[Federal Register Volume 81, Number 110 (Wednesday, June 8, 2016)]
[Proposed Rules]
[Pages 36826-36831]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-13219]


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DEPARTMENT OF LABOR

Mine Safety and Health Administration

30 CFR Parts 57, 70, 72, and 75

RIN 1219-AB86
[Docket No. MSHA-2014-0031]


Exposure of Underground Miners to Diesel Exhaust

AGENCY: Mine Safety and Health Administration, Labor.

ACTION: Request for information.

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SUMMARY: The Mine Safety and Health Administration (MSHA) is requesting 
information and data on approaches to control and monitor miners' 
exposures to diesel exhaust. Epidemiological studies by the National 
Institute for Occupational Safety and Health (NIOSH) and the National 
Cancer Institute (NCI) have found that diesel exhaust exposure 
increases miners' risk of death due to lung cancer. In June 2012, the 
International Agency for Research on Cancer (IARC) classified diesel 
exhaust as a human carcinogen. Because of the carcinogenic health risk 
to miners from exposure to diesel exhaust and to prevent material 
impairment of miners' health, MSHA is reviewing the Agency's existing 
standards and policy guidance on controlling miners' exposures to 
diesel exhaust to evaluate the effectiveness of the protections now in 
place to preserve miners' health.

DATES: Comments must be received or postmarked by midnight Eastern 
Standard Time on September 1, 2016.

ADDRESSES: Submit comments and informational materials, identified by 
RIN 1219-AB86 or Docket No. MSHA-2014-0031, by one of the following 
methods:
     Federal E-Rulemaking Portal: http://www.regulations.gov. 
Follow the on-line instructions for submitting comments.
     Electronic Mail: [email protected].
     Mail: MSHA, Office of Standards, Regulations, and 
Variances, 201 12th Street South, Arlington, Virginia 22202-5452.
     Hand Delivery or Courier: 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.
     Fax: 202-693-9441.
    Instructions: All submissions must include ``RIN 1219-AB86'' or 
``Docket No. MSHA-2014-0031.'' Do not include personal information that 
you do not

[[Page 36827]]

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.
    E-Mail Notification: To subscribe to receive an email notification 
when MSHA publishes rules in the Federal Register, go to http://www.msha.gov.

FOR FURTHER INFORMATION CONTACT: Sheila A. McConnell, Acting 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: 

Table of Contents

I. Background
    A. Regulatory History
    B. Recent Research
    C. Health Hazard Alerts
    D. Recent State Actions
II. Information Request
    A. Non-Permissible, Light-Duty, Diesel-Powered Equipment in 
Underground Coal Mines
    B. Maintenance of Diesel-Powered Equipment in Underground Coal 
Mines and Recordkeeping Requirements
    C. Exhaust After-Treatment Technology
    D. Monitoring MNM Miners' Exposures to DPM
    E. Other Information

I. Background

A. Regulatory History

1. DPM in Underground Coal Mines
    On October 25, 1996, MSHA published a final rule establishing 
revised requirements for the approval of diesel engines and related 
components used in underground coal mines; requirements for coal mine 
operators' monitoring of diesel exhaust emissions; and safety standards 
for the use of diesel-powered equipment in underground coal mines (61 
FR 55412). The rule required clean-burning engines on diesel-powered 
equipment and training for persons maintaining the equipment. The rule 
also required sufficient ventilating air where diesel-powered equipment 
is operated.
    On January 19, 2001, MSHA published a final rule (66 FR 5526) 
limiting diesel particulate matter (DPM) exposure in underground coal 
mines. This standard is based on laboratory analysis of engine exhaust. 
It requires that the exhaust of certain pieces of equipment be 
restricted to the following prescribed levels:
     Permissible equipment must not emit more than 2.5 grams 
per hour (g/hr) of DPM;
     Non-permissible heavy-duty equipment, as defined by 30 CFR 
75.1908(a) and operated in underground areas of underground coal mines, 
must not emit more than 2.5 g/hr of DPM (30 CFR 72.501(c));
     Non-permissible light-duty equipment, as defined by 30 CFR 
75.1908(b), must not emit more than 5.0 g/hr of DPM (30 CFR 72.502(a)).

