specific work positions at each mine where DWP samples
shall be collected include:
(1) Each highwall drill operator (MSHA occupation code 384);
(2) Bulldozer operators (MSHA occupation code 368); and
(3) Other work positions designated by the District Manager for
sampling in accordance with Sec. 71.206(m).
(d) Operators with multiple work positions specified in paragraphs
(b)(2) and (3) of this section shall sample the DWP exposed to the
greatest respirable dust concentration in each work position performing
the same activity or task at the same location at the mine and exposed
to the same dust generation source. Each operator shall provide the
District Manager with a list identifying the specific work positions
where DWP samples will be collected for:
(1) Active mines--by October 1, 2014.
(2) New mines--Within 30 calendar days of mine opening.
(3) DWPs with a change in operational status that increases or
reduces the number of active DWPs--within 7 calendar days of the change
in status.
(e) Each DWP sample shall be taken on a normal work shift. If a
normal work shift is not achieved, the respirable dust sample shall be
transmitted to MSHA with a notation by the person certified in sampling
on the back of the dust data card stating that the sample was not taken
on a normal work shift. When a normal work shift is not achieved, the
sample for that shift may be voided by MSHA. However, any sample,
regardless of whether a normal work shift was achieved, that exceeds
the standard by at least 0.1 mg/m\3\ shall be used in the determination
of the equivalent concentration for that occupation.
(f) Unless otherwise directed by the District Manager, DWP samples
shall be taken by placing the sampling device as follows:
(1) Equipment operator: On the equipment operator or on the
equipment within 36 inches of the operator's normal working position.
(2) Non-equipment operators: On the miner assigned to the DWP or at
a location that represents the maximum concentration of dust to which
the miner is exposed.
(g) Upon notification from MSHA that any valid representative
sample taken from a DWP to meet the requirements of paragraph (a) of
this section exceeds the standard, the operator shall, within 15
calendar days of notification, sample that DWP each normal work shift
until five valid representative samples are taken. The operator shall
begin sampling on the first normal work shift following receipt of
notification.
(h) When a valid representative sample taken in accordance with
this section meets or exceeds the excessive concentration value (ECV)
in table 1 to this section that corresponds to the particular sampling
device used, the mine operator shall:
(1) Make approved respiratory equipment available to affected
miners in accordance with Sec. 72.700 of this chapter;
(2) Immediately take corrective action to lower the concentration
of respirable coal mine dust to at or below the standard; and
(3) Make a record of the corrective actions taken. The record shall
be certified by the mine foreman or equivalent mine official, no later
than the end of the mine foreman's or equivalent official's next
regularly scheduled working shift. The record shall be made in a secure
book that is not susceptible to alteration or electronically in a
computer system so as to be secure and not susceptible to alteration.
Such records shall be retained at a surface location at the mine for at
least 1 year and shall be made available for inspection by authorized
representatives of the Secretary and the representative of miners.
(i) Noncompliance with the standard is demonstrated during the
sampling period when:
(1) Two or more valid representative samples meet or exceed the ECV
in table 1 to this section that corresponds to the particular sampling
device used; or
(2) The average for all valid representative samples meets or
exceeds the ECV in table 1 to this section that corresponds to the
particular sampling device used.
(j) Unless otherwise directed by the District Manager, upon
issuance of a citation for a violation of the standard, paragraph (a)
of this section shall not apply to that DWP until the violation is
abated and the citation is terminated in accordance with paragraphs (j)
and (k) of this section.
(k) Upon issuance of a citation for violation of the standard, the
operator shall take the following actions sequentially:
(1) Make approved respiratory equipment available to affected
miners in accordance with Sec. 72.700 of this chapter;
(2) Immediately take corrective action to lower the concentration
of respirable coal mine dust to at or below the standard; and
(3) Make a record of the corrective actions taken. The record shall
be certified by the mine foreman or equivalent mine official, no later
than the end of the mine foreman's or equivalent official's next
regularly scheduled working shift. The record shall be made in a secure
book that is not susceptible to alteration or electronically in a
computer system so as to be secure and not susceptible to alteration.
Such records shall be retained at a surface location at the mine for at
least 1 year and shall be made available for inspection by authorized
representatives of the Secretary and the representative of miners.
(4) Begin sampling, within 8 calendar days after the date the
citation is issued, the environment of the affected DWP on consecutive
normal work shifts until five valid representative samples are taken.
[[Page 28478]]
(l) A citation for violation of the standard shall be terminated by
MSHA when the equivalent concentration of each of the five valid
representative samples is at or below the standard.
(m) The District Manager may designate for sampling under this
section additional work positions at a surface coal mine and at a
surface work area of an underground coal mine where a concentration of
respirable dust exceeding 50 percent of the standard has been measured
by one or more MSHA valid representative samples.
(n) The District Manager may withdraw from sampling any DWP
designated for sampling under paragraph (m) of this section upon
finding that the operator is able to maintain continuing compliance
with the standard. This finding shall be based on the results of MSHA
and operator valid representative samples taken during at least a 12-
month period.
Table 1 to Sec. 71.206T--Excessive Concentration Values (ECV) Based on a Single Sample, Two Samples, or the
Average of Five Full-Shift CMDPSU/CPDM Concentration Measurements
----------------------------------------------------------------------------------------------------------------
ECV (mg/m\3\)
Section Samples -------------------------------
CMDPSU CPDM
----------------------------------------------------------------------------------------------------------------
71.206(h).................................. Single sample...................... 1.79 1.70
71.206(i)(1)............................... 2 or more samples.................. 1.79 1.70
71.206(i)(2)............................... 5 sample average................... 1.63 1.59
71.206(l).................................. Each of 5 samples.................. 1.79 1.70
----------------------------------------------------------------------------------------------------------------
Sec. 71.206 [Removed]
0
46. Effective April 14, 2025, remove Sec. 71.206.
Sec. 71.206T [Redesignated as Sec. 71.206]
0
47. Effective April 14, 2025, redesignate Sec. 71.206T as Sec. 71.206
and redesignate table 1 to Sec. 71.206T as table 1 to Sec. 71.206.
