[Federal Register Volume 84, Number 168 (Thursday, August 29, 2019)]
[Proposed Rules]
[Pages 45452-45456]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-18478]


-----------------------------------------------------------------------

DEPARTMENT OF LABOR

Mine Safety and Health Administration

30 CFR Parts 56, 57, 70, 71, 72, and 90

[Docket No. MSHA-2016-0013]
RIN 1219-AB36


Respirable Silica (Quartz)

AGENCY: Mine Safety and Health Administration, Labor.

ACTION: Request for information.

-----------------------------------------------------------------------

SUMMARY: Metal and nonmetal (MNM) miners and coal miners exposed to 
silica (quartz) in respirable dust can develop various forms of 
pneumoconiosis that are irreversible, life limiting, and may lead to 
death. MSHA's existing standards limit miners' exposures to quartz in 
respirable dust. In this Request for Information (RFI), MSHA solicits 
information and data on feasible, best practices to protect miners' 
health from exposure to quartz in respirable dust, including an 
examination of an appropriately reduced permissible exposure limit, 
potential new or developing protective technologies, and/or technical 
and educational assistance.

DATES: Comments must be received or postmarked by midnight (12 a.m.) 
Eastern Daylight Savings Time on October 28, 2019.

ADDRESSES: Submit comments and informational materials, identified by 
RIN 1219-AB36 or Docket No. MSHA 2016-0013, by one of the following 
methods:
     Federal E-Rulemaking Portal: https://www.regulations.gov. 
Follow the on-line instructions for submitting comments.
     Email: [email protected].
     Mail: MSHA, Office of Standards, Regulations, and 
Variances, 201 12th Street South, Suite 4E401, Arlington, Virginia 
22202-5452.
     Hand Delivery or Courier: 201 12th Street South, Suite 
4E401, Arlington, Virginia, between 9:00 a.m. and 5:00 p.m. Monday 
through Friday, except Federal holidays. Sign in at the receptionist's 
desk on the 4th floor East, Suite 4E401.
     Fax: 202-693-9441.
    Instructions: All submissions must include RIN 1219-AB36 or Docket 
No. MSHA 2016-0013. Do not include personal information that you do not 
want publicly disclosed; MSHA will post all comments without change to 
http://www.regulations.gov and http://arlweb.msha.gov/currentcomments.asp, including any personal information provided.
    Docket: For access to the docket to read comments received, go to 
http://www.regulations.gov or http://arlweb.msha.gov/currentcomments.asp. To read background documents, go to http://www.regulations.gov. Review the docket in person at MSHA, Office of 
Standards, Regulations, and Variances, 201 12th Street South, 
Arlington, Virginia, between 9:00 a.m. and 5:00 p.m. Monday through 
Friday, except Federal Holidays. Sign in at the receptionist's desk in 
Suite 4E401.
    Email Notification: To subscribe to receive email notification when 
MSHA publishes rulemaking documents in the Federal Register, go to 
https://www.msha.gov/subscriptions.

FOR FURTHER INFORMATION CONTACT: Sheila A. McConnell, Director, Office 
of Standards, Regulations, and Variances, MSHA, at 
[email protected] (email), 202-693-9440 (voice), or 202-693-
9441 (fax). These are not toll-free numbers.

SUPPLEMENTARY INFORMATION: 

[[Page 45453]]

I. Background

A. Crystalline Silica Sources, Adverse Health Effects, and Existing 
Standards in Metal and Nonmetal (MNM) and Coal Mining