These standards also require mine operators to use engineering controls 
to reduce DPM exposures of underground coal miners. Mine operators must 
provide annual training to all miners exposed to DPM and maintain an 
inventory of the mine's diesel-powered equipment.
    Under 30 CFR 72.502(b), non-permissible, light-duty, diesel-powered 
equipment must be deemed in compliance with 30 CFR 72.502(a) if it uses 
an engine that meets or exceeds the applicable Environmental Protection 
Agency (EPA) particulate matter emissions requirements. In promulgating 
its DPM rule, which allows more particulate emissions for light-duty 
equipment than for heavy-duty equipment, MSHA assumed that diesel 
engine manufacturers would comply with EPA standards and that, when 
replacing vehicles in the mine's light-duty fleet, mine operators would 
purchase newer (new or used) vehicles that met EPA emissions standards, 
thus accelerating the turnover to a newer generation of technology. 
MSHA expected a significant reduction in the amount of DPM emitted by 
the underground fleet as these cleaner engines replaced or supplemented 
older engines in underground coal mines.
    MSHA had considered establishing stricter standards for certain 
types of equipment and covering more light-duty equipment, but 
concluded that such actions would either be technologically or 
economically infeasible for the coal mining industry as a whole at that 
time. MSHA concluded that the introduction of newer and cleaner engines 
underground that met EPA standards, and the continued development of 
after-treatment and other control technologies, would allow additional 
reductions in DPM levels to become feasible for the industry as a 
whole.
    For this reason, MSHA's January 2001 DPM standards incorporated 
EPA's then-applicable standards for light-duty diesel engine emissions. 
In 2004, EPA phased in even lower emissions standards for light-duty 
diesel engines.
    All MSHA diesel equipment is classified as ``nonroad'' under EPA 
rules. EPA nonroad diesel engine regulations were structured as a 4-
tiered progression. Each tier involved a phased-in lowering of 
emissions standards over several years based on the size (power) of the 
engine.
    EPA published Tier 1 standards on June 17, 1994 (59 FR 31306, 40 
CFR part 89) for nonroad compression-ignition engines (which include 
diesel engines). Under these standards, for engines at and above 130 
kilowatts (kW), emissions of particulate matter could not exceed .54 g/
kW and carbon monoxide could not exceed 11.4 g/kW. These standards were 
phased in by engine size for model years 1996 to 2000. In addition, all 
engines greater than or equal to 37 kW were subject to an oxides of 
nitrogen (NOX, consisting of NO and NO2) 
emissions limit of 9.2 g/kW-hr, phased in by engine size over model 
years 1998 through 2000 (59 FR 31341). However, EPA explicitly excluded 
engines regulated by MSHA. Id. at 31340.
    On October 23, 1998, EPA published Tier 1 DPM standards for nonroad 
compression-ignition engines less than 37 kW (50 hp), setting a 1.2 g/
kW-hr particulate matter limit phased in by engine size over model 
years 1999 and 2000. The rule also established a Tier 1 NOX 
limit of 14.6 g/kW-hr for engines 37 kW and above, phased in by engine 
size over model years 1996 through 2000.
    In addition, the rule required more stringent Tier 2 DPM standards 
for all nonroad diesel engines, ranging from 1.0 g/kW-hr for the 
smallest engines to .54 g/kW-hr for the largest engines, phased in by 
engine size over model years 2001 to 2006. Under the rule, Tier 3 DPM 
standards for engines 37 kW and above were the same as the Tier 2 
standards, but for these engines Tier 3 introduced additional limits 
for other types of emissions (hydrocarbons plus NOX). The 
rule also introduced Tier 3 standards for engines 37-560 kW for these 
same other types of emissions, phased in by engine size over model 
years 2006 through 2008 (40 CFR 89.112). MSHA-regulated engines 
continued to be exempted from the EPA rule.