Subpart D--Respirable Dust Control Plans
0
48. Amend Sec. 71.300 by adding introductory text to read as follows:
Sec. 71.300 Respirable dust control plan; filing requirements.
The following is required until April 14, 2025:
* * * * *
0
49. Add Sec. 71.300T to read as follows:
Sec. 71.300T Respirable dust control plan; filing requirements.
As of April 14, 2025:
(a) Within 15 calendar days after the termination date of a
citation for violation of the standard, the operator shall submit to
the District Manager for approval a written respirable dust control
plan applicable to the DWP identified in the citation. The respirable
dust control plan and revisions thereof shall be suitable to the
conditions and the mining system of the coal mine and shall be adequate
to continuously maintain respirable dust to at or below the standard at
the DWP identified in the citation.
(1) The mine operator shall notify the representative of miners at
least 5 days prior to submission of a respirable dust control plan and
any revision to a dust control plan. If requested, the mine operator
shall provide a copy to the representative of miners at the time of
notification;
(2) A copy of the proposed respirable dust control plan, and a copy
of any proposed revision, submitted for approval shall be made
available for inspection by the representative of miners; and
(3) A copy of the proposed respirable dust control plan, and a copy
of any proposed revision, submitted for approval shall be posted on the
mine bulletin board at the time of submittal. The proposed plan or
proposed revision shall remain posted until it is approved, withdrawn,
or denied.
(4) Following receipt of the proposed plan or proposed revision,
the representative of miners may submit timely comments to the District
Manager, in writing, for consideration during the review process. Upon
request, a copy of these comments shall be provided to the operator by
the District Manager.
(b) Each respirable dust control plan shall include at least the
following:
(1) The mine identification number and DWP number assigned by MSHA,
the operator's name, mine name, mine address, and mine telephone number
and the name, address, and telephone number of the principal officer in
charge of health and safety at the mine;
(2) The specific DWP at the mine to which the plan applies;
(3) A detailed description of the specific respirable dust control
measures used to abate the violation of the respirable dust standard;
and
(4) A detailed description of how each of the respirable dust
control measures described in response to paragraph (b)(3) of this
section will continue to be used by the operator, including at least
the specific time, place and manner the control measures will be used.
Sec. 71.300 [Removed]
0
50. Effective April 14, 2025, remove Sec. 71.300.
Sec. 71.300T [Redesignated as Sec. 71.300]
0
51. Effective April 14, 2025, redesignate Sec. 71.300T as Sec.
71.300.
0
52. Amend Sec. 71.301 by adding introductory text to read as follows:
Sec. 71.301 Respirable dust control plan; approval by District
Manager and posting.
The following is required until April 14, 2025:
* * * * *
0
53. Add Sec. 71.301T to read as follows:
Sec. 71.301T Respirable dust control plan; approval by District
Manager and posting.
As of April 8, 2026:
(a) The District Manager will approve respirable dust control plans
on a mine-by-mine basis. When approving respirable dust control plans,
the District Manager shall consider whether:
(1) The respirable dust control measures would be likely to
maintain concentrations of respirable coal mine dust at or below the
standard; and
(2) The operator's compliance with all provisions of the respirable
dust control plan could be objectively ascertained by MSHA.
(b) MSHA may take respirable dust samples to determine whether the
respirable dust control measures in the operator's plan effectively
maintain concentrations of respirable coal mine dust at or below the
applicable standard.
(c) The operator shall comply with all provisions of each
respirable dust control plan upon notice from MSHA that the respirable
dust control plan is approved.
(d) The approved respirable dust control plan and any revisions
shall be:
[[Page 28479]]
(1) Provided upon request to the representative of miners by the
operator following notification of approval;
(2) Made available for inspection by the representative of miners;
and
(3) Posted on the mine bulletin board within 1 working day
following notification of approval, and shall remain posted for the
period that the plan is in effect.
(e) The operator may review respirable dust control plans and
submit proposed revisions to such plans to the District Manager for
approval.
Sec. 71.301 [Removed]
0
54. Effective April 14, 2025, remove Sec. 71.301.
Sec. 71.301T [Redesignated as Sec. 71.301]
0
55. Effective April 14, 2025, redesignate Sec. 71.301T as Sec.
71.301.
PART 72--HEALTH STANDARDS FOR COAL MINES
0
56. The authority citation for part 72 continues to read as follows:
Authority: 30 U.S.C. 811, 813(h), 957.
Subpart E--Miscellaneous
0
57. Revise Sec. 72.710 to read as follows:
Sec. 72.710 Selection, fit, use, and maintenance of approved
respirators.
The following is required until April 14, 2025. In order to ensure
the maximum amount of respiratory protection, approved respirators
shall be selected, fitted, used, and maintained in accordance with the
provisions of the American National Standards Institute's (ANSI)
Practices for Respiratory Protection ANSI Z88.2-1969, which is
incorporated by reference into this section with the approval of the
Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part
51. This incorporation by reference (IBR) material is available for
inspection at the Mine Safety and Health Administration (MSHA) and at
the National Archives and Records Administration (NARA). Contact MSHA
at: MSHA's Office of Standards, Regulations, and Variances, 201 12th
Street South, Arlington, VA 22202-5450; (202) 693-9440; or any Mine
Safety and Health Enforcement District Office. For information on the
availability of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected].
0
58. Add Sec. 72.710T to read as follows:
Sec. 72.710T Selection, fit, use, and maintenance of approved
respirators.
As of April 14, 2025: Approved respirators shall be selected,
fitted, used, and maintained in accordance with the provisions of a
written respiratory protection program consistent with the requirements
of ASTM F3387-19. ASTM F3387-19, Standard Practice for Respiratory
Protection, approved August 1, 2019, is incorporated by reference into
this section with the approval of the Director of the Federal Register
under 5 U.S.C. 552(a) and 1 CFR part 51. This incorporation by
reference (IBR) material is available for inspection at the Mine Safety
and Health Administration (MSHA) and at the National Archives and
Records Administration (NARA). Contact MSHA at: MSHA's Office of
Standards, Regulations, and Variances, 201 12th Street South,
Arlington, VA 22202-5450; (202) 693-9440; or any Mine Safety and Health
Enforcement District Office. For information on the availability of
this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email [email protected]. The material may be obtained
from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West
Conshohocken, PA 19428-2959; www.astm.org.