    Crystalline silica refers to a chemical compound, silicon dioxide 
(SiO2), that 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. Quartz is found in rocks such as granite, sandstone, 
limestone, and shale. Mining, milling, and processing crystalline 
silica-containing substances can create airborne respirable particles. 
Some activities generate more respirable dust than others including, 
but not limited to, cutting, sanding, drilling, crushing, grinding, 
milling, sawing, scraping, jack hammering, excavating, or disturbing 
materials that contain quartz.
    Mechanized operations can generate large amounts of dust, 
potentially exposing miners to elevated levels of airborne dust, 
including quartz.\1\ Particles with an aerodynamic diameter smaller 
than 10 micrometer ([micro]m) are more likely to be respirable, and as 
particle diameter decreases, the proportion of particles that can reach 
the lungs' alveolar region increases. Quartz particles that are small 
enough to reach the alveolar spaces (respirable particles) may be 
deposited and retained there, leading to disease development. The 
amount of time for a miner to develop lung disease such as chronic 
obstructive pulmonary disease (COPD) or various forms of pneumoconiosis 
such as silicosis, coal workers' pneumoconiosis (CWP), progressive 
massive fibrosis (PMF), and rapidly progressive pneumoconiosis (RPP) 
depends on various factors such as cumulative dust exposure and genetic 
predisposition to lung damage.2 3 The MNM mining industry 
includes many commodities that contain various percentages of quartz. 
MNM miners' exposure to quartz dust depends, in part, on the type of 
rock or mineral being mined or processed. Each commodity, however, has 
common dust sources related to the mining process, which includes 
drilling, blasting, loading, hauling, and crushing. MSHA regulates MNM 
miners' exposure to respirable dust containing quartz under 30 CFR 
56.5001 for surface mining operations and under 30 CFR 57.5001 for 
underground mining operations. MSHA's existing standard is based on the 
American Conference of Governmental Industrial Hygienists (ACGIH) 
Threshold Limit Value (TLV)[supreg] published in 1973 \4\ that was 
incorporated by reference by MSHA's predecessor agency, the Mine 
Enforcement Safety Administration (MESA) in 1974 \5\ and then 
recodified by MSHA in 1985.\6\ MSHA's existing standard for MNM mines 
is 10 mg/m\3\/(percent respirable quartz + 2) expressed as the 
concentration of respirable dust for a full shift or an 8-hour 
equivalent time-weighted average (TWA).\7\
---------------------------------------------------------------------------

    \1\ National Institute for Occupational Safety and Health 
(NIOSH). 2019. Dust control handbook for industrial minerals mining 
and processing. Second edition. By Cecala AB, O'Brien AD, Schall J, 
Colinet JF, Franta RJ, Schultz MJ, Haas EJ, Robinson J, Patts J, 
Holen BM, Stein R, Weber J, Strebel M, Wilson L, and Ellis M. 
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. 2019-
124, RI 9701. https://doi.org/10.26616/NIOSHPUB2019124.
    \2\ Blanc P. and A. Seaton. 2016. Editorial Pneumoconiosis 
Redux--Coal Workers' Pneumoconiosis and Silicosis Are Still a 
Problem. Am J Respir Crit Care Med. 193(6): 603-604.
    \3\ Cohen, R. 2015. Clarifying Distribution, Trends, and 
Determinants of Adverse Health in United States Miners: Exploration 
and Integration of Existing Data Systems. ALPHA Foundation for the 
Improvement of Mine Safety and Health--Final Technical Report. Grant 
Number: AFC113-4. University of Illinois at Chicago, School of 
Public Health.
    \4\ American Conference of Governmental Industrial Hygienists 
(ACGIH). 1973. TLVs Threshold Limit Values for Chemical Substances 
in Workroom Air Adopted by ACGIH for 1973. Cincinnati, Ohio.
    \5\ Mine Enforcement Safety Administration (MESA). 1974. Parts 
55/56/57--Health and Safety Standards--Miscellaneous Amendments. 39 
FR 24316.
    \6\ Mine Safety and Health Administration (MSHA). 1985. 
Recodification of Safety and Health Standards for Metal and Nonmetal 
Mines--Final Rule. 50 FR 4048.
    \7\ Example: If the quartz content of the sample is 18.0%, the 
TLV[supreg] for quartz is: 10 mg/m\3\/18.0% quartz + 2 = 10 mg/m\3\/
20.0 = 0.50 mg/m\3\.
---------------------------------------------------------------------------