[[Page 36828]]

    On June 29, 2004, the EPA published a final rule introducing even 
lower Tier 4 emissions standards for new compression-ignition engines 
of all sizes. (69 FR 38958, 40 CFR 1039). This rule provided for 
``interim'' Tier 4 standards applicable to engines for model years 2014 
and earlier and final Tier 4 standards applicable to model years after 
the 2014 model year. Based on engine size, the final standards set 
particulate matter limits of .04 to .40 g/kW-hr, NOX limits 
of .40 to 3.5 g/kW-hr, and carbon monoxide limits of 3.5 to 6.6 g/kW-
hr. The final standards also imposed lower hydrocarbon limits. 40 CFR 
1039.101. Again, MSHA-regulated engines were explicitly excluded from 
these standards. 40 CFR 1039.5(c). Tier 4 engines were expected to have 
90 percent lower DPM emissions than the same types of engines under 
Tier 3 standards (69 FR 38958, 40 CFR 1039).
2. DPM in Underground Metal and Nonmetal Mines
    In 2001, MSHA published a final rule establishing new health 
standards for underground metal and nonmetal mines that use equipment 
powered by diesel engines (30 CFR part 57). This rule established a 
concentration limit for DPM and required mine operators to use 
engineering and work practice controls to reduce DPM to that limit. 
Operators were required to comply in accordance with a phase-in period, 
with the final limit to be in effect by January 20, 2006. In the rule, 
MSHA provided operators with the opportunity to obtain a special 
extension if engineering and work practice controls that would reduce a 
miner's personal exposure to the final exposure limit could not be 
implemented by the deadline due to technological constraints. This 
extension opportunity did not apply to newer mines.
    MSHA published another final rule (70 FR 32868; June 6, 2005) that 
replaced the concentration limit for DPM exposures of MNM miners from a 
total carbon (TC) permissible exposure limit (PEL) to a comparable 
elemental carbon (EC) PEL. This was not intended to be a substantive 
change to the exposure limits; rather, MSHA believed that EC renders a 
more accurate measure of DPM exposure than does TC. The first phase of 
the PEL reduction would have required a PEL of 308 micrograms of EC per 
cubic meter of air (308EC [mu]g/m\3\), effective on May 20, 
2006.
    After publishing this 2005 rule, however, MSHA found that the 
engineering applications and related technological implementation 
issues were more complex and extensive than previously thought. In 
response, the Agency published a proposed rule (70 FR 53280; September 
7, 2005) seeking specific comments and data on an appropriate 
conversion factor for the final DPM limit from TC to EC and related 
technological implementation issues.
    On May 18, 2006, MSHA published a final rule (71 FR 28924) that 
reverted back to using TC to measure DPM exposure. This rule phased-in 
a final DPM PEL of 160 micrograms of TC per cubic meter of air 
(160TC [mu]g/m\3\) over a two-year period. MSHA believed 
that the industry as a whole was capable of attaining this DPM PEL 
within the timeframes established using existing DPM control methods 
and not requiring the development of new technologies.
    MSHA stated that the development of high temperature disposable 
diesel particulate filter (HTDPF) systems would fill a critical gap in 
available filter technology because they demonstrated high filtration 
efficiency for EC, and did not increase NO2 emissions. MSHA 
also anticipated that production of biodiesel fuel would increase 
dramatically, making it easier for mine operators to gain access to a 
reliable supply of this alternative fuel. In addition, MSHA anticipated 
that EPA-compliant engines along with other engineering and 
administrative controls would enable the underground MNM mining 
industry as a whole to resolve lingering implementation challenges 
relating to the 160TC [mu]g/m\3\ DPM final exposure limit.
    In the May 18, 2006 final rule, MSHA also: (1) Finalized provisions 
addressing medical evaluation and transfer of miners who are unable to 
wear respirators for medical reasons; (2) committed the Agency to 
proposing a rule in the near future to convert the DPM limit from TC to 
EC; (3) deleted the provision that restricts newer mines from applying 
for an extension of time in which to meet the final concentration 
limit; and (4) addressed technological and economic feasibility issues 
and the costs and benefits of the rule. 30 CFR part 57. In accordance 
with the phase-in schedule, the DPM PEL was reduced to 350TC 
[micro]g/m\3\ effective January 20, 2007. The final limit of 
160TC [micro]g/m\3\ became effective on May 20, 2008.
    On May 20, 2008 (73 FR 29058), MSHA published a Federal Register 
document announcing that it had decided not to engage in rulemaking to 
convert the TC limit to a comparable EC limit. This decision was based 
on MSHA's assessment that the latest available scientific evidence 
regarding the variability of the TC to EC ratio, at levels below 230 
[micro]g TC, was insufficient to suggest an appropriate conversion 
factor. Because the Agency could not support an appropriate EC limit, 
MSHA's existing DPM standard presently remains at 160TC 
[micro]g/m\3\.
    The existing standards are based on a miner's personal exposure to 
DPM and specify that, in an underground MNM mine, such exposure must 
not exceed an average 8-hour equivalent, full-shift airborne 
concentration of 160 micrograms of total carbon (TC) per cubic meter of 
air (160TC [micro]g/m\3\) when measured as an 8-hour, time-
weighted average concentration (TWA8). 30 CFR 57.5060(b)(3). 
These standards require mine operators to use engineering and/or 
workplace controls to reduce miners' exposures to a level as low as 
feasible and, where controls do not reduce exposure to the PEL or 
below, to supplement controls with respiratory protection. 30 CFR 
57.5060(d). These standards also provide that a physician or other 
licensed health care professional conduct a medical evaluation of 
miners to determine the miner's ability to wear respiratory protection. 
30 CFR 57.5060(d)(3).