Sec. 72.710 [Removed]
0
59. Effective April 14, 2025, remove Sec. 72.710.
Sec. 72.710T [Redesignated as Sec. 72.710]
0
60. Effective April 14, 2025, redesignate Sec. 72.710T as Sec.
72.710.
0
61. Revise Sec. 72.800 to read as follows:
Sec. 72.800 Single, full-shift measurement of respirable coal mine
dust.
The Secretary will use a single, full-shift measurement of
respirable coal mine dust to determine the average concentration on a
shift since that measurement accurately represents atmospheric
conditions to which a miner is exposed during such shift. Until April
14, 2025, noncompliance with the respirable dust standard, in
accordance with this subchapter, is demonstrated when a single, full-
shift measurement taken by MSHA meets or exceeds the applicable ECV in
table 1 to Sec. 70.208, table 1 to Sec. 70.209, table 1 to Sec.
71.206, or table 1 to Sec. 90.207 of this chapter that corresponds to
the particular sampling device used. Upon issuance of a citation for a
violation of the standard, and for MSHA to terminate the citation, the
mine operator shall take the specified actions in this subchapter.
0
62. Add Sec. 72.800T to read as follows:
Sec. 72.800T Single, full-shift measurement of respirable coal mine
dust.
The Secretary will use a single, full-shift measurement of
respirable coal mine dust to determine the average concentration on a
shift since that measurement accurately represents atmospheric
conditions to which a miner is exposed during such shift. As of April
14, 2025, noncompliance with the respirable dust standard, in
accordance with this subchapter, is demonstrated when a single, full-
shift measurement taken by MSHA meets or exceeds the applicable ECV in
table 1 to Sec. 70.208, table 1 to Sec. 70.209, table 1 to Sec.
71.206, or table 1 to Sec. 90.207 of this chapter that corresponds to
the particular sampling device used. Upon issuance of a citation for a
violation of the standard, and for MSHA to terminate the citation, the
mine operator shall take the specified actions in this subchapter.
Sec. 72.800 [Removed]
0
63. Effective April 14, 2025, remove Sec. 72.800.
Sec. 72.800T [Redesignated as Sec. 72.800]
0
64. Effective April 14, 2025, redesignate Sec. 72.800T as Sec.
72.800.
PART 75--MANDATORY SAFETY STANDARDS--UNDERGROUND COAL MINES
0
65. The authority citation for part 75 continues to read as follows:
Authority: 30 U.S.C. 811, 813(h), 957.
Subpart D--Ventilation
0
66. Amend Sec. 75.350 by adding introductory text to read as follows:
Sec. 75.350 Belt air course ventilation.
The following is required until April 14, 2025:
* * * * *
0
67. Add Sec. 75.350T to read as follows:
Sec. 75.350T Belt air course ventilation.
As of April 14, 2025:
(a) The belt air course must not be used as a return air course;
and except as provided in paragraph (b) of this section, the belt air
course must not be used to provide air to working sections or to areas
where mechanized mining equipment is being installed or removed.
(1) The belt air course must be separated with permanent
ventilation controls from return air courses and from other intake air
courses except as provided in paragraph (c) of this section.
[[Page 28480]]
(2) Effective December 31, 2009, the air velocity in the belt entry
must be at least 50 feet per minute. When requested by the mine
operator, the district manager may approve lower velocities in the
ventilation plan based on specific mine conditions. Air velocities must
be compatible with all fire detection systems and fire suppression
systems used in the belt entry.
(b) The use of air from a belt air course to ventilate a working
section, or an area where mechanized mining equipment is being
installed or removed, shall be permitted only when evaluated and
approved by the district manager in the mine ventilation plan. The mine
operator must provide justification in the plan that the use of air
from a belt entry would afford at least the same measure of protection
as where belt haulage entries are not used to ventilate working places.
In addition, the following requirements must be met:
(1) The belt entry must be equipped with an AMS that is installed,
operated, examined, and maintained as specified in Sec. 75.351.
(2) All miners must be trained annually in the basic operating
principles of the AMS, including the actions required in the event of
activation of any AMS alert or alarm signal. This training must be
conducted prior to working underground in a mine that uses belt air to
ventilate working sections or areas where mechanized mining equipment
is installed or removed. It must be conducted as part of a miner's 30
CFR part 48 new miner training (Sec. 48.5), experienced miner training
(Sec. 48.6), or annual refresher training (Sec. 48.8).
(3)(i) The average concentration of respirable dust in the belt air
course, when used as a section intake air course, shall be maintained
at or below 0.5 milligrams per cubic meter of air (mg/m\3\).
(ii) A permanent designated area (DA) for dust measurements must be
established at a point no greater than 50 feet upwind from the section
loading point in the belt entry when the belt air flows over the
loading point or no greater than 50 feet upwind from the point where
belt air is mixed with air from another intake air course near the
loading point. The DA must be specified and approved in the ventilation
plan.
(4) The primary escapeway must be monitored for carbon monoxide or
smoke as specified in Sec. 75.351(f).
(5) The area of the mine with a belt air course must be developed
with three or more entries.
(6) In areas of the mine developed after the effective date of this
rule, unless approved by the district manager, no more than 50% of the
total intake air, delivered to the working section or to areas where
mechanized mining equipment is being installed or removed, can be
supplied from the belt air course. The locations for measuring these
air quantities must be approved in the mine ventilation plan.
(7) The air velocity in the belt entry must be at least 100 feet
per minute. When requested by the mine operator, the district manager
may approve lower velocities in the ventilation plan based on specific
mine conditions.
(8) The air velocity in the belt entry must not exceed 1,000 feet
per minute. When requested by the mine operator, the district manager
may approve higher velocities in the ventilation plan based on specific
mine conditions.