    Coal miners are exposed to quartz during the extraction and 
processing of coal. Exposure to quartz during extraction occurs when 
miners disturb the rock above, below, or within the coal seam. Exposure 
also occurs in processing plants as the coal is being sized, crushed, 
dried, and conveyed. MSHA's standards (30 CFR 70.101, 71.101, and 
90.101) limit coal miners' exposure to respirable quartz in relation to 
the respirable dust standard. When respirable dust samples are analyzed 
for quartz and the concentration of quartz exceeds 0.1 mg/m\3\ (100 
micrograms per cubic meter of air or [micro]g/m\3\) MRE (British Mining 
Research Establishment) equivalent concentration, MSHA reduces the 
applicable respirable dust standard for sections of the mine 
represented by the sample data. MSHA computes the reduced dust standard 
by dividing 10 by the percent of quartz (10/percent quartz \8\).
---------------------------------------------------------------------------

    \8\ Example: A valid representative dust sample with an 
equivalent concentration of 1.12 mg/m\3\ contains 12.3% of quartz 
dust corresponds to a quartz concentration of 138 mg/m\3\. The 
respirable dust standard when quartz is present is maintained on 
each shift at or below 0.8 mg/m\3\ (10/12.3% = 0.8 mg/m\3\).
---------------------------------------------------------------------------

    Since 1974, the National Institute for Occupational Safety and 
Health (NIOSH) has recommended an exposure limit for respirable 
crystalline silica (quartz) of 0.05 mg/m\3\ (50 [mu]g/m\3\) ISO.\9\ In 
2000, the ACGIH revised its Threshold Limit Value (TLV[supreg]) for 
respirable crystalline silica (quartz) to 50 [mu]g/m\3\ (ISO) and has 
since further lowered its TLV[supreg] to 25 [mu]g/m\3\ (ISO).\10\ In 
2016, the Occupational Safety and Health Administration (OSHA) amended 
MSHA's existing respirable crystalline silica standards to establish a 
permissible exposure limit (PEL) of 50 [mu]g/m\3\ (ISO).\11\
---------------------------------------------------------------------------

    \9\ National Institute for Occupational Safety and Health 
(NIOSH). 1974. Criteria for a recommended standard . . . 
Occupational Exposure to Crystalline Silica. HEW Publication No. 
(NIOSH) 75-120.
    \10\ American Conference of Governmental Industrial Hygienists 
(ACGIH). 2006. Silica, Crystalline: [alpha]-Quartz and cristobalite. 
Cincinnati, Ohio.
    \11\ Occupational Safety and Health Administration (OSHA). 2016. 
Occupational Exposure to Respirable Crystalline Silica--Final Rule. 
81 FR 16286.
---------------------------------------------------------------------------

B. Existing Controls, Including Respiratory Protection

    MSHA requires engineering or environmental controls as the primary 
means of controlling respirable dust. This is consistent with section 
202(h) of the Federal Mine Safety and Health Act of 1977 (Mine Act), 
which provides that the use of respirators shall not be substituted for 
environmental control measures in the active workings. Engineering or 
environmental controls reduce dust generation by suppressing, diluting, 
capturing, or diverting the dust being generated by the mining process.
    MSHA addressed the use of supplementary means of controlling 
miners' exposures to respirable dust in previous rulemakings. In the 
preambles to the 2000 \12\ and 2003 \13\ proposed rules \14\ on 
Verification of Underground

[[Page 45454]]