B. Recent Research

    The National Cancer Institute (NCI) (Silverman et al.) and the 
National Institute for Occupational Safety and Health (NIOSH) (Attfield 
et al.) completed the Diesel Exhaust in Miners Study in March 2012. 
This epidemiological study included 12,315 workers from eight nonmetal 
mining facilities (three potash, three trona, one limestone, and one 
salt (halite) facility) located in Ohio, Missouri, New Mexico, and 
Wyoming. The study was conducted to determine whether breathing diesel 
exhaust could lead to lung cancer and other health outcomes. Two 
evaluations of this study are published in the Journal of the National 
Cancer Institute, as follows:

    D. Silverman et al. (2012). ``The Diesel Exhaust in Miners 
Study: A Nested Case-Control Study of Lung Cancer and Diesel 
Exhaust.'' Journal of the National Cancer Institute, 104(11):855-68. 
doi: 10.1093/jnci/djs034
    M. Attfield et al. (2012). ``The Diesel Exhaust in Miners Study: 
A Cohort Mortality Study with Emphasis on Lung Cancer.'' Journal of 
the National Cancer Institute, 104(11):869-83. doi: 10.1093/jnci/
djs035

    Silverman et al. concluded that diesel exhaust exposure may cause 
lung cancer in humans and may represent a potential public health 
burden. Attfield et al. concluded that diesel exhaust increases the 
risk of death from lung cancer and has important public health 
implications.
    Both the case-control study (Silverman et al.) and the mortality

[[Page 36829]]

study (Attfield et al.) showed a strong relationship between the levels 
of exposure to diesel exhaust and risk of death from lung cancer. In 
both studies, the relationship between lung cancer risk and diesel 
exhaust exposure remained after controlling for smoking and other lung 
cancer risk factors. The death rates were about three to five times 
greater for workers with the highest exposures to diesel exhaust than 
for workers who had the lowest exposures.
    On June 12, 2012, the International Agency for Research on Cancer 
(IARC) \1\ concluded that there is sufficient evidence of 
carcinogenicity in humans from diesel exhaust exposure to upgrade its 
classification of diesel exhaust from ``probably carcinogenic'' to 
``carcinogenic to humans''.\2\
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    \1\ International Agency for Research on Cancer, World Health 
Organization, Press Release No. 213, ``IARC: Diesel Engine Exhaust 
Carcinogenic,'' June 12, 2012.
    \2\ International Agency for Research on Cancer, 
``Carcinogenicity of Diesel-Engine and Gasoline-Engine Exhausts and 
Some Nitroarenes,'' IARC Monographs, Volume 105, World Health 
Organization, 2013.
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    In November 2015, the Health Effects Institute \3\ completed its 
evaluation of recent epidemiological evidence for assessing the risk of 
lung cancer from exposure to diesel exhaust. The evaluation concluded 
that the Diesel Exhaust in Miners Study and the Trucking Industry 
Particle Study were ``well designed and carefully conducted, embodying 
the attributes of epidemiological studies that are considered important 
for quantitative risk assessment.'' \4\
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    \3\ The Health Effects Institute is an independent, non-profit 
research institute funded jointly by the U.S. Environmental 
Protection Agency and industry to provide credible, high quality 
science on air pollution and health for air quality decisions. HEI 
sponsors do not participate in the selection, oversight, or review 
of HEI science, and HEI's reports do not necessarily represent their 
views.
    \4\ HEI Press Release, ``New Report Examines Latest Studies of 
Lung Cancer Risk in Workers Exposed to Exhaust from Older Diesel 
Engines,'' November 24, 2015.
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C. Health Hazard Alerts