(c) Notwithstanding the provisions of Sec. 75.380(g), additional
intake air may be added to the belt air course through a point-feed
regulator. The location and use of point feeds must be approved in the
mine ventilation plan.
(d) If the air through the point-feed regulator enters a belt air
course which is used to ventilate a working section or an area where
mechanized mining equipment is being installed or removed, the
following conditions must be met:
(1) The air current that will pass through the point-feed regulator
must be monitored for carbon monoxide or smoke at a point within 50
feet upwind of the point-feed regulator. A second point must be
monitored 1,000 feet upwind of the point-feed regulator unless the mine
operator requests that a lesser distance be approved by the district
manager in the mine ventilation plan based on mine specific conditions;
(2) The air in the belt air course must be monitored for carbon
monoxide or smoke upwind of the point-feed regulator. This sensor must
be in the belt air course within 50 feet of the mixing point where air
flowing through the point-feed regulator mixes with the belt air;
(3) The point-feed regulator must be provided with a means to close
the regulator from the intake air course without requiring a person to
enter the crosscut where the point-feed regulator is located. The
point-feed regulator must also be provided with a means to close the
regulator from a location in the belt air course immediately upwind of
the crosscut containing the point-feed regulator;
(4) A minimum air velocity of 300 feet per minute must be
maintained through the point-feed regulator;
(5) The location(s) and use of a point-feed regulator(s) must be
approved in the mine ventilation plan and shown on the mine ventilation
map; and
(6) An AMS must be installed, operated, examined, and maintained as
specified in Sec. 75.351.
Sec. 75.350 [Removed]
0
68. Effective April 14, 2025, remove Sec. 75.350.
Sec. 75.350T [Redesignated as Sec. 75.350]
0
69. Effective April 14, 2025, redesignate Sec. 75.350T as Sec.
75.350.
PART 90--MANDATORY HEALTH STANDARDS--COAL MINERS WHO HAVE EVIDENCE
OF THE DEVELOPMENT OF PNEUMOCONIOSIS
0
70. The authority citation for part 90 continues to read as follows:
Authority: 30 U.S.C. 811, 813(h), 957.
Subpart A--General
0
71. Revise Sec. 90.2 to read as follows:
Sec. 90.2 Definitions.
Until April 14, 2025, the following definitions apply in this part:
Act. The Federal Mine Safety and Health Act of 1977, Public Law 91-
173, as amended by Public Law 95-164 and Public Law 109-236.
Active workings. Any place in a coal mine where miners are normally
required to work or travel.
Approved sampling device. A sampling device approved by the
Secretary and Secretary for Health and Human Services (HHS) under part
74 of this subchapter.
Certified person. An individual certified by the Secretary in
accordance with Sec. 90.202 to take respirable dust samples required
by this part or certified in accordance with Sec. 90.203 to perform
the maintenance and calibration of respirable dust sampling equipment
as required by this part.
Coal mine dust personal sampler unit (CMDPSU). A personal sampling
device approved under part 74, subpart B, of this subchapter.
Concentration. A measure of the amount of a substance contained per
unit volume of air.
Continuous personal dust monitor (CPDM). A personal sampling device
approved under part 74, subpart C, of this subchapter.
District Manager. The manager of the Coal Mine Safety and Health
District in which the mine is located.
Equivalent concentration. The concentration of respirable coal mine
dust, including quartz, expressed in milligrams per cubic meter of air
(mg/
[[Page 28481]]
m\3\) as measured with an approved sampling device, determined by
dividing the weight of dust in milligrams collected on the filter of an
approved sampling device by the volume of air in cubic meters passing
through the filter (sampling time in minutes (t) times the sampling
airflow rate in cubic meters per minute), and then converting that
concentration to an equivalent concentration as measured by the Mining
Research Establishment (MRE) instrument. When the approved sampling
device is:
(1) The CMDPSU, the equivalent concentration is determined by
multiplying the concentration of respirable coal mine dust by the
constant factor prescribed by the Secretary.
(2) The CPDM, the device shall be programmed to automatically
report end-of-shift concentration measurements as equivalent
concentrations.
Mechanized mining unit (MMU). A unit of mining equipment including
hand loading equipment used for the production of material; or a
specialized unit which uses mining equipment other than specified in
Sec. 70.206(b) or in Sec. 70.208(b) of this subchapter. Each MMU will
be assigned a four-digit identification number by MSHA, which is
retained by the MMU regardless of where the unit relocates within the
mine. However, when:
(1) Two sets of mining equipment are used in a series of working
places within the same working section and only one production crew is
employed at any given time on either set of mining equipment, the two
sets of equipment shall be identified as a single MMU.
(2) Two or more sets of mining equipment are simultaneously engaged
in cutting, mining, or loading coal or rock from working places within
the same working section, each set of mining equipment shall be
identified as a separate MMU.
MRE instrument. The gravimetric dust sampler with a four channel
horizontal elutriator developed by the Mining Research Establishment of
the National Coal Board, London, England.
MSHA. The Mine Safety and Health Administration of the U.S.
Department of Labor.
Normal work duties. Duties which the part 90 miner performs on a
routine day-to-day basis in his or her job classification at a mine.
Part 90 miner. A miner employed at a coal mine who has exercised
the option under the old section 203(b) program (30 CFR part 90,
effective as of July 1, 1972), or under Sec. 90.3 of this part to work
in an area of a mine where the average concentration of respirable dust
in the mine atmosphere during each shift to which that miner is exposed
is continuously maintained at or below the applicable standard, and who
has not waived these rights.
Quartz. Crystalline silicon dioxide (SiO2) not chemically combined
with other substances and having a distinctive physical structure.
Representative sample. A respirable dust sample, expressed as an
equivalent concentration, that reflects typical dust concentration
levels in the working environment of the part 90 miner when performing
normal work duties.
Respirable dust. Dust collected with a sampling device approved by
the Secretary and the Secretary of HHS in accordance with part 74 (Coal
Mine Dust Sampling Devices) of this subchapter.
Secretary. The Secretary of Labor or a delegate.
Secretary of Health and Human Services. The Secretary of Health and
Human Services (HHS) or the Secretary of Health, Education, and
Welfare.