Coal Mine Operators' Dust Control Plans and Compliance Sampling for 
Respirable Dust (Plan Verifications proposed rules), MSHA discussed a 
petition for rulemaking to allow the use of powered air purifying 
respirators (PAPRs) as a supplemental means of compliance. In the 
preamble to the 2000 proposed rule, MSHA proposed to ``permit, under 
certain circumstances, the limited use of either approved loose-fitting 
PAPRs or verifiable administrative controls for compliance purposes'' 
(65 FR 42135). In the preamble to the 2003 proposed rule, MSHA proposed 
to ``permit the limited use of either approved PAPRs, administrative 
controls, or a combination of both for compliance purposes in those 
circumstances where further reduction of dust levels cannot be 
reasonably achieved using all feasible engineering controls.'' (68 FR 
10800).
---------------------------------------------------------------------------

    \12\ Mine Safety and Health Administration (MSHA). 2000. 
Verification of Underground Coal Mine Operators' Dust Control Plans 
and Compliance Sampling for Respirable Dust--Proposed rule; notice 
of hearings. 65 FR 42122.
    \13\ Mine Safety and Health Administration (MSHA). 2003. 
Verification of Underground Coal Mine Operators' Dust Control Plans 
and Compliance Sampling for Respirable Dust--Proposed rule; notice 
of hearings; close of record. 68 FR 10784.
    \14\ The 2010 proposed rule (75 FR 64413) combined the following 
rulemaking actions: (1) ``Occupational Exposure to Coal Mine Dust 
(Lowering Exposure);'' (2) ``Verification of Underground Coal Mine 
Operators' Dust Control Plans and Compliance Sampling for Respirable 
Dust'' (Plan Verification) (65 FR 42122, July 7, 2000, and 68 FR 
10784, March 6, 2003); (3) ``Determination of Concentration of 
Respirable Coal Mine Dust'' (Single Sample) (65 FR 42068, July 7, 
2000, and 68 FR 10940 March 6, 2003); and (4) ``Respirable Coal Mine 
Dust: Continuous Personal Dust Monitor (CPDM)'' (74 FR 52708, 
October 14, 2009). The 2010 proposed rule was finalized on May 1, 
2014 (84 FR 24814).
---------------------------------------------------------------------------

    MSHA explained that there may be only limited situations where 
exposures could not be consistently controlled by available 
technologies (65 FR 42134; 68 FR 10798-10799, 10818). MSHA reiterated 
that engineering or environmental controls are the primary means to 
control respirable dust in the mine atmosphere, which is consistent 
with sections 201(b) and 202(h) of the Mine Act. MSHA also noted that 
the Dust Advisory Committee unanimously recommended that respiratory 
protection should not replace engineering or environmental controls, 
but should continue to be provided to miners until controls are 
implemented that are capable of maintaining respirable dust levels in 
compliance with the standards.\15\ In those limited situations, mine 
operators are required to provide respiratory protection to miners 
while they adjust engineering and environmental controls to reduce dust 
levels to at or below the standard.
---------------------------------------------------------------------------

    \15\ U.S. Department of Labor, Mine Safety and Health 
Administration. 1996. Report of the Secretary of Labor's Advisory 
Committee on the Elimination of Pneumoconiosis Among Coal Mine 
Workers. Washington, DC. October 1996.
---------------------------------------------------------------------------

    In addition, in MSHA's 2014 rulemaking on Lowering Miners' Exposure 
to Respirable Coal Mine Dust, including Continuous Personal Dust 
Monitors (Dust Rule),\16\ commenters advocated the use of PAPRs, not 
only as a temporary supplementary control, but also as an engineering 
control. Other commenters stated that using respirators as a means of 
complying with the dust standard is contrary to the Mine Act and would 
provide miners with a false sense of protection. Some commenters cited 
the difficulty of wearing respirators in hot and sweaty jobs, and in 
dusty, dirty conditions, including in low coal. While the final rule 
allows operators to use engineering and administrative controls, the 
rule did not contain provisions to allow operators to use respirators, 
including PAPRs, as supplementary controls to achieve compliance with 
the respirable dust standards. As specified in Sections 201(b) and 
202(h) of the Mine Act and since passage of the Federal Coal Mine 
Health and Safety Act of 1969, MSHA has enforced an environmental 
standard at coal mines; that is, the concentration of respirable dust 
in the mine atmosphere is measured rather than the breathing zone of 
any individual miner.
---------------------------------------------------------------------------

