[Federal Register Volume 68, Number 157 (Thursday, August 14, 2003)]
[Proposed Rules]
[Pages 48668-48721]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-20190]



[[Page 48667]]

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Part II





Department of Labor





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Mine Safety and Health Administration



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30 CFR Part 57



Diesel Particulate Matter Exposure of Underground Metal and Nonmetal 
Miners; Proposed Rule

  Federal Register / Vol. 68, No. 157 / Thursday, August 14, 2003 / 
Proposed Rules  

[[Page 48668]]


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DEPARTMENT OF LABOR

Mine Safety and Health Administration

30 CFR Part 57

RIN 1219-AB29


Diesel Particulate Matter Exposure of Underground Metal and 
Nonmetal Miners

AGENCY: Mine Safety and Health Administration (MSHA), Labor.

ACTION: Proposed rule; notice of public hearings; close of comment 
period; request for data.

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SUMMARY: This proposed rule would: Revise the existing diesel 
particulate matter (DPM) interim concentration limit measured by total 
carbon (TC) to a comparable permissible exposure limit (PEL) measured 
by elemental carbon (EC) which renders a more accurate DPM exposure 
measurement; increase flexibility of compliance by requiring MSHA's 
longstanding hierarchy of controls for its other exposure-based health 
standards at metal and nonmetal mines, but prohibit rotation of miners 
for compliance; allow MSHA to consider economic as well as 
technological feasibility in determining if operators qualify for an 
extension of time in which to meet the DPM limits; and simplify 
requirements for a DPM control plan. The proposed rule would also make 
conforming changes to existing provisions concerning compliance 
determinations, environmental monitoring and recordkeeping.
    The existing final rule pertaining to ``Diesel Particular Matter 
Exposure of Underground Metal and Nonmetal Miners,'' was published in 
the Federal Register on January 19, 2001 (66 FR 5706, RIN 1219-AB11) 
and amended on February 27, 2002 (67 FR 9180). This rulemaking is part 
of a settlement agreement reached in response to a legal challenge to 
the January 19, 2001 diesel particular matter (DPM) standard.
    Specifically in this proposal, MSHA intends to revise existing 
Sec.  57.5060(a), limit on concentration of DPM; including designating 
elemental carbon as an appropriate surrogate for measuring the interim 
DPM limit; Sec.  57.5060(c), addressing application and approval 
requirements for an extension of time in which to reduce the 
concentration of DPM; Sec.  57.5060(d), addressing certain exceptions 
to the concentration limits; Sec.  57.5060(e), prohibiting use of 
personal protective equipment to comply with the concentration limits; 
Sec.  57.5060(f) prohibiting use of administrative controls to comply 
with the concentration limits, and Sec.  57.5062, addressing the diesel 
particulate control plan. Also, MSHA intends to make conforming changes 
in this rulemaking to existing Sec.  57.5061, addressing compliance 
determinations; Sec.  57.5071, addressing exposure monitoring; and 
Sec.  57.5075, addressing recordkeeping requirements.
    MSHA has incorporated into the record of this rulemaking the 
existing rulemaking record, including the risk assessment to the 
January 19, 2001 standard. Commenters are encouraged to submit 
additional evidence of new scientific data related to the health risk 
to underground metal and nonmetal miners from exposure to DPM.
    MSHA encourages mine operators to submit information in response to 
these provisions, including their current experiences with controlling 
miners' exposures to DPM.
    In addition, under the terms of the settlement agreement, MSHA 
agreed to propose to change the existing DPM surrogate from total 
carbon to elemental carbon for both the interim DPM limit currently in 
effect and the final DPM limit that is applicable after January 19, 
2006. In the Agency's Advance Notice of Proposed Rulemaking published 
on September 25, 2002 (67 FR 60199), MSHA notified the mining community 
that this rulemaking would revise both the interim concentration limit 
of 400 micrograms per cubic meter of air and the final concentration 
limit of 160 micrograms per cubic meter of air under Sec.  57.5060 (a) 
and (b) of the existing standard. Some commenters to the ANPRM 
recommended that MSHA propose separate rulemakings for revising the 
interim and final DPM limits to give MSHA an opportunity to gather 
further information to establish a final DPM limit. The Agency agrees, 
and solicits information that would lead to an appropriate final DPM 
standard. The Agency will propose a separate rulemaking to amend the 
existing final concentration limit in the near future. With regard to 
the final DPM limit of 160 micrograms, MSHA requests comments on an 
appropriate final DPM limit.

DATES: All comments on the proposed rule, including post-hearing 
comments, must be received by October 14, 2003. The public hearing 
dates and locations are listed in the Public Hearings section under 
SUPPLEMENTARY INFORMATION. Individuals or organizations wishing to make 
oral presentations for the record should submit a request at least 5 
days prior to the hearing dates.

ADDRESSES: Comments must be clearly identified as such and may be 
transmitted electronically to [email protected], by facsimile to (202) 
693-9441, or by regular mail or hand delivery to MSHA, Office of 
Standards, Regulations, and Variances, 1100 Wilson Blvd., Room 2313, 
Arlington, Virginia 22209-3939. We intend to post comments on our 
website shortly after they are received.
    Information Collection Requirements: Comments concerning 
information collection requirements must be clearly identified as such 
and sent to both MSHA and the Office of Management and Budget (OMB) as 
follows:
    (1) Send information collection comments to MSHA at the addresses 
above.
    (2) Send comments to OMB by regular mail addressed to the Office of 
Information and Regulatory Affairs, Office of Management and Budget, 
New Executive Office Building, 725 17th Street, NW., Washington, DC 
20503, Attn: Desk Officer for MSHA.

FOR FURTHER INFORMATION CONTACT: Marvin W. Nichols, Jr., Director, 
Office of Standards, Regulations, and Variances, MSHA, 1100 Wilson 
Blvd., Room 2313, Arlington, Virginia 22209-3939, [email protected], (202) 693-9440 (telephone), or (202) 693-9441 
(facsimile).
    You can access this proposed rule and the Preliminary Regulatory 
Economic Analysis (PREA) at http://www.msha.gov. You can obtain these 
documents in alternative formats, such as large print and electronic 
files, by contacting MSHA.

SUPPLEMENTARY INFORMATION:

I. Public Hearings

    The public hearings will begin at 9 a.m. and will end after the 
last scheduled speaker testifies. The hearings will be held on the 
following dates at the locations indicated:

------------------------------------------------------------------------
              Date                      Location           Telephone
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September 16, 2003..............  University Park         (801) 581-1000
                                   Marriott, 480
                                   Wakara Way, Salt
                                   Lake City, UT
                                   84108.

[[Page 48669]]

 
September 18, 2003..............  Renaissance St.         (314) 429-1100
                                   Louis Hotel
                                   Airport, 9801
                                   Natural Bridge
                                   Road, St. Louis,
                                   MO 63134.
September 23, 2003..............  Hilton Pittsburgh,      (412) 391-4600
                                   600 Commonwealth
                                   Place, Pittsburgh,
                                   PA 15222.
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    The hearings will begin with an opening statement from MSHA, 
followed by an opportunity for members of the public to make oral 
presentations. You do not have to make a written request to speak. 
Speakers will speak in the order that they sign in. Any unallotted time 
will be made available for persons making same-day requests. At the 
discretion of the presiding official, the time allocated to speakers 
for their presentation may be limited. Speakers and other attendees may 
also present information to the MSHA panel for inclusion in the 
rulemaking record.
    The hearings will be conducted in an informal manner. The hearing 
panel may ask questions of speakers. Although formal rules of evidence 
or cross examination will not apply, the presiding official may 
exercise discretion to ensure the orderly progress of the hearing and 
may exclude irrelevant or unduly repetitious material and questions.
    A verbatim transcript of the proceedings will be included in the 
rulemaking record. Copies of this transcript will be available to the 
public, and can be viewed at http://www.msha.gov.
    MSHA will accept post-hearing written comments and other 
appropriate data for the record from any interested party, including 
those not presenting oral statements, prior to the close of the comment 
period on October 7, 2003.

II. Background

    On January 19, 2001, MSHA published a final rule addressing diesel 
particulate matter exposure in underground metal and nonmetal mines (66 
FR 5706, amended on February 27, 2002 at 67 FR 9180). The final rule 
established new health standards for underground metal and nonmetal 
mines that use equipment powered by diesel engines. The effective date 
of the rule was listed as March 20, 2001. On January 29, 2001, 
AngloGold (Jerritt Canyon) Corp. and Kennecott Greens Creek Mining 
Company filed a petition for review of the final rule in the District 
of Columbia Circuit Court of Appeals. On February 7, 2001, the Georgia 
Mining Association, the National Mining Association, the Salt 
Institute, and the Methane Awareness Resource Group (MARG) Diesel 
Coalition filed a similar petition in the Eleventh Circuit. On March 
14, 2001, Getchell Gold Corporation petitioned for review of the rule 
in the District of Columbia Circuit. The three petitions were 
consolidated and are pending in the District of Columbia Circuit. The 
United Steelworkers of America (USWA) intervened in the litigation.
    While these challenges were pending, the AngloGold petitioners 
filed with MSHA an application for reconsideration and amendment of the 
final rule and to postpone the effective date of the final rule pending 
judicial review. The Georgia Mining petitioners similarly filed with 
MSHA a request for an administrative stay or postponement of the 
effective date of the rule. On March 15, 2001, MSHA delayed the 
effective date of the rule until May 21, 2001, in accordance with a 
January 20, 2001 memorandum from the President's Chief of Staff (66 FR 
15032). The delay was necessary to give Department of Labor officials 
the opportunity for further review and consideration of new 
regulations. On May 21, 2001 (66 FR 27863), MSHA published a notice in 
the Federal Register delaying the effective date of the final rule 
until July 5, 2001. The purpose of this delay was to allow the 
Department of Labor the opportunity to engage in further negotiations 
to settle the legal challenges to this rule.

First Partial Settlement Agreement

    As a result of a partial settlement agreement with the litigants, 
MSHA published two documents in the Federal Register on July 5, 2001 
addressing the January 19, 2001 DPM rule. One document (66 FR 35518) 
delayed the effective date of Sec.  57.5066(b) regarding the tagging 
provision of the maintenance standard; clarified the effective dates of 
certain provisions of the final rule; and included correction 
amendments.
    The second document (67 FR 35521) proposed a rule to clarify 
Sec. Sec.  57.5066(b)(1) and (b)(2) regarding maintenance and to add a 
new subparagraph (b)(3) to Sec.  57.5067 regarding the transfer of 
existing equipment between underground mines. MSHA published these 
changes as a final rule on February 27, 2002 (67 FR 9180), with an 
effective date of March 29, 2002.
    Under the first partial settlement agreement, MSHA also conducted 
joint sampling with industry and labor at 31 underground metal and 
nonmetal mines to determine existing concentration levels of DPM; to 
assess the performance of the SKC submicron dust sampler with the NIOSH 
Method 5040; to assess the feasibility of achieving compliance with the 
standard's concentration limits at the 31 mines; and to assess the 
impact of interferences on samples collected in the metal and nonmetal 
underground mining environment before the limits established in the 
final rule become effective. The final report was issued on January 6, 
2003.

Second Partial Settlement Agreement

    Settlement negotiations continued on the remaining unresolved 
issues in the litigation. On July 15, 2002, the parties signed an 
agreement that is the basis for this proposed rule. On July 18, 2002, 
MSHA published a notice in the Federal Register (67 FR 47296) 
announcing that the following provisions of the January 19, 2001 rule 
would become effective on July 20, 2002:
    (a) Sec.  57.5060(a), addressing the interim concentration limit of 
400 micrograms of total carbon per cubic meter of air;
    (b) Sec.  57.5061, compliance determinations; and
    (c) Sec.  57.5071, environmental monitoring.
    The notice also announced that the following provisions of the rule 
would continue in effect:
    (a) Sec.  57.5065, Fueling practices;
    (b) Sec.  57.5066, Maintenance standards;
    (c) Sec.  57.5067, Engines;
    (d) Sec.  57.5070, Miner training; and
    (e) Sec.  57.5075, Diesel particulate records, as they relate to 
the requirements of the rule that are in effect on July 20, 2002.
    The notice also stayed the effectiveness of the following 
provisions pending completion of rulemaking:
    (a) Sec.  57.5060(d), permitting miners to work in areas where the 
level of diesel particulate matter exceeds the applicable concentration 
limit with advance approval from the Secretary;
    (b) Sec.  57.5060(e), prohibiting the use of personal protective 
equipment to comply with the concentration limits;

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    (c) Sec.  57.5060(f) prohibiting the use of administrative controls 
to comply with the concentration limits; and
    (d) Sec.  57.5062, DPM control plan.
    Finally, the notice outlined the terms of the DPM settlement 
agreement and announced MSHA's intent to propose specific changes to 
the rule, as discussed below.
    On September 25, 2002, MSHA published an Advance Notice of Proposed 
Rulemaking (67 FR 60199) to revise the DPM rule. The comment period 
closed on November 25, 2002. MSHA received comments from underground 
metal and nonmetal mine operators, trade associations, organized labor, 
individual mine operators, public interest groups and individuals. A 
number of commenters from industry and labor requested that MSHA 
propose the final DPM limit at a later date to allow MSHA to obtain 
more data. Commenters suggested that the Agency needs to determine the 
efficiency of different filtration devices, the relationship between 
elemental carbon and total carbon, and the feasibility of a DPM 
exposure limit.
    This proposed rule would revise existing Sec.  57.5060(a), 
addressing the interim concentration limit for DPM and the surrogate 
for measuring DPM limit; Sec.  57.5060(c), addressing application and 
approval requirements for an extension of time in which to reduce the 
concentration of DPM; Sec.  57.5060(d), addressing certain exceptions 
to the concentration limit; Sec.  57.5060(e), prohibiting use of 
personal protective equipment to comply with the concentration limits; 
Sec.  57.5060(f) prohibiting use of administrative controls to comply 
with the concentration limits, and Sec.  57.5062, addressing the diesel 
particulate control plan. MSHA is also proposing conforming changes to 
existing Sec.  57.5061, addressing compliance determinations; Sec.  
57.5071, addressing exposure monitoring; and Sec.  57.5075, addressing 
recordkeeping requirements.
    MSHA solicits comments on these provisions, as well as on 
experiences with controlling miners' exposures to DPM. MSHA also 
encourages commenters to submit additional evidence or new scientific 
data related to the health risk of DPM exposure in underground metal 
and nonmetal mines.

III. The Final PEL

    MSHA intends to propose a revision to the final DPM limit in Sec.  
57.5060(b) that would reflect an appropriate permissible exposure limit 
rather than a concentration limit and would change the surrogate from 
total carbon to elemental carbon. Although the final limit is not a 
part of this proposed rule, MSHA solicits comments on an appropriate 
final DPM limit.

IV. Executive Summary of the 31-Mine Study

    The following is the executive summary from ``MSHA's Report on Data 
Collected During a Joint MSHA/Industry Study of DPM Levels in 
Underground Metal And Nonmetal Mines'' (31-Mine Study) signed by MSHA 
on January 6, 2003. The Preliminary Regulatory Economic Analysis (PREA) 
for this proposed rule is not based on the 31-Mine Study.

    On January 19, 2001, MSHA published a final standard on exposure 
of underground metal and nonmetal miners to diesel particulate 
matter (DPM). The rule was to become effective 60 days later, 
however, prior to the effective date, the rule was challenged by 
industry trade associations and mining companies. The United 
Steelworkers of America (USWA) also intervened in the litigation. In 
June 2001, agreement was reached on some of the issues in dispute. 
The parties further agreed to conduct a study involving joint in-
mine DPM sampling to determine existing concentration levels of DPM 
in operating mines and to measure DPM levels in the presence of 
known or suspected interferences. The goals of the study were to use 
the sampling results and related information to assess:

--The validity, precision and feasibility of the sampling and 
analysis method specified by the diesel standard (NIOSH Method 
5040);
--The magnitude of interferences that occur when conducting 
enforcement sampling for total carbon as a surrogate for diesel 
particulate matter (DPM) in mining environments; and
--The technological and economic feasibility of the underground 
metal and nonmetal (MNM) mine operators to achieve compliance with 
the interim and final DPM concentration limits.

    The parties developed a joint MSHA/Industry study protocol to 
guide sampling and analysis of DPM levels in 31 mines. The parties 
also developed four subprotocols to guide investigations of the 
known or suspected interferences, which included mineral dust, drill 
oil mist, oil mist generated during ammonium nitrate/fuel oil (ANFO) 
loading operations, and environmental tobacco smoke (ETS). The 
parties also agreed to study other potential sampling problems, 
including any manufacturing defects of the DPM sampling cassette.
    Major conclusions drawn from the study are as follows:

--The analytical method specified by the diesel standard gives an 
accurate measure of the TC content of a filter sample and the 
analytical method is appropriate for making compliance 
determinations of DPM exposures of underground metal and nonmetal 
miners.
--SKC satisfactorily addressed concerns over defects in the DPM 
sampling cassettes and availability of cassettes to both MSHA and 
mine operators.
--Compliance with both the interim and final concentration limits 
may be both technologically and economically feasible for metal and 
nonmetal underground mines in the study. MSHA, however, has limited 
in-mine documentation on DPM control technology. As a result, MSHA's 
position on feasibility does not reflect consideration of current 
complications with respect to implementation of controls, such as 
retrofitting and regeneration of filters. MSHA acknowledges that 
these issues may influence the extent to which controls are 
feasible. The Agency is continuing to consult with the National 
Institute of Occupational Safety and Health, industry and labor 
representatives on the availability of practical mine worthy filter 
technology.
--The submicron impactor was effective in removing the mineral dust, 
and therefore its potential interference, from DPM samples. 
Remaining interference from carbonate interference is removed by 
subtracting the 4th organic peak from the analysis. No reasonable 
method of sampling was found to eliminate interferences from oil 
mist or that would effectively measure DPM levels in the presence of 
ETS with TC as the surrogate. Results and findings of the study are 
summarized below.

Sampling at 31 Mines

    There are a number of methods that can measure DPM 
concentrations with reasonable accuracy when it is at high 
concentrations and the purpose is exposure assessment. These methods 
do not at this time provide the accuracy required to support 
compliance determinations at the concentration levels required to be 
achieved under the DPM rule. The NIOSH Method 5040 provides an 
accurate method of determining the total carbon content of a sample 
collected in any underground metal or nonmetal mine when the 
submicron impactor is used. MSHA's January 2001 regulation requires 
using total carbon (TC) as a surrogate for DPM because a consistent 
quantitative relationship has been established between total carbon 
concentrations and the concentration of DPM as a whole. TC 
concentrations measured during the study ranged from 13 to 2065 
[mu]/m\3\, with a mean of 345 [mu]/m\3\. To put these sampling 
results into context, the interim concentration limit specified in 
the final rule, effective after July 19, 2002, is 400 micrograms of 
TC per cubic meter of air ([mu]/m\3\). The final concentration limit 
is 160 micrograms of TC per cubic meter of air ([mu]/m\3\), 
effective after January 19, 2006.
    TC concentrations at the non-trona mines were four to five times 
higher than at the trona mines. TC concentrations measured using 
area samples were found to be 38 to 62 percent of the levels found 
using occupational or personal samples.

Interferences

    The submicron impactor removes 94% of the mineral dust from DPM 
samples. Remaining carbonate interference, if any, is removed by 
subtracting the 4th organic peak

[[Page 48671]]

from the analysis. For typical gold mine samples, the interference 
from elemental carbon (graphite) would be less than 1.5 [mu]/m\3\. 
The use of the impactor also eliminates the need to acidify samples, 
including samples from trona mines. For typical non-acidified trona 
mine samples, the interference from bicarbonate would be less than 
0.5 [mu]/m\3\. Overload of particulate matter on the impactor 
substrate to the filter was not observed.
    Interference from drill oil mist was found on personal samples 
collected on the drillers and on area samples collected in the stope 
where drilling was being performed. Use of a dynamic blank did not 
eliminate drill oil mist interference. Tests to confirm whether oil 
mist from ANFO loading operations could be interference were not 
conclusive. Blasting did not interfere with diesel particulate 
measurements. MSHA found no reasonable method of sampling to 
eliminate interferences from oil mist when TC is used as the 
surrogate.
    No reliable marker was identified for confirming the presence of 
ETS in an atmosphere containing DPM. Use of the impactor does not 
remove the ETS as an interferent. No reasonable method of sampling 
was found that would effectively measure DPM levels in the presence 
of ETS with TC as the surrogate.

Laboratory Analytical Procedures and Sampling Cassettes

    Intra- and inter-laboratory analytical imprecision appear to be 
in line with other airborne contaminants monitored by MSHA and other 
regulatory agencies. Each of the samples collected in the study was 
analyzed twice for TC content. To do this, two standard punches were 
taken from each exposed and each unexposed (i.e., control) filter. 
One punch was always analyzed using the same instrument in MSHA's 
laboratory. The second punch from the same filter was either 
analyzed in MSHA's laboratory using one of two different instruments 
or sent out to one of three other laboratories, NIOSH, Natlsco or 
Clayton.
    The supplier has satisfactorily addressed concerns over possible 
manufacturing defects in the specialized SKC DPM sampling cassette. 
MSHA believes that the performance of this cassette will be adequate 
for compliance sampling purposes.

Technological Feasibility

    Technological feasibility for mine operators to achieve 
compliance with the interim and final DPM concentration limits was 
assessed for the 31 mines in the study on a mine-by-mine basis using 
a computerized Microsoft[reg] 7 Excel spreadsheet program called the 
Estimator, combined with sampling results from the 31 mines. The 
Estimator mathematically calculates the effect of any combination of 
engineering and ventilation controls on existing DPM concentrations 
in a given production area of a mine. The analyses were based on the 
highest DPM sample result obtained at each mine and all major DPM 
emission sources at each mine plus spare equipment.
    MSHA, however, has limited in-mine documentation on DPM control 
technology. Moreover, these sampling results were obtained at a time 
that few mine operators had implemented controls to reduce DPM 
concentrations at the subject mines. As a result, MSHA's position on 
feasibility does not reflect consideration of current complications 
with respect to implementation of controls, such as retrofitting and 
regeneration of filters. MSHA acknowledges that these issues may 
influence the extent to which controls are feasible. The Agency is 
continuing to consult with the National Institute of Occupational 
Safety and Health, industry and labor representatives on the 
availability of practical mine worthy filter technology.
    The study found that five mines were already in compliance with 
the interim concentration limit, and another two mines were already 
in compliance with the lower, final concentration limit. The 
Estimator predicted that eleven of the 31 mines could achieve 
compliance with both limits through installation of DPM filters 
alone. Ventilation upgrades were specified for only 5 of the 31 
mines in this study, and then only to achieve the final 
concentration limit.
    The Estimator predicted that compliance with the interim and 
final concentration limits would be possible without requiring major 
ventilation installations (new main fan, repowering main fan, etc.) 
or requiring environmental cabs as a means of controlling DPM at any 
of the 31 mines. Industry commenters questioned whether practical 
mine-worthy filters were available for all engine sizes and whether 
more expensive controls would be necessary.

Economic Feasibility

    Yearly costs for complying with both the interim and final 
concentration limits were determined for each of the 31 mines in the 
study. Cost estimates included the purchase cost of DPM controls 
specified for that mine in the technological feasibility assessment, 
plus related installation and operating costs. The aggregate yearly 
cost for all 31 mines to comply with the interim limit was estimated 
to be $2.1 million. Compliance with the final limit was estimated to 
cost an additional $1.1 million (in 2002 dollars). The yearly total 
to comply with both the interim and final concentration limits was 
estimated to be $3.2 million. The estimated costs in this report are 
based on the accuracy of the Estimator as reported in Appendix A, 
and therefore, do not include consideration of current 
implementation complications that could increase compliance costs.
    MSHA concludes that a regulation is economically infeasible if 
it would threaten an industry's viability or competitive structure. 
In rulemaking, economic feasibility, as well as technological 
feasibility, is not defined for individual firms, but for an 
industry. As a screening device, MSHA has historically questioned 
economic feasibility if yearly compliance costs equal or exceed one 
percent of an industry's annual revenues.
    MSHA developed a rough estimate of annual mine revenues using 
each mine's annual employee work hours and the production value per 
employee hour for the commodity produced. Summing the individual 
revenue figures resulted in an estimate of total revenues for the 31 
mines in the study of $1.8 billion in 2000.
    On this basis, MSHA estimates that the 31 mines in the study 
would incur yearly costs equal to 0.12 percent of their annual 
revenues to comply with the interim concentration limit and 
additional yearly costs equal to 0.06 percent of their annual 
revenues to comply with the final concentration limit. To comply 
with both the interim and final concentration limits, the 31 mines 
would incur yearly costs equal to 0.18 percent of their annual 
revenues. Since estimated yearly compliance costs are less than the 
screening benchmark of one percent or more of annual revenues, the 
data in this report supports a finding that the interim and final 
concentration limits are economically feasible. Industry questions 
whether all costs for active filter regeneration were considered and 
whether the proper controls (that is, filters) were used in the cost 
analysis. In particular, industry questions whether compliance with 
the interim concentration limit would require some mine operators to 
make major ventilation upgrades in their mines.