Transfer. Any change in the work assignment of a part 90 miner by
the operator and includes:
(1) Any change in occupation code of a part 90 miner;
(2) any movement of a part 90 miner to or from an MMU; or
(3) any assignment of a part 90 miner to the same occupation in a
different location at a mine.
Valid respirable dust sample. A respirable dust sample collected
and submitted as required by this part, including any sample for which
the data were electronically transmitted to MSHA, and not voided by
MSHA.
0
72. Add Sec. 90.2T to read as follows:
Sec. 90.2T Definitions.
As April 14, 2025, the following definitions apply in this part:
Act. The Federal Mine Safety and Health Act of 1977, Public Law 91-
173, as amended by Public Law 95-164 and Public Law 109-236.
Active workings. Any place in a coal mine where miners are normally
required to work or travel.
Approved sampling device. A sampling device approved by the
Secretary and Secretary for Health and Human Services (HHS) under part
74 of this subchapter.
Certified person. An individual certified by the Secretary in
accordance with Sec. 90.202 to take respirable dust samples required
by this part or certified in accordance with Sec. 90.203 to perform
the maintenance and calibration of respirable dust sampling equipment
as required by this part.
Coal mine dust personal sampler unit (CMDPSU). A personal sampling
device approved under part 74, subpart B, of this subchapter.
Concentration. A measure of the amount of a substance contained per
unit volume of air.
Continuous personal dust monitor (CPDM). A personal sampling device
approved under part 74, subpart C, of this subchapter.
District Manager. The manager of the Coal Mine Safety and Health
District in which the mine is located.
Equivalent concentration. The concentration of respirable coal mine
dust, including quartz, expressed in milligrams per cubic meter of air
(mg/m\3\) as measured with an approved sampling device, determined by
dividing the weight of dust in milligrams collected on the filter of an
approved sampling device by the volume of air in cubic meters passing
through the filter (sampling time in minutes (t) times the sampling
airflow rate in cubic meters per minute), and then converting that
concentration to an equivalent concentration as measured by the Mining
Research Establishment (MRE) instrument. When the approved sampling
device is:
(1) The CMDPSU, the equivalent concentration is determined by
multiplying the concentration of respirable coal mine dust by the
constant factor prescribed by the Secretary.
(2) The CPDM, the device shall be programmed to automatically
report end-of-shift concentration measurements as equivalent
concentrations.
Mechanized mining unit (MMU). A unit of mining equipment including
hand loading equipment used for the production of material; or a
specialized unit which uses mining equipment other than specified in
Sec. 70.206(b) or in Sec. 70.208(b) of this subchapter. Each MMU will
be assigned a four-digit identification number by MSHA, which is
retained by the MMU regardless of where the unit relocates within the
mine. However, when:
(1) Two sets of mining equipment are used in a series of working
places within the same working section and only one production crew is
employed at any given time on either set of mining equipment, the two
sets of equipment shall be identified as a single MMU.
(2) Two or more sets of mining equipment are simultaneously engaged
in cutting, mining, or loading coal or rock from working places within
the same working section, each set of mining equipment shall be
identified as a separate MMU.
[[Page 28482]]
MRE instrument. The gravimetric dust sampler with a four channel
horizontal elutriator developed by the Mining Research Establishment of
the National Coal Board, London, England.
MSHA. The Mine Safety and Health Administration of the U.S.
Department of Labor.
Normal work duties. Duties which the part 90 miner performs on a
routine day-to-day basis in his or her job classification at a mine.
Part 90 miner. A miner employed at a coal mine who has exercised
the option under the old section 203(b) program (30 CFR part 90,
effective as of July 1, 1972), or under Sec. 90.3 to work in an area
of a mine where the average concentration of respirable dust in the
mine atmosphere during each shift to which that miner is exposed is
continuously maintained at or below the standard, and who has not
waived these rights.
Representative sample. A respirable dust sample, expressed as an
equivalent concentration, that reflects typical dust concentration
levels in the working environment of the part 90 miner when performing
normal work duties.
Respirable dust. Dust collected with a sampling device approved by
the Secretary and the Secretary of HHS in accordance with part 74 (Coal
Mine Dust Sampling Devices) of this subchapter.
Secretary. The Secretary of Labor or a delegate.
Secretary of Health and Human Services. The Secretary of Health and
Human Services (HHS) or the Secretary of Health, Education, and
Welfare.
Transfer. Any change in the work assignment of a part 90 miner by
the operator and includes:
(1) Any change in occupation code of a part 90 miner;
(2) any movement of a part 90 miner to or from an MMU; or
(3) any assignment of a part 90 miner to the same occupation in a
different location at a mine.
Valid respirable dust sample. A respirable dust sample collected
and submitted as required by this part, including any sample for which
the data were electronically transmitted to MSHA, and not voided by
MSHA.
Sec. 90.2 [Removed]
0
73. Effective April 14, 2025, remove Sec. 90.2.
Sec. 90.2T [Redesignated as Sec. 90.2]
0
74. Effective April 14, 2025, redesignate Sec. 90.2T as Sec. 90.2.
0
75. Amend Sec. 90.3 by adding the introductory text to read as
follows:
Sec. 90.3 Part 90 option; notice of eligibility; exercise of option.
The following is required until April 14, 2025:
* * * * *
0
76. Add Sec. 90.3T to read as follows:
Sec. 90.3T Part 90 option; notice of eligibility; exercise of option.
Effective April 14, 2025:
(a) Any miner employed at a coal mine who, in the judgment of the
Secretary of HHS, has evidence of the development of pneumoconiosis
based on a chest X-ray, read and classified in the manner prescribed by
the Secretary of HHS, or based on other medical examinations shall be
afforded the option to work in an area of a mine where the average
concentration of respirable dust in the mine atmosphere during each
shift to which that miner is exposed is continuously maintained at or
below the standard. Each of these miners shall be notified in writing
of eligibility to exercise the option.
(b) Any miner who is a section 203(b) miner on January 31, 1981,
shall be a part 90 miner on February 1, 1981, entitled to full rights
under this part to retention of pay rate, future actual wage increases,
and future work assignment, shift and respirable dust protection.