    \16\ Mine Safety and Health Administration (MSHA). 2014. 
Lowering Miners' Exposure to Respirable Coal Mine Dust, Including 
Continuous Personal Dust Monitors--Final rule. 79 FR 24814.
---------------------------------------------------------------------------

    Engineering controls, also known as environmental controls, are the 
most protective means of controlling dust generation at the source. 
MSHA is aware that there may be conditions where existing engineering 
or environmental controls may not be adequate to continuously protect 
miners' health in areas where there are high levels of quartz dust.
    NIOSH researchers have documented large clusters of coal miners in 
eastern Kentucky, West Virginia, and southwest Virginia with PMF, the 
most severe form of black lung disease.17 18 NIOSH reported 
that a high proportion of these cases had r-type opacities, category B 
and C large opacities, and coal mining tenure of less than 20 years, 
which are indications of exceptionally severe and rapidly progressive 
disease. Historically, the typical progression (latency) from a normal 
chest X-ray to advanced pneumoconiosis in coal miners exposed to coal 
dust was 15 to 25 years of working tenure.\19\ However, as mining has 
become highly mechanized, some miners may be exposed to higher 
concentrations of dusts, including quartz.\20\ NIOSH defined rapid 
progression of the disease as an increase of greater than one small ILO 
(International Labor Organization) category within a period of 5 years, 
or the development of PMF.21 22 23 Researchers also noted 
that one potential cause of a rapidly progressive disease is 
overexposure to respirable quartz.24 25 26
---------------------------------------------------------------------------

    \17\ Blackley, D., C. Halldin, and A. Laney. 2016. Resurgence of 
Progressive Massive Fibrosis in Coal Miners--Eastern Kentucky, 2016. 
Morbidity and Mortality Weekly Report, 65 (49):1385-9.
    \18\ Blackley, D., L. Reynolds, C. Short, et al. 2018b. Research 
Letter: Progressive Massive Fibrosis in Coal Miners from 3 Clinics 
in Virginia. JAMA, 319(5):500-1.
    \19\ Petsonk, E., C. Rose, and R. Cohen. 2013. Coal Mine Dust 
Lung Disease--New Lessons from an Old Exposure. Am J Respir Crit 
Care Med., 187(11):1178-1185.
    \20\ ``Drilling into the typical quartz-containing rock 
surrounding coal seams (e.g., driving tunnels to the seam and 
drilling the roof to bolt supports to rock above to prevent 
collapse) long has been recognized to cause silicosis. In addition, 
however, extrusions of quartz into coal seams may occur . . . 
accelerated silicosis may result from exploitation of thin seams 
using coal cutters that take slices of the roof and floor'' (Blanc 
and Seaton, 2016, page 604).
    \21\ Antao, V.C. dos S., E.L. Petsonk, L.Z. Sokolow, et. al. 
2005. Rapidly Progressive Coal Workers' Pneumoconiosis in the United 
States: Geographic Clustering and Other Factors. Occup Environ Med., 
62(10):670-674.
    \22\ Cohen, R.A., A. Patel, and F.H. Green. 2008. Lung Disease 
Caused By Exposure to Coal Mine and Silica Dust. Seminars in 
Respiratory and Critical Care Medicine, 29(6):651-661. Epub. Feb 16, 
2009.
    \23\ National Academies of Sciences, Engineering, and Medicine. 
2018. Monitoring and Sampling Approaches to Assess Underground Coal 
Mine Dust Exposures. Washington, DC: The National Academies Press. 
doi: https://www.nap.edu/catalog/25111/monitoring-and-sampling-approaches-to-assess-underground-coal-mine-dust-exposures. Page 16.
    \24\ Halldin, C., A. Wolfe, and A. Laney. 2015(b). Debilitating 
Lung Disease Among Surface Coal Miners With No Underground Mining 
Tenure. JOEM, 57():62-67.
    \25\ Petsonk, E., C. Rose, and R. Cohen. 2013. Coal Mine Dust 
Lung Disease--New Lessons from an Old Exposure. Am J Respir Crit 
Care Med., 187(11):1178-1185.
    \26\ Cohen, RA., E. Petsonk, C. Rose, et al. 2016. Lung 
Pathology in U.S. Coal Workers with Rapidly Progressive 
Pneumoconiosis Implicates Silica and Silicates. Am J Respir Crit 
Care Med Vol 193(6): 673-680.
---------------------------------------------------------------------------