    Following the IARC classification of diesel exhaust as a human 
carcinogen, MSHA issued two Health Hazard Alerts: one on diesel exhaust 
and DPM in underground coal and MNM mines, and one on nitrogen dioxide 
(NO2) emissions in underground coal mines. The first Health 
Hazard Alert was issued in partnership with the Occupational Safety and 
Health Administration (OSHA) on January 10, 2013. It provided 
information about diesel exhaust and DPM in underground coal and MNM 
mines, occupations with potential exposure, the health hazards of 
exposure, engineering and workplace controls, respiratory protection, 
and the standards in place to protect miners from exposure.
    MSHA issued a second Health Hazard Alert on August 6, 2013. The 
alert reinforced the dangers of platinum-based particulate filters as a 
source of increased concentrations of nitrogen dioxide (NO2) 
in underground coal mines. MSHA had addressed these dangers before. On 
May 16, 2011, MSHA had published a Program Information Bulletin NO. 
P11-38, Re-Issue of P02-04--Potential Health Hazard Caused by Platinum-
Based Catalyzed Diesel Particulate Matter Exhaust Filters, informing 
mine operators of a potential health hazard caused by then-available 
platinum-based catalyzed diesel particulate matter (DPM) exhaust 
filters for diesel-powered equipment. The PIB advised that the use of 
these filters may result in increased production of nitrogen dioxide 
(NO2) gas, as compared to NO2 emissions produced 
by engines operating without these filters, causing miners to be 
exposed to increased concentrations of NO2.

D. State Actions

    West Virginia, Pennsylvania, and Ohio require diesel-powered 
equipment used in underground coal mines to include an exhaust 
emissions control and conditioning system that meets the following 
requirements:
     DPM emissions that do not exceed an average concentration 
of 0.12 milligrams of DPM per cubic meter of air (mg/m\3\) when diluted 
by 100 percent (West Virginia and Ohio) or by 50 percent (Pennsylvania) 
of the MSHA Part 7 approved ventilation rate for that diesel engine.
     An oxidation catalyst or other gaseous emissions control 
device capable of reducing undiluted carbon monoxide (CO) emissions to 
100 parts per million (ppm) or less under all conditions of operation 
within the normal engine operating temperature range.
     A DPM filter capable of reducing DPM concentrations by at 
least 75 percent (West Virginia) or by an average of 95 percent 
(Pennsylvania) or to a level that does not exceed an average 
concentration of 0.12 milligrams per cubic meter (mg/m\3\) of air when 
diluted by 100 percent of the MSHA Part 7 approved ventilation rate for 
that diesel engine (Ohio).
    In addition, West Virginia, Ohio, and Pennsylvania limit ambient 
concentrations of exhaust gases to a ceiling of 35 parts per million 
(ppm) for carbon monoxide (CO) and 3 ppm for nitrogen dioxide 
(NO2). West Virginia and Pennsylvania also limit ambient 
concentrations of nitric oxide (NO) to 25 ppm. If the concentrations of 
these emissions exceed 75 percent of these limits, these states require 
mine operators to make changes to the use of diesel equipment, mine 
ventilation, or other modifications to the mining process.
    All three states require mine operators to keep written records of 
emissions tests, pre-operational examinations, and maintenance and 
repairs for all diesel equipment operated underground. These states 
also require specific information to be recorded that MSHA does not 
require, e.g., the results of testing the engine at full throttle 
against the brakes with loaded hydraulics (engine speed tests), 
operating hour meter hours, total intake restriction, total exhaust 
back pressure, cooled exhaust gas temperature, coolant temperature, 
engine oil pressure, and engine oil temperature.