(c) Any part 90 miner who is transferred to a position at the same
or another coal mine shall remain a part 90 miner entitled to full
rights under this part at the new work assignment.
(d) The option to work in a low dust area of the mine may be
exercised for the first time by any miner employed at a coal mine who
was eligible for the option under the old section 203(b) program
(www.msha.gov/REGSTECHAMEND.htm), or is eligible for the option under
this part by sending a written request to the Chief, Division of
Health, Mine Safety and Health Enforcement, MSHA, 201 12th Street
South, Arlington, VA 22202-5452.
(e) The option to work in a low dust area of the mine may be re-
exercised by any miner employed at a coal mine who exercised the option
under the old section 203(b) program (www.msha.gov/REGSTECHAMEND.htm)
or exercised the option under this part by sending a written request to
the Chief, Division of Health, Mine Safety and Health Enforcement,
MSHA, 201 12th Street South, Arlington, VA 22202-5452. The request
should include the name and address of the mine and operator where the
miner is employed.
(f) No operator shall require from a miner a copy of the medical
information received from the Secretary or Secretary of HHS.
Sec. 90.3 [Removed]
0
77. Effective April 14, 2025, remove Sec. 90.3.
Sec. 90.3T [Redesignated as Sec. 90.3]
0
78. Effective April 14, 2025, redesignate Sec. 90.3T as Sec. 90.3.
Subpart B--Dust Standards, Rights of Part 90 Miners
0
79. Amend Sec. 90.100 by adding introductory text to read as follows:
Sec. 90.100 Respirable dust standard.
The following is required until April 14, 2025. After the 20th
calendar day following receipt of notification from MSHA that a part 90
miner is employed at the mine, the operator shall continuously maintain
the average concentration of respirable dust in the mine atmosphere
during each shift to which the part 90 miner in the active workings of
the mine is exposed, as measured with an approved sampling device and
expressed in terms of an equivalent concentration, at or below:
* * * * *
0
80. Add Sec. 90.100T to read as follows:
Sec. 90.100T Respirable dust standard.
The following is required as of April 14, 2025. After the 20th
calendar day following receipt of notification from MSHA that a part 90
miner is employed at the mine, the operator shall continuously maintain
the average concentration of respirable dust in the mine atmosphere
during each shift to which the part 90 miner in the active workings of
the mine is exposed, as measured with an approved sampling device and
expressed in terms of an equivalent concentration, at or below 0.5 mg/
m\3\.
Sec. 90.100 [Removed]
0
81. Effective April 14, 2025, remove Sec. 90.100.
Sec. 90.100T [Redesignated as Sec. 90.100]
0
82. Effective April 14, 2025, redesignate Sec. 90.100T as Sec.
90.100.
Sec. 90.101 [Removed and Reserved]
0
83. Effective April 14, 2025, remove and reserve Sec. 90.101.
0
84. Amend Sec. 90.102 by adding introductory text to read as follows:
Sec. 90.102 Transfer; notice.
The following is required until April 14, 2025:
* * * * *
0
85. Add Sec. 90.102T to read as follows:
Sec. 90.102T Transfer; notice.
As of April 14, 2025:
[[Page 28483]]
(a) Whenever a part 90 miner is transferred in order to meet the
standard, the operator shall transfer the miner to an existing position
at the same coal mine on the same shift or shift rotation on which the
miner was employed immediately before the transfer. The operator may
transfer a part 90 miner to a different coal mine, a newly created
position or a position on a different shift or shift rotation if the
miner agrees in writing to the transfer. The requirements of this
paragraph do not apply when the respirable dust concentration in a part
90 miner's work position complies with the standard but circumstances,
such as reductions in workforce or changes in operational status,
require a change in the miner's job or shift assignment.
(b) On or before the 20th calendar day following receipt of
notification from MSHA that a part 90 miner is employed at the mine,
the operator shall give the District Manager written notice of the
occupation and, if applicable, the MMU unit to which the part 90 miner
shall be assigned on the 21st calendar day following receipt of the
notification from MSHA.
(c) After the 20th calendar day following receipt of notification
from MSHA that a part 90 miner is employed at the mine, the operator
shall give the District Manager written notice before any transfer of a
part 90 miner. This notice shall include the scheduled date of the
transfer.
Sec. 90.102 [Removed]
0
86. Effective April 14, 2025, remove Sec. 90.102.
Sec. 90.102T [Redesignated as Sec. 90.102]
0
87. Effective April 14, 2025, redesignate Sec. 90.102T as Sec.
90.102.
0
88. Revise Sec. 90.104 to read as follows:
Sec. 90.104 Waiver of rights; re-exercise of option.
The following is required until April 14, 2025:
(a) A part 90 miner may waive his or her rights and be removed from
MSHA's active list of miners who have rights under part 90 by:
(1) Giving written notification to the Chief, Division of Health,
Mine Safety and Health Enforcement, MSHA, that the miner waives all
rights under this part;
(2) Applying for and accepting a position in an area of a mine
which the miner knows has an average respirable dust concentration
exceeding the applicable standard; or
(3) Refusing to accept another position offered by the operator at
the same coal mine that meets the requirements of Sec. Sec. 90.100,
90.101 and 90.102(a) after dust sampling shows that the present
position exceeds the applicable standard.
(b) If rights under part 90 are waived, the miner gives up all
rights under part 90 until the miner re-exercises the option in
accordance with Sec. 90.3(e) (Part 90 option; notice of eligibility;
exercise of option).
(c) If rights under part 90 are waived, the miner may re-exercise
the option under this part in accordance with Sec. 90.3(e) (Part 90
option; notice of eligibility; exercise of option) at any time.
0
89. Add Sec. 90.104T to read as follows:
Sec. 90.104T Waiver of rights; re-exercise of option.