    Recent studies indicate that over-exposure to quartz presents same 
health risks to MNM miners.27 28 29 30 Although

[[Page 45455]]

most MNM miners with early-stage silicosis (ILO categories 0/1 or 1/0) 
typically do not experience respiratory symptoms, the primary risk to 
the affected miner is progression of disease with progressive decline 
of lung function. Several studies of MNM miners exposed to respirable 
crystalline silica (quartz) have shown that, once silicosis is detected 
by x-ray, a substantial proportion of affected miners can progress 
beyond ILO category 1 silicosis, even after exposure has 
ceased.31 32 33 34
---------------------------------------------------------------------------

    \27\ Institute of Occupational Medicine (IOM 2011). Health, 
socio-economic and environmental aspects of possible amendments to 
the EU Directive on the protection of workers from the risks related 
to exposure to carcinogens and mutagens at work--Respirable 
crystalline silica. IOM Research Project: P937/8. May 2011. 
Edinburgh, UK.
    \28\ National Institute for Occupational Safety and Health 
(NIOSH). 2019. Dust control handbook for industrial minerals mining 
and processing. Second edition. By Cecala AB, O'Brien AD, Schall J, 
Colinet JF, Franta RJ, Schultz MJ, Haas EJ, Robinson J, Patts J, 
Holen BM, Stein R, Weber J, Strebel M, Wilson L, and Ellis M. 
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. 2019-
124, RI 9701. https://doi.org/10.26616/NIOSHPUB2019124.
    \29\ Occupational Safety and Health Administration (OSHA). 2016. 
Occupational Exposure to Respirable Crystalline Silica--Final Rule. 
81 FR 16286.
    \30\ U.S. Department of Labor (USDOL). 2008. A Practical Guide 
to an Occupational Health Program for Respirable Crystalline Silica. 
A Joint Project of: The Industrial Minerals Association--North 
America and the Mine Safety and Health Administration. Instruction 
Guide Series IG 103. January 25, 2008.
    \31\ Hessel, P.A., G.K. Sluis-Cremer, E. Hnizdo; et al. 1988. 
Progression OF Silicosis in Relation to Silica Dust Exposure. Ann. 
O. Hyg., 32(Suppl 1):689-696.
    \32\ Kreiss K. and B. Zhen. 1996. Risk of silicosis in a 
Colorado mining community. Am J Ind Med., 30(5):529-39.
    \33\ Ng T.P., S.L. Chan, and K.P. Lam. 1987a. Radiological 
progression and lung function in silicosis: A ten year follow up 
study. Br Med J., 295:164-168.
    \34\ Yang, H., L. Yang, J. Zhang, et al. 2006. Natural Course of 
Silicosis in Dust-exposed Workers. J. Huazhong University of Science 
and Technology, [Med Sci]. 26(2):257-260.
---------------------------------------------------------------------------