II. Information Request

    MSHA requests information and data on the effectiveness of the 
existing standards in controlling miners' exposures to diesel exhaust, 
including DPM. MSHA specifically requests input from industry, labor, 
and other interested parties on approaches that may enhance control of 
DPM and diesel exhaust exposures to improve protections for miners in 
underground coal and MNM mines. When responding--
     Address your comments to the topic and question number. 
For example, the response to questions regarding underground coal 
mines, Question 1, would be identified as ``A.1''.
     Explain the rationale supporting your views and, where 
possible, include specific examples.
     Provide sufficient detail in your responses to enable 
proper Agency review and consideration.
     Identify the information on which you rely and include 
applicable experiences, data, models, calculations, studies and 
articles, standard professional practices, availability of technology, 
and costs.
    MSHA invites comment in response to the specific questions posed 
below and encourages commenters to include any related cost and benefit 
data, and any specific issues related to the impact on small mines.

A. Non-Permissible, Light-Duty, Diesel-Powered Equipment in Underground 
Coal Mines

    It has been 14 years since MSHA promulgated its DPM rule for

[[Page 36830]]

underground coal mines. At that time, MSHA had estimated a service life 
of 10 years for non-permissible, light-duty, diesel-powered equipment. 
Based on this estimate, MSHA expects that all the non-permissible, 
light-duty, diesel-powered equipment in use at that time has now been 
replaced with equipment having newer and cleaner diesel engines. MSHA's 
latest diesel inventory for underground coal mines indicates that this 
newer light-duty equipment makes up about 66 percent of the total 
existing diesel-powered fleet. MSHA believes that this newer equipment 
has resulted in a decrease in the overall levels of diesel emissions in 
underground coal mines. Diesel engine manufacturers have integrated a 
variety of advanced technologies into new engine designs to reduce 
engine emissions to meet EPA requirements.
    To assist MSHA in determining whether it is feasible to lower the 
emissions limits for non-permissible, light-duty, diesel-powered 
equipment to 2.5 g/hr of DPM or less, please respond to the following 
questions. For each response, please provide data, the specific type of 
equipment, manufacturer, engine type, filter type, level of DPM, and 
comments that support your response.
    1. Is there evidence that non-permissible, light-duty, diesel-
powered equipment currently being operated in underground mines emits 
2.5 g/hr of DPM or less? If so, please provide this evidence.
    2. What administrative, engineering, and technological challenges 
would the coal mining industry face in meeting a 2.5 g/hr DPM emissions 
level for non-permissible, light-duty, diesel-powered equipment?
    3. What costs would the coal mining industry incur to lower 
emissions of DPM to 2.5 g/hr or less on non-permissible, light-duty 
diesel-powered equipment? What are the advantages, disadvantages of 
requiring that light-duty diesel-powered equipment emit no more than 
2.5 g/hr of DPM?
    4. What percentage of non-permissible, light-duty, diesel-powered 
equipment operating underground does not meet the current EPA emissions 
standards?
    5. What modifications could be applied to non-permissible, light-
duty, diesel-powered equipment to meet current EPA emissions standards? 
What percentage of this equipment could not be modified to meet current 
EPA emissions standards? If these are specific types of equipment, 
please list the manufacturers and model numbers.
    6. What are the advantages, disadvantages, and costs associated 
with requiring all non-permissible, light-duty, diesel-powered 
equipment operating in underground coal mines to meet current EPA 
emissions standards? Please be specific and include the rationale for 
your response.
    7. West Virginia, Pennsylvania, and Ohio limit diesel equipment in 
the outby areas of underground coal mines based on the air quantity 
approved on the highest ventilation plate. What are the advantages, 
disadvantages, and costs of MSHA adopting such an approach?