V. Compliance Assistance

A. Baseline Sampling Summary

    Under the DPM Settlement Agreement, MSHA agreed to provide 
compliance assistance to the metal and nonmetal underground mining 
industry for a one-year period from July 20, 2002 through July 19, 
2003. As part of MSHA's compliance assistance activities, the Agency 
conducted baseline sampling of miners' personal exposures at every 
underground mine covered by the existing regulation. The results of 
this sampling were used by MSHA in this preamble to estimate current 
DPM exposure levels in these mines. These sampling results also assist 
mine operators in developing compliance strategies based on actual 
exposure levels. This compliance assistance sampling began in October 
2002.
    This section summarizes the analytical results of 885 personal DPM 
samples collected from 171 mines between October 30, 2002 and March 26, 
2003 as part of a compliance assistance initiative. Eleven of the 885 
samples were invalid samples due to abnormal sample deposits, broken 
cassettes or filters, contaminated backup pads, or instrument or pump 
failure. Table V-1 lists the frequencies of invalid samples within each 
commodity.
    The mines that were sampled produce clay, sand, gypsum, copper, 
gold, platinum, silver, gem stones, dimension marble, granite, lead-
zinc, limestone, lime, potash, molybdenum, salt, trona, and other 
miscellaneous metal ores. These commodities were grouped into

[[Page 48672]]

four general categories for calculating summary statistics: metal, 
stone, trona, and other nonmetal (N/M) mines. These categories were 
selected to be consistent with the categories used for analysis of data 
for the 31-Mine Study. Most commodities are well represented in this 
analysis (average of 5.1 samples per mine). Some of these mines, such 
as the gold mines, have an average of only 2.0 samples per mine. MSHA 
is conducting additional compliance assistance sampling at these mines, 
however, the results are not available for inclusion in this analysis. 
Table V-2 lists the number of samples for each category of commodity.
    MSHA used the same sampling strategies for collecting baseline 
samples as it intends to use for collecting samples for enforcement 
purposes. These sampling procedures are described in the Metal and 
Nonmetal Health Inspection Procedures Handbook (PH90-IV-4), Chapter A, 
``Compliance Sampling Procedures'' and Draft Chapter T, ``Diesel 
Particulate Matter Sampling.'' Chapter A includes detailed guidelines 
for selecting and obtaining personal samples for various contaminants. 
All personal samples were collected for the miner's full-shift 
regardless of the number of hours worked, and in the miner's breathing 
zone. For the 874 valid personal samples, 83% were collected for at 
least eight hours. Total and elemental carbon levels, as well as DPM 
levels, are reported in units of micrograms per cubic meter for an 8-
hour full shift equivalent.
    The equation used to calculate a 480-minute (8-hour) full shift 
equivalent (FSE) exposure of total carbon is Total Carbon Concentration 
=
[GRAPHIC] [TIFF OMITTED] TP14AU03.000

Where:

EC = The corrected elemental carbon concentration measured in the 
thermal/optical carbon analyzer
OC = The corrected organic carbon concentration measured in the 
thermal/optical carbon analyzer
A = The surface area of the deposit on the filter media used to collect 
the sample
Flow Rate = Flow rate of the air pump used to collect the sample 
measured in Liters per minute
480 minutes = Standardized eight-hour workshift

    All levels of carbon or DPM are reported in 8-hour full shift 
equivalent (FSE) total carbon concentrations measured in [mu]g/
m3.
    Because personal sampling was conducted and no attempt was made to 
avoid interference from cigarette smoke or other organic carbon 
sources, total carbon was also calculated using the formula prescribed 
in the DPM settlement agreement:
    Total Carbon Concentration = EC x 1.3.
    MSHA agreed to use the lower of the two values (EC x 1.3 or EC + 
OC) for enforcement until a final rule is published reflecting EC as 
the surrogate.
    MSHA collected DPM samples with SKC submicron dust samplers that 
use Dorr-Oliver cyclones and submicron impactors. The samples were 
analyzed either at MSHA's Pittsburgh Safety and Health Technology 
Center, Dust Division Laboratory or at the Clayton Laboratory using 
MSHA Method P-13 (NIOSH Analytical Method 5040, NIOSH Manual of 
Analytical Methods (NMAM), Fourth Edition, September 30, 1999) for 
determining the total carbon content. Each sample was analyzed for 
organic, elemental, and carbonaceous carbon and calculated total 
carbon. Raw analytical results from both laboratories as well as 
administrative information about the sample are stored electronically 
in MSHA's Laboratory Information Management System.
    If a raw carbon result was greater than or equal to 30 [mu]g/
cm2 of EC or 40 [mu]g/cm2 of TC from the exposed 
filter loading, then the analysis was repeated using a separate punch 
of the same filter. The results of these two analyses were then 
averaged. The companion dynamic blank was also tested for the same 
analytes. Otherwise, an unexposed filter from the same manufacturer's 
lot was used to correct for background levels. In the event the initial 
total carbon result was greater than 100EC [mu]g/
cm2, a smaller punch of the same exposed filter (in 
duplicate and corresponding blank) was taken and used in the analysis. 
Blank-corrected averaged results were used in the analysis when the 
sample was tested in duplicate.
    Generally the lowest reporting limit is 3TC [mu]g/
cm2. However, for this analysis, MSHA used all results below 
this limit. Due to variations in the analytical method, three samples 
have blank corrected elemental carbon results slightly below 
0EC [mu]g/m3. This occurred because the 
corresponding blank filters have TC results slightly more than the 
exposed filter. Median values are not affected by the distribution of 
data and MSHA included them where appropriate.
    The electronic records of the 885 samples that were available for 
analysis were reviewed for inconsistencies. Internally inconsistent or 
extreme values were questioned, researched, and verified. Although no 
samples were invalidated as a result of the administrative 
verification, eleven samples (1.2%) were removed from the data set for 
reasons unrelated to the values obtained. The reasons for invalidating 
these samples are listed in Table V-1. Accordingly, MSHA has included 
874 samples from miners in the analyses. Table V-2 is a list of the 
number of valid samples by commodity.

                                    Table V-1.--Reasons for Excluding Samples
----------------------------------------------------------------------------------------------------------------
       Reason for excluding from analysis           Metal        Stone        Trona      Other N/M      Total
----------------------------------------------------------------------------------------------------------------
Abnormal Sample Deposit........................            0            1            0            0            1
Cassette/Filter Broken.........................            0            2            0            1            3
Contaminated Backup Pad........................            1            0            0            0            1
Instrument Failure.............................            1            1            0            0            2
Pump Failed....................................            1            3            0            0            4
                                                --------------
    Total......................................            3            7            0            1           11
----------------------------------------------------------------------------------------------------------------


[[Page 48673]]


                           Table V-2.--Number of Mines and Valid Samples, by Commodity
----------------------------------------------------------------------------------------------------------------
                                                                                                  Average number
                                                                     Number of       Number of       of valid
                            Commodity                                  mines       valid samples    samples by
                                                                                                       mine
----------------------------------------------------------------------------------------------------------------
Metal...........................................................              36             189             5.3
Stone...........................................................             109             519             4.8
Trona...........................................................               3              15             5.0
Other N/M.......................................................              23             151             6.6
                                                                 -----------------
    Total.......................................................             171             874             5.1
----------------------------------------------------------------------------------------------------------------

    Table V-3 lists the number of samples collected by specific 
commodities at the time the data set was compiled (March 26, 2003) and 
sorted by the average number of samples per mine. Although MSHA made 
efforts to sample all underground metal and nonmetal mines covered by 
this rulemaking within the specified time frame, several mines have few 
or no samples for DPM in this analysis. Some metal and nonmetal mining 
operations are seasonal in that they are operated intermittently or 
operate at less than full production during certain times. These types 
of variable production schedules limited efforts to collect compliance 
assistance samples. MSHA continued to collect baseline samples during 
the compliance assistance period, especially at those mines with a low 
sampling frequency or where no samples were collected as of March 26, 
2003. Future analyses will incorporate all subsequent valid samples.

     Table V-3.--Number of Valid Samples per Mine for Specific Mines
------------------------------------------------------------------------
                                                               Average
        Specific commodity          Number of    Number of   samples per
                                      mines       samples        mine
------------------------------------------------------------------------
GEMSTONES MINING, N.E.C..........            1            2          2.0
GOLD ORE MINING, N.E.C...........           17           34          2.0
DIMENSION MARBLE MINING..........            3            9          3.0
LIMESTONE........................            2            6          3.0
TALC MINING......................            1            3          3.0
CRUSHED & BROKEN MARBLE MINING...            4           16          4.0
GYPSUM MINING....................            2            8          4.0
CRUSHED & BROKEN STONE MINING,               5           23          4.6
 N.E.C...........................
CRUSHED & BROKEN LIMESTONE                  85          413          4.9
 MINING, N.E.C...................
CLAY, CERAMIC & REFRACTORY                   1            5          5.0
 MINERALS MINING, N.E.C..........
CONSTRUCTION SAND & GRAVEL                   1            5          5.0
 MINING, N.E.C...................
COPPER ORE MINING, N.E.C.........            1            5          5.0
CRUSHED & BROKEN SANDSTONE MINING            1            5          5.0
HYDRAULIC CEMENT.................            1            5          5.0
LIME, N.E.C......................            4           20          5.0
TRONA MINING.....................            3           15          5.0
DIMENSION LIMESTONE MINING.......            4           22          5.5
LEAD-ZINC ORE MINING, N.E.C......           10           70          7.0
SALT MINING......................           14           98          7.0
MISCELLANEOUS METAL ORE MINING,              1            9          9.0
 N.E.C...........................
MOLYBDENUM ORE MINING............            2           19          9.5
PLATINUM GROUP ORE MINING........            2           20         10.0
POTASH MINING....................            3           30         10.0
SILVER ORE MINING, N.E.C.........            3           32         10.7
AVERAGE OF ALL SAMPLES...........          171          874          5.1
------------------------------------------------------------------------

    There are 63 different occupations in underground metal and 
nonmetal mines represented in this analysis. The most frequently 
sampled occupations are Blaster, Drill Operator, Front-end Loader 
Operator, Truck Driver, Scaling (Mechanical), and Mechanic. Table V-4 
lists the number of valid samples by occupation and commodity. Only 
occupations with 14 or more samples are listed. Occupations with fewer 
samples were aggregated for this table.

                           Table V-4.--Valid Samples, by Occupation and Mine Category
----------------------------------------------------------------------------------------------------------------
                   Occupation                       Metal        Stone        Trona      Other N/M      Total
----------------------------------------------------------------------------------------------------------------
Truck Driver...................................           55          121            0            7          183
Front-end Loader Operator......................           23          115            4           13          155
Blaster, Powder Gang...........................            9           72            0           19          100
Scaling (mechanical)...........................            1           53            0            9           63
Drill Operator, Rotary.........................            0           53            0            5           58
Mechanic.......................................            6           10            0           10           26

[[Page 48674]]

 
Drill Operator, Jumbo Perc.....................            4            9            0            8           21
Mucking Mach. Operator.........................           15            0            0            3           18
Utility Man....................................            5            3            8            2           18
Scaling (hand).................................            3           12            0            2           17
Complete Load-Haul-Dump........................            1            0            0           16           17
Roof Bolter, Rock..............................            3            6            0            5           14
Drill Operator, Rotary Air.....................            1           12            0            1           14
Crusher Oper/Worker............................            0           12            0            2           14
All Others Combined............................           63           41            3           49          156
                                                --------------
        Totals.................................          189          519           15          151          874
----------------------------------------------------------------------------------------------------------------

    TC levels calculated by EC x 1.3 were lower than TC levels 
calculated by OC + EC in 663 (76%) of the 874 baseline samples. Of the 
211 samples where TC = OC + EC was the lower value, 64% of the TC = EC 
x 1.3 values were within 12% of the TC = OC + EC value. Table V-5 
summarizes the results of the baseline samples when determining the TC 
level using either EC x 1.3 or OC + EC. Approximately 6.3% of results 
did not concur when measuring TC by the two calculations. Approximately 
15.7% of the samples were above the 400TC [mu]g/
m3 interim concentration limit when using TC = EC x 1.3 and 
approximately 19.5% were above the concentration limit when using TC = 
OC + EC. There is 93.7% concurrence between the two methods of 
calculating TC and comparing the calculations to the 400TC 
[mu]g/m3 interim concentration limit.

           Table V-5.--Comparison of Results With 400TC [mu]g/m3 Calculating TC by OC + EC or EC x 1.3
----------------------------------------------------------------------------------------------------------------
                                                         EC x 1.3  400 [mu]g/m3
 All Valid Samples--OC + EC  400 [mu]g/m3  --------------------------------------        Total
                                                               No                Yes
----------------------------------------------------------------------------------------------------------------
No...................................................        693 (79.3%)         11 (1.3%)         704 (80.5%)
Yes..................................................         44 (5.0%)         126 (14.4%)        170 (19.5%)
                                                      --------------------
  Total..............................................        737 (84.3%)        137 (15.7%)        874 (100.0%)
----------------------------------------------------------------------------------------------------------------

    Table V-6 lists the 19 occupations found to have at least one 
sample in which the level of TC was over the interim 400TC 
[mu]g/m3 concentration limit (TC = EC x 1.3). Table V-6 is 
sorted by the median TC result. The table also lists the minimum value, 
median value, and the total number of valid samples for these 
occupations. TC values varied widely among all miners' occupations.

            Table V-6.--Occupations With at Least One Sample Greater Than or Equal to 400TC [mu]g/m3
----------------------------------------------------------------------------------------------------------------
                   Occupation                      Total samples      Minimum         Median          Maximum
----------------------------------------------------------------------------------------------------------------
Engineer........................................               1             438             438             438
Roof Bolter, Mounted............................               8              98             335             588
Miner, Stope....................................              11             165             330             622
Clean Up Man....................................               2              66             283             499
Mucking Machine Operator........................              18              15             278             872
Shuttle Car, Diesel.............................               2              95             257             419
Drill Operator, Rotary Air......................              14              56             231            1145
Belt Crew.......................................               8              26             225             502
Blaster, Powder Gang............................             101               6             216             960
Drill Operator, Jumbo...........................              21              41             194             708
Complete Load-Haul-Dump.........................              17              42             188             824
Miner, Drift....................................              14              16             185            1459
Scaling (Hand)..................................              17              18             166            2014
Roof Bolter, Rock...............................              14              63             157             829
Truck Driver....................................             184               0             155            1074
Front End Loader................................             155               0             136            1743
Drill Operator, Rotary..........................              58               3             133            1109
Scaling (Mechanical)............................              63               0             131             750
Utility Man.....................................              18              29              93             638
Supervisor......................................              10               1              87             856
Crusher Operator................................              14               1              47             427
----------------------------------------------------------------------------------------------------------------

    Table V-7 and Chart V-1 provide the frequencies and percent of 
overexposures among the four commodities. Chart V-2 provides the 
frequency of overexposures among the commodities. The metal mines have 
the

[[Page 48675]]

highest percent of overexposures followed by stone than other N/M 
mines. All 15 samples collected in trona mines were less than 
200TC [mu]g/m3. For all samples combined, 15.7% 
were above 400TC [mu]g/m3.

                             Table V-7.--Baseline Samples by Commodity (TC=EC x 1.3)
----------------------------------------------------------------------------------------------------------------
                                                                   Number  400         Total        thn-eq>400
                                                    [mu]g/m3 TC     [mu]g/m3 TC                     [mu]g/m3 TC
----------------------------------------------------------------------------------------------------------------
Metal...........................................             148              41             189            21.7
Stone...........................................             435              84             519            16.2
Other N/M.......................................             139              12             151             7.9
Trona...........................................              15               0              15             0.0
                                                 -----------------
    All Mines...................................             737             137             874            15.7
----------------------------------------------------------------------------------------------------------------

BILLING CODE 4510-43-P
[GRAPHIC] [TIFF OMITTED] TP14AU03.001


[[Page 48676]]


    Chart V-3 shows the number of mines with a specific number of 
overexposures. Examination of the frequency of mines with one or more 
overexposures shows that 51 (29.8%) mines are in this category.
[GRAPHIC] [TIFF OMITTED] TP14AU03.002

    At 14 of the mines, all the samples were above 400TC 
[mu]g/m3. Between one and five samples were taken at each of 
these mines. No overexposures were found in 120 (70%) of the mines 
sampled. (See Chart V-4.)
[GRAPHIC] [TIFF OMITTED] TP14AU03.003

BILLING CODE 4510-43-C
    Tables V-8 and V-9 summarize sample statistics by commodity for 
total carbon calculated by TC = EC x 1.3 and TC = EC + OC respectively. 
Overall, the mean TC as calculated by EC x 1.3 is 222 [mu]g/
m3. The median level is 153 [mu]g/m3. The mean TC 
level by OC + EC is 263 [mu]g/m3 and the median level is 209 
[mu]g/m3. Individual exposure levels of TC vary widely 
within all commodities and most mines. The statistics reported in 
Tables V-8 and V-9 were chosen to be consistent with those reported in 
the 31-Mine Study and the Exposure Assessment.
    The mean TC values (EC x 1.3) are somewhat lower than the interim 
compliance limit of 400 [mu]g/m3. The mean (median) TC value 
for metal mines is 296(239) [mu]g/m3. The mean for stone is 
214(136), other N/M is 170(129) and for trona mines is 90(91) [mu]g/
m3. Table V-8 lists additional statistics for EC values 
compiled by commodity.

[[Page 48677]]



             Table V-8.--Average Levels of Total Carbon by Commodity Measured in [mu]g/m3 (EC x 1.3)
                      [Estimated 8-hour Full Shift Equivalent TC Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
                    EC x 1.3                        Metal        Stone      Other N/M      Trona      All mines
----------------------------------------------------------------------------------------------------------------
Number of Samples..............................          189          519          151           15          874
Maximum........................................        2,014        1,743          824          194        2,014
Median.........................................          239          136          129           91          153
Mean...........................................          296          214          170           90          222
------------------------------------------------
    Std. Error.................................           19           10           11           13            8
    95% CI Upper...............................          333          233          191          119          236
    95% CI Lower...............................          258          195          148           62          207
----------------------------------------------------------------------------------------------------------------

    The mean TC values as calculated by OC + EC are also somewhat lower 
than the interim compliance limit of 400 [mu]g/m3. The mean 
(median) TC value for metal mines is 323(285) [mu]g/m3. The 
mean for stone is 263(200), other N/M is 202(168) and for trona mines 
is 128(126) [mu]g/m3. Table V-9 lists additional statistics 
for TC values compiled by commodity.

             Table V-9.--Average Levels of Total Carbon by Commodity Measured in [mu]g/m3 (OC + EC)
                      [Estimated 8-hour Full Shift Equivalent TC Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
                    OC + EC                         Metal        Stone      Other N/M      Trona      All mines
----------------------------------------------------------------------------------------------------------------
Number of Samples..............................          189          519          151           15          874
Maximum........................................        1,742        1,559          740          218        1,742
Median.........................................          285          200          168          126          209
Mean...........................................          323          263          202          128          263
------------------------------------------------
    Std. Error.................................           17           11           11           12            8
    95% CI Upper...............................          356          284          223          154          278
    95% CI Lower...............................          289          243          181          102          248
----------------------------------------------------------------------------------------------------------------

    Tables V-10 and V-11 show total DPM exposures for the baseline and 
the 31-Mine Study. For baseline sampling DPM was calculated by EC x 1.3 
x 1.25. The 1.25 factor represents the assumption that TC comprises 80 
percent of DPM. Section VI-B-3 discusses the relationship between 
elemental and total carbon. The mean (median) value is 369(299) [mu]g/
m3 for metal mines, 267(170) for stone mines, 212(162) for 
other NM, and 113(113) [mu]g/m3 for trona mines. The total 
DPM exposures for table V-11 were calculated as (OC + EC) x 1.25. The 
mean values from the baseline samples appear to be lower than the mean 
values obtained during the 31-Mine Study.

            Table V-10.--Baseline DPM Concentrations (EC x 1.3 x 1.25, [mu]g/m \3\), by Mine Category
----------------------------------------------------------------------------------------------------------------
                                                    Metal        Stone      Other N/M      Trona      All mines
----------------------------------------------------------------------------------------------------------------
Number of Samples..............................          189          519          151           15          874
Maximum........................................         2518         2178         1030          242         2518
Median.........................................          299          170          162          113          191
Mean...........................................          369          267          212          113          277
    Std. Error.................................           24           12           14           17            9
    95% UCL....................................          416          291          239          149          296
    95% LCL....................................          323          243          185           77          259
----------------------------------------------------------------------------------------------------------------


           Table V-11.--Baseline DPM Concentrations ((EC + OC) x 1.25, [mu]g/m \3\), by Mine Category
----------------------------------------------------------------------------------------------------------------
                                                    Metal        Stone      Other N/M      Trona      All mines
----------------------------------------------------------------------------------------------------------------
Number of Samples..............................          189          519          151           15          874
Maximum........................................         2177         1949          925          273         2177
Median.........................................          357          250          211          158          261
Mean...........................................          403          329          252          160          329
    Std. Error.................................           21           13           13           15           10
    95% CI Upper...............................          445          355          279          193          348
    95% CI Lower...............................          361          303          226          127          310
----------------------------------------------------------------------------------------------------------------


[[Page 48678]]


                 Table V-12.--31-Mine Study DPM Concentrations ( [mu]g/m \3\), by Mine Category
----------------------------------------------------------------------------------------------------------------
                                                                 Metal        Stone      Other N/M      Trona
----------------------------------------------------------------------------------------------------------------
Number of Samples...........................................          116          105           83           54
Maximum.....................................................         2581         1845         1210          331
Median......................................................          491          331          341           82
Mean........................................................          610          466          359           94
    Std. Error..............................................           45           36           27            9
    95% CI Upper............................................          699          537          412          113
    95% CI Lower............................................          522          394          306           75
----------------------------------------------------------------------------------------------------------------

    Chart V-5 compares the means from Tables V-10, V-11 and V-12. The 
mines selected in the 31-Mine Study (Table V-12) were not randomly 
selected and is therefore not considered representative of the 
underground M/NM mining industry. Additionally the industry has 
continued to change the diesel-powered fleet to low emission engines 
that reduce diesel particulate matter exposure. Workers inside 
equipment cabs were not sampled during the 31-Mine Study due to 
possible interference from cigarette smoke. Personal samples taken 
inside cabs were not avoided during baseline compliance assistance 
sampling.
[GRAPHIC] [TIFF OMITTED] TP14AU03.004

B. DPM Control Technology

    In addition to conducting baseline DPM sampling at underground 
metal and nonmetal mines, MSHA participated in a number of compliance 
assistance activities directed at improving sampling and assisting mine 
operators with selection and implementation of appropriate DPM control 
technology. Some of these activities were directed to a segment of, or 
the entire mining industry. Others were conducted on a mine specific 
basis. In general, those activities directed toward a large number of 
mines included outreach programs, workshops, Web site postings and 
publications. Those activities directed at an individual mine included 
evaluation of a specific control technology, a review of the technology 
in use, or that would be available at a specific mine.
    Regional DPM Seminars. During September and October 2002, MSHA 
conducted regional DPM seminars at Ebensburg, PA, Knoxville, TN, 
Lexington, KY, Des Moines, IA, Kansas City, MO, Albuquerque, NM, Coeur 
d'Alene, ID, Green River, WY, and Elko, NV. These full-day seminars 
were offered free of charge in the major underground metal and nonmetal 
mining regions of the country to facilitate attendance by key mining 
industry personnel. The seminars covered the health effects of DPM 
exposure, the history and specific provisions of the regulation, DPM 
controls, DPM sampling, and the DPM Estimator, which is an interactive 
computer spreadsheet program used for analyzing a mine's DPM sources 
and controls.
    NIOSH Diesel Emission Workshops. MSHA staff participated in two 
NIOSH Diesel Emissions and Control Technologies in Underground Metal 
and Nonmetal Mines in February and March 2003 in Cincinnati, OH and 
Salt Lake City, UT. These workshops provided technical presentations 
and a forum for discussing issues relating to control technologies for 
reducing miners' exposure to particulate matter and gaseous emissions 
from the exhaust of diesel-powered vehicles in underground mines, and 
to help mine managers, maintenance personnel, safety and health 
professionals, and ventilation engineers select and apply diesel 
particulate filters and other control technologies in their mines. 
Speakers represented MSHA, NIOSH, and several mining companies, and 
ample time was provided for questions and in-depth technical discussion 
of issues raised by attendees.