As of April 14, 2025:
(a) A part 90 miner may waive his or her rights and be removed from
MSHA's active list of miners who have rights under part 90 by:
(1) Giving written notification to the Chief, Division of Health,
Mine Safety and Health Enforcement, MSHA, that the miner waives all
rights under this part;
(2) Applying for and accepting a position in an area of a mine
which the miner knows has an average respirable dust concentration
exceeding the standard; or
(3) Refusing to accept another position offered by the operator at
the same coal mine that meets the requirements of Sec. Sec. 90.100,
90.101 and 90.102(a) after dust sampling shows that the present
position exceeds the applicable standard.
(b) If rights under part 90 are waived, the miner gives up all
rights under part 90 until the miner re-exercises the option in
accordance with Sec. 90.3(e) (Part 90 option; notice of eligibility;
exercise of option).
(c) If rights under part 90 are waived, the miner may re-exercise
the option under this part in accordance with Sec. 90.3(e) (Part 90
option; notice of eligibility; exercise of option) at any time.
Sec. 90.104 [Removed]
0
90. Effective April 14, 2025, remove Sec. 90.104.
Sec. 90.104T [Redesignated as Sec. 90.104]
0
91. Effective April 14, 2025, redesignate Sec. 90.104T as Sec.
90.104.
Subpart C--Sampling Procedures
0
92. Amend Sec. 90.205 by adding introductory text to read as follows:
Sec. 90.205 Approved sampling devices; operation; air flowrate.
The following is required until April 14, 2025:
* * * * *
0
93. Add Sec. 90.205T to read as follows:
Sec. 90.205T Approved sampling devices; operation; air flowrate.
As of April 14, 2025:
(a) Approved sampling devices shall be operated at the flowrate of
2.0 L/min if using a CMDPSU; at 2.2 L/min if using a CPDM; or at a
different flowrate recommended by the manufacturer.
(b) If using a CMDPSU, each approved sampling device shall be
examined each shift, by a person certified in sampling during:
(1) The second hour after being put into operation to assure it is
in the proper location, operating properly, and at the proper flowrate.
If the proper flowrate is not maintained, necessary adjustments shall
be made by the certified person. This examination is not required if
the sampling device is being operated in an anthracite coal mine using
the full box, open breast, or slant breast mining method.
(2) The last hour of operation to assure that the sampling device
is operating properly and at the proper flowrate. If the proper
flowrate is not maintained, the respirable dust sample shall be
transmitted to MSHA with a notation by the certified person on the back
of the dust data card stating that the proper flowrate was not
maintained. Other events occurring during the collection of respirable
dust samples that may affect the validity of the sample, such as
dropping of the sampling head assembly onto the mine floor, shall be
noted on the back of the dust data card.
(c) If using a CPDM, the person certified in sampling shall monitor
the dust concentrations and the sampling status conditions being
reported by the sampling device at mid-shift or more frequently as
specified in the approved respirable dust control plan, if applicable,
to assure: The sampling device is in the proper location and operating
properly; and the work environment of the Part 90 miner being sampled
remains in compliance with the standard at the end of the shift. This
monitoring is not required if the sampling device is being operated in
an anthracite coal mine using the full box, open breast, or slant
breast mining method.
Sec. 90.205 [Removed]
0
94. Effective April 14, 2025, remove Sec. 90.205.
[[Page 28484]]
Sec. 90.205T [Redesignated as Sec. 90.205]
0
95. Effective April 14, 2025, redesignate Sec. 90.205T as Sec.
90.205.
0
96. Amend Sec. 90.206 by adding introductory text to read as follows:
Sec. 90.206 Exercise of option or transfer sampling.
The following is required until April 14, 2025:
* * * * *
0
97. Add Sec. 90.206T to read as follows:
Sec. 90.206T Exercise of option or transfer sampling.
(a) The operator shall take five valid representative dust samples
for each part 90 miner within 15 calendar days after:
(1) The 20-day period specified for each part 90 miner in Sec.
90.100; and
(2) Implementing any transfer after the 20th calendar day following
receipt of notification from MSHA that a part 90 miner is employed at
the mine.
(b) Noncompliance with the standard shall be determined in
accordance with Sec. 90.207(d).
(c) Upon issuance of a citation for a violation of the standard,
the operator shall comply with Sec. 90.207(f).
Sec. 90.206 [Removed]
0
98. Effective April 14, 2025, remove Sec. 90.206.
Sec. 90.206T [Redesignated as Sec. 90.206]
0
99. Effective April 14, 2025, redesignate Sec. 90.206T as Sec.
90.206.
0
100. Amend Sec. 90.207 by adding introductory text to read as follows:
Sec. 90.207 Quarterly sampling.
The following is required until April 14, 2025:
* * * * *
0
101. Add Sec. 90.207T to read as follows:
Sec. 90.207T Quarterly sampling.
As of April 14, 2025:
(a) Each operator shall take five valid representative samples
every calendar quarter from the environment of each part 90 miner while
performing normal work duties. Part 90 miner samples shall be collected
on consecutive work days. The quarterly periods are:
(1) January 1-March 31
(2) April 1-June 30
(3) July 1-September 30
(4) October 1-December 31.
(b) [Reserved]
(c) When a valid representative sample taken in accordance with
this section meets or exceeds the ECV in table 1 to this section
corresponding to the particular sampling device used, the mine operator
shall:
(1) Make approved respiratory equipment available to affected
miners in accordance with Sec. 72.700 of this chapter;
(2) Immediately take corrective action to lower the concentration
of respirable coal mine dust to below the standard; and
(3) Make a record of the corrective actions taken. The record shall
be certified by the mine foreman or equivalent mine official, no later
than the end of the mine foreman's or equivalent official's next
regularly scheduled working shift. The record shall be made in a secure
book that is not susceptible to alteration or electronically in a
computer system so as to be secure and not susceptible to alteration.
Such records shall be retained at a surface location at the mine for at
least 1 year and shall be made available for inspection by authorized
representatives of the Secretary and the part 90 miner.
(d) Noncompliance with the standard is demonstrated during the
sampling period when:
(1) Two or more valid representative samples meet or exceed the ECV
in table 1 to this section that corresponds to the particular sampling
device used; or
(2) The average for all valid representative samples meets or
exceeds the ECV in table 1 to this section that corresponds to the
particular sampling device used.