B. Maintenance of Diesel-Powered Equipment in Underground Coal Mines 
and Recordkeeping Requirements

    Performing routine preventive maintenance of diesel engines helps 
ensure that the engines are maintained in approved condition. Under 30 
CFR 75.1914(f), all diesel-powered equipment must be examined and 
tested weekly in accordance with approved checklists and manufacturers' 
maintenance manuals. Under 30 CFR 75.1914(g), diesel-powered equipment 
approved under 30 CFR part 36 and non-permissible, heavy-duty, diesel-
powered equipment in underground coal mines are tested and evaluated on 
a weekly basis in accordance with mine operator-developed standard 
operating procedures. These procedures must provide for carbon monoxide 
sampling; carbon monoxide concentration must not exceed 2500 parts per 
million.
    8. What would be the advantages, disadvantages, safety and health 
benefits, and costs of testing non-permissible, light-duty, underground 
diesel-powered equipment on a weekly basis for carbon monoxide as 
required for permissible diesel-powered equipment and non-permissible, 
heavy-duty, diesel-powered equipment?
    9. Reducing the emissions of nitric oxide (NO) and nitrogen dioxide 
(NO2) is one way that engine manufacturers can control 
particulate production indirectly. What are the advantages, 
disadvantages, and costs of expanding exhaust emissions tests to 
include NO and NO2 to determine the effectiveness of 
emissions controls in underground coal mines? Please provide data and 
comments that support your response.
    10. Should MSHA require that diagnostics system tests include 
engine speed (testing the engine at full throttle against the brakes 
with loaded hydraulics), operating hour meter, total intake 
restriction, total exhaust back pressure, cooled exhaust gas 
temperature, coolant temperature, engine oil pressure, and engine oil 
temperature, as required by some states? Why or why not?
    11. What would be the advantages, disadvantages, and costs 
associated with requiring additional records to document the testing 
and maintenance of diesel-powered equipment in underground coal mines, 
such as the testing described above? Please be specific and include the 
rationale for your response.
    12. If your mine is in West Virginia, Pennsylvania, or Ohio, what 
is your experience with the resources expended to keep testing records? 
How have these records been used, e.g., have you analyzed the records 
for trends? Have you made any changes in the use of the diesel-powered 
equipment, emissions controls, or mine ventilation based on the records 
of emissions testing? If so, please provide examples.
    13. Please provide information related to additional training 
requirements for persons who operate and maintain diesel equipment. 
Please be specific on the types of training required, time associated 
with training, and additional safety and health benefits provided.

C. Exhaust After-Treatment and Engine Technologies

    Options for reducing diesel exhaust emissions that are available 
include integration of advanced technologies into new engine designs 
and exhaust after-treatment systems. Reduction of diesel exhaust 
emissions prior to their release into the mine environment is an 
effective strategy used to prevent or reduce exposure of underground 
miners to diesel exhaust. The underground coal and MNM mining 
industries use exhaust after-treatment technology to control and reduce 
DPM and gaseous emissions from the existing fleet of diesel-powered 
equipment. While existing DPM standards provide for flexibility of 
controls to reach the required limit (i.e., controls that reduce engine 
emissions), MSHA expected that most operators would use hot gas 
(ceramic) filters to comply.
    MSHA is requesting information on the types and effectiveness of 
exhaust after-treatment technologies used in underground mines. Please 
describe some best practices for selecting and using after-treatment 
devices.
    14. What exhaust after-treatment technologies are currently used on 
diesel-powered equipment? What are the costs associated with acquiring 
and maintaining these after-treatment technologies and by how much did 
they reduce DPM emissions? How durable and reliable are after-treatment 
technologies and how often should these technologies be replaced? 
Please be specific and include examples and the rationale for your 
response.

[[Page 36831]]