[[Page 48679]]

    NSSGA DPM Sampling Workshop: As part of the Kentucky Stone 
Association Seminar, MSHA staff conducted a diesel particulate sampling 
workshop in Louisville, Kentucky from December 11 through 13, 2002. The 
three day seminar was hosted by the National Stone Sand and Gravel 
Association. On the first day of the seminar, diesel particulate 
sampling procedures were reviewed. The participants were trained in 
pump calibration, sample train assembly and note taking. On the second, 
participants traveled to the Rogers Group Jefferson County Mine and 
conducted full shift sampling on underground workers. MSHA technical 
support staff took ventilation measurements and collected area samples 
to assess mine DPM emissions. On the final day of the seminar, engine 
emission and ventilation measurements were reviewed with the 
participants. Additionally, the MSHA DPM outreach material was reviewed 
and discussed. Approximately 10 industry participants attended the 
seminar.
    Nevada Mining Association Safety Committee. MSHA staff attended a 
meeting of the Nevada Mining Association Safety Committee in Elko, NV 
in April 2003 to discuss DPM control technologies. Discussion topics 
included bio-diesel fuel blends, various fuel additives and fuel pre-
treatment devices, to mine ventilation, environmental cabs, clean 
engines, and diesel particulate filter systems. The mining companies' 
experiences with and perspectives on these technologies were discussed, 
along with MSHA's experiences, observations made at various mines, and 
results of laboratory and field testing.
    MSHA South Central Joint Mine Safety and Health Conference. A DPM 
workshop was presented at this conference in April 2003 in New Orleans, 
LA. This workshop included a detailed history and explanation of the 
provisions of the MNM DPM regulation, and a technical presentation on 
feasible DPM engineering controls.
    2003 Joint National Meeting of the Joseph A. Holmes Safety 
Association, National Association of State Mine Inspection and Training 
Agencies, Mine Safety Institute of America, and Western TRAM (Training 
Resources Applied to Mining). A DPM workshop was presented at this 
joint conference in June 2003 in Reno, NV. This workshop included a 
detailed history and explanation of the provisions of the MNM DPM 
regulation, and a technical presentation on DPM sampling, analytical 
tools for identifying and evaluating DPM sources in mines, and feasible 
DPM engineering controls.
    Web site postings. MSHA created a single source page for DPM final 
rules for Metal/Nonmetal Mines on its Web site, www.msha.gov. Links 
were established to obtain information on specific topics, including:
    --DRAFT Metal and Nonmetal Health Inspection Procedures Handbook, 
Chapter T--Diesel Particulate Matter Sampling
    --DRAFT Diesel Particulate Matter Sampling Field Notes
    --Metal and Nonmetal Diesel Particulate Matter (DPM) Standard Error 
Factor for TC Analysis Written Compliance Strategy
    --Metal and Nonmetal Diesel Particulate Matter (DPM) Standard Draft 
Compliance Guide
    --Other Resources
    --NIOSH Listserve
    --Diesel Emissions and Control Technologies in Underground Metal 
and Nonmetal Mines
    --Metal and Nonmetal Diesel Particulate Filter Selection Guide
    --Baseline DPM Sample Results
    --PowerPoint Presentations
    --From Compliance Assistance Workshops on Diesel Rule
    --Summary of Requirements Mine Safety and Health Administration's 
(MSHA's) Standard on Diesel Particulate Matter Exposure of Underground 
Metal and Nonmetal Miners that are in effect as of July 20, 2002.
    --SKC Diesel Particulate Matter Cassette with Precision-jeweled 
Impactor
    --Diesel Particulate Matter (DPM) Control Technologies with Percent 
Removal Efficiency
    --Diesel Particulate Matter (DPM) Control Technologies
    --Table I: Non-Catalyzed Particulate Filters, Base Metal 
Particulate Filters, and Paper Filters
    --Table II: Catalyzed (Platinum Based) Diesel Particulate Filters
    --Work Place Emissions Control Estimator
    --Advanced Notice of Proposed Rule Making (ANPRM)
    --Diesel Particulate Matter Exposure of Underground Metal and 
Nonmetal Miners (ANPRM)--09/25/2002
    --Final Rules
    --Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of 
Underground Metal and Nonmetal Miners--01/19/2001
    --Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of 
Underground Metal and Nonmetal Miners--Delay of Effective Dates--05/21/
2001
    --Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of 
Underground Metal and Nonmetal Miners--Final Rule and Proposed Rule--
07/05/2001
    --Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of 
Underground Metal and Nonmetal Miners; Final Rule--02/27/2002
    --Part II--30 CFR Part 57--Diesel Particulate Matter Exposure of 
Underground Metal and Nonmetal Miners; Final Rule--07/18/2002
    --Regulatory Economic Analysis
    --Final Regulatory Economic Analysis And Regulatory Flexibility 
Analysis for Final Rule on 30 CFR Parts 57 Final Standards and 
Regulations--Diesel Particulate Matter Exposure of Underground Metal 
and Nonmetal Miners
    --News Releases
    --MSHA Rules Will Control Miners' Exposure to Diesel Particulate--
01/18/2001
    --Program Information Bulletins
    --PIB01-10 Diesel Particulate Matter Exposure of Underground Metal 
and Nonmetal Miners--08/28/2001
    --PIB02-04 Potential Health Hazard Caused by Platinum-Based 
Catalyzed Diesel Particulate Matter Exhaust Filters--05/31/2002--
    --PIB02-08 Diesel Particulate Matter Exposure of Underground Metal 
and Nonmetal Miners-Summary of Settlement Agreement--08/12/2002
    In addition to the Web site postings specifically intended for the 
metal and nonmetal mining industry, MSHA has created a Diesel Single 
Source Page for the coal industry. A list of approved engines is 
accessible from the coal page. Many of the other topics found on that 
page may also be of interest to the metal and nonmetal mining industry, 
particularly for those operations at gassy metal/nonmetal mines where 
permissible equipment is required.
    Publications: As part of the settlement agreement, MSHA agreed to 
issue citations for violations of the interim concentration limit only 
after MSHA and NIOSH are satisfied with the performance characteristics 
of the SKC sampler. During the 31-Mine study, MSHA observed that the 
deposit area of the SKC submicron impactor filter was not as consistent 
as those obtained for preliminary evaluation. This was attributed to 
inconsistent crimping of the aluminum foil cone on the filter capsule.
    NIOSH, in collaboration with MSHA and SKC undertook a project to 
redesign the filter capsule and improve the consistency of the deposit 
area. This was accomplished by replacing the cone with a 32-mm inside 
diameter ring and replacing the 37-mm filter with a 38-mm filter. These 
modifications provided a

[[Page 48680]]

consistent 8.04 square centimeter deposit and eliminated leakage around 
the filter. The results of this project were prepared into a scientific 
publication ``Sampling Results of the Improved SKC Diesel Particulate 
Matter Cassette'' by James D. Noll, Robert J. Timko, Linda McWilliams, 
Peter Hall, and Robert A. Haney. This paper is being peer reviewed for 
publication in a scientific journal. The following abstract was 
prepared for the study results:

Diesel particulate matter (DPM) cassettes, manufactured by SKC, 
Inc., Eighty Four, PA, are designed to collect airborne particulates 
being emitted by diesel powered machinery. These devices, primarily 
used in underground metal/non-metal mines, enable officials to 
determine miner exposure to DPM. The SKC DPM cassette is a size 
selective sampler that was designed by researchers with the U.S. 
Bureau of Mines, now a part of the National Institute for 
Occupational Safety and Health (NIOSH), and SKC engineers to collect 
DPM. This cassette is preferred to a conventional respirable dust 
sampler because, if DPM is sampled in the presence of carbonaceous 
ore dust, the ore dust and DPM will collect on the quartz filter, 
causing the carbon attributed to DPM to be artificially high. In 
this study, NIOSH researchers investigated the ability of the SKC 
DPM cassette to collect DPM while preventing mineral dust from 
collecting on the filter. This cassette discriminated dusts and 
efficiently collected DPM in both laboratory and field evaluations. 
In the presence of carbon-based mineral dust having an average 
concentration of 8 mg/m\3\, no mineral dust was found on SKC DPM 
cassette filters. NIOSH researchers did discover that DPM deposits 
on filters that were manufactured prior to August 2002 were non-
uniform and inconsistent across the filter surfaces. DPM deposit 
cross-sectional areas varied from 6 to 9 cm\2\. To correct this 
problem, SKC modified the cassette. The resulting cassette produced 
areas of DPM deposit between 8.11 and 8.21 cm\2\, a difference of 
less than 2%.

    Specific control technology studies. Following the settlement 
agreement, MSHA was invited by various mining companies to evaluate the 
effectiveness of several different control technologies for diesel 
particulate matter. These control technologies included ceramic 
filters, bio-diesel fuel and a fuel oxygenator. Company participation 
was essential to the success of each study. Ceramic filters were 
evaluated in two mines, one where MSHA was the only investigator and 
one where NIOSH was the primary investigator. In the MSHA study, DPM on 
a production unit was evaluated with and without ceramic filters 
installed on the loader and trucks. In the NIOSH study a variety of 
ceramic filters were tested in an isolated zone.
    Bio-diesel fuel was evaluated in two mines. In one mine, a 20 and 
50 percent recycled bio-diesel fuel and a 50 percent new bio-diesel 
were evaluated. In the second mine, a 35 percent recycled bio-diesel 
fuel and a 35 percent new bio-diesel fuel were evaluated.
    The fuel oxygenator system was evaluated in one mine. The mine 
exhaust was sampled with and without the units installed. For the tests 
with the oxygenator units, the oxygenator units were installed on all 
production equipment.
    Following is a summary of the five individual mine technology 
evaluation studies:
    Kennecott Greens Creek Mining Company: The Mine Safety and Health 
Administration and Kennecott Greens Creek Mining Company participated 
in a collaborative study to verify the efficiency of catalyzed ceramic 
diesel particulate filters for reducing diesel emissions. The goal of 
the study was the identification of site-specific, practical mine-
worthy filter technology.
    This series of tests was designed to determine the reduction in 
emissions and personal exposure that can be achieved when ceramic 
filters are installed on a loader and associated haulage trucks 
operating in a production stope. Relative engine gaseous and diesel 
particulate matter emissions were also determined for the equipment 
under specific load condition.
    The tests were conducted over a two-week period. Three shifts were 
sampled with ceramic after-filters installed; and three shifts were 
sampled without the after-filters installed. Personal samples were 
collected to assess worker exposures. Area samples were collected to 
assess engine emissions. Both gaseous and diesel particulate 
measurements were taken.
    Sampling results indicate significant reductions in both personal 
exposures and engine emissions. These results also indicated that 
factors such as diesel particulate contamination of intake air, stope 
ventilation parameters, and isolated atmospheres in vehicle cabs as 
well as the ceramic diesel particulate filters may have a significant 
impact on personal exposures. The following findings and conclusions 
were obtained from the study:
    1. The results of the raw exhaust gas measurements conducted during 
the study indicated that the engines were operating properly.
    2. The ceramic filters installed on the machines used in this study 
did not adversely affect the machine operation. Even with some apparent 
visual cracking from the rotation of the filter media, the ceramic 
filters removed more than 90% of the DPM. The filters passively 
regenerated during machine operation.
    3. The Bosch smoke test provides an indication of filter 
deterioration; however, the colorization method does not quantify the 
results.
    4. Personal DPM exposures were reduced by 60 to 68 percent when 
after-filters were used.
    5. CO levels decreased by up to one-half when the catalyzed filters 
were being used. There appeared to be an increase in NO2 
when catalyzed filters are being used; however, it was unclear whether 
this increase was due to data variability, changes in ventilation rate, 
or the use of the catalyzed filters.
    6. The use of cabs reduced DPM concentrations by 75 percent when 
after-filters were used and by 80 percent when after-filters were not 
in use.
    7. Ventilation airflow was provided to the stopes through fans with 
rigid and bag tubing. Airflow was the same or greater than the 
Particulate Index, but typically lower than the gaseous ventilation 
rate.
    8. The use of ceramic after-filters reduced average engine DPM 
emissions by 96 percent.
    9. The reduction in personal exposure was not attributed solely to 
after-filter performance because other factors such as ventilation, 
upwind equipment use, and cabs also influence personal exposure.
    Carmeuse North America, Inc., Maysville Mine: MSHA entered into a 
collaborative effort with NIOSH, Industry, and the Kentucky Department 
of Energy to test DPM emissions and exposures when using various blends 
of bio-diesel fuels in an underground stone mine. As part of its 
compliance assistance program, MSHA provides support to mining 
operations to evaluate diesel particulate control technologies. The 
study was initiated by the industry partner, with MSHA and NIOSH 
providing support for study design, data collection, and sample and 
data analysis. Project funding was provided by Carmeuse and Kentucky 
Department of Energy, through the Kentucky Clean Fuels Coalition.
    The initial study was conducted in two phases, a 20% bio-diesel and 
a 50% bio-diesel blend of recycled vegetable oil, each mixed with 100% 
low sulfur No. 2 standard diesel fuel. Baseline conditions were 
established using low sulfur No. 2 standard diesel fuel. In a third 
phase of the study, a 50% blend of new soy bio-diesel fuel was tested.
    Area samples were collected at shafts to assess equipment 
emissions. Personal samples were collected to assess worker exposure. 
These samples were analyzed by NIOSH using the NIOSH 5040

[[Page 48681]]

method to determine total carbon and elemental carbon concentrations. 
Results indicate that significant reductions in emissions and worker 
exposure were obtained for all bio-diesel mixtures. These reductions 
were in terms of both elemental and total carbon. Preliminary results 
for the 20% and 50% recycled vegetable oil indicated 30 and 50 percent 
reductions in DPM emissions and exposures, respectively. Preliminary 
results for the tests on the 50% blend of new soy bio-diesel fuel, 
showed about a 30 percent reduction in DPM emissions and exposures.
    Carmeuse North America, Inc., Black River Mine: Following the 
success of the bio-diesel tests at Maysville Mine, Carmeuse requested 
assistance in continuing the bio-diesel optimization testing at their 
Black River Mine. In this test two bio-diesel blends along with a 
baseline test were made. For each test personal exposures and the mine 
exhaust were tested for two shifts. The two bio-diesel blends included 
a 35% recycled vegetable oil and a 35% blend of new soy oil. 
Preliminary results for both the 35% recycled vegetable oil and the 35% 
blend of new soy bio-diesel fuel showed about a 30 percent reduction in 
DPM emissions and exposures.
    Rogers Group, Jefferson County Mine: MSHA personnel were invited by 
the Company to evaluate a fuel oxygenation system. The oxygenator is 
installed in the fuel line of the diesel equipment. The company was 
installing the units to increase fuel economy and was interested in 
determining their effect on DPM. MSHA conducted baseline sampling prior 
to the installation of the units. Personal samples were collected on 
production workers and area samples were collected in the mine exhaust 
airflow. The units were installed on loaders and trucks. The sampling 
was repeated after the units had accumulated 100 hours of operation. 
Preliminary results indicated that the use of the fuel oxygenator had 
no measurable effect on either DPM exposure or emissions.
Review of the Technology in Use Assistance
    Martin Marietta Aggregates, North Indianapolis Mine: MSHA personnel 
provided DPM compliance assistance at this mine during a full-day visit 
in March 2003. The mine's DPM sampling history was reviewed, along with 
current operating and equipment maintenance practices, mine 
ventilation, diesel equipment inventory, and steps taken to date and 
future plans to reduce DPM exposures. Currently, mechanical ventilation 
is used at the mine and an upgrade to the ventilation system was in 
progress. The full range of DPM engineering controls was discussed, an 
exhaust temperature measurement and data logging system was 
demonstrated, and easy-to-use computer software for using such data to 
select appropriate DPM filter systems was presented. A simple approach 
for measuring the effectiveness of cab air filtering and pressurization 
systems was demonstrated, MSHA's computer spreadsheet software for 
evaluating the individual and combined effect of DPM emission sources 
and controls was presented, the highest DPM-emitting equipment was 
identified (so that future equipment-specific DPM control efforts could 
be appropriately focused), and the likely effect of various ventilation 
system upgrades was discussed.
    Martin Marietta Aggregates, Parkville Mine: MSHA personnel provided 
DPM compliance assistance at this mine during a full-day visit in April 
2003. The mine's DPM sampling history was reviewed, along with current 
operating and equipment maintenance practices, mine ventilation, diesel 
equipment inventory, and steps taken to date and future plans to reduce 
DPM exposures. Mechanical ventilation is currently used at the mine and 
an upgrade to the ventilation system was in progress. The full range of 
DPM engineering controls was discussed, an exhaust temperature 
measurement and data logging system was demonstrated, and easy-to-use 
computer software for using such data to select appropriate DPM filter 
systems was presented. A simple approach for measuring the 
effectiveness of cab air filtering and pressurization systems was 
demonstrated, computer spreadsheet software for evaluating the 
individual and combined effect of DPM emission sources and controls was 
presented, the highest DPM-emitting equipment were identified (so that 
future equipment-specific DPM control efforts could be appropriately 
focused), and the likely effect of various ventilation system upgrades 
was discussed.
    Martin Marietta Aggregates, Kaskaskia Mine: MSHA personnel provided 
DPM compliance assistance at this mine during a full-day visit in May 
2003. The mine's DPM sampling history was reviewed, along with current 
operating and equipment maintenance practices, mine ventilation, diesel 
equipment inventory, and steps taken to date and future plans to reduce 
DPM exposures. Currently, natural ventilation is used at the mine. The 
full range of DPM engineering controls was discussed, an exhaust 
temperature measurement and data logging system was demonstrated, and 
easy-to-use computer software for using such data to select appropriate 
DPM filter systems was presented. A simple approach for measuring the 
effectiveness of cab air filtering and pressurization systems was 
demonstrated, computer spreadsheet software for evaluating the 
individual and combined effect of DPM emission sources and controls was 
presented, the highest DPM-emitting equipment were identified (so that 
future equipment-specific DPM control efforts could be appropriately 
focused), and the likely effect of various ventilation system upgrades 
was discussed.
    Martin Marietta Aggregates, Manheim Mine: MSHA personnel provided 
DPM compliance assistance at this mine during a full-day visit in May 
2003. The mine's DPM sampling history was reviewed, along with current 
operating and equipment maintenance practices, mine ventilation, diesel 
equipment inventory, and steps taken to date and future plans to reduce 
DPM exposures. Currently, natural ventilation is used at the mine. The 
full range of DPM engineering controls was discussed, an exhaust 
temperature measurement and data logging system was demonstrated, and 
easy-to-use computer software for using such data to select appropriate 
DPM filter systems was presented. A simple approach for measuring the 
effectiveness of cab air filtering and pressurization systems was 
demonstrated, computer spreadsheet software for evaluating the 
individual and combined effect of DPM emission sources and controls was 
presented, the highest DPM-emitting equipment were identified (so that 
future equipment-specific DPM control efforts could be appropriately 
focused), and the likely effect of various ventilation system upgrades 
was discussed.
    Rogers Group, Oldham County Mine: MSHA personnel provided DPM 
compliance assistance at this mine during a full-day visit in November 
2002. Extensive DPM sampling was conducted at this mine. Both personal 
exposure samples and area samples were collected. None of the personal 
samples exceeded 160 [mu]g/m\3\. Current operating and equipment 
maintenance practices were reviewed, along with mine ventilation, 
diesel equipment inventory, and steps taken to date and future plans to 
reduce DPM exposures. Mechanical ventilation was provided for the mine. 
The full range of DPM engineering controls was discussed. DPM samples 
were collected inside and outside equipment cabs. Results from this 
survey indicate the environmental cabs provided significant reduction 
in

[[Page 48682]]

the DPM exposure of the equipment operators.
    Rogers Group, Jefferson County Mine: MSHA personnel provided DPM 
compliance assistance at this mine during a full-day visit in December 
2002. Both personal exposure samples and area samples were collected. 
The highest personal sample, collected on the loader, was 468 [mu]g/
m\3\. The loader was operated with the window open. Current operating 
and equipment maintenance practices were reviewed, along with mine 
ventilation, diesel equipment inventory, and steps taken to date and 
future plans to reduce DPM exposures. Mechanical ventilation was 
provided for the mine. The full range of DPM engineering controls was 
discussed. The Estimator, MSHA's computer spreadsheet software for 
evaluating the individual and combined effect of DPM emission sources 
and controls, was presented, the highest DPM-emitting equipment were 
identified so that future equipment-specific DPM control efforts could 
be appropriately focused. Finally, the likely effect of various 
ventilation system upgrades was discussed.
    Nalley and Gibson, Georgetown Mine: MSHA personnel provided DPM 
compliance assistance at this mine during a full-day visit in May 2003. 
The mine's DPM sampling history was reviewed, along with current 
operating and equipment maintenance practices, mine ventilation, diesel 
equipment inventory, and steps taken to date and future plans to reduce 
DPM exposures. DPM samples were collected to assess improvements since 
the baseline sampling. Currently, mechanical ventilation provides 
airflow to the mine. The full range of DPM engineering controls was 
discussed, an exhaust temperature measurement and data logging system 
was demonstrated. An easy-to-use computer software for using such data 
to select appropriate DPM filter systems was presented. A simple 
approach for measuring the effectiveness of cab air filtering and 
pressurization systems was demonstrated. The Estimator, MSHA's computer 
spreadsheet software for evaluating the individual and combined effect 
of DPM emission sources and controls, was presented. The highest DPM-
emitting equipment were identified so that future equipment-specific 
DPM control efforts could be appropriately focused, and the likely 
effect of various ventilation system upgrades was discussed.
    Stone Creek Brick Company: MSHA personnel provided DPM compliance 
assistance at this mine during a full-day visit in May 2003. DPM 
samples were collected on underground workers. The mine's DPM sampling 
history was reviewed, along with current operating and equipment 
maintenance practices, mine ventilation, diesel equipment inventory, 
and steps taken to date and future plans to reduce DPM exposures. The 
mine uses mechanical ventilation to provide airflow to the mine. The 
full range of DPM engineering controls was discussed. None of the 
equipment were equipped with environmental cabs. The Estimator, MSHA's 
computer spreadsheet software for evaluating the individual and 
combined effect of DPM emission sources and controls, was presented. 
The highest DPM-emitting equipment were identified so that future 
equipment-specific DPM control efforts could be appropriately focused. 
Also, the likely effect of various ventilation system upgrades was 
discussed.
    Wisconsin Industrial Sand Co., Maiden Rock Mine: MSHA personnel 
provided DPM compliance assistance at this mine during a full-day visit 
in May 2003. The mine's DPM sampling history was reviewed, along with 
current operating and equipment maintenance practices, mine 
ventilation, diesel equipment inventory, and steps taken to date and 
future plans to reduce DPM exposures. The full range of DPM engineering 
controls was discussed. The Estimator, MSHA's computer spreadsheet 
software for evaluating the individual and combined effect of DPM 
emission sources and controls, was presented. The highest DPM-emitting 
equipment were identified so that future equipment-specific DPM control 
efforts could be appropriately focused.
    Gouverneur Talc Company, Inc., No. 4 Mine: MSHA personnel provided 
DPM compliance assistance at this mine during a full-day visit in May 
2003. DPM samples were collected on underground workers. The mine's DPM 
sampling history was reviewed, along with current operating and 
equipment maintenance practices, mine ventilation, diesel equipment 
inventory, and steps taken to date and future plans to reduce DPM 
exposures. The full range of DPM engineering controls was discussed, an 
exhaust temperature measurement and data logging system was 
demonstrated, and easy-to-use computer software for using such data to 
select appropriate DPM filter systems was presented. A simple approach 
for measuring the effectiveness of cab air filtering and pressurization 
systems was demonstrated, a computer spreadsheet software for 
evaluating the individual and combined effect of DPM emission sources 
and controls was presented, the highest DPM-emitting equipment was 
identified (so that future equipment-specific DPM control efforts could 
be appropriately focused), and the likely effect of various ventilation 
system upgrades was discussed.
    Laboratory Compliance Assistance conducted by MSHA: In addition to 
the compliance assistance field tests, MSHA's diesel testing laboratory 
has been working with manufacturers to evaluate various types of DPM 
control technologies. Certain of these technologies can be applied in 
either underground metal/nonmetal or coal mines.
    Evaluating paper/synthetic media as exhaust filters: MSHA has been 
evaluating paper/synthetic media as exhaust filters. These filters have 
shown high DPM removal efficiencies in excess of 90% in the laboratory 
when tested on MSHA's test engine using the test specified in subpart E 
of 30 CFR part 7. The laboratory has tested approximately 20 different 
paper/synthetic media from 10 different filter manufacturers. Even 
though much of this work is directed to underground coal mine 
applications for use on permissible equipment, this technology is 
available for use on permissible equipment that is used in underground 
gassy metal/nonmetal mines. In addition, some underground coal mine 
operators have considered adding exhaust heat exchanger systems to 
nonpermissible equipment in order to use the paper/synthetic filters in 
place of ceramic filters (a heat exchanger is needed to reduce the 
exhaust gas temperature to below 302 [deg]F for these types of 
filters). This could also be an option for metal/nonmetal equipment 
that would need DPM filter technology, particularly in operations in 
gassy mines where permissible equipment is required.
    Evaluating Ceramic Filter Systems: MSHA has worked with six 
different ceramic filter system manufacturers to evaluate the effects 
of their catalytic washcoats on NO2 production. As discussed 
elsewhere in this preamble, catalytic washcoats on the ceramic filters 
may cause increases in NO2 levels. MSHA used its test engine 
and followed the test procedures in subpart E of 30 CFR part 7. MSHA 
has posted on its Web site on the Diesel Single Source Page a list of 
ceramic filters that have significantly increased NO2 
levels. MSHA has also listed the ceramic filters that are not known to 
have increased NO2 levels. MSHA also checked the DPM removal 
efficiencies for these filters during the laboratory tests and the 
efficiency results have agreed with the efficiencies posted on the 
Diesel Single Source Page of 85% for cordierite and 87% for silicon 
carbide. MSHA also worked with NIOSH during these tests

[[Page 48683]]

to collect DPM samples for EC analysis using the NIOSH 5040 method. The 
laboratory results showed that the filters removed EC with efficiencies 
up to 99%.
    Evaluation of Fuel Oxygenator System: MSHA recently completed 
laboratory tests on a Rentar in-line fuel catalyst. The Rentar unit was 
installed on a Caterpillar 3306ATAAC which was coupled to a generator. 
An electrical load bank was used to load the engine under various 
operating conditions. The engine was baselined for gaseous and DPM 
emissions without the Rentar; then, the Rentar was installed and 
operated for 100 hours of break-in. The gaseous and DPM emission 
measurements were repeated after the 100 hour break-in. The preliminary 
laboratory results showed some measurable reductions in whole DPM. 
Samples were also collected for EC analysis using the NIOSH 5040 
method. Those results are currently being evaluated by NIOSH.
    Evaluation of a Magnet System: MSHA is preparing to perform 
laboratory tests for Ecomax, a manufacturer of a magnet system 
installed on the fuel line, oil filter, air intake and radiator. A 
preliminary MSHA field test of this product was done at a surface 
aggregate operation. The magnetic device demonstrated a 30% reduction 
in CO levels. Subsequent laboratory testing will include DPM 
measurements.
    Additional Testing: MSHA is also planning a lab test on a 
manufacturer's fluidized bed, several types of fuel additives, and a 
fuel preparative. The test plans and the required test hardware are 
currently being discussed with the respective manufactures of these 
products.

VI. Exposure Assessment and Literature Update

A. Introduction

    Section VI.B summarizes new exposure data that have become 
available since publication, on January 19, 2001, of the existing rule 
limiting DPM levels in underground metal and nonmetal mines. Next, in 
Section VI.C, we survey the most recent scientific literature (April 
2000-March 2003) pertaining to adverse health effects of DPM and fine 
particulates in general.

B. DPM Exposures in Underground Metal and Nonmetal Mines

    In the existing risk assessment (66 FR 5752) we evaluated exposures 
based on 355 samples collected at 27 underground U.S. M/NM mines prior 
to the rule's promulgation. Mean DPM concentrations found in the 
production areas and haulageways at those mines ranged from about 285 
[mu]g/m\3\ to about 2000 [mu]g/m\3\, with some individual measurements 
exceeding 3500 [mu]g/m\3\. The overall mean DPM concentration was 808 
[mu]g/m\3\. All of the samples considered in the existing risk 
assessment were collected prior to 1999, and some were collected as 
long ago as 1989.
    Two new bodies of DPM exposure data, collected subsequent to 
promulgation of the 2001 rule, have now been compiled for underground 
M/NM mines: (1) Data collected in 2001 from 31 mines for purposes of 
the 31-Mine Study (Ref. 31-Mine Study) and (2) data collected between 
10/30/2002 and 3/26/2003 from 171 mines to establish a baseline for 
future samples (Ref. Baseline Samples, 2003). Both of these datasets 
have been placed into the public record, and they are summarized in the 
next two subsections below. Following these summaries, we discuss the 
relationship between EC and TC, including the ratio of EC to TC 
(EC:TC). This discussion will be based entirely on samples taken for 
the 31-Mine Study, since those samples were controlled for potential TC 
interferences from tobacco smoking and oil mist, whereas the baseline 
samples were not.
1. Data from Joint Study
    As described in greater detail in MSHA's final report on the 31-
Mine Study, MSHA collected 464 DPM samples in 2001 at 31 underground M/
NM mines. Of these 464 samples, 106 were voided, most of them due to 
potential interferences resulting in invalid TC content used to 
evaluate DPM exposures. Table VI-1 shows how the remaining 358 valid 
DPM samples were distributed across four broad mine categories. All 
samples at one of the metal mines were voided, leaving 30 mines with 
valid samples indicating DPM concentrations.