(e) Unless otherwise directed by the District Manager, upon
issuance of a citation for a violation of the standard, paragraph (a)
of this section shall not apply to that Part 90 miner until the
violation is abated and the citation is terminated in accordance with
paragraphs (e) and (f) of this section.
(f) Upon issuance of a citation for a violation of the standard,
the operator shall take the following actions sequentially:
(1) Make approved respiratory equipment available to the affected
part 90 miner in accordance with Sec. 72.700 of this subchapter.
(2) Immediately take corrective action to lower the concentration
of respirable dust to below the standard. If the corrective action
involves:
(i) Reducing the respirable dust levels in the work position of the
part 90 miner identified in the citation, the operator shall implement
the proposed corrective actions and begin sampling the affected miner
within 8 calendar days after the date the citation is issued, until
five valid representative samples are taken.
(ii) Transferring the Part 90 miner to another work position at the
mine to meet the standard, the operator shall comply with Sec. 90.102
and then sample the affected miner in accordance with Sec. 90.206(a).
(3) Make a record of the corrective actions taken. The record shall
be certified by the mine foreman or equivalent mine official, no later
than the end of the mine foreman's or equivalent official's next
regularly scheduled working shift. The record shall be made in a secure
book that is not susceptible to alteration or electronically in a
computer system so as to be secure and not susceptible to alteration.
Such records shall be retained at a surface location at the mine for at
least 1 year and shall be made available for inspection by authorized
representatives of the Secretary and the part 90 miner.
(g) A citation for a violation of the standard shall be terminated
by MSHA when the equivalent concentration of each of the five valid
representative samples is below the standard.
Table 1 to Sec. 90.207T--Excessive Concentration Values (ECV) Based on a Single Sample, Two Samples, or the
Average of Five Full-Shift CMDPSU/CPDM Concentration Measurements
----------------------------------------------------------------------------------------------------------------
ECV (mg/m\3\)
Section Samples -------------------------------
CMDPSU CPDM
----------------------------------------------------------------------------------------------------------------
90.207(c).................................. Single sample...................... 0.74 0.57
90.207(d)(1)............................... 2 or more samples.................. 0.74 0.57
90.207(d)(2)............................... 5 sample average................... 0.61 0.53
90.207(g).................................. Each of 5 samples.................. 0.74 0.57
----------------------------------------------------------------------------------------------------------------
[[Page 28485]]
Sec. 90.207 [Removed]
0
102. Effective April 14, 2025, remove Sec. 90.207.
Sec. 90.207T [Redesignated as Sec. 90.207]
0
103. Effective April 14, 2025], redesignate Sec. 90.207T as Sec.
90.207.
Subpart D--Respirable Dust Control Plans
0
104. Amend Sec. 90.300 by adding introductory text to read as follows:
Sec. 90.300 Respirable dust control plan; filing requirements.
The following is required until April 14, 2025:
* * * * *
0
105. Add Sec. 90.300T to read as follows:
Sec. 90.300T Respirable dust control plan; filing requirements.
As of April 14, 2025:
(a) If an operator abates a violation of the standard by reducing
the respirable dust level in the position of the Part 90 miner, the
operator shall submit to the District Manager for approval a written
respirable dust control plan for the Part 90 miner in the position
identified in the citation within 15 calendar days after the citation
is terminated. The respirable dust control plan and revisions thereof
shall be suitable to the conditions and the mining system of the coal
mine and shall be adequate to continuously maintain respirable dust
below the standard for that Part 90 miner.
(b) Each respirable dust control plan shall include at least the
following:
(1) The mine identification number assigned by MSHA, the operator's
name, mine name, mine address, and mine telephone number and the name,
address and telephone number of the principal officer in charge of
health and safety at the mine;
(2) The name and MSHA Individual Identification Number of the part
90 miner and the position at the mine to which the plan applies;
(3) A detailed description of how each of the respirable dust
control measures used to continuously maintain concentrations of
respirable coal mine dust below the standard; and
(4) A detailed description of how each of the respirable dust
control measures described in response to paragraph (b)(3) of this
section will continue to be used by the operator, including at least
the specific time, place, and manner the control measures will be used.
Sec. 90.300 [Removed]
0
106. Effective April 14, 2025, remove Sec. 90.300.
Sec. 90.300T [Redesignated as Sec. 90.300]
0
107. Effective April 14, 2025, redesignate Sec. 90.300T as Sec.
90.300.
0
108. Amend Sec. 90.301 by adding introductory text to read as follows:
Sec. 90.301 Respirable dust control plan; approval by District
Manager; copy to part 90 miner.
The following is required until April 14, 2025:
* * * * *
0
109. Add Sec. 90.301T to read as follows:
Sec. 90.301T Respirable dust control plan; approval by District
Manager; copy to part 90 miner.
As of April 14, 2025:
(a) The District Manager will approve respirable dust control plans
on a mine-by-mine basis. When approving respirable dust control plans,
the District Manager shall consider whether:
(1) The respirable dust control measures would be likely to
maintain concentrations of respirable coal mine dust below the
standard; and
(2) The operator's compliance with all provisions of the respirable
dust control plan could be objectively ascertained by MSHA.
(b) MSHA may take respirable dust samples to determine whether the
respirable dust control measures in the operator's plan effectively
maintain concentrations of respirable coal mine dust below the
standard.
(c) The operator shall comply with all provisions of each
respirable dust control plan upon notice from MSHA that the respirable
dust control plan is approved.
(d) The operator shall provide a copy of the current respirable
dust control plan required under this part to the part 90 miner. The
operator shall not post the original or a copy of the plan on the mine
bulletin board.
(e) The operator may review respirable dust control plans and
submit proposed revisions to such plans to the District Manager for
approval.
Sec. 90.301 [Removed]
0
110. Effective April 14, 2025, remove Sec. 90.301.
Sec. 90.301T [Redesignated as Sec. 90.301]
0
111. Effective April 14, 2025, redesignate Sec. 90.301T as Sec.
90.301.
[FR Doc. 2024-06920 Filed 4-16-24; 8:45 am]
BILLING CODE 4520-43-P