    15. What are the advantages, disadvantages, and relative costs of 
using DPM filters capable of reducing DPM concentrations by at least 75 
percent or by an average of 95 percent or to a level that does not 
exceed an average concentration of 0.12 milligrams per cubic meter (mg/
m\3\) of air when diluted by 100 percent of the MSHA Part 7 approved 
ventilation rate for that diesel engine? How often do the filters need 
to be replaced?
    16. What sensors (e.g. ammonia, nitrogen oxide (NO), nitrogen 
dioxide (NO2)) are built into the after-treatment devices 
used on the diesel-powered equipment?
    17. Are integrated engine and exhaust after-treatment systems used 
to control DPM and gaseous emissions in the mining industry? If so, 
please describe the costs associated with acquiring and maintaining 
integrated systems, and the reduction in DPM emissions produced.
    18. What are the advantages, disadvantages, and relative costs of 
requiring that all light-duty diesel-powered equipment be equipped with 
high-efficiency DPM filters?
    As discussed above, on June 29, 2004, EPA adopted Tier 4 diesel 
engine standards. These standards are performance-based and technology-
neutral in the sense that manufacturers are responsible for determining 
which emissions control technologies will be needed to meet the 
requirements. Engine manufacturers will produce new engines with 
advanced emissions control technologies to comply with Tier 4 emissions 
standards. Exhaust emissions from these engines are expected to 
decrease by more than 90 percent.
    19. In the mining industry, are operators replacing the engines on 
existing equipment with Tier 4i (interim) or Tier 4 engines? If so, 
please specify the type of equipment (make and model) and engine size 
and tier. Please indicate how much it costs to replace the engine 
(parts and labor).
    20. What types of diesel equipment purchased new for use in the 
mining industry is powered by Tier 4i or Tier 4 engines? What types of 
diesel-powered equipment, purchased used for use in the mining 
industry, are powered by Tier 3, Tier 4i or Tier 4 engines?
    21. Are Tier 4i or Tier 4 engines used in underground mines 
equipped with diesel particulate filter (DPF) systems (e.g., advanced 
diesel engines with integrated after-treatment systems)? Please provide 
specific examples.
    22. How long have Tier 4i or Tier 4 engines been in use in the 
mining industry and what additional cost is associated with maintaining 
equipment equipped with these engines?
    23. What percentage of underground coal mines' total diesel 
equipment inventory is equipped with Tier 4i or Tier 4 engines?

D. Monitoring MNM Miners' Exposures to DPM

    Under the existing standards, MSHA uses total carbon (TC) 
measurements as a surrogate for DPM when determining MNM miners' DPM 
exposures.
    24. MSHA requests information on alternative surrogates, other than 
TC, to estimate a miner's DPM exposure. What is the surrogate's limit 
of detection and what are potential interferences in a mine 
environment?
    25. What are the advantages, disadvantages, and relative costs for 
using the alternative surrogate to determine a MNM miner's exposure to 
DPM? Please be specific and include the rationale for your response.
    26. MSHA requests information on advances in sampling and 
analytical technology and other methods for measuring a MNM miner's DPM 
exposure that may allow for a reduced exposure limit.

E. MNM Miners' Personal Exposure Limit (PEL)

    MSHA analyzed its sampling data from 2006 (when the final PEL was 
published) to 2015, and found that the average exposures of MNM miners 
decreased by 57 percent from 253TC to 109TC 
[mu]g/m\3\ in MNM mines. Further analysis of the data revealed that 
approximately 63 percent of the mines sampled had average exposures 
below 100TC [mu]g/m\3\ in 2015 and 75 percent of the mines 
sampled have average exposures below 122TC [mu]g/m\3\. 
Overall, 50 percent of the mines sampled have average exposures between 
48TC and 122TC [mu]g/m\3\. For operators who have 
had success in reducing exposures below the existing standard, please 
describe the best practices that you have used to reduce controls. MSHA 
intends to share this information with the underground metal and 
nonmetal mining community.
    27. What existing controls were most effective in reducing 
exposures since 2006? Are these controls available and applicable to 
all MNM mines?
    28. Based on MSHA's data, MNM miners' average exposures are well 
below the existing standard of 160TC [mu]g/m\3\. What are 
the technological challenges and relative costs of reducing the DPM 
exposure limit?

F. Other Information

    Please provide any other data or information that may be useful to 
MSHA in evaluating miners' exposures to harmful diesel exhaust 
emissions, including the effectiveness of existing control mechanisms 
for reducing harmful diesel emissions and limiting miners' exposures to 
harmful diesel exhaust emissions.

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

Joseph A. Main,
Assistant Secretary of Labor for Mine Safety and Health.
[FR Doc. 2016-13219 Filed 6-7-16; 8:45 am]
BILLING CODE 4520-43-P