                              Table VI-1.--Number of DPM Samples, by Mine Category
----------------------------------------------------------------------------------------------------------------
                                                          Number of mines                      Average Number of
                                                             with valid      Number of valid   valid samples per
                                                              samples            samples              mine
----------------------------------------------------------------------------------------------------------------
Metal..................................................                 11                116               10.5
Stone..................................................                  9                105               11.7
Trona..................................................                  3                 54               18.0
Other..................................................                  7                 83               11.9
                                                        --------------------
    Total..............................................                 30                358               12.5
----------------------------------------------------------------------------------------------------------------

    Table VI-2 summarizes the valid DPM concentrations observed in each 
mine category, assuming that submicrometer TC, as measured by the SKC 
sampler, comprises 80 percent of all DPM. The mean concentration across 
all 358 valid samples was 432 [mu]g/m\3\ (Std. error = 21.0 [mu]g/
m\3\). The mean concentration was greatest at metal mines, followed by 
stone and ``other N/M.'' At the three trona mines sampled, both the 
mean and median DPM concentration were substantially lower than what 
was observed for the other categories. This was due to the increased 
ventilation used at these mines to control methane emissions.

           Table VI-2.--DPM Concentrations ([mu]g/m\3\), By Mine Category. DPM Is Estimated by TC/0.8
----------------------------------------------------------------------------------------------------------------
                                     Metal                Stone                Trona              Other N/M
----------------------------------------------------------------------------------------------------------------
Number of samples...........                116                  105                   54                   83
Minimum.....................                 46.                  16.                  20.                  27.
Maximum.....................               2581.                1845.                 331.                1210.
Median......................                491.                 331.                  82.                 341.

[[Page 48684]]

 
Mean........................                610.                 465.                  94.                 359.
-----------------------------
    Std. Error..............                 44.7                 36.0                  9.4                 26.6
    95% UCL.................                699.                 537.                 113.                 412.
    95% LCL.................                522.0                394.                  75.                 306.
----------------------------------------------------------------------------------------------------------------

    After adjusting for differences in sample types and in occupations 
sampled, DPM concentrations at the non-trona mines were estimated to be 
about four to five times the concentrations found at the trona mines. 
Although there were significant differences between individual mines, 
the adjusted differences between the general categories of metal, 
stone, and other N/M mines were not statistically significant.\1\ For 
the 304 valid samples taken at mines other than trona, the mean DPM 
concentration was 492 [mu]g/m\3\ (Std. error = 23.0).
---------------------------------------------------------------------------

    \1\ These conclusions derive from an analysis of variance, based 
on TC measurements, as described in the report of the 31-Mine Study. 
They depend on an assumption that the ratio of DPM to TC is 
uncorrelated with mine category, sample type (i.e., personal or 
area), and occupation.
---------------------------------------------------------------------------

    Again assuming that submicrometer TC as measured by the SKC sampler 
comprises 80 percent of DPM, the mean DPM concentration observed was 
1019 [mu]g/m\3\ at the single mine exhibiting greatest DPM levels. Four 
of the nine valid samples at this mine exceeded 1487 [mu]g/m\3\. In 
contrast, DPM concentrations never exceeded 500 [mu]g/m\3\ at 8 of the 
30 mines with valid samples (2 of the 11 metal mines, 1 of the 3 stone, 
all 3 trona, and 2 of the 7 other N/M). (Note that 500 [mu]g/m\3\ is 
the whole particulate equivalent of the 400 [mu]g/m\3\ interim 
standard.) Some individual measurements exceeded 200DPM [mu]g/m\3\ at 
all but one of the mines sampled.
2. Baseline Data
    An analysis of MSHA's baseline sampling appears in Section V, 
Compliance Assistance, and is used as the basis for this dicussion.
    Table VI-1 summarizes, by general commodity, the EC levels measured 
during this sampling. The overall mean eight-hour full shift equivalent 
EC concentration of samples in this study was 170 [mu]g/m\3\, and the 
overall median was 117 [mu]g/m\3\. Table VI-2 provides a similar 
summary for estimated DPM levels, using TC/0.8 and TC [ap] 1.3 x EC.\2\ 
Under these assumptions, the estimated mean DPM level was 277 [mu]g/
m\3\, and the median was 191 [mu]g/m\3\. Since the baseline data and 
the 31-Mine study both showed significantly lower levels at trona mines 
than at other underground M/NM mines, Tables VI-7 and VI-8 present 
overall results both including and excluding the three underground 
trona mines sampled.
---------------------------------------------------------------------------

    \2\ The relationship DPM [ap] TC/0.8 is the same as that assumed 
in the existing risk assessment. The relationship TC [ap] 1.3 x EC 
was formulated under the settlement agreement, based on TC:EC ratios 
observed in the joint 31-Mine Study, as described in the next 
subsection of this exposure assessment.

                                                         Table VI-1.--Baseline EC Concentrations
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               8-hour full shift equivalent EC concentration--([mu]g/m\3\)
                                                               -----------------------------------------------------------------------------------------
                                                                                                                                               Total
                                                                    Metal          Stone        Other N/M        Trona          Total        excluding
                                                                                                                                               Trona
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of samples.............................................          189            519            151             15            874            859
Maximum.......................................................         1549           1340            634            149           1549           1549
Median........................................................          184            104             99             70            117            120
Mean..........................................................          227            164            130             69            170            172
---------------------------------------------------------------
    Std. Error................................................           14.6            7.5            8.5           10.3            5.8            5.9
    95% UCL...................................................          256            179            147             92            182            184
    95% LCL...................................................          198            150            115             47            159            161
--------------------------------------------------------------------------------------------------------------------------------------------------------


                                                        Table VI-2.--Baseline DPM Concentrations
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Estimated 8-hour full shift equivalent DPM concentration--([mu]g/m\3\)
                                                               -----------------------------------------------------------------------------------------
                                                                                                                                               Total
                                                                    Metal          Stone        Other N/M        Trona          Total        excluding
                                                                                                                                               Trona
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of samples.............................................          189            519            151             15            874            859
Maximum.......................................................         2518.          2178.          1030.           242.          2518.          2518.
Median........................................................          299.           170.           162.           113.           191.           195.
Mean..........................................................          369.           267.           212.           113.           277.           280.
---------------------------------------------------------------
    Std. Error................................................           23.8           12.2           13.8           16.7            9.4            9.5
    95% UCL...................................................          416.           291.           239.           149.           295.           299.
    95% LCL...................................................          323.           243.           185.            77.           259.           261.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Baseline EC sample results varied widely between mines within 
commodities and also within most mines. Table VI-3 summarizes baseline 
EC results for the 19 occupations found to have at least one sample 
where the

[[Page 48685]]

EC level exceeded the proposed 308 [mu]g/m\3\ 8-hour full shift 
equivalent interim EC limit. As indicated by the table, EC levels 
varied widely within each occupation.

  Table VI-3.--Baseline EC Concentrations for Occupations With at Least One Value Exceeding Proposed Interim EC
                                                      Limit
----------------------------------------------------------------------------------------------------------------
                                              8-hour full shift equivalent EC concentration ([mu]g/m\3\)
                                     ---------------------------------------------------------------------------
             Occupation                Number of valid
                                           samples            Minimum             Median            Maximum
----------------------------------------------------------------------------------------------------------------
Scaling (hand)......................                 17                 14                128              1,549
Front-end Loader....................                155                  0                104              1,340
Miscoded............................                  3                395                450              1,123
Drill Operator......................                 93                  2                122                880
Truck Driver........................                183                  0                118                826
Blaster, Power Gang.................                100                  5                165                738
Miner, Drift........................                 13                 12                134                712
Mucking Machine.....................                 18                 12                213                671
Supervisor..........................                 10                  1                 67                658
Roof Bolter.........................                 22                 48                167                638
Complete Loader.....................                 17                 32                145                634
Scaling (mechanical)................                 63                  0                101                577
Utility Man.........................                 18                 22                 71                491
Miner, Stope........................                 11                127                254                479
Belt Crew...........................                  8                 20                173                386
Cleanup Man.........................                  2                 51                217                384
Engineer............................                  1                337                337                337
Crusher operator....................                 14                  1                 36                328
Shuttle car operator................                  3                 14                 73                323
----------------------------------------------------------------------------------------------------------------

    Figure VI-1 depicts, by mine category, the percentage of baseline 
samples that exceed the proposed interim limit of 308 [mu]g/
m3. Underground metal mines exhibited the highest proportion 
of samples exceeding this limit, followed by stone and then other 
nonmetal mines. All 15 samples collected in the three trona mines met 
the proposed limit. Across all commodities, 15.7 percent of the 874 
valid baseline samples exceeded the interim EC limit.
[GRAPHIC] [TIFF OMITTED] TP14AU03.005

    Figure VI-2 shows how samples exceeding the proposed interim EC 
limit were distributed over individual mines. One to five baseline 
samples were taken at each mine. In 120 of the 171 mines sampled (70 
percent), none of the

[[Page 48686]]

baseline EC measurements exceeded 308 [mu]g/m3. The 
remaining 51 mines (30 percent) had at least one sample for which EC 
exceeded 308 [mu]g/m3. All samples taken at 14 of the mines 
exceeded the proposed interim limit.
[GRAPHIC] [TIFF OMITTED] TP14AU03.006

3. Relationship Between Elemental and Total Carbon
    Unlike the 31-Mine Study, no special precautions were taken during 
MSHA's baseline sampling to avoid tobacco smoke or other substances 
that could potentially interfere with using TC (i.e., EC + OC) as a 
surrogate measure of DPM. Therefore, the baseline data should not be 
used to evaluate the OC content of DPM or the ratio of EC to TC within 
DPM. In the 31-Mine Study, great care was taken to void all samples 
that may have been exposed to tobacco smoke or other extraneous sources 
of organic carbon. Accordingly, the analysis of the EC:TC ratio we 
present here relies entirely on data from the 31-Mine Study. It is 
important to note that most of the samples in this study were taken in 
the absence of exhaust filters to control DPM emissions. Since exhaust 
filters may have different effects on EC and OC emissions, the results 
described here apply only to mine areas where exhaust filters are not 
employed.
    Figure VI-3 plots the EC:TC ratios observed in the 31-Mine Study 
against the corresponding TC concentrations. The various symbols shown 
in the plot identify samples taken at the same mine. The EC:TC ratio 
ranged from 23 percent to 100 percent, with a mean of 75.7 percent and 
a median of 78.2 percent. Note that the reciprocal of 0.78, which is 
1.3, equals the median of the TC:EC ratio observed in these samples.\3\ 
The 1.3 TC:EC ratio was the value accepted, under terms of the 
settlement agreement, for the purpose of temporarily converting EC 
measurements to TC measurements.
---------------------------------------------------------------------------

    \3\ The median of reciprocal values is always equal to the 
reciprocal of the median. This relationship does not hold for the 
mean.

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

[[Page 48687]]

[GRAPHIC] [TIFF OMITTED] TP14AU03.007

    The existing rule defines an interim TC limit of 400 [mu]g/m\3\. 
Under the current proposal, this interim limit would be replaced with 
an interim EC limit of 308 [mu]g/m\3\. Table VI-4 indicates the impact 
of this proposed change, based on the EC and TC data obtained from the 
31-Mine Study. Both the 400 [mu]g/m\3\ TC limit and the 308 [mu]g/m\3\ 
EC limit were exceeded by about 31 to 32 percent of the samples. The 
difference (one sample out of 358) is not statistically significant in 
the aggregate. Seven samples, however, exceeded the TC limit but not 
the EC limit, and six samples exceeded the EC limit but not the TC 
limit.

[[Page 48688]]



          Table VI-4.--Compliance With 400 [mu]g/m\3\ TC Limit and/or Proposed 308 [mu]g/m\3\ EC Limit.
                                    [Numbers in parentheses are percentages.]
----------------------------------------------------------------------------------------------------------------
                                                             TC  400 [mu]g/m\3\
             EC  308 [mu]g/m\3\              --------------------------------------       Total
                                                                 No                Yes
----------------------------------------------------------------------------------------------------------------
no.....................................................         239 (66.8)            7 (2.0)         246 (68.7)
yes....................................................            6 (1.7)         106 (29.6)         112 (31.3)
                                                        --------------------
    Total..............................................         245 (68.4)         113 (31.6)        358 (100.0)
----------------------------------------------------------------------------------------------------------------

C. Health Effects Literature Update

    We have identified additional scientific literature pertaining to 
health effects of fine particulates in general and DPM in particular 
published subsequent to the January 19, 2001 final rule.

                  Table VI-5 Studies of Human Respiratory and Immunological Effects, 2000-2002
----------------------------------------------------------------------------------------------------------------
          Authors, year                         Description                             Key results
----------------------------------------------------------------------------------------------------------------
Frew et al., 2001...............  25 healthy subjects and 15 subjects     Both the asthmatic and healthy
                                   with mild asthma were exposed to        subjects developed increased airway
                                   diesel exhaust (108 [mu]g/m\3\) or      resistance after exposure to diesel
                                   filtered air for 2 hr, with             emissions, but airway inflammatory
                                   intermittent exercise. Lung function    responses were different for the 2
                                   was assessed using a computerized       groups. The healthy subjects showed
                                   whole body plethysmograph. Airway       statistically significant BW
                                   responses were sampled by bronchial     neutrophilia and BAL lymphocytosis 6
                                   wash (BW), bronchoalveolar lavage       hr after exposure. The neutrophilic
                                   (BAL), and mucosal biopsies 6 hr.       response of the healthy subjects was
                                   after ceasing exposures.                less intense than that seen in a
                                                                           previous study using a DPM
                                                                           concentration of 300 [mu]g/m\3\.
Fusco et al., 2001..............  Analysis of daily hospital admissions   Respiratory admissions among adults
                                   for acute respiratory infections,       were significantly correlated with CO
                                   COPD, asthma, and total respiratory     and NO2 levels, but not with
                                   conditions in Rome, Italy.              suspended particles. The authors
                                                                           noted that since CO and NO2 are good
                                                                           indicators of combustion products in
                                                                           vehicular exhaust, the detected
                                                                           effects may be due to unmeasured fine
                                                                           and ultrafine particles.
Holgate et al., 2002............  25 healthy and 15 asthmatic subjects    Healthy and asthmatic subjects
                                   were exposed for 2 hours to 100 [mu]g/  exhibited evidence of
                                   m\3\ of DPM and to filtered air on      bronchioconstriction immediately
                                   separate days. Another 30 healthy       after exposure.
                                   subjects were exposed for 2 hours to   Biochemical tests of inflammation
                                   DPM concentrations ranging from 25 to   yielded mixed results but showed
                                   311 [mu]g/m\3\ and compared to 12       small inflammatory changes in healthy
                                   different healthy subjects exposed to   subjects after DPM inhalation.
                                   filtered air. Exposure effects were
                                   assessed using lung function tests
                                   and biochemical tests of bronchial
                                   tissue samples.
Oliver et al., 2001.............  Pulmonary function tests and            After adjusting for smoking and some
                                   questionnaire data were obtained for    other potential confounders, HH
                                   359 ``heavy and highway'' (HH)          workers showed elevated risk of
                                   construction workers. Intensity of      asthma. One subgroup (tunnel workers)
                                   DPM exposure was estimated according    also showed elevated risk of both
                                   to job classification. Duration of      undiagnosed asthma and chronic
                                   exposure was estimated based on         bronchitis, compared to other HH
                                   length of union membership.             workers.
                                                                          Respiratory symptoms appeared to
                                                                           decline with exposure duration as
                                                                           measured by length of union
                                                                           membership. The authors interpreted
                                                                           this as suggesting that HH workers
                                                                           tend to leave their trade when they
                                                                           experience adverse respiratory
                                                                           symptoms.
Salvi et al., 2000..............  15 healthy nonsmoking volunteers were   Diesel exhaust exposure enhanced gene
                                   exposed to 300 [mu]g/m\3\ DPM and       transcription of IL-8 in the
                                   clean air for one hour at least three   bronchial tissue and airway cells and
                                   weeks apart.                            increased IL-8 and GRO-[alpha]
                                  Biochemical analyses were performed on   protein expression in the bronchial
                                   bronchial tissue and bronchial wash     epithelium. This was accompanied by a
                                   cells obtained six hours after each     trend toward increased IL-5 mRNA gene
                                   exposure.                               transcripts in the bronchial tissue.
                                                                           Study showed effects on chemokine and
                                                                           cytokine production in the lower
                                                                           airways of health adults. These
                                                                           substances attract and activate
                                                                           leukocytes. They are associated with
                                                                           the pathophysiology of asthma and
                                                                           allergic rhinitis.

[[Page 48689]]

 
Svartengren et al., 2000........  Twenty nonsmoking subjects with mild    Subjects with PM2.5 exposure--100
                                   allergic asthma were exposed for 30     [mu]g/m\3\ exhibited slightly
                                   minutes to high and low levels of       increased asthmatic responses.
                                   engine exhaust air pollution on two    Associations with adverse outcome
                                   separate occasions at least four        variables were weaker for
                                   weeks apart. Respiratory symptoms and   particulates than for NO2.
                                   pulmonary function were measured
                                   immediately before, during and after
                                   both exposure periods. Four hours
                                   after each exposure, the test
                                   subjects were challenged with a low
                                   dose of inhaled allergen. Lung
                                   function and asthmatic reactions were
                                   monitored for several hours after
                                   exposure.
----------------------------------------------------------------------------------------------------------------


                Table VI-6.--Review Articles on Respiratory and Immunological Effects, 1999-2002
----------------------------------------------------------------------------------------------------------------
          Authors, Year                         Description                             Key results
----------------------------------------------------------------------------------------------------------------
Gavett and Koren, 2001..........  Summarizes results of EPA studies done  Studies indicate that PM enhances
                                   to determine whether PM can enhance     allergic sensitization in animal
                                   allergic sensitization or exacerbate    models of allergy and exacerbate
                                   existing asthma or asthma-like          inflammation and airway hyper-
                                   responses in humans and animal models.  responsiveness in asthmatics and
                                                                           animal models of asthma.
Pandya et al. 2002..............  Reviews human and animal research       Evidence indicates that DPM is
                                   relevant to question of whether DPM     associated with the inflammatory and
                                   is associated with asthma.              immune responses involved in asthma,
                                                                           but DPM appears to have a far greater
                                                                           impact as an adjuvant with allergens
                                                                           than alone. DPM appears to augment
                                                                           IgE, trigger eosinophil
                                                                           degranulation, and stimulate release
                                                                           of numerous cytokines and chemokines.
                                                                           DPM may also promote the cytotoxic
                                                                           effects of free radicals in the
                                                                           airways.
Patton and Lopez, 2002..........  Review of evidence and mechanisms for   Evidence suggests that air pollutants
                                   the role of air pollutants in           (including DPM) ``affect allergic
                                   allergic airway diseases.               response by different mechanisms.
                                                                           Pollutants may increase total IgE
                                                                           levels and potentiate the initial
                                                                           sensitization to allergens and the
                                                                           IgE response to a subsequent allergen
                                                                           exposure. Pollutants also may act by
                                                                           increasing allergic airway
                                                                           inflammation and by directly
                                                                           stimulating airway inflammation. In
                                                                           addition, it is well known that
                                                                           pollutants can be direct irritants of
                                                                           the airways, increasing symptoms in
                                                                           patients with allergic syndromes.''
Peden, 2002.....................  Review of ``studies that exemplify the  DPM ``may play a significant role not
                                   impact of ozone, particulates, and      only in asthma exacerbation but also
                                   toxic components of particulates on     in TH2 inflammation via the actions
                                   asthma.''.                              of polyaromatic hydrocarbons on B
                                                                           lymphocytes.'' ``* * * PM in which
                                                                           the active agents are biologically
                                                                           active metal ions and organic
                                                                           residues * * * may have significant
                                                                           effects on asthma, especially
                                                                           modulating immune function, as
                                                                           demonstrated by the role of
                                                                           polyaromatic hydrocarbons from diesel
                                                                           exhaust in IgE production.''
Sydbom et al. 2001..............  Review of scientific literature on      The epidemiological support for
                                   health effects of diesel exhaust,       particle effects on asthma and
                                   especially the DPM components.          respiratory health is very evident;
                                                                           and respiratory, immunological, and
                                                                           systemic effects of DPM have been
                                                                           documented in a wide variety of
                                                                           experimental studies.
                                                                          Acute effects of DPM exposure include
                                                                           irritation of the nose and eyes, lung
                                                                           function changes, and airway
                                                                           inflammation.
                                                                          Exposure studies in healthy humans
                                                                           have documented a number of profound
                                                                           inflammatory changes in the airways,
                                                                           notably, before changes in pulmonary
                                                                           function can be detected. Such
                                                                           effects may be even more detrimental
                                                                           in subjects with compromised
                                                                           pulmonary function.
                                                                          Ultrafine particles are currently
                                                                           suspected of being the most
                                                                           aggressive particulate component of
                                                                           diesel exhaust.
----------------------------------------------------------------------------------------------------------------


[[Page 48690]]


             Table VI-7.--Studies Relating to Cardiovascular and Cardiopulmonary Effects, 2000-2002
----------------------------------------------------------------------------------------------------------------
          Authors, Year                         Description                             Key Results
----------------------------------------------------------------------------------------------------------------
Lippmann et al., 2000...........  Day-to-day fluctuations in particulate  After adjustment for the presence of
                                   air pollution in the Detroit area       other pollutants, significant
                                   were compared with corresponding        associations were found between
                                   fluctuations in daily deaths and        particulate levels and an increased
                                   hospital admissions for 1985-1990 and   risk of death due to circulatory
                                   1992-1994.                              causes. However, relative risks were
                                                                           about the same for PM2.5 and larger
                                                                           particles.
Magari et al., 2001.............  Longitudinal study of a male            After adjusting for potential
                                   occupational cohort examined the        confounding factors such as age, time
                                   relationship between PM2.5 exposure     of day, and urinary nicotine level,
                                   and cardiac autonomic function.         PM2.5 exposure was significantly
                                                                           associated with disturbances in
                                                                           cardiac autonomic function.
Pope et al., 2002...............  Prospective cohort mortality study,     After adjustment for other risk
                                   based on data collected for Cancer      factors potential using a variety of
                                   Prevention II study, which began in     statistical consumption, and methods,
                                   1982.                                   fine particulate (PM2.5) exposures
                                  Questionnaires were used to obtain       were significantly associated with
                                   individual risk factor data (age,       cardiopulmonary mortality (and also
                                   sex, race, weight, height, smoking      with lung cancer).
                                   history, education, marital status,    Each 10-[mu]g/m3 increase in mean
                                   diet, alcohol confounders, and          level of ambient fine particulate air
                                   occupational exposures). For about      pollution was associated with an
                                   500,000 adults, these were combined     increase of approximately 6 percent
                                   with air pollution data for             in the risk of cardiopulmonary
                                   metropolitan areas throughout the       mortality.
                                   United States and with vital status
                                   and cause of death data through 1998.
Samet et al., 2000a, 2000b......  Time series analyses were conducted on  Results of both the 20-city and 90-
                                   data from the 20 and 90 largest U.S.    city mortality analyses are
                                   cities to investigate relationships     consistent with an average increase
                                   between PM10 and other pollutants and   in cardiovascular and cardiopulmonary
                                   daily mortality.                        deaths of more than 0.5% for every 10
                                                                           [mu]g/m3 increase in PM10 measured
                                                                           the day before death.
Wichmann et al., 2000...........  Time series analyses were conducted on  Higher levels of both fine and
                                   data from Erfurt, Germany to            ultrafine particle concentrations
                                   investigate relationships between the   were significantly associated with
                                   number and mass concentrations of       increased mortality rate.
                                   ultrafine and fine particles and
                                   daily mortality.
----------------------------------------------------------------------------------------------------------------


                    Table VII.-8.--Studies and Review of Article on Cancer Effects, 2000-2002
----------------------------------------------------------------------------------------------------------------
          Authors, year                         Description                             Key results
----------------------------------------------------------------------------------------------------------------
Boffetta et al, 2001............  Cohort studied was entire Swedish       Relative risks (RR) of lung cancer
                                   working population (other than          among men were 0.95, 1.1, and 1.3 for
                                   farmers). Job title and industry were   job categories with low, medium, and
                                   classified according to probability     high exposure to diesel exhaust
                                   and intensity of diesel exhaust         compared to workers in jobs
                                   exposure for years 1960 and 1970, and   classified as having no occupational
                                   according to authors' confidence in     exposure. Elevated risks for medium
                                   assessment.                             and high exposure groups were
                                  Cohort members followed up for           statistically significant, and no
                                   mortality for 19-year period from       similar pattern was observed for
                                   1971 through 1989. Cause of death,      other cancer types.
                                   specific cancer type, when
                                   applicable, obtained through national
                                   registries.
Gustavsson et al, 2000..........  Case-control study involving all 1,042  Adjusted RR for the highest quartile
                                   male cases of lung cancer and 2,364     of estimated lifetime exposure was
                                   randomly selected controls (matched     1.63, compared to the group with no
                                   by age and inclusion year) in           exposure.
                                   Stockholm County, Sweden from 1985
                                   through 1990. Occupational exposure,
                                   smoking habits, and other risk
                                   factors assessed based on written
                                   questionnaires mailed to subjects or
                                   next of kin. Relative Risk (RR)
                                   estimates adjusted for age, selection
                                   year, tobacco smoking, residential
                                   radon, occupational exposures to
                                   asbestos and combustion products, and
                                   environmental exposure to NO2.
Pope et al., 2002...............  Prospective cohort lung cancer          After adjusting for other risk factors
                                   mortality study using data collected    and potential cofounders, chronic
                                   for the American Cancer Society         PM2.5 exposures found to be
                                   Cancer Prevention II Study (began       significantly associated with
                                   1982). Questionnaires used to obtain    elevated lung cancer mortality.
                                   individual risk factor data including  Each 10 g/m3 increase in mean level of
                                   age, sex, race, weight, height,         ambient fine particulate air
                                   smoking history, education, marital     pollution associated with
                                   status, diet, alcohol consumption,      statistically significant increase of
                                   and occupational exposures. This risk   approximately 8 percent in risk of
                                   factor data combined with air           lung cancer mortality.
                                   pollution data for metropolitan areas
                                   throughout United States and vital
                                   status and cause of death data
                                   through 1998 for about 500,000 adults.