    Respiratory protection may play an important role in reducing 
miners' exposure to respirable quartz. MSHA's existing coal (30 CFR 
72.700, 72.701, and 72.710) and MNM standards (30 CFR 56/57.5005) 
require respiratory protection to be approved by NIOSH under 42 CFR 
part 84 (Approval of Respiratory Protective Devices), and incorporate 
by reference the American National Standards Institute's (ANSI's) 
``Practices for Respiratory Protection ANSI Z88.2-1969'' standard.\35\ 
MSHA is aware that in 2015, ANSI updated the Z88.2 standard.\36\ A copy 
of the 2015 ANSI standard is in the docket and MSHA seeks comment on 
this updated standard.
---------------------------------------------------------------------------

    \35\ American National Standards Institute (ANSI). 1969. 
Practices for Respiratory Protection ANSI Z88.2-1969. New York, New 
York.
    \36\ American National Standards Institute (ANSI). American 
National Standard--Practices for Respiratory Protection--ANSI/ASSE 
Z88.2-2015. American National Standards Institute, Inc. American 
Society of Safety Engineers, Park Ridge, Illinois. Approved March 4, 
2015.
---------------------------------------------------------------------------

    Under MSHA's MNM standards (30 CFR 56/57.5005), control of miners' 
exposure to respirable quartz must, where feasible, be achieved 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, miners may work for 
reasonable periods of time in a location where concentrations of 
respirable quartz exceed permissible levels only if they are protected 
by appropriate respiratory protective equipment.
    MSHA's standards for coal dust (30 CFR 70.208, 70.209, 71.206, and 
90.207) require that either during operator exposure monitoring when a 
valid representative sample meets or exceeds the excessive 
concentration value, or when the mine operator receives a citation for 
a violation of the applicable standard, the mine operator must take 
actions to protect miners, including making respiratory protection 
available while evaluating and implementing dust control measures, as 
necessary, to reduce miners' exposures to respirable dust. Under MSHA's 
existing coal standards, however, miners are not compelled to wear 
respirators and mine operators cannot use respirators as a substitute 
for engineering or environmental controls. Also MSHA cannot credit mine 
operators' use of respiratory protection in achieving compliance.

C. Hierarchy of Controls

    Controlling exposures to occupational hazards is the primary way to 
protect workers. Traditionally, mine operators use a hierarchy of 
controls to determine how to implement feasible and effective control 
solutions and are considered generally accepted industry hygiene 
principles. The hierarchy of controls begins with the most effective 
controls: Elimination and substitution of hazards. Elimination and 
substitution of hazards, while most effective at reducing risks, are 
not feasible to reduce exposures to respirable crystalline quartz for 
MNM or coal mining. The controls that are relevant in mining are: 
Engineering controls, administrative controls, and personal protective 
equipment (PPE).
    Engineering controls are favored over administrative controls and 
PPE for controlling miner exposures in the workplace because they are 
designed to remove the hazard at the source, before miners are exposed. 
Well-designed, installed, and maintained engineering controls can be 
highly effective in protecting miners and are typically independent of 
worker interactions (human factors) to provide a high level of 
protection.\37\
---------------------------------------------------------------------------

    \37\ National Institute for Occupational Safety and Health 
(NIOSH). 2015. Hierarchy of Controls. NIOSH website at: https://www.cdc.gov/niosh/topics/hierarchy/. Accessed June 4, 2019, last 
reviewed January 13, 2015.
---------------------------------------------------------------------------