[[Page 48691]]

 
Boffetta and Silverman, 2001....  Meta-analysis performed on 44           Overall Relative Risk (RR) was 1.37
                                   independent results from 29 distinct    for heavy equipment operators, 1.17
                                   studies of bladder cancer in            for truck drivers, 1.33 for bus
                                   occupational groups having varying      drivers, and 1.13 for JEM.
                                   exposure to diesel exhaust (studies     Quantitiatives meta-analysis also
                                   included only if at least 5 years       performed on 8 independent studies
                                   between first exposure and bladder      showing results for ``high'' diesel
                                   cancer development). Separate           exposure. Combined results were
                                   quantitative meta-analyses performed    RR=1.23 for ``any exposure,'' and
                                   for heavy equipment operators, truck    RR=1.44 for ``high exposure.''
                                   drivers, bus drivers, and studies
                                   with semi-quantitative exposure
                                   assessments based on a job exposure
                                   matrix (JEM).
Zeegers et al., 2001............  Prospective case-cohort study           Relative risk for category with
                                   involving 98 bladder cancer cases       highest cumulative probability of
                                   among men occupationally exposed to     exposure was 1.17.
                                   diesel exhaust. A cohort of 58,279
                                   men who were 55-69 years old in 1986
                                   was followed up through 1992.
                                   Exposure assessed by job history
                                   given on self- administered
                                   questionnaire, combined with expert
                                   assessment of exposure probability.
                                   ``Cumulative probability of
                                   exposure'' determined by multiplying
                                   job duration by exposure probability.
                                  Four categories of relative cumulative
                                   exposure probability defined: none,
                                   lowest third, middle third, highest
                                   third. Relative risks adjusted for
                                   age, cigarette smoking, and exposure
                                   to other occupational risk factors.
Ojajarvi et al, 2000............  Meta-analysis of 161 independent        Based on 20 populations, no elevated
                                   results (populations) from 92 studies   risk associated with diesel exposure.
                                   on relationship between worksite        Combined relative risk was 1.0. This
                                   exposures and pancreatic cancer.        result consistent with existing risk
                                                                           assessment which identified lung and
                                                                           bladder cancer as the only forms of
                                                                           cancer for which there was evidence
                                                                           of an association with DPM exposure.
Szadkowska-stanczyk and           Literature review of studies relating   Authors conclude long-term exposure
 Ruszkowska, 2000.                 to carcinogenic effects of diesel       (20 years) associated with
                                   emissions. (Article in Polish; MSHA     30% to 40% increase in lung cancer
                                   had access only to English              risk in workers in transport
                                   translation of Abstract.).              industry.
----------------------------------------------------------------------------------------------------------------


                    Table VI-8.--Studies On Toxicological Effects of DPM Exposure, 2000-2002
----------------------------------------------------------------------------------------------------------------
          Authors, Year                   Description                Key results          Agent(s) of toxicity
----------------------------------------------------------------------------------------------------------------
Al-Humadi et al., 2002...........  IT instillation in rats    Exposure to DPM or        DPM and carbon black
                                    of 5 mg/kg saline, DPM,    carbon black augments     particles.
                                    or carbon black.           OVA sensitization;
                                                               particle composition
                                                               (of DPM) may not be
                                                               critical for adjuvant
                                                               effect.
Bunger et al., 2000..............  In Vitro: assessment of    Production of black       DE generated from diesel
                                    content of polynuclear     carbon and polynuclear    engine
                                    aromatic compounds and     aromatic engine          DPM collected on filters
                                    mutagenicity of DPM        compounds that are        and soluble organic
                                    generated from four        mutagenic; correlation    extracts prepared.
                                    fuels, Ames assay used.    with sulfur content of
                                                               fuel and engine speed.
Carero et al., 2001..............  In Vitro: assessment of    DNA damage produced, but  DPM, urban particulate
                                    DPM, carbon black, and     no cytotoxicity           matter (UPM), and
                                    urban particulate matter   produced.                 carbon black (CB).
                                    genotoxicity, human                                 DPM, UPM purchased from
                                    alveolar epithelial                                  NIST, CB purchased from
                                    cells used.                                          Cabot.
Castranova et al., 2001..........  In Vitro: assessment of    DPM depresses             No information on
                                    DPM on alveolar            antimicrobial potential   generation of DPM
                                    macrophage functions and   of macrophages, thereby  (details may be found in
                                    role of adsorbed           increasing                previous publications
                                    chemicals; rat alveolar    susceptibility of lung    from this lab).
                                    macrophages used.          to infections, this
                                   In Vivo: assessment of      inhibitory effect due
                                    DPM on alveolar            to adsorbed chemicals
                                    macrophage functions and   rather than carbon core
                                    role of adsorbed           of DPM.
                                    chemicals, use of IT
                                    instillation in rats.

[[Page 48692]]

 
Fujimaki et al., 2001............  In Vitro: assessment of    Adverse effects of DE on  DE generated from diesel
                                    cytokine production,       cytokine and antibody     engine DPM, CO2, SO2 NO/
                                    spleen cells used.         production by creating    NO2/NOX measured.
                                   In Vivo: assessment of      an imbalance of helper
                                    cytokine production        T-cell functions.
                                    profile following IP
                                    sensitization to OA and
                                    subsequent exposure to
                                    1.0 mg/mg3 DE for 12 hr/
                                    day, 7 days/week over 4
                                    weeks, mouse inhalation
                                    model used.
Gilmour et al., 2001.............  In Vivo: assessment of     Exposure to woodsmoke     Woodsmoke, oil furnace
                                    infectivity and            increased                 emissions, and residual
                                    allergenicity following    susceptibility to and     oil fly ash (ROFA) used
                                    exposure to woodsmoke,     severity of
                                    oil furnace emissions,     streptococcal
                                    or residual oil fly ash,   infection, exposure to
                                    mouse inhalation model     residual oil fly ash
                                    used, IT instillation      increased pulmonary
                                    used in rats.              hypersensitivity
                                                               reactions.
Hsiao et al., 2000...............  In Vitro: assessment of    Seasonal variations in    PM collected Hong Kong
                                    cytotoxic effects (cell    PM, in their              area and solvent-
                                    proliferation, DNA         solubility, and in        extractable organic
                                    damage) of PM2.5 (fine     their ability to          compounds used.
                                    PM) and PM2.5-10 (coarse   produce cytotoxicity.
                                    PM), rat embryo           Long-term exposure to
                                    fibroblast cells used.     non-killing doses of PM
                                                               may lead to
                                                               accumulation of DNA
                                                               lesions.
Kuljukka-Rabb et al., 2001.......  In Vitro: assessment of    Temporal and dose-        Some DPM purchased from
                                    of adduct formation        dependent DNA adduct      NIST, some DPM
                                    following exposure to      formation by PAHs.        collected on filters
                                    DPM, DPM extracts,        Carcinogenic PAHs from     from diesel vehicle,
                                    benzo[a]pyrene, or 5-      diesel extracts lead to   and solvent-extractable
                                    methyl-chrysene, mammary   stable DNA adduct         organic compounds used.
                                    carcinoma cells used.      formation.
Moyer et al., 2002...............  In Vivo: 2-phase           Induction and/or          Indium phosphide, cobalt
                                    retrospective study,       exacerbation of           sulfate heptahydrate,
                                    review of NTP data from    arteritis following       vanadium pentoxide,
                                    90-day and 2-yr            chronic exposure          gallium arsenide,
                                    exposures to               (beyond 90-day) to        nickel oxide, nickel
                                    particulates, use of       particulates.             subsulfide, nickel
                                    mouse inhalation model.                              sulfate hexahydrate,
                                                                                         talc, molybdenum
                                                                                         trioxide used.
Saito et al., 2002...............  In Vivo: assessment of     DE alters immunological   DE generated from diesel
                                    cytokine expression        responses in the lung     engine DPM, CO, SO2,
                                    following exposure to DE   and may increase          and NO2 measured.
                                    (100 [mu]g/m3 or 3 mg/m3   susceptibility to
                                    DPM) for 7-hrs/day x 5     pathogens, low-dose DE
                                    days/wk x 4 wks, mouse     may induce allergic/
                                    inhalation model used..    asthmatic reactions.
Sato et al., 2000................  In Vivo: assessment of     DE produced lesions in    DE generated from light-
                                    mutant frequency and       DNA and was mutagenic     duty diesel engine
                                    mutation spectra in lung   in rat lung.             Concentration of
                                    following 4-wk exposure                              suspended particulate
                                    to 1 or 6 mg/m3 DE,                                  matter (SPM) measured,
                                    transgenic rat                                       11 PAHs and nitrated
                                    inhalation model used.                               PAHs identified and
                                                                                         quantitated in SPM.
Van Zijverden et al., 2000.......  In Vivo: assessment of     DPM skew immune response  DPM, carbon black
                                    immuno-modulating          toward T helper 2 (Th2)   particles (CBP) and
                                    capacity of DPM, carbon    side, and may             silica particles (SIP)
                                    black, and silica          facilitate initiation     used.
                                    particles, mouse model     of allergy.              DPM donated by Nijmegen
                                    used (sc injection into                              University, CBP and SIP
                                    hind footpad).                                       purchased from
                                                                                         BrunschwichChemie and
                                                                                         Sigma Chemical Co.,
                                                                                         respectively.
Vincent et al., 2001.............  In Vivo: assessment of     Increases in endothelin - Diesel soot, carbon
                                    cardiovascular effects     1 and -3 (two             black and urban air
                                    following 4-hr exposure    vasoregulators)           particulates used.
                                    to 4.2 mg/m3 diesel        following ambient urban  Diesel soot purchased
                                    soot, 4.6 mg/m3 carbon     particulates and diesel   from NIST, carbon black
                                    black, or 48 mg/m3         soot exposure.            donated by University
                                    ambient urban             Small increases in blood   of California, urban
                                    particulates, rat          pressure following        air particulates
                                    inhalation model used.     exposure to ambient       collected in Ottawa.
                                                               urban particulates.
Walters et al., 2001.............  In Vivo: assessment of     Dose and time-dependent   DPM, PM, and coal fly
                                    airway reactivity/         changes in airway         ash used.
                                    responsiveness, and BAL    responsiveness and       DPM purchased from NIST,
                                    cells and BAL cytokines    inflammation following    PM collected in
                                    following exposure to      exposure to PM.           Baltimore, and coal fly
                                    0.5 mg/mouse aspirated    Increase in BAL            ash obtained from
                                    DPM, ambient PM, or coal   cellularity following     Baltimore power plant.
                                    fly ash.                   exposure to DMP, but
                                                               airway reactivity/
                                                               unchanged.

[[Page 48693]]

 
Whitekus et al., 2002............  In Vitro: assessment of    Thio antioxidants (given  DE generated from light-
                                    ability of six             as a pre-treatment)       duty diesel engine, DPM
                                    antioxidants to            inhibit adjuvant          collected, dissolved in
                                    interfere in DPM-          effects of DPM in the     saline, and
                                    mediated oxidative         induction of OA           aerosolized.
                                    stress, cell cultures      sensitization.
                                    used.
                                   In Vivo: assessment of
                                    sensitization to OA and/
                                    or DPM and possible
                                    modulation by thiol
                                    antioxidants, mouse
                                    inhalation model used.
----------------------------------------------------------------------------------------------------------------
*Key:
(A) immunological and/or allergic reactions.
(B) inflammation.
(C) mutagenicity/DNA adduct formation.
(D) Induction of free oxygen radicals.
(E) airflow obstruction.
(F) impaired clearance.
(G) reduced defense mechanisms.
(H) adverse cardiovascular effects.


                Table VI-9.--Review Articles on Toxicological Effects of DPM Exposure, 2000-2002
----------------------------------------------------------------------------------------------------------------
          Authors, Year                   Description                Conclusions          Agent(s) of toxicity
----------------------------------------------------------------------------------------------------------------
ILSI Risk Science Institute        Review of rat inhalation   No overload of rat lungs  Poorly soluble
 Workshop Participants, 2000.       studies on chronic         at lower lung doses of    particles, nonfibrous
                                    exposures to DPM and to    DPM and no lung cancer    particles of low acute
                                    other poorly, soluble      hazard anticipated at     toxicity and not
                                    nonfibrous particles of    lower doses.              directly genotoxic
                                    low acute toxicity that                              (PSPs)
                                    are not directly
                                    genotoxic.
Nikula, 2000.....................  Review of animal           Species differences in    DE, carbon black,
                                    inhalation studies on      pulmonary retention       titanium dioxide, talc
                                    chronic exposures to DE,   patterns and lung         and coal dust
                                    carbon black, titanium     tissue responses
                                    dioxide, talc and coal     following chronic
                                    dust.                      exposure to DE.
Oberdoerster, 2002...............  In Vivo: review of         High-dose rat lung        Fibrous particles, and
                                    toxicokinetics and         tumors produced by        nonfibrous particles
                                    effects of fibrous and     poorly soluble            that are poorly soluble
                                    nonfibrous particles.      particles of low          and have low
                                                               cytotoxicity (e.g.,       cytotoxicity (PSP)
                                                               DPM) not appropriate
                                                               for low-dose
                                                               extrapolation (to
                                                               humans); lung overload
                                                               occurs in rodents at
                                                               high doses.
Veronesi and Oortigiesen, 2001...  In Vitro: review of nasal  Pulmonary receptors       PM: residual oil fly
                                    and pulmonary              stimulated/activated by   ash, woodstove
                                    innervation (receptors)    PM, leading to            emissions, volcanic
                                    and pulmonary responses    inflammatory responses.   dust, urban ambient
                                    to PM, mainly BEAS cells                             particulates, coal fly
                                    and sensory neurons used.                            ash, and oil fly ash.
----------------------------------------------------------------------------------------------------------------
* Key:
(A) immunological and/or allergic reactions.
(B) inflammation.
(C) mutagenicity/DNA adduct formation.
(D) Induction of free oxygen radicals.
(E) airflow obstruction.
(F) impaired clearance.
(G) reduced defense mechanisms.
(H) adverse cardiovascular effects.

VII. Feasibility

A. Background on Feasibility

    Section 101(a)(6)(A) of the Federal Mine Safety and Health Act of 
1977 (Mine Act) requires the Secretary of Labor to establish health 
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 over his or her working lifetime. Such 
standards must be based upon:

    Research, demonstrations, experiments, and such other 
information as may be appropriate. In addition to the attainment of 
the highest degree of health and safety protection for the miner, 
other considerations shall be the latest available scientific data 
in the field, the feasibility of the standards, and experience 
gained under this or other health and safety laws. Whenever 
practicable, the mandatory health or safety standard promulgated 
shall be expressed in terms of objective criteria and of the 
performance desired. (Section 101(a)(6)(A)).

    The legislative history of the Mine Act states:

    This section further provides that ``other considerations'' in 
the setting of health standards are ``the latest available 
scientific data in the field, the feasibility of the standards, and 
experience gained under this and other health and safety laws.'' 
While feasibility of the standard may be taken into consideration 
with respect to engineering controls, this factor should have a 
substantially less significant role. Thus, the Secretary may 
appropriately consider the state of the engineering art in industry 
at the time the standard is promulgated. However, as the circuit 
courts of appeals have recognized, occupational safety and health 
statutes should be viewed as ``technology-

[[Page 48694]]

forcing'' legislation, and a proposed health standard should not be 
rejected as infeasible ``when the necessary technology looms on 
today's horizon''. AFL-CIO v. Brennan, 530 F.2d 109 (3d Cir. 1975); 
Society of Plastics Industry v. OSHA, 509 F.2d 1301 (2d Cir. 1975), 
cert. denied, 427 U.S. 992 (1975). Similarly, information on the 
economic impact of a health standard which is provided to the 
Secretary of Labor at a hearing or during the public comment period, 
may be given weight by the Secretary. In adopting the language of 
[this section], the Committee wishes to emphasize that it rejects 
the view that cost benefit ratios alone may be the basis for 
depriving miners of the health protection which the law was intended 
to insure. S. Rep. No. 95-181, 95th Cong. 1st Sess. 21 (1977).

    Though the Mine Act and its legislative history are not specific in 
defining feasibility, the courts have clarified the meaning of 
feasibility. The Supreme Court, in American Textile Manufacturers' 
Institute v. Donovan (OSHA Cotton Dust), 452 U.S. 490, 508-509 (1981), 
defined the word ``feasible'' as ``capable of being done, executed, or 
effected.''
    In promulgating standards, hard and precise predictions from 
agencies regarding feasibility are not required. The ``arbitrary and 
capricious test'' is usually applied to judicial review of rules issued 
in accordance with the Administrative Procedures Act. The legislative 
history of the Mine Act indicates that Congress explicitly intended the 
``arbitrary and capricious test'' be applied to judicial review of 
mandatory MSHA standards. ``This test would require the reviewing court 
to scrutinize the Secretary's action to determine whether it was 
rational in light of the evidence before him and reasonably related to 
the law's purposes.'' S. Rep. No. 95-181, 95th Cong., 1st Sess. 21 
(1977).
    Thus, MSHA must base its predictions on reasonable inferences drawn 
from existing facts. In order to establish the economic and 
technological feasibility of a new rule, an agency is required to 
produce a reasonable assessment of the likely range of costs that a new 
standard will have on an industry, and the agency must show that a 
reasonable probability exists that the typical firm in an industry will 
be able to develop and install controls that will meet the standard.

B. Technological Feasibility

    At this stage of the rulemaking, MSHA concludes that a permissible 
exposure limit of 308 micrograms of EC per cubic meter of air 
(308EC [mu]g/m\3\) is technologically feasible for the metal 
and nonmetal underground mining industry. Courts have ruled that in 
order for a standard to be technologically feasible an agency must show 
that modern technology has at least conceived some industrial 
strategies or devices that are likely to be capable of meeting the 
standard, and which industry is generally capable of adopting. United 
Steelworkers of America, AFL-CIO-CLC v. Marshall, (OSHA Lead) 647 F.2d 
1273 (D.C. Cir. 1981) cert. denied, 453 U.S. 918 (1981) (citing 
American Iron and Steel Institute v. OSHA, (AISI-I) 577 F.2d 825 (3d 
Cir. 1978) at 834; and, Industrial Union Dep't., AFL-CIO v. Hodgson, 
499 F.2d 467 (D.C. Cir.1974)). The existence of general technical 
knowledge relating to materials and methods which may be available and 
adaptable to a specific situation establishes technical feasibility. A 
control may be technologically feasible when Aif through reasonable 
application of existing products, devices or work methods with human 
skills and abilities, a workable engineering control can be applied'' 
to the source of the hazard. It need not be an ``off-the-shelf'' 
product, but ``it must have a realistic basis in present technical 
capabilities.'' (Secretary of Labor v. Callanan Industries, Inc. 
(Noise), 5 FMSHRC 1900 (1983)).
    The Secretary may also impose a standard that requires protective 
equipment, such as respirators, if technology does not exist to lower 
exposures to safe levels. See United Steelworkers of America, AFL-CIO-
CLC v. Marshall, (OSHA Lead) 647 F.2d 1164.
    MSHA has established that technology is available that can 
accurately and reliably measure miners' exposures to DPM in all types 
of underground metal and nonmetal mines. MSHA intends to sample miners' 
exposures by using a respirable dust sampler equipped with a 
submicrometer impactor and analyze samples for the amount of elemental 
carbon using the NIOSH Analytical Method 5040, or any other method that 
NIOSH determines gives equal or improved accuracy, as stated in 
existing Sec.  57.5061(b) and in this proposed rule.
    MSHA is changing the surrogate that it uses to measure DPM 
exposures from total carbon (TC) to elemental carbon (EC). This change 
will avoid interferences associated with organic carbon that could 
collect on the filter and increase the likelihood of contaminating the 
sample with OC from non-diesel sources. MSHA agreed to propose this 
change as dictated by the DPM Settlement Agreement and the entire 
mining community supports this change.
    Control mechanisms also exist that are capable of reducing DPM 
exposures to the interim PEL of 308 micrograms in all types of 
underground metal and nonmetal mines. MSHA believes that mine operators 
will choose from various control options that are currently available, 
including diesel particulate filter (DPF) systems, ventilation 
upgrades, oxidation catalytic converters, alternative fuels, fuel 
aditives, enclosures such as cabs and booths, improved maintenance 
procedures, newer engines (less DPM emitting), and various work 
practices and administrative controls. MSHA has given the mining 
industry flexibility in selecting DPM control options that best suit 
the mine operator's specific needs.
    Based on the current information in the rulemaking record, MSHA 
concludes that it has a technologically feasible measurement method 
that operators and the Agency can use to accurately determine if 
miners' exposures exceed the limit. Both control mechanisms and the DPM 
sampling method are discussed elsewhere in this preamble. MSHA believes 
that the proposed standard would adequately address feasibility issues 
in one of two ways:
    (1) Pursuant to Sec.  57.5060(a) and (d) of the proposed rule. If 
MSHA determines that feasible engineering and administrative controls 
are being installed, used, and maintained and still do not reduce a 
miner's exposure to the limit, mine operators would be required to 
supplement controls with a respiratory protection program; or,
    (2) Mine operators may apply to the MSHA district manager for 
approval for an extension of time in which to reduce miners' exposures 
to the DPM limit. MSHA is not proposing any maximum limit on the number 
of extensions an operator may have, since MSHA's decision hinges upon 
feasibility.
    The proposal permits operators greater flexibility in complying 
with the DPM limit, contrary to the existing prohibition against using 
administrative controls and respiratory protection. Mine operators who 
need on-site technical assistance should contact the respective MSHA 
district manager for assistance. MSHA will continue to assist mine 
operators in special mining situations that could affect the successful 
use of DPM filters.
    Section IV above contains the executive summary of the 31-Mine 
Study. As that section explains, the technical feasibility analyses in 
the 31-Mine Study were based on the highest DPM sample result obtained 
at each

[[Page 48695]]

mine and on all major DPM emission sources at each mine in addition to 
spare equipment. The study found that five mines were already in 
compliance with the interim concentration limit, and another two mines 
were already in compliance with the existing lower, final concentration 
limit.
    MSHA predicted that eleven of the 31 mines could achieve compliance 
with both limits through installation of DPM filters alone. Ventilation 
upgrades were specified for only 5 of the 31 mines in this study, and 
then only to achieve the final concentration limit. MSHA projected that 
compliance with the interim and final concentration limits could be 
achieved without requiring major ventilation installations such as new 
main fans and repowering main fans. In the existing standard, the 
agency based its feasibility projections on an average DPM 
concentration level of over 800 [mu]g/m\3\. MSHA believes that miners' 
exposures are now much lower, probably as a result of the introduction 
of clean engines, better maintenance, and the elimination of 
interferences as confirmed by MSHA's compliance assistance baseline 
sampling.
    MSHA collected baseline samples at most underground mines with 
diesel powered equipment. Samples were collected in the same manner as 
MSHA intends to sample for enforcement under the proposed rule. MSHA 
found the average exposure (based on EC x 1.3) in the baseline sampling 
to be 222 [mu]g/m\3\ resulting in greater compliance feasibility with 
the proposed rule.
    In spite of the concentrations observed in the 31-Mine Study, the 
industry parties in the litigation continued to stress that compliance 
with the existing standard was infeasible in that DPF systems could not 
be retrofitted properly and could not effectively achieve regeneration. 
Some operators also noted that they experienced difficulty in ordering 
and obtaining DPF systems. MSHA could not confirm these statements, but 
during the 31-Mine Study, the Agency did not find that mine operators 
were using filtration devices. Moreover, few mine operators actually 
contacted MSHA to ask for compliance assistance visits, in spite of the 
Agency's repeated offers to help. Once MSHA initiated its comprehensive 
compliance assistance work at underground mine sites, the Agency found 
that most mines did not have complete information on the available 
control technologies. Accordingly, MSHA stated in its final report on 
the 31-Mine Study regarding feasibility:

    Compliance with both the interim and final concentration limits 
may be both technologically and economically feasible for metal and 
nonmetal underground mines in the study. MSHA, however, has limited 
in-mine documentation on DPM control technology. As a result, MSHA's 
position on feasibility does not reflect consideration of current 
complications with respect to implementation of controls such as 
retrofitting and regeneration of filters. MSHA acknowledges that 
these issues influence the outcome of feasibility of controls. The 
agency is continuing to consult with NIOSH, industry and labor 
representatives on the availability of practical mine worthy filter 
technology.

    Since this finding, however, MSHA and NIOSH have been working with 
the metal and nonmetal underground mining community and equipment 
manufacturers to continually refine and improve application of existing 
DPM control technology. The Agency has made considerable strides in 
resolving mine operators' concerns with the mine worthiness of DPF 
systems.
    During data collection for the 31-Mine Study, mine operators also 
questioned the performance of the SKC sampler, especially in light of 
modifications to it. Additionally, some commenters requested that MSHA 
revise its internal sampling methodology and analysis for inspectors 
and laboratory personnel.
    MSHA disagrees. One of the objectives of the 31-Mine Study was to 
examine the performance of the SKC sampler. The Agency is satisfied 
with the performance of the SKC cassette in collecting DPM while 
avoiding mineral dust. NIOSH's laboratory and field data show that the 
SKC cassette collected DPM efficiently. Under a side protocol of the 
31-Mine Study, MSHA tested the efficiency of the SKC cassette in 
avoiding mineral dust at four mines. In these tests, no mineral dust 
was measured on the filters of the SKC samplers. This finding was 
confirmed by NIOSH laboratory tests. However, NIOSH discovered that in 
many cases, the DPM deposit area was irregular in shape, and the shapes 
varied among samples. Since the DPM deposit area is used to calculate 
carbon concentrations attributed to DPM, the varied shapes can cause an 
error in determining DPM concentrations. With the cooperation of MSHA 
and the technical recommendations and extensive experimental 
verification by NIOSH, SKC was able to modify the cassette design to 
produce a consistent and regular DPM deposit area, satisfactorily 
resolving the problem.
    The fact that the deposit area was assumed constant when in fact 
there were variations in the boundary (shape) and area of deposit of 
the SKC cassette samples taken in the 31-Mine Study affects only the 
reported concentrations of the carbon values (EC, OC, and TC) because 
deposit area is used in concentration calculation. The results of the 
inter-laboratory and intra-laboratory studies that compared the 
analysis of the punches of those (or any) filters from the SKC cassette 
are unaffected for two reasons: (1) The deposit area does not enter 
into the calculations (surface densities of carbon in ug/cm \2\ were 
compared), and (2) the punches were taken from filters inside the 
boundary of the area of deposits, where the deposits were uniform.
    In their comments to the ANPRM, mine operators continued to 
emphasize the need for more research on control technology. 
Additionally, NIOSH commented:

    In conclusion, various manufacturers offer the particulate 
filters for diesel engines rated from 15 to several hundred hp. 
Although on the market for more than a decade, DPF systems have been 
only sporadically deployed and tested on underground mining 
vehicles. The DEEP-sponsored evaluation tests at Noranda BM&S and 
INCO Stobie Mines are based on our knowledge, the best organized 
attempts to evaluate DPFs in the underground environment. The 
results from these tests reveal that the DPF systems that have been 
evaluated on heavy-duty vehicles powered by engines rated over 277 
hp and on light duty vehicles powered by 50 hp engines offer 
promising technology. However, this technology needs significant 
additional evaluation and some possible re-engineering for 
underground mining applications. In-use deficiencies, secondary 
emissions, engine backpressure, DPF regeneration, DPF reliability 
and durability are major issues requiring additional research and 
engineering. In addition, it is been found that deployment of most 
systems, particularly those which require active means of 
regeneration, require major changes in miners' attitudes toward 
engine and DPF maintenance. NIOSH's DEEP experienced showed that 
emission-based engine maintenance, greater discipline on the part of 
the vehicle operator, and better operational logistics (e.g., 
multiple locations of regeneration stations for a single vehicle) 
are imperative for success of DPF technology.

    To the contrary, the NIOSH comments in response to the ANPRM 
include a summary of their experience with retrofitting existing diesel 
powered equipment. NIOSH acknowledges that although diesel particulate 
filters have been available to U.S. mines for many years, they have not 
been extensively used and documented. NIOSH states that in-mine 
experience with filters is limited, but NIOSH also related their 
experience with the Diesel Emissions Evaluation Program (DEEP) in 
Canada. NIOSH stated:


[[Page 48696]]


    [The DEEP program] has shown that these filters have significant 
potential for reducing DPM exposure of miners, but that there are 
numerous technical and operational issues that need to be addressed 
through research and in-mine evaluations before they can be readily 
implemented on a broad-based scale in U.S. mines.

    MSHA has found that most mine operators can successfully resolve 
their implementation issues if they make informed decisions regarding 
filter selection, retrofitting, engine and equipment deployment, 
operations, and maintenance. The Agency recognizes that practical mine-
worthy DPF systems for retrofitting most existing diesel powered 
equipment in underground metal and nonmetal mines are commercially 
available and are mine worthy to effectively reduce miners' exposures 
to DPM. MSHA also recognizes that installation of DPF systems will 
require mine operators to work through technical and operational 
situations unique to their specific mining circumstances. In view of 
that, MSHA has provided comprehensive compliance assistance to the 
underground metal and nonmetal mining industry.
    Commenters to the ANPR responded to the question of changing a 
diesel engine model to accommodate a control device by stating that 
anything other than the original engine model is essentially 
incompatible and would require prohibitive design engineering analysis 
and implementation. MSHA agrees that it may not be feasible to change 
engines on some diesel powered equipment. However, as engine 
manufacturers develop cleaner engines over time, they are phasing out 
older models and newer, cleaner engine models are available from the 
same engine manufacturer. In some cases, the new engine models are 
direct replacements for an older model. The benefits of retrofitting a 
machine with a cleaner engine are better fuel economy, less DPM emitted 
from the tailpipe, better lubrication systems, and better diagnostic 
tools, especially with the electronic engines. A cleaner engine that 
emits less DPM will deposit less DPM on the filter, thus permitting 
more time between regeneration, especially in active regeneration 
systems or combination active/passive regeneration systems.
Filter Workshops
    Recently, government, labor and industry sponsored two workshops on 
``Diesel Emissions and Control Technologies in Underground Metal and 
Nonmetal Mines'' held in Cincinnati, Ohio, on February 27, 2003, and 
Salt Lake City, Utah, on March 4, 2003. These workshops focused on 
implementation of DPM control technologies capable of reducing DPM 
exposures to particulate matter and gaseous emissions from diesel-
powered vehicles that are presently available to the underground metal 
and nonmetal mining industry in this country. The workshops provided an 
excellent forum for open discussion and the exchange of ideas and 
experiences relative to the use of diesel powered equipment in 
underground mines.
    At the workshops, industry experts discussed issues pertaining to 
the installation and use of DPFs in underground mines. Application of 
technology and mine operators' experiences with using filters on their 
diesel powered equipment are becoming more commonplace in the mining 
industry since the promulgation of the DPM rule.
    MSHA, NIOSH, and industry speakers presented their first-hand 
experiences with the implementation and use of diesel particulate 
filters in underground mines since promulgation of the existing DPM 
rule. Major diesel filter manufacturers and vendors of control 
technologies and engines also participated in the workshops.
    NIOSH compiled a summary report to capture presentations, comments 
and discussions rendered at the workshops, including comments offered 
by industry representatives who shared their experiences with the 
effectiveness of DPM filters. MSHA believes that NIOSH's account of the 
workshops helps to demonstrate feasibility of control technology 
measures that mine operators have found beneficial and effective. MSHA 
mailed copies of the NIOSH report to mine operators covered by the 
proposed rule. This information also is available on the NIOSH Diesel 
List Server. At the workshops, the following information was discussed:
    DPF Efficiency: Laboratory and field studies indicate that 
filtration efficiency for elemental carbon is above 95% and perhaps is 
as high as 99%.
    MSHA worked with NIOSH at MSHA's laboratory to determine the 
efficiency of several ceramic filters. MSHA ran steady state tests on 
the dynamometer and collected DPM samples for NIOSH 5040 analysis. The 
results of the filter tests showed efficiency results close to 99% for 
elemental carbon. NIOSH commented:

    The INCO project includes two Kubota M5400 tractors powered by 
Kubota F2803B 50 hp engines [Stachulak 2002]. Both are fitted with 
actively regenerated DPFs that have a silicon carbide (SiC) filter 
core. The SiC cores come from the same manufacturer; the DPF systems 
are supplied by different manufacturers. The filtration efficiency 
at the tailpipe is 99 percent for EC as determined by 
NIOSH using the EchoChem Analytics PAS 2000 carbon particle 
analyzer. One DPF system uses active on-board regeneration; electric 
heating coils are integrated into the unit and the unit is plugged 
into a regeneration controller mounted off board. The other unit is 
an active off-board system in which the DPF is removed from the 
vehicle and exchanged with the previously regenerated filter. The 
soot-laden filter is placed in a regeneration station. Both vehicles 
are assigned to ``special groups'' of individuals who ensure that 
the regenerations are performed as needed.

    MSHA stated in the preamble to the January 19, 2001 Final Rule that 
filter efficiency for cordierite and silicon carbide media used in many 
DPF systems is 85% and 87% respectively for diesel DPM. These 
efficiencies were based on whole diesel particulate as collected per 
part 7, subpart E specifications for measuring DPM. The mining industry 
has expressed concern that laboratory results do not reflect the real 
world in both duty cycle and operational environment, so the Metal and 
Nonmetal Diesel Partnership and MSHA will conduct a set of in-mine 
tests before mid-2003.
    DPF Selection: To use DPF systems successfully, mine operators must 
do their homework prior to ordering DPF systems. It is critical for 
filter performance and efficiency to match the filters to the diesel 
powered equipment and consider how the equipment is to be used in the 
underground mine. Mine operators should assume that every application 
is unique.
    Following promulgation of the existing DPM rule, most mine 
operators were unaware that filter selection involves consideration of 
these factors. Therefore, in February 2003, MSHA and NIOSH posted on 
their web sites a comprehensive compliance assistance tool titled ``A 
DPM Filter Selection Guide for Diesel Equipment In Underground Mines'' 
(Filter Selection Guide). The guide provides mine operators with 
detailed step-by-step considerations in selecting DPF system compatible 
with the specific equipment. Also, the Filter Selection Guide provides 
information on modifications and adjustments to diesel powered 
equipment that mine operators may have to make to successfully apply 
DPF systems.
    Mine operators should start by making certain that they are 
properly maintaining their engines and not consuming excessive amounts 
of crankcase oil. The mine operator may then obtain exhaust temperature 
logs or traces for several shifts, and use these

[[Page 48697]]

traces to select the DPF systems with the regeneration options that 
will work for that piece of equipment. Exhaust temperature traces can 
be analyzed by mine personnel or given to several DPF suppliers to use 
to provide the operator with options.
    Exhaust temperatures govern the DPF regeneration options. These 
options are provided in the Table VII-1.

                 Table VII-1.--DPF Regeneration Options
------------------------------------------------------------------------
                                DPF system (media
Temperature that the exhaust       consists of
  exceeds 30% of the time,        cordierite or           Comments
          degrees C              silicon carbide
                                    ceramic)
------------------------------------------------------------------------
550..............  Uncatalyzed media...  Rarely, if ever,
                                                     occurs.
390-420..........  Base metal catalyzed  No increase in NO2.
                               cordierite.
340..............  Lightly platinum      Special provisions
                               catalyzed ceramic     must be made to
                               with CDT fuel         ensure additive is
                               additive.             always present in
                                                     fuel and that
                                                     equipment w/o DPFs
                                                     cannot be fueled
                                                     with additive-
                                                     containing fuel. No
                                                     increase in NO2.
325..............  Platinum catalyzed    Lab results indicate
                               ceramic.              significant NO to
                                                     NO2 conversion;
                                                     field results are
                                                     mixed.
Any temperature    Active (Manually)     Insufficient exhaust
 below 325.                    regenerated system.   temperature to
                                                     support spontaneous
                                                     regeneration during
                                                     shift. DPFs are
                                                     regenerated in
                                                     place with
                                                     equipment off-duty
                                                     or DPF is swapped
                                                     out.
------------------------------------------------------------------------

    As Table VII-1 shows, a DPF system will function successfully at or 
above an exhaust gas temperature specified by the manufacturer's 
regeneration temperature, that is, an active regenerating system will 
work at all exhaust temperatures, and a platinum catalyzed system at 
any temperature above 325[deg]C. However, these exhaust gas 
temperatures must be achieved at least 30% of the time during the day 
to be sufficient for passive regeneration. In addition, the tune of the 
engine will also be a factor for proper regeneration. If an engine goes 
out of tune and begins to emit higher DPM concentrations in the 
exhaust, the exhaust backpressure may increase more quickly. Therefore, 
it is recommended that mine operators install backpressure devices on 
machines equipped with filters in order to properly monitor the 
condition of the filter and regeneration of the filter.
    Table VII-1 also provides information in the ``Comments'' column on 
the effect of the filters coated with a catalyst on NO2 
emissions. MSHA has tested in their laboratory the types of filters 
listed and has posted on its Web site a list of the filters that can 
cause NO2 increases from the engine and those catalytic 
formulations that do not significantly increase NO2.
    NO2 is formed from NO in the engine's exhaust in the 
presence of the catalyst. This reaction occurs at exhaust gas 
temperatures at approximately 325[deg]C. This temperature is also the 
temperature at which the platinum catalyst will allow for passive 
regeneration. Filter manufacturers have normally wash-coated their 
filters with large amounts of platinum to make sure that the filters 
will regenerate. This large concentration of platinum, in combination 
with longer retention time of the exhaust gas in the filter, results in 
the formation of NO2. Manufacturers have been looking at 
wash-coat formulations containing less platinum loading to lower the 
NO2 effects. Catalytic converters are also wash-coated with 
platinum, however, the loading used on catalytic converters is lower 
than ceramic filters. Due to faster movement of the exhaust gas through 
the catalytic converter compared to the ceramic filter, the effect of 
NO2 increase is minimized.
    MSHA is not aware of overexposures to NO2 with the use 
of those catalyzed traps that MSHA has identified. MSHA issued a 
Program Information Bulletin (PIB 02-04, May 31, 2002) which alerted 
mine operators that catalyzed traps identified on our Web site could 
increase NO2. Mine operators were advised to conduct 
sampling for NO2 when these filters were used to ensure 
miners' are not overexposed or that the filters were causing a general 
increase of NO2 in the mine's ambient environment. Mine 
operators who use catalyzed filters (which have the potential to 
increase NO2) should have ventilation systems that are able 
to remove or dilute the NO2 to a non-hazardous 
concentration. However, operators must be aware of localized areas 
where NO2 could build up more quickly and create a health 
hazard for exposed miners.
    As discussed in the Greens Creek report, the use of catalyzed 
filters on those machines used in the study did not indicate any 
substantial increase in NO2. MSHA is continuing to work with 
filter manufacturers to evaluate catalytic formulations on 
NO2 generation from the exhaust.
    Active regeneration systems discussed below are normally not 
catalyzed which would then not produce an increase in NO2. 
As stated above, NO2 is generated when exhaust gas 
temperatures are normally high enough for passive regeneration. If the 
filter can passively regenerate, then there is a potential for 
increases in NO2 emissions.

                                 Table VII-2.--Scenarios for Active Regeneration
----------------------------------------------------------------------------------------------------------------
                                                               Regenerating controller
           System name               Regenerating location            location                  Comments
----------------------------------------------------------------------------------------------------------------
On-board-On-board................  On Equipment.............  On Equipment............  Requires source of
                                                                                         electric power,
                                                                                         normally 440 or 480
                                                                                         VAC.
On-board-Off-board...............  On Equipment.............  Designated and fixed-     Requires equipment to
                                                               location.                 come to a specific
                                                                                         regeneration site.

[[Page 48698]]

 
Off-board........................  Off equipment............  Fixed-location..........  DFPs are exchanged and
                                                                                         must be small enough to
                                                                                         be handled by one
                                                                                         person. Increases
                                                                                         number of DPFs needed.
On-board fuel burner.............  On-equipment.............  On-equipment during       System is complex yet
                                                               operation.                provides advantages of
                                                                                         operating during
                                                                                         equipment use;
                                                                                         manufacture has been
                                                                                         discontinued.
----------------------------------------------------------------------------------------------------------------

    Scenarios for active regeneration systems are listed in Table VII-
2. The first two systems listed in Table VII-2 may require sufficient 
machine down time for regeneration, which is usually about one hour 
between shifts. Also, the equipment should be parked at a designated 
location during the regeneration period. MSHA recognizes that presently 
in some mines, production equipment is not brought to a specific 
location at the end of a shift. At mines where this occurs, mine 
operators may need to make changes to accommodate such DPF regeneration 
designs. Alternatively, mine operators may choose to have the equipment 
operator remove the DPF at the end of each shift and have the next 
operator replace it with a regenerated unit at the start of the shift. 
In short, mine operators must plug in the regeneration system at the 
end of the shift, or DPFs must be transported from the regeneration 
area to the equipment location. Multiple filters may be installed on a 
machine in the place of one filter in order to decrease the size and 
weight of the filters.
    Under certain circumstances, some passive DPF systems have 
exhibited marginal regeneration. This is due to the fact that the duty 
cycle exhaust temperature is such that some but not all of the DPM is 
removed during the normal work shift. Slowly the DPM builds up until 
the DPF must be regenerated manually. In some instances, this needs to 
be done every 250 hours which would coincide with the regular 
preventive maintenance cycle for diesel powered equipment.
    Achieving a long service life: The key to achieving a long service 
life from any DPF is to monitor and strictly adhere to exhaust back 
pressure limits and taking action appropriately. Passive regenerating 
systems are especially sensitive to equipment duty cycle. A change in 
duty cycle may reduce exhaust temperatures to a point that regeneration 
does not spontaneously occur. It is crucial that prompt attention is 
given to this situation and it is remedied before exhaust backpressures 
even reach the specified backpressure limit. Continuing to operate with 
an increasing exhaust backpressure will lead to overloading the DPF 
with soot. When regeneration is initiated, the large mass of soot may 
create temperatures hot enough to crack or melt the filter element, 
thus compromising the filter's efficiency. A similar scenario applies 
to active systems. Failure to timely regenerate the filter will cause 
increases in back pressure during a production shift which, if 
continued, will cause loss of engine power and may invalidate engine 
warranties.
    Thermal runaway may also occur during manual regeneration. Because 
of the build up of ash, an unburnable component of diesel soot arising 
from burning lubrication oil, the baseline back pressure of any DPF 
will rise slowly. Approximately every 1,000 hours, the DPF should be 
cleaned of the ash following the manufacturer's procedure.
    Engine malfunctions and effects on DPF: Normally in mining, engine 
malfunctions are indicated by excessively smoky exhaust. That indicator 
will not occur with DPF systems. Malfunctions such as excessive soot 
emissions, intake air restriction, fouled injector, and over-fueling, 
may result in an abnormal rise in back pressure in systems that do not 
spontaneously regenerate. Also, these conditions could lead to abnormal 
changes in back pressure in passive systems because the malfunction may 
raise exhaust temperatures causing the excess soot to be burned off. 
These malfunctions may be detected during the usual 250-hour 
maintenance and emissions checks conducted upstream of the DPF using 
carbon monoxide (CO) as an indicator.
    The other major filter malfunction is excessive oil consumption 
that is sometimes associated with blue smoke that could be masked by 
the performance of the DPF. However, excessive oil consumption leads to 
a rapid increase in baseline backpressure due to ash accumulation. 
Excessive oil consumption can be detected if records are kept on oil 
usage.
    Detecting malfunctioning DPF: As noted above, the DPF can be 
damaged mainly by thermal events such as thermal runaway. Shock, 
vibration, or improper ``canning'' of the filter element in the DPF can 
also lead to leaks around the filter element. A Bacharach/Bosch smoke 
spot test can be used to verify the integrity of a DPF. Smoke spot 
numbers below ``1'' indicate a good filter; smoke numbers above ``2'' 
indicate that the DPF may be cracked or leaking. Smoke spot and CO 
tests during routine 250 hour preventative maintenance is a good 
diagnostic practice. Note that although a smoke spot number above ``2'' 
may indicate a cracked or leaking filter, such a result does not 
necessarily mean the filter has ``failed'' and is not functioning 
adequately. In MSHA evaluations of DPF performance at the Greens Creek 
mine, filters that tested with smoke numbers above ``2'' were still 
shown to be over 90% effective in capturing elemental carbon, based on 
subsequent NIOSH 5040 analysis of the smoke spot filters.
    Some commenters have suggested that diesel particulate filters are 
not a feasible DPM control option because they are not commercially 
available for the full range of engine horsepowers used in underground 
metal and nonmetal mining equipment, especially low horsepower units 
(less than 50 hp) and high horsepower units (greater than 250 hp). MSHA 
has found that suitable DPFs for engines of the horsepowers used in 
underground metal and nonmetal mining equipment are commercially 
available. The following discussion addresses low horsepower and high 
horsepower applications, respectively.
    Low horsepower engines ranging from around 5 horsepower to around 
100 horsepower are frequently used in ancillary and support mining 
equipment such as personnel transports, utility tractors, ``gators,'' 
fork lifts, pumps, welders, compressors, and similar equipment, both 
mobile and stationary. The duty cycle of this type of equipment

[[Page 48699]]

is not sufficient to support passively controlled regeneration of a 
DPF. Thus, either on-board or off-board active filter regeneration is 
necessary.
    In sizing an actively regenerated filter for these small horsepower 
engines, the only significant selection criterion is the desired time 
interval between active regenerations. For example, if the user wishes 
to regenerate a filter no more often than once per day, then the filter 
must have the capacity to store the maximum amount of soot generated by 
the subject engine over the period of one day while maintaining 
acceptable engine backpressure. If physical space to mount a filter is 
limited, the smallest filter having adequate soot storage capacity at 
the maximum acceptable backpressure would be selected. If space 
constraints are not an issue, a larger capacity filter would also be 
acceptable, with the larger size permitting a longer time interval 
between regenerations.
    As a point of reference, a once-per-day actively regenerated DPF 
for a 60 hp personnel transport tractor operated for one shift per day 
is about 20 inches long by about 10 inches in diameter, and such 
filters are commercially available from multiple sources. If the same 
filter is fitted to a 30 hp engine having the same duty cycle and 
emission rate (expressed as g/bhp-hr), that filter will function just 
as well, but the time interval between regenerations would roughly 
double. Based on this DPF selection process, there is probably no lower 
limit to the size engine that can be effectively filtered using any of 
several commercially available active systems.
    DPFs for low horsepower engines can also be provided by the 
original equipment manufacturer (OEM) or distributor as standard or 
optional equipment. An example is a Series 7 Toyota forklift equipped 
with a 40 hp 1DZ-II diesel engine for which a DPF-II diesel particulate 
filter is offered as an OEM or dealer-installed option. The DPF unit is 
about 14-inches long and about 8-inches in diameter, and is mounted on 
the rear of the forklift body.
    Regarding high horsepower applications of DPF systems, for purposes 
of this discussion, ``high'' horsepower is meant to include engines of 
250 horsepower and higher because this is the horsepower range 
addressed by the commenter. Engines of this size would typically be 
installed on production equipment such as loaders and haulage trucks 
and are commercially available from several manufacturers.
    There are two approaches to filtering diesel particulate emissions 
that can be implemented on high horsepower engines using current 
commercially available DPF units: large capacity single unit DPFs; and 
multiple DPFs that are either manifolded to the same exhaust pipe, or 
separate DPFs that are provided on each side of a dual exhaust system.
    An example of a large capacity single unit DPF system is the 
Engelhard model 9121A 15-inch long by 15-inch diameter Pt-catalyzed 
filters installed on the LHD and haulage trucks that were the subject 
of MSHA's compliance assistance diesel emissions tests at the Greens 
Creek mine. The LHD and all three haulage trucks were equipped with the 
same MSHA Approved 12.7 L engines rated at 475 hp at 2100 rpm. The LHD 
engine was derated to 300 hp, but this value still exceeds the 
commenter's threshold level of concern of 250 hp, and the truck engines 
were generating the full 475 hp. These DPFs passively regenerated on 
both the loader and haulage trucks, and the emission testing 
demonstrated filter efficiencies of greater than 90%.
    The other approach to filtering high horsepower engines is to 
provide multiple filters. When an engine's exhaust is routed through a 
single exhaust pipe, the exhaust can be split into two parallel paths, 
with each path being equipped with a filter. When an engine has a dual 
exhaust system (i.e. separate exhaust pipes on either side of the 
engine, which is the most common arrangement on high horsepower 
engines), a DPF can be fitted to each exhaust pipe. This approach 
actually simplifies a DPF installation on an engine with dual exhausts, 
as installing a single filter would require modification of the exhaust 
system to join together the dual exhausts into a single exhaust pipe 
upstream of the filter. On underground equipment where space is at a 
premium, it may be easier to install two smaller filters than to find a 
space large enough to install one large filter.
    Depending on the horsepower of an engine, space constraints, method 
of filter regeneration, and other factors, it may be necessary to split 
an engine's exhaust into more than two parallel paths for DPF 
installation. For example, each side of a dual exhaust system could be 
split into two parallel paths to facilitate the installation of DPFs on 
all four of the resulting exhaust pipes. There is no upper limit on the 
horsepower of an engine that could be filtered with standard, 
commercially available DPFs. For example, MSHA is aware of a stationary 
diesel-powered generator station rated at about 12,000 hp that has been 
filtered in this manner.
    Although sizing a ceramic (SiC or cordierite) DPF is a rather 
complicated process that must take into account consideration for 
engine horsepower, engine DPM emissions (g/bhp-hr), duty cycle, 
constraints on regeneration, and other factors, the ``rule-of-thumb'' 
starting point for most filter manufacturers is typically 8 cubic 
inches of filter media volume per horsepower for an engine having a DPM 
emission rate of 0.1 g/bhp-hr. Due to manufacturing complications for 
larger units, the filter media is typically limited to a maximum size 
of 15-inches long by 15-inches in diameter. These dimensions correspond 
to a maximum of 330 hp per filter for an engine having an emission rate 
of 0.1 g/bhp-hr. For cleaner engines like those used in the Greens 
Creek mine testing, these dimensions correspond to a proportionally 
larger horsepower engine.
    If each side of a dual exhaust system is split only once, requiring 
four separate DPFs, installation of 15x15 filters on each of the four 
branches would adequately filter a 0.1 g/bhp-hr emission engine rated 
at greater than 1,300 hp, which is larger than any engine currently 
used in underground metal and nonmetal mining, or likely to be used in 
the foreseeable future.
    Importance of preventing exhaust leaks: Because the DPF is greater 
than 95% effective in removing elemental carbon from the exhaust, it is 
extremely important that the exhaust system upstream of the DPF be 
leak-tight. Leaks will leave a shadow of soot and are thus self-evident 
unless covered by insulation that disperses the leaking exhaust so that 
no distinct soot shadow is produced. Flex-pipe joints should be 
fastened securely using wide band clamps. Operators should not use flat 
flanges with gaskets, but use tapered tongue and groove joints to 
attain a positive seal.
Alternative Options
    In addition to the feasibility of engineering control technology 
that was discussed at the NIOSH workshops (low emission engines, 
maintenance, fuels, and DPFs), MSHA believes that enhancing ventilation 
and enclosing miners in cabs or other filtered areas also are effective 
engineering controls for significantly reducing DPM exposures.
    Administrative controls can effectively reduce miners' exposure to 
DPM. These include such practices as: reducing diesel engine idling 
time, reducing lugging of engines, designating certain areas ``off 
limits'' for operating diesel equipment, and establishing speed limits 
and one way travel.

[[Page 48700]]

    MSHA acknowledges that depending upon the circumstances in a 
particular underground mine, some mine operators may face feasibility 
challenges implementing current DPM control methods. These operators 
should contact the MSHA district manager for compliance assistance.
    Several commenters expressed the view that ventilation system 
upgrades, though potentially effective in principle, would be 
infeasible to implement for many mines. Specific problems that could 
prevent mines from increasing ventilation system capacity include 
inherent mine design geometry and configurations (drift size and 
shape), space limitations, and other external prohibitions, as well as 
economic considerations.
    MSHA acknowledges that ventilation system upgrades may not be the 
most cost effective DPM control for many mines, and for others, 
ventilation upgrades may be entirely impractical. However, at many 
other mines, perhaps the majority of mines affected by this rule, 
ventilation improvements would be an attractive DPM control option, 
either implemented by themselves or in combination with other types of 
controls.
    At many high-back room-and-pillar stone mines, MSHA has observed 
ventilation systems that are characterized by (1) Inadequate main fan 
capacity (or no main fan at all); (2) ventilation control structures 
(air walls, stoppings, curtains, regulators, air doors, and brattices, 
etc.) that are poorly positioned, in poor condition, or altogether 
absent; (3) free standing booster fans that are too few in number, of 
too small a capacity, and located inappropriately; and, (4) no 
auxiliary ventilation for development ends (working faces). At some 
mines, the ``piston effect'' of trucks traveling along haul roads 
underground provides the primary driving force to move air.
    Often, the result of these deficiencies is a ventilation system 
that provides insufficient dilution of airborne contaminants, short 
circuiting, and airflow direction and volume controlled only by natural 
ventilation. These systems are barely adequate (and sometimes 
inadequate) for maintaining acceptable air quality with respect to 
gaseous pollutants (CO, CO2, NO, NO2, 
SO2, etc.), and are totally inadequate as stand-alone 
controls for maintaining acceptable DPM levels.
    Mines experiencing these problems could benefit greatly from 
upgrading main, booster, and/or auxiliary fans, along with the 
construction and maintenance of effective ventilation control 
structures. During DPM compliance assistance visits to several stone 
mines, MSHA has observed mine operators beginning to implement limited 
ventilation system upgrades, such as the addition of booster fans, 
brattice lines, and auxiliary ventilation in development ends, along 
with replacing older, high-polluting engines with newer, low-polluting 
models. MSHA believes that such ventilation upgrades, along with the 
replacement of as few as one to three engines may be sufficient for 
many stone mines to achieve compliance with the interim DPM limit.
    Deep multi-level metal mines have entirely different geometries and 
configurations from high-back room-and-pillar stone mines. They 
typically require highly complex ventilation systems to support mine 
development and production. These systems are professionally designed, 
they require large capital investments in shafts, raises, control 
structures, fans, and duct work, and they are costly to maintain and 
operate. At these mines, ventilation system costs provide a major 
economic incentive to operators to optimize system design and 
performance, and therefore, there are typically few if any feasible 
upgrades to main ventilation system elements that these mines have not 
implemented already.
    Despite these built-in incentives, however, MSHA has observed 
aspects of ventilation system operation at those types of mines that 
can be improved, usually relating to auxiliary ventilation in stopes. 
Auxiliary fans are sometimes sized inappropriately for a given 
application, being either too small (not enough air flow) or 
incorrectly placed (causing recirculation). Auxiliary fans that are 
poorly positioned draw a mixture of fresh and recirculated air into a 
stope. Auxiliary fans are sometimes connected to multiple branching 
ventilation ducts, so that the air volume reaching a particular stope 
face may be considerable less than the fan is capable of delivering. 
Perhaps most often, the ventilation duct is in poor repair, was 
installed improperly, or has been damaged by blasting or passing 
equipment to the extent that the volume of air reaching the face is 
only a tiny fraction of that supplied by the fan. MSHA believes that 
these, and similar problems, exist at many mines, even if the main 
ventilation system is well designed and efficiently operated.
    Optimized auxiliary ventilation system performance alone, as one 
commenter noted, will not necessarily insure compliance with the DPM 
interim limit. Auxiliary ventilation systems simply direct air to a 
stope face so that the DPM generated within the stope can be diluted 
and carried back to the main ventilation air course. If air is already 
heavily contaminated with DPM when it is drawn into a stope by the 
auxiliary system, as could happen at mines employing series or 
cascading ventilation, the auxiliary system's ability to dilute newly-
generated DPM is diminished.
    In these situations, the intake to the auxiliary system must be 
sufficiently free of DPM to achieve the desired amount of dilution, 
requiring implementation of effective DPM controls upstream of the 
auxiliary system intake. Such upstream controls might include a variety 
of approaches, such as DPM filters, low-polluting engines, alternative 
fuels, and various work practice controls, as well as main ventilation 
system upgrades at the few mines where they might be feasible. Toward 
the return end of a series or cascading ventilation system, if the DPM 
concentration of the auxiliary system intake is still excessive, other 
engineering control options would include enclosed cabs with filtered 
breathing air on the equipment that operates within the stope, or 
remote control operation of the equipment in the stope to remove the 
operator from the stope altogether. Some commenters stated that 
feasibility was extensively reviewed in the existing rulemaking. These 
commenters noted that MSHA already determined that feasibility 
established for the existing rule must be presumed feasible until 
proven otherwise. In response to these commenters, MSHA emphasizes that 
since the agency is engaged in rulemaking that involves changing the 
surrogate, the DPM limit, as well as the hierarchy of controls, the 
Agency must review its existing position on feasibility of compliance 
for the mining industry. MSHA has done so in this preamble. Other 
commenters stated that mine operators have attempted to purchase and 
install DPM controls and they are either unavailable or, are neither 
technically and economically feasible. One issue raised by the 
commenters was the availability of filters for engines below 50 hp. 
Filter manufacturers supply filters for all horsepower sizes. MSHA is 
not aware of any gaps in filter availability. As stated at the recent 
workshops, most filter vendors stated that they have experience 
installing DPM filters on all horsepower size engines. However, 
normally with smaller engines, it would be expected that these systems 
would have to be regenerated with an active system. Again, MSHA is not 
aware of any problems with an active system for

[[Page 48701]]

smaller engines. In regard to larger horsepower engines, again, at the 
workshops filter vendors stated that most had experience with larger 
horsepower engines. They referred to installations that were greater 
than 500 hp. As stated by the manufacturers, this is normally 
accomplished with multiple filters to accommodate the larger engines' 
higher exhaust flow rates. Again, either passive or active regeneration 
systems have been identified as being available for these large 
engines.
    As discussed elsewhere in this preamble, the work conducted at the 
Greens Creek mine in Alaska showed that large horsepower engines, 475 
hp used at this mine, could be equipped with ceramic filters and these 
DPFs were regenerated through passive regeneration. A filter rotation 
issue was identified at the beginning of this study, however, after 
further discussions with the filter vendor, it was determined that the 
problem was a manufacturing issue and was being worked out between the 
mine and the vendor. Even with the observed cracks due to the rotation 
of the filters, the results of tests showed that the filters continued 
to significantly reduce DPM from the engine, thus lowering the DPM in 
the test area.
    A commenter also related a filter scenario that failed. This was 
reported as a cooperative effort between the machine manufacturer, 
engine manufacturer, and filter manufacturer for selection of a filter 
system for a 300 hp truck. The commenter stated that with this group 
working together, the filter system installed failed. MSHA was aware of 
this situation and understands that the problem was related to 
regeneration of the filter and not a filtration issue. MSHA believes 
that even with this cooperation, a vital piece of information 
concerning the duty cycle and exhaust gas temperatures generated from 
this truck was not properly communicated to the parties involved. This 
would lead to a failure where the system would have been set up to 
regenerate through a passive method, but in actuality, the machine 
needed an active system or active/passive system. As stated elsewhere, 
accurate information on the duty cycle/exhaust gas temperature of a 
vehicle is critical for successful filter installations. The condition 
of the engine and backpressure monitoring is also essential in choosing 
and installing a filter system.
    As discussed previously in this preamble, MSHA and NIOSH developed 
the filter guide which makes mine operators and machine manufacturers 
aware of the issues that must be addressed to successfully engineer a 
filter to work on a machine. MSHA believes that if mine operators and 
equipment manufacturers utilize this guide, many of the problems 
identified with regeneration would be eliminated.
    Other commenters stated that the existing limits are not feasible 
unless MSHA allows mine operators to use administrative controls and 
personal protective equipment, both of which are prohibited under the 
existing DPM rule. Consistent with the DPM settlement agreement, MSHA 
proposes to require its long-standing hierarchy of controls for 
engineering, administrative, and personal protective equipment. Some 
commenters stated that if elemental carbon (EC) is used, periodic 
diagnostic emission tests similar to those required under MSHA's 
existing standards for underground coal mines at Sec.  75.1914(g) 
should be required for metal and nonmetal underground mines in order to 
compare emissions against an engine baseline to determine if elevated 
organic carbon levels are actually DPM rather than an interferent. 
These commenters also stated that OC and EC may not increase 
proportionally in an engine that is in a state of deterioration.
    Section 75.1914(g) for underground coal mines requires weekly 
emission checks on the engine to determine the tune of the engine. The 
CO concentration must be measured during a repeatable loaded engine 
test, namely at torque stall. By measuring the CO on a weekly basis, a 
baseline is established for each engine. Any changes to the baseline of 
the CO concentration when the repeatable engine test is performed could 
be an indication that the engine is out of tune. This could be the 
result, for example, of a clogged intake air filter or a faulty 
injector. Whereas MSHA agrees that this type of engine testing could be 
useful as a diagnostic tool to determine the tune of the engine, MSHA 
noted in its ANPRM as well as in this proposal that the scope of this 
rulemaking is limited to the terms of the settlement agreement. 
However, MSHA requests specific comments from the mining community as 
to whether this test should be required in the final rule. Commenters 
should include whether or not any aspects of the current provision at 
Sec.  75.1914(g) should be adopted or revised as part of the final 
rule.
    It is well documented that an engine that is not in tune will emit 
higher levels of gaseous emissions and DPM emissions. An engine that is 
not tuned could have an immediate effect on miners' personal DPM 
exposures. The same commenter stated that the out-of-tune engine could 
be dismissed in the results of the ambient Method 5040 sampling as an 
interferent instead of an increase in DPM. The effects of individual 
engines would be very hard to localize with ambient testing. MSHA 
agrees that maintenance procedures that could detect any increases in 
exhaust emissions would aid in limiting miners' DPM exposures. The 
Agency's current DPM standard at Sec.  57.5066 addresses both 
maintenance and tagging of equipment for out-of-tune engines. Poor 
engine performance will most likely result in black smoke that must be 
the reported to the mine operator and promptly given attention by a 
mechanic.
    The Agency is aware of another diagnostic tool to determine the 
effectiveness of a ceramic filter. In a diagnostic ``smoke test,'' a 
sample of DPM is collected as a smoke dot on a filter paper and 
visually compared against a colorimetric scale. The test would be 
conducted while the diesel powered equipment is in a torque stall 
condition, which is a repeatable, high engine load condition for making 
this comparison. Normally, the raw exhaust before a filter would give a 
black spot. A sample taken after the filter should be basically white, 
indicating that the filter was working at its highest efficiency. Any 
cracks or defects in a ceramic filter would give a darker, grayish to 
black spot. This would be an indication to the mine operator of the 
current condition of the filter and of possible filter deterioration.
    Smoke dot tests were conducted at the Greens Creek mine as a part 
of DPM compliance assistance activities at that mine. On one particular 
filter, the smoke dot produced after the DPM filter appeared to be as 
dark as the smoke dot before the DPM filter. Visual examination of the 
DPM filter showed cracks along its outer edges. When quantitative 
analysis of the dots was conducted using the NIOSH Method 5040 
analysis, DPM filter efficiency was determined to be 92%. The 
efficiency of a different filter without any visual cracks was 
determined to be 99%. This demonstrates the value of the smoke dot test 
to detect a filter problem before filter performance has deteriorated 
significantly. However, even though defects in the DPM filter can 
affect its efficiency, this may or may not affect a miner's personal 
exposure to DPM. The smoke test can be done with a commercially 
available ECOM AC gas analyzer or a Bacharach/Bosch smoke test 
Apparatus. MSHA believes that this also is a good diagnostic tool for 
DPM filters. Running this test on a routine basis would give 
indications with any changes in the filter media. However, changes in 
the color of the smoke dot may not indicate that miners would be

[[Page 48702]]

overexposed to DPM or that the filter should be removed from service. 
This test may give an indication to the mine operator that a fault is 
starting in the filter, and subsequently, that the DPM emissions could 
be increasing.
    MSHA asked for comments concerning what technical assistance the 
Agency should provide to mine operators in retrofitting DPM control 
devices and evaluating ventilation systems or filtration of cabs. 
Commenters stated that MSHA should provide guidance in all these areas 
that involve control technologies. MSHA has been and will continue to 
provide these types of compliance assistance to underground metal and 
nonmetal mine operators. Mine operators are encouraged to use the 
Agency's DPM Single Source Page that includes comprehensive compliance 
assistance tools addressing the aforementioned issues as well as 
others.
    MSHA has been instrumental in providing compliance assistance to 
the mining industry. MSHA conducted a number of outreach workshops 
throughout the country to discuss requirements of the DPM standard and 
sampling and control technology information. These meetings were held 
in Lexington, Kentucky; Kansas City, Missouri; Green River, Wyoming; 
Albuquerque, New Mexico; Elko, Nevada; Coeur d'Alene, Idaho; Knoxville, 
Tennessee; Des Moines, Iowa; and Ebensburg, Pennsylvania. MSHA also 
completed baseline sampling at the underground mines covered by the DPM 
standard, and made site-specific compliance assistance visits.
    To further assist mine operators, MSHA and NIOSH have developed 
compliance assistance tools, many of which are currently available to 
operators on MSHA's DPM Single Source Page on MSHA's web site. The 
NIOSH mining web page is available to mine operators as well. Mine 
operators should give special attention to MSHA/NIOSH's Filter 
Selection Guide. As explained earlier in this preamble, this document 
provides mine operators with detailed step-by-step selection factors 
that can be applied to particular pieces of diesel-powered equipment in 
their mine. It is an interactive compliance assistance tool that allows 
mine operators to answer questions on their individual mining operation 
to select, retrofit and maintain the best available filter technology. 
This guide will be updated as new technologies are introduced in the 
underground mining industry.
    Also included on MSHA's DPM sole source web page are the Estimator 
computer program; a list of available filters and manufacturers; the 
draft DPM compliance guide which contains MSHA's enforcement policy; 
MSHA sampling procedures; the slide presentation from MSHA's outreach 
seminars on the requirements of the DPM standard; information on how 
MSHA calculated the error factor to be used when making compliance 
determinations; a troubleshooting guide for addressing problems with 
control technology; along with the NIOSH notes from the filter 
workshops as discussed above. In addition, MSHA has posted ``Best 
Practices'' for various issues concerning the use of DPM filters.
    MSHA also provided compliance assistance at individual mines 
through its involvement with bio-diesel projects, fuel catalyst 
installations, and in-mine evaluations of DPM filter technologies. 
MSHA's diesel testing laboratory located in Triadelphia, WV has been 
active in evaluating many of these control technologies. The Agency 
tested and provided information on the effects, if any, on nitrogen 
dioxide production for specific catalyzed DPM filters.
    The Agency continues to consult with the Metal and Nonmetal Diesel 
Partnership (the Partnership). The Partnership is composed of NIOSH, 
industry trade associations, and organized labor. MSHA is not a member 
of the Partnership due to its ongoing DPM rulemaking activities.
    A discussion of additional comments follows.
    One commenter responded to MSHA's ANPRM questions regarding 
retrofitting engines by stating that anything other than the original 
engine model is unsuitable for a piece of diesel powered equipment. 
According to this commenter, this would require prohibitive design 
engineering analysis and implementation. MSHA agrees that on some 
machines it may not be feasible to change engines. As engine 
manufacturers develop cleaner engines, however, the older models are 
being phased out and newer, cleaner engine models are available from 
the same engine manufacturer. In some cases, the new engine models are 
direct replacements for an older model. Among the benefits of 
retrofitting a piece of diesel powered equipment with a cleaner engine 
are better fuel economy, reduced DPM emissions, improved lubrication 
systems, and better diagnostic tools, especially with the electronic 
engines. A cleaner engine that emits less DPM will deposit less DPM on 
the filter, thus resulting in longer intervals between regenerations, 
especially in active regeneration systems or combination active/passive 
regeneration systems.
    MSHA asked for comments on whether cabs would be feasible and 
appropriate for controlling DPM exposures. Commenters responded that 
operators normally would not purchase a cab to control DPM. Cabs are 
used for controlling exposures to respirable dust, however, and the 
results of MSHA's sampling at the Greens Creek mine (MSHA, January 
2003) show approximately 85% reduction in DPM when using a filtered cab 
on a loader. Cabs, however, do not protect workers outside the cab or 
downwind in series ventilation systems.
    Another commenter stated that dimensional constraints of their mine 
preclude use of cabs on equipment. MSHA is aware that some mines may 
not be able to use cabs due to dimensional constraints. Environmental 
cabs can be an effective feasible DPM control device for some mine 
operators. Many new pieces of diesel powered equipment are sold with 
enclosed cabs. Besides DPM exposure, an enclosed cab with filtered 
breathing air would also help reduce exposure to other airborne 
contaminants and noise.
    Commenters provided information on the cost of filters, for both 
passive and active systems. Information stated that active systems, 
depending on product specifications, had a higher cost. MSHA agrees 
with the commenters on cost. However, some of the higher costs of the 
active system can be spread out over several vehicles. This means that 
several filters that need active regeneration can be done at the same 
regeneration station when filters are removed from the machine. The 
mine can purchase backup filters for each machine and only one 
regeneration station. If operators chose active, on-board, 
regeneration, the unit that the machine plugs into can be available for 
several machines. As stated previously, mine operators may need to 
administratively adjust machine operating schedules to accommodate 
active regeneration. MSHA believes that this filter technology is 
economically feasible for the industry.
    One commenter stated that there has been little experience with off 
board regeneration. MSHA is aware of successful applications in M/NM 
mines with active regeneration units. MSHA has posted on its homepage 
best practices for active regeneration stations in M/NM mines. Several 
problems that have been reported on active regeneration stations are 
discussed below in association with regeneration stations located at 
mines greater than 5000 feet in elevation.

[[Page 48703]]

    The Agency requested data and information from the mining community 
in its ANPRM on high altitude effects on control devices. Commenters 
noted that MSHA had conducted the test in an underground coal mine 
located in a high altitude area and that used diesel powered equipment. 
MSHA worked with the coal mining industry to determine whether high 
altitudes affected the performance of ceramic filters in controlling 
DPM emissions. The Agency found no evidence to conclude that altitude 
affects filtration performance. Some initial verbal comments were 
received stating that active regeneration stations could not operate 
effectively at higher altitudes, but further investigation by the coal 
mine operators and the filter manufacturers indicated that the problem 
was due to improper use of the equipment. One situation was that an 
incorrect setting in the control panel on an active regeneration 
station was determined to be the problem. In another instance, the mine 
was not following the schedule for active regeneration and allowed the 
filter to become overloaded with DPM thus preventing proper 
regeneration. MSHA has made mine operators aware of these problems.
    The Agency believes that at high altitudes, excessive DPM is 
produced whenever the engine is improperly derated for elevation, such 
as, the fuel:air ratio is not properly set. Mine operators should check 
with the engine manufacturer or the engine distributor to verify that 
the engine is set to the proper fuel setting specification, especially 
when the engine is operating above 1000 feet in elevation. Increases in 
DPM emitted could overload the filter and not allow proper regeneration 
of either a passive or active system. Mine operators should install 
backpressure monitoring devices when a filter is installed and follow 
engine manufacturers' recommendations for maximum allowable exhaust 
backpressure.
    Some commenters to the ANPRM stated that diesel particulate filters 
cannot work in their mines, or DPM filters are not feasible for a 
number of reasons. MSHA has stated that all commercially available 
ceramic filters can significantly reduce DPM levels. Regeneration 
schemes have been identified in this preamble that can be feasibly 
applied to all types of underground mining machines. Commenters also 
stated that active regeneration systems are not feasible in their 
mining operations although no specific scenarios were provided to the 
Agency to respond to the concern. MSHA believes that the active systems 
offer a variety of advantages, such as no dependence on exhaust gas 
temperature or duty cycle, no increases in NO2, and easier 
installation due to less restraints for installation of filters close 
to the exhaust outlet. MSHA understands that active regeneration 
systems may require mines to make adjustments in their fleet management 
in order to guarantee that active regeneration works. However, active 
regeneration systems are commercially available and feasible. MSHA 
requests that mine operators provide more specific information on the 
issues associated with the diesel powered equipment that would need 
active regeneration systems.
    Several commenters expressed the view that ventilation system 
upgrades, though potentially effective in principle, would be 
infeasible to implement for many mines. Specific problems that could 
prevent mines from increasing ventilation system capacity include 
inherent mine design and configurations (drift size and shape), space 
limitations, and other external prohibitions, as well as economic 
considerations. MSHA acknowledges that ventilation system upgrades may 
not be a cost effective DPM control for mines with these limitations. 
To the contrary, MSHA anticipates the metal and nonmetal underground 
mining industry will comply with the DPM interim limit primarily 
through the application of DPF systems rather than ventilation 
upgrades.
    At this time, MSHA estimates that mine operators may not be able to 
achieve compliance with the proposed DPM limit for every underground 
miner on every shift, particularly those engaged in inspection, 
maintenance and repair activities. Existing Sec.  57.5060(d)(2) 
identifies exceptional conditions where MSHA anticipates that it may 
not be feasible for many mine operators to use engineering and 
administrative controls. These conditions, which presently exist in 
some mines include inspection, maintenance, and repair activities 
conducted exclusively outside of environmentally controlled cabs or 
enclosed booths. The existing rule requires mine operators to apply to 
the Secretary for relief from applying control technology to reduce the 
concentration limit. MSHA traditionally does not accept use of personal 
protective equipment for compliance with its other exposure-based 
standards applicable to metal and nonmetal mines, except while 
establishing controls or during occasional entry into hazardous 
atmospheres to perform maintenance or investigations. This proposal 
would allow the use of personal protective equipment when all feasible 
and administrative controls have been implemented. MSHA has included in 
this proposed rule a tiered approach in controlling miners' exposures 
that operators must use in achieving compliance. MSHA anticipates that 
very few mine operators will have significant compliance problems with 
meeting the proposed DMP limit in circumstances other than inspection, 
maintenance, and repair activities.
    The exposure data relied on by MSHA in making its technological 
feasibility determinations include the final report on the 31-Mine 
Study, and results of MSHA's DPM baseline compliance assistance 
sampling conducted at each underground mine covered by the standard. In 
the 31-Mine Study, the data showed that many miners' exposures are 
below the proposed DPM limit without application of any additional 
engineering or administrative controls. The sampling data includes 
miners' exposures by job category to permit the Agency to pinpoint 
those occupations in need of additional controls to achieve compliance 
with the interim PEL.
    DPM engineering controls are not new technology. Moreover, the 
existing DPM standard was promulgated on January 19, 2001 (66 FR 5706) 
with an effective date of July 19, 2002 for existing Sec.  57.5060(a). 
As a result of the settlement agreement, MSHA allowed mine operators to 
take an additional year in which to begin to install appropriate 
controls to reduce DPM concentrations due to feasibility constraints. 
Any controls currently used to meet the existing concentration limit 
may also be used to reduce miners' exposures to DPM required under this 
rulemaking.
    Because of the lack of documented feasibility data for an interim 
proposed PEL of less than 308 micrograms per cubic meter of air, MSHA 
has concluded that there is insufficient information available to 
support the feasibility of lowering the DPM limit at this time. The 
Agency believes that this level is a reasonable interim limit for which 
MSHA currently can document feasibility across the affected sector of 
underground metal and nonmetal mines. MSHA is continuing to gather 
information on the feasibility of compliance with a final DPM PEL of 
less than 308 micrograms.

C. Economic Feasibility

    MSHA believes the requirements for engineering and administrative 
controls clearly meet the feasibility requirements of the Mine Act, its 
legislative history, and related case law. A PEL of 308

[[Page 48704]]

micrograms per cubic meter of air is economically feasible for the 
metal and nonmetal mining industry. Demonstrating economic feasibility 
does not guarantee the continued viability of individual employers. It 
would not be inconsistent with the Mine Act to have a company which 
turned a profit by lagging behind the rest of an industry in providing 
for the health and safety of its workers to consequently find itself 
financially unable to comply with a new standard; Cf, United 
Steelworkers, 647 F.2d at 1265. Although it was not Congress' intent to 
protect workers by putting their employers out of business, the 
increase in production costs or the decrease in profits would not be 
sufficient to strike down a standard. Industrial Union Dep't., 499 F.2d 
at 477. On the contrary, a standard would not be considered 
economically feasible if an entire industry's competitive structure 
were threatened. Id. at 478; see also, AISI-II, 939 F.2d at 980; United 
Steelworkers, 647 F.2d at 1264-65; AISI-I, 577 F.2d at 835-36. This 
would be of particular concern in the case of foreign competition, if 
American companies were unable to compete with imports or substitute 
products. The cost to government and the public, adequacy of supply, 
questions of employment, and utilization of energy may all be 
considered.
    MSHA determined that an elemental carbon PEL comparable to the 
existing concentration limit, along with primacy of engineering and 
administrative controls as proposed would reduce the cost for 
compliance required under the existing rule, and industry agrees. 
Industry commenters stated that operator costs will be reduced since 
MSHA would be changing the DPM surrogate from TC to EC which would 
reduce the likelihood of contamination and eliminates the necessity to 
re-sample. MSHA describes its finding in this preamble under section 
VIII, ``Summary of Costs and Benefits,'' and in more detail in section 
X, ``Regulatory Impact Analysis.'' A more comprehensive version is 
available in the Preliminary Regulatory Economic Analysis on MSHA's web 
site.
    MSHA also believes that the proposed effective date of 30 days for 
a final rule is feasible for underground mine operators in this sector 
since the EC surrogate standard is comparable to the existing TC 
surrogate standard which has been in effect since July 2002. 
Additionally, as a result of a DPM partial settlement agreement mine 
operators were given an additional year to begin to develop a written 
strategy of how they intended to comply with the interim DPM 
concentration limit. Operators with DPM levels above the concentration 
limit were to begin to order and install controls to be in compliance 
by July 20, 2003.
    Nevertheless, MSHA recognizes that, in a few cases, individual mine 
operators, particularly small operators, may have difficulty in 
achieving full compliance with the interim limit immediately because of 
a lack of financial resources to purchase and install engineering 
controls. However, MSHA expects that these mine operators will be able 
to achieve compliance with the recommended interim limit of 308 
micrograms. Whether controls are feasible for individual mine operators 
is based in part upon legal guidance from the Federal Mine Safety and 
Health Review Commission (Commission). According to the Commission, a 
control is feasible when it: (1) Reduces exposure; (2) is economically 
achievable; and (3) is technologically achievable. Secretary of Labor 
v. Callanan Industries, Inc., 5 FMSHRC 1900 (1983). In determining the 
technological feasibility of an engineering control, the Commission in 
Callanan has ruled that a control is deemed achievable if, through 
reasonable application of existing products, devices, or work methods, 
with human skills and abilities, a workable engineering control can be 
applied. The control does not have to be an ``off-the-shelf'' item, but 
it must have a realistic basis in present technical capabilities. Ibid. 
at 1908.
    In determining the economic feasibility of an engineering control, 
the Commission has ruled that MSHA must assess whether the costs of the 
control is disproportionate to the expected benefits, and whether the 
costs are so great that it is irrational to require its use to achieve 
those results. The Commission has expressly stated that cost-benefit 
analysis is unnecessary in order to determine whether a noise control 
is required. Ibid.
    Consistent with Commission case law, MSHA considers three factors 
in determining whether engineering controls are feasible at a 
particular mine: (1) The nature and extent of the overexposure; (2) the 
demonstrated effectiveness of available technology; and (3) whether the 
committed resources are wholly out of proportion to the expected 
results. A violation under the final standard would entail an Agency 
determination that a miner has been overexposed, that controls are 
feasible, and that the mine operator failed to install or maintain such 
controls. According to the Commission, an engineering control may be 
feasible even though it fails to reduce exposure to permissible levels 
contained in the standard, as long as there is a significant reduction 
in a miner's exposure. Todilto Exploration and Development Corporation 
v. Secretary of Labor, 5 FMSHRC 1894, 1897 (1983). In Todilto, the 
Commission ruled that engineering controls may also be feasible even 
though they fail to reduce exposure to permissible levels contained in 
the standard, as long as there is a significant reduction in exposure.
    Current data establishes that DPF systems are extremely efficient 
in that they reduce elemental carbon emissions from the tailpipe of a 
piece of diesel powered equipment by as much as 99%. MSHA believes that 
this is an exceptionally high efficiency rate for a single engineering 
control in the mining industry. Therefore, MSHA intends to identify the 
source or sources of DPM emissions leading to a miner's overexposure. A 
mine operator would be required to install a single control or a 
combination of controls that is capable of reducing the miners' DPM 
exposure by 25%.
    MSHA evaluated various engineering and administrative controls and 
their related costs. Mine operators would have the flexibility under 
the proposed rule to select the type of engineering and administrative 
controls of their choice in order to reduce a miner's exposure to the 
DPM limit. MSHA, however, believes that the most cost effective control 
would be to install DPF systems due to their high rate of efficiency, 
especially with respect to EC.
    If MSHA finds that a miner is overexposed to the DPM standard, and 
determines that engineering and administrative controls are feasible, 
and that the operator failed to install or maintain such controls, MSHA 
would issue a citation to the mine operator for overexposing the miner 
to DPM. The citation would include an appropriate abatement date for 
installing feasible controls. In the interim, a respiratory protection 
program would be required while controls are being installed. As long 
as miners' DPM exposures are reduced to or below the DPM limit, mine 
operators have the flexibility under the proposed rule to choose the 
engineering or administrative controls that best suit the mines' 
circumstances. MSHA emphasizes that it is available to provide 
compliance assistance to mine operators to help them select appropriate 
control methods for reducing miners exposures based upon demonstrated 
experience.
    MSHA asked for comments concerning what type of technical 
assistance the Agency should provide to mine operators in retrofitting 
DPM

[[Page 48705]]

control devices, evaluating ventilation systems or filtration of cabs. 
Commenters stated that MSHA should be providing guidance in all areas 
that involve control technologies. MSHA agrees and will continue to 
assist mine operators, however, MSHA expects mine operators to make 
good faith efforts in attempting to achieve compliance, such as 
beginning to order control technology to reduce DPM exposures.

VIII. Summary of Costs and Benefits

    The provisions in this proposed rule will assist mine operators in 
complying with the existing rule, thereby reducing a significant health 
risk to underground miners. This risk includes lung cancer and death 
from cardiovascular, cardiopulmonary, or respiratory causes, as well as 
sensory irritation and respiratory symptoms. In Chapter III of the 
Regulatory Economic Analysis in support of the January 19, 2001 final 
rule (2001 REA), the Agency demonstrated that the rule will reduce a 
significant health risk to underground miners. This risk included the 
potential for illnesses and premature death, as well as the attendant 
costs to the miners' families, to the miners' employers, and to society 
at large. Benefits of the January 19, 2001 final rule include 
reductions in lung cancers. MSHA estimated that in the long run, as the 
mining population turns over, a minimum of 8.5 lung cancer deaths per 
year will be avoided. MSHA noted that this estimate was a lower bound 
figure that could significantly underestimate the magnitude of the 
health benefits. For example the estimate based on the mean value of 
all the studies examined in the January 19, 2001 rule was 49 lung 
cancer deaths avoided per year.
    The proposed rule results in net cost savings of approximately 
$15,641 annually, primarily due to reduced recordkeeping requirements. 
All MSHA cost estimates are presented in 2001 dollars. This represents 
an average savings of $86 per mine for the 182 underground metal/non-
metal mines that would be affected by this proposed rule. Of these 182 
mines, 65 have fewer than 20 workers, 113 have 20 to 500 workers; and 4 
have more than 500 workers. The cost savings per mine for mines in 
these three size classes would be $102, $77, and $77, respectively. In 
the 2001 REA, the Agency estimated that the costs per underground 
dieselized metal or nonmetal mine to be about $128,000 annually, and 
the total cost to the mining sector to be about $25.1 million a year, 
even with the extended phase-in time. Nearly all of those anticipated 
costs would be investments in equipment to meet the interim and final 
concentration limits.

IX. Section-by-Section Discussion of the Proposed Rule

A. Section 57.5060(a)

    Existing Sec.  57.5060(a) establishes an interim DPM concentration 
limit of 400 micrograms of TC per cubic meter of air (400TC 
[mu]g/m\3\). In the settlement agreement, MSHA agreed to propose to 
change the surrogate from TC to EC, and to propose to establish an 
interim limit based on a miner's personal exposure rather than an 
environmental concentration. Accordingly, the proposed rule would 
establish an interim permissible exposure limit (PEL) of 308 micrograms 
of EC per cubic meter of air (308TC [mu]g/m\3\). This 
proposed EC-based limit represents the existing TC limit divided by a 
conversion factor of 1.3, as established in the settlement agreement. 
MSHA believes that the proposed limit is equivalent to the existing 
interim concentration limit of 400TC [mu]g/m\3\.
    MSHA's position at this time is that a limit of 308 [mu]g/m\3\, 
based on EC, is both technologically and economically feasible for the 
metal and nonmetal mining indutry to achieve. Although the risk 
assessment indicates that a lower interim DMP limit would enhance miner 
protection, it would be infeasible for the underground metal and 
nonmetal mining industry to reach a lower interim limit.
    MSHA is not reducing the protection for miners afforded by the 
existing interim TC concentration limit. MSHA intends to finalize an 
interim EC limit that provides at least the same degree of protection 
to miners as the existing interim limit. MSHA believes that 
establishing a standard that focuses control efforts on diminishing the 
DPM level in air breathed by the miner is at least as protective as the 
interim concentration limit.
    The basis for this position is found in the 31-Mine Study, which 
concluded that the submicron impactor was effective in removing the 
mineral dust, and therefore its potential interference, from the DPM 
sample. Remaining carbonate interference is removed by subtracting the 
4th organic peak from the analysis. No reasonable method of sampling 
was found that would eliminate interferences from oil mist or that 
would effectively measure DPM levels in the presence of environmental 
tobacco smoke (ETS) with TC as the surrogate.
    Using EC as the surrogate would enable MSHA to directly sample 
miners, such as those who smoke or load ANFO, for whom valid personal 
sampling would be difficult when TC is the surrogate.
    Because EC comprises only a fraction of the TC, a conversion factor 
must be used to convert the interim concentration limit to an EC 
exposure limit. To convert the interim TC concentration limit in Sec.  
57.5060(a) to an equivalent EC exposure limit, MSHA is proposing to use 
a factor of 1.3, to be divided into 400TC [mu]g/
m3. Thus, the measured value of EC times 1.3 produces a 
reasonable estimate of TC. This 1.3 factor was specified under the 
terms of the settlement agreement to convert an EC measurement into an 
estimate of TC without interferences and is based on the median total 
carbon to elemental carbon (TC/EC) ratio observed for valid samples in 
the 31-Mine Study. The 1.3 factor is also consistent with information 
supplied by NIOSH indicating that the ratio of TC to EC in the 31-Mine 
Study is 1.25 to 1.67. Most commenters to MSHA's ANPRM supported an 
interim EC PEL of 400TC [mu]g/m3 / 1.3 = 
308EC [mu]g/m3.
    Commenters representing the metal and nonmetal mining industry and 
labor strongly supported a change in the surrogate from TC to EC. These 
commenters stated that, given the interferences known to be present in 
underground mining environments, using EC as the surrogate would 
improve the validity of samples. They also pointed out that this change 
is consistent with the settlement agreement. Other commenters opposed 
changing the surrogate. Some of these commenters stated that since DPM 
has many components, and there is no formula for the exact amount of EC 
in diesel exhaust, TC is a more accurate measure of DPM than is EC, 
presumably because it includes more of the DPM.
    Some commenters also stated that there is no evidence in the 
rulemaking record to support this change. According to these 
commenters, NIOSH must provide a clear statement that EC is an accurate 
surrogate over the full range of mining conditions and must also 
provide a formula for converting EC to DPM that meets the NIOSH 
accuracy criterion. In response, the existing DPM rulemaking record 
contains NIOSH's position on an appropriate surrogate, and NIOSH 
recommended that EC rather than TC should be used as the surrogate for 
DPM. MSHA agrees.
    MSHA has found that EC more consistently represents DPM. In 
comparison to using TC as the DPM surrogate, using EC would impose 
fewer restrictions or caveats on sampling strategy (locations and 
durations), would produce a measurement much

[[Page 48706]]

less subject to questions, and inherently would be more precise. 
Furthermore, NIOSH, the scientific literature, and the MSHA laboratory 
tests indicate that DPM, on average, is approximately 60 to 80% 
elemental carbon, firmly establishing EC as a valid surrogate for DPM.
    Some commenters opposing a change in the surrogate stressed that 
the mix of EC + OC (to equal TC) is highly variable. Some commenters 
questioned the use of EC as a surrogate for DPM because the EC:TC ratio 
varies with each engine and EC is emitted from other sources. Other 
commenters, noting that a specific mine in the 31-Mine Study had an 
EC:TC ratio of 85%, stated that there is no perfect way to monitor DPM 
using surrogates.
    MSHA agrees that the EC:TC ratio can vary significantly, not only 
from mine to mine but also within a mine, depending on equipment 
configuration and usage. MSHA also agrees that there is no perfect way 
to precisely quantify DPM. Using EC as a surrogate, however, results in 
a much more accurate assessment of miners' exposures to DPM than using 
TC. MSHA seeks information and data on the appropriateness of 1.3 as 
the factor to convert EC to TC, and an interim EC limit of 308 
micrograms.
    As part of the settlement agreement, MSHA agreed that the Agency 
will issue citations for violations of the interim exposure limit only 
after MSHA and NIOSH are satisfied with the performance characteristics 
of the SKC sampler and the availability of practical mine worthy filter 
technology, and MSHA has had the opportunity to train inspectors, 
conduct baseline sampling and provide compliance assistance at 
underground metal and nonmetal mines using diesel-powered equipment. 
MSHA will continue consulting with NIOSH, industry and labor 
representatives on the performance of the SKC sampler and the 
availability of practical mine-worthy filter technology.
    MSHA trained the Metal and Nonmetal district health specialists and 
industrial hygienists on diesel particulate sampling in Beckley, West 
Virginia in September 2002. These individuals returned to their 
respective districts and trained MSHA compliance specialists on diesel 
particulate sampling. MSHA has completed the commpliance assistance 
baseline sampling. As part of its compliance assistance efforts, MSHA 
personnel were available during the baseline sampling to provide 
guidance to mine operators on sampling procedures.
    Additionally, MSHA trained members of the mining industry on 
conducting DPM sampling and made that training available to industry 
personnel at compliance assistance workshops following the Outreach 
Seminars on Diesel Particulate Rules for Underground Metal and Nonmetal 
Mines. These seminars and workshops were conducted at nine cities 
during September and October 2002.
    MSHA and NIOSH have reviewed the performance characteristics of the 
SKC sampler and are satisfied that it accurately measures exposures to 
DPM. Results of the 31-Mine Study demonstrated that the SKC submicron 
impactor removed potential interferences from mineral dust from the 
collected sample. MSHA concluded in its findings in the study, however, 
that:

No reasonable method of sampling was found that could eliminate 
interferences from oil mist or that would effectively measure DPM 
levels in the presence of ETS with TC as the surrogate.

    Furthermore, MSHA has found that use of elemental carbon eliminates 
potential sample interference from drill oil mist, tobacco smoke, and 
organic solvents.
    Some industry commenters stated that the sampling and analytical 
processes are too new for regulatory use. According to these 
commenters, SKC recently changed the impactor, and NIOSH should test 
the new SKC sampler and evaluate its comparability to the model used in 
the 31-Mine Study. One of these commenters stated that the shelf life 
of the prior sampler affected TC measurements by adsorbing OC from the 
polystyrene assembly onto the filter media and increasing TC 
measurement. Some commenters also stated that there are significant 
back-order and manufacturing delays for samplers and that operators who 
sample alongside MSHA need ample notice to have enough samplers 
available.
    MSHA purchased many of the initial production runs of these 
samplers to conduct its compliance assistance baseline sampling. Once 
the initial orders were filled, the sampler became more widely 
available.
    Prior to the 31-Mine Study, MSHA had determined the deposit area of 
the sample filter to be 9.12 square centimeters with a standard 
deviation of 3.1 percent. During the initial phases of the 31-Mine 
Study, it became apparent that the variability of the deposit area was 
greater than originally determined. The filter area is critical to the 
concentration calculation. The filter area (square centimeters) is 
multiplied times the results of the analysis (micrograms per square 
centimeter) to get the total filter loading (micrograms). While 
individual filter areas could be measured, it is more practical to have 
a uniform deposit area for the calculations. As a result, NIOSH and 
MSHA consulted with SKC to develop an improved filter cassette design. 
SKC, in cooperation with MSHA and NIOSH, then modified the DPM cassette 
following the 31-Mine Study.
    The modification was limited to replacing the foil filter capsule 
with a 32-mm ring. This was done to give a more uniform deposit area 
(8.04 square centimeters) and to accommodate two 38-mm quartz fiber 
filters in tandem (double filters). These double filters are assembled 
into a single cassette along with the impactor. The 32-mm ring gives a 
filter deposit area of 8.04 square centimeters, with negligible 
variability. The 38-mm filters also eliminate cassette leakage around 
the filters. These modifications were completed and incorporated into 
units manufactured after November 1, 2002. Because the design of the 
inlet cyclone, impaction nozzles, the impaction plate and the flow rate 
did not change, the modifications to the filter assembly did not alter 
the collection or separation performance of the impactor. Throughout 
the compliance baseline sampling, the impactor has been a consistent 
and reliable sampling cassette.
    Tandem filters were used in the oil mist and ANFO interference 
evaluations. The top filter collects the sample and the bottom filter 
is a ``dynamic blank.'' The dynamic blank provides a unique field blank 
for each DPM cassette. The proposed use of elemental carbon as a 
surrogate would resolve the commenter's concern about shelf life and OC 
out-gassing on the filter. Shelf life and OC out-gassing are issues 
relative to organic carbon measurements. These two issues do not apply 
to an elemental carbon measurement. Once the cassettes have been 
preheated, during manufacturing, there is no source, other than 
sampling, to add elemental carbon to the sealed cassette filters.
    In the ANPRM, MSHA asked questions on three topics relating to DPM 
sampling and analysis:
(1) Interferences
    In response to the question on interferences when EC is used as the 
surrogate, some commenters stated that interferences were thoroughly 
discussed in the final rule preamble and that reasonable practices to 
avoid them were stipulated in the rule itself. According to these 
commenters, this problem should not be revisited in this rulemaking.

[[Page 48707]]

    Other commenters maintained that the 31-Mine Study did not contain 
the necessary protocols to address all potential interferences. Thus, 
in their view, MSHA does not have all the data required to answer this 
question. More specifically, some commenters stated that carbonaceous 
particulate in host rock has a smaller diameter than the impactor cut 
point and so may contaminate EC samples. No data were presented to 
support this claim. These commenters concluded that MSHA should propose 
additional research and seek comments on the research before concluding 
that sampling EC with an impactor will eliminate all interference 
problems. On the other hand, NIOSH, in its response to the ANPRM, 
stated that the only non-diesel source of EC that is known to be 
present in a metal/non-metal mine is graphitic mineral ore dust. NIOSH 
further stated that collection of this dust on the sample filter is 
prevented by the impaction plate in the SKC DPM cassette.
(2) Field Blanks
    A field blank is an unexposed control filter meant to account for 
background interferences and systematic contamination in the field, 
spurious effects due to manufacturing and storage of the filter, and 
systematic analytical errors. The tandem filter arrangement in the 
sample cassette provides a primary filter for collecting an air sample 
and a second filter, behind (after) the primary, that provides a 
separate control filter for each sample. This is especially convenient 
for industry sampling, since it eliminates the need to send a separate 
control filter to the analytical lab. MSHA requests comments as to 
industry experience with this sampling equipment.
    In its comments on the ANPRM, NIOSH noted that two types of blanks, 
media and field, are normally used for quality assurance purposes. A 
media blank accounts for systematic contamination that may occur during 
manufacturing or storage. A field blank accounts for possible 
systematic contamination in the field. NIOSH does not recommend use of 
field blanks when EC is the surrogate. This is because EC measurements 
are not subject to sources of contamination in the field that would 
affect OC and TC results. Quartz-fiber filters are prone to OC vapor 
contamination in the field and to contamination by less volatile OC 
(e.g., oils) during handling. However, such contamination is irrelevant 
when EC is the surrogate.
    Several commenters supported the use of field blanks, even if EC is 
the surrogate. These commenters pointed out that using field blanks is 
standard IH practice and stated that manufacturing problems with SKC 
impactor provide further justification. One commenter asked that we use 
one blank from the same and one from a different manufacturer lot.
    MSHA agrees both media and field blanks are desirable, even when 
elemental carbon is used as the surrogate. The use of such blanks is 
standard laboratory procedure and adds credibility to sample results. 
Field blanks adjust for systematic laboratory errors and for systematic 
contamination of samples from unforeseen or uncontrollable sources. 
Accordingly, MSHA will adjust the EC result obtained for each sample by 
the result obtained for the corresponding media blank when a compliance 
concentration is measured and by the field blank (tandem filter) result 
when a noncompliance determination is made.
(3) Error Factor
    MSHA intends to cite a violation of the DPMEC exposure 
limit only when there is validated evidence that a violation actually 
occurred. As with all other measurement-based metal/nonmetal compliance 
determinations, MSHA would issue a citation only if a measurement 
demonstrated noncompliance with at least 95-percent confidence. We 
would achieve this 95-percent confidence level by comparing each EC 
measurement to the EC exposure limit multiplied by an appropriate 
``error factor.''
    Most commenters concurred with MSHA's intention to apply such an 
error factor, though they differed as to how this error factor should 
be established. Some other commenters, however, recommended citing at a 
substantially lower confidence level, using the limit of detection of 
the sampling instrument as replacement for the error factor. These 
commenters gave two reasons in support of this recommendation: (1) In 
issuing a citation for noncompliance, the standard of proof should, 
according to this commenter, be preponderance of evidence rather than 
beyond a reasonable doubt. The preponderance of evidence indicates a 
violation whenever a measurement exceeds the exposure limit plus the 
limit of detection. (2) Conventional public health reasoning and legal 
precedents call for caution on the side of protecting health, rather 
than preventing unwarranted citations. In addition, commenters stated 
that if a measurement failed to demonstrate compliance at a 95-percent 
confidence level, then this should trigger some action such as 
additional sampling, i.e., the EC measurement should be divided, rather 
than multiplied, by MSHA's proposed error factor to provide an ``action 
level.''
    Contrary to these commenters' suggestions, the historical and 
prevailing practice, in both OSHA and MSHA, traditionally has been to 
cite noncompliance only when noncompliance is indicated at a high level 
of confidence. Although, the citation threshold value suggested by 
these commenters accounts for some analytical imprecision, as 
quantified by the limit of detection, it fails to account for other 
sources of measurement uncertainty, such as random variability of 
airflow through the filter.
    Another commenter questioned the use of any constant error factor, 
because of changes in the EC:OC ratio under varying maintenance and 
operating conditions. Although MSHA regards such variability as 
relevant to the issue of choosing an appropriate surrogate, it is not 
relevant to determining an appropriate error factor if EC is selected 
as the surrogate. EC is the quantity to be measured under the proposal, 
and variability in the EC:OC ratio has no known impact on the accuracy 
of an EC concentration measurement made using the SKC sampler and the 
NIOSH 5040 analytical method.
    Among those commenters supporting MSHA's use of an error factor 
providing 95-percent confidence in each citation, some advocated 
continued use of the factor specified in the settlement agreement: 
12.2% for an interim EC limit of 308 [mu]g/m3. This value 
was based on the paired punch data obtained from the 31-Mine Study, 
combined with independent estimates of variability in airflow and the 
deposit area on the sample filter. Other commenters, noting changes in 
the design of the SKC sampler since the 31-Mine Study, stated that 
sampler accuracy should be re-evaluated based on the redesigned sampler 
and that establishment of the error factor should be made a part of the 
rulemaking process.
    MSHA disagrees that the establishment of an error factor for an 
airborne contaminant should be part of the rulemaking process. MSHA is 
not proposing an error factor in this rulemaking, but rather, 
discussing the procedure used to obtain the error factor. This 
procedure is further discussed on the MSHA web site--Single Source Page 
for Metal and Nonmetal Diesel Particulate Matter Regulations. Error 
factors are based on sampling and analytic errors. The manufacturers of 
sampling devices thoroughly investigate and quantify the error factors 
for their devices. While

[[Page 48708]]

MSHA does not frequently change an error factor, it retains that 
latitude should significant changes to either analytical or sampling 
technology occur.
    The formula for the error factor was based on three factors 
included in the DPM settlement agreement and involved in an eight-hour 
equivalent full-shift measurement of EC concentration using Method 
5040: (1) Variability in air volume (i.e., pump performance relative to 
the nominal airflow of 1.7 L/min), (2) variability of the deposit area 
of particles on the filter (cm2), and (3) accuracy of the 
laboratory analysis of EC density within the deposit ([mu]g/
cm2). Modifications made to the sampler since the time of 
the 31-Mine Study have no bearing on the first and third of these 
factors. For the error factor specified in the settlement agreement, 
variability of the filter deposit area was represented by a 3.1 percent 
coefficient of variation, based on an experiment carried out before the 
foil filter capsule in the sampling cassette was replaced by a 32-mm 
ring. Measurements subsequent to introduction of the ring show that 
variability of the filter deposit area is now less than 3.1 percent 
(Noll, J. D., et al., ``Sampling Results of the Improved SKC Diesel 
Particulate Matter Cassette''). This change slightly reduces the error 
factor stipulated for EC measurements in the settlement agreement, but 
not by enough to be of any practical significance.
    Another commenter, stressing the interdependence of inter- and 
intra-laboratory analytical variability, stated:

    MSHA should create an error factor model that accounts for the 
joint and related variability in laboratory analysis, and then 
combine that variability with pump flow rate, sample collection 
size, other sampling and analytic variables * * * [t]hen, based upon 
a statistically strong database, determine the appropriate error 
factor for elemental carbon samples.

    MSHA agrees and this was done for the error factor stipulated in 
the settlement agreement.
    This commenter also suggested that the error factor should include 
a ``component accounting for location on the filter from which the 
sample punch was collected.'' The analytical method (NIOSH 5040) relies 
on a punch taken from inside the deposit area on the sample filter. In 
effect, the punch is a sample of the dust sample. Presumably, the 
purpose of the suggested error factor component would be to account for 
uniformity in the distribution of DPM deposited on the filter, as 
reflected by different possible locations at which a punch might be 
extracted. MSHA agrees that uniformity of the DPM deposit should be 
included in the error factor. The method MSHA used to evaluate the 
accuracy of the analytical method involved comparing two punches taken 
from different locations on the same filter. Therefore, variability 
between punch results due to their location on the filter is already 
included in the error factor as calculated by MSHA.
    The commenter further recommended that MSHA implement