    Administrative controls and PPE are frequently used with existing 
workplace practices where hazards are not well controlled. These 
methods for protecting miners have proven to be less effective than 
engineering controls, requiring significant effort by the mine operator 
and affected miners.
    In mining, engineering or environmental controls include all 
methods that control the level of respirable dust by reducing dust 
generation (machine parameters) or by suppressing (water sprays, 
wetting agents, foams, water infusion, etc.), diluting (ventilation), 
capturing dust (dust collectors) or diverting dust (shearer clearer, 
passive barriers, etc.).
    Administrative controls refer to work practices that reduce miners' 
daily exposure to respirable dust hazards by altering the way in which 
work is performed. Administrative controls consists of such actions as 
rotation of miners to areas having lower dust concentrations, 
rescheduling of tasks, and modifying work activities. The effectiveness 
of administrative controls requires oversight to ensure that miners 
adhere to the controls, such as restrictions of time in an area or 
switching duties. Using administrative controls also requires a 
sufficient number of qualified miners available to perform the specific 
duties.
    A form of PPE, an air purifying respirator is designed to protect 
miners from the inhalation of hazardous contaminants. Respirators can 
protect miners by removing contaminants from the air they breathe. 
Particulate air-purifying respirators remove or filter airborne 
contaminants from the air before they can be inhaled. Examples of this 
type of respirator include dust masks (filtering face pieces), half or 
full-mask (elastomeric) respirators, and PAPRs.
    Engineering controls are more effective than respirators in 
continuously protecting miners from respirable crystalline quartz. Many 
factors affect the effectiveness of respirators to protect miners. The 
protection of a respirator is reduced dramatically or voided when the 
respirator is improperly worn such as with facial hair that interferes 
with the seal or when the respirator is removed in contaminated 
atmospheres during periods of exposure, even for short durations. For 
example, if a miner properly wears a half-mask respirator continually 
during an 8-hour exposure duration, the protection factor afforded is 
10; however, removing the respirator for 24 minutes during the 8-hour 
exposure duration reduces the protection factor to 6.9. If the miner 
wears the respirator for only half of the exposure duration, the 
protection factor is reduced to 1.8 (2015 ANSI Z88.2--Table A.7-1). 
Many respirators may not be comfortable, and a miner's tolerance to 
wearing a respirator can decrease

[[Page 45456]]

over an extended period of time. Miners are also likely to remove 
respirators when performing arduous tasks, communicating, chewing 
tobacco, are sick, hot or sweaty, or when the respirator is 
uncomfortable, thereby subjecting miners to respirable crystalline 
silica concentrations above the standard.
    MSHA addressed the ``hierarchy of controls'' in the 2000 (65 FR 
42122) and 2003 (68 FR 10784) Plan Verification proposed rules, and in 
the 2014 Dust rule (79 FR 24814). Commenters to the Dust rule noted 
that MSHA permits the use of ``hierarchy of controls'' in MNM mines to 
control miners' exposure to diesel particulate matter (79 FR 24930). In 
the Plan Verification proposed rules, and in the Dust rule, MSHA 
reiterated that engineering or environmental controls are the primary 
means to control respirable dust in the mine atmosphere, which is 
consistent with sections 201(b) and 202(h) of Mine Act. However, MSHA 
also recognizes the importance of controlling miners' exposure to 
quartz and seeks information and data to determine if existing 
engineering and environmental controls can continuously protect miners 
and ensure that they do not suffer material impairment of health or 
functional capacity over their working lives from working in areas with 
high levels of quartz.

II. Information Request

    MSHA is interested in data and information on economically and 
technologically feasible best practices to protect coal and MNM miners' 
health from exposure to quartz, including a reduced standard, new or 
developing protective technologies, and/or technical and educational 
assistance.
    MSHA specifically requests input from industry, labor, and other 
interested parties on best practices that will improve health 
protections for coal and MNM miners from exposure to quartz dust.
    1. Please provide any information on new or developing technologies 
and best practices that can be used to protect miners from exposure to 
quartz dust.
    2. Please provide any information on 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. Please provide any information on additional feasible dust-
control methods that could be used by mining operations to reduce 
miners' exposure to respirable quartz during high-silica cutting 
situations, such as on development sections, shaft and slope work, and 
cutting overcasts.
    4. Please provide any other experience, data, or information that 
may be useful to MSHA in evaluating miners' exposures to quartz.

    Authority:  30 U.S.C. 811, 813(h), 957.

David G. Zatezalo,
Assistant Secretary of Labor for Mine Safety and Health Administration.
[FR Doc. 2019-18478 Filed 8-28-19; 8:45 am]
 BILLING CODE 4520-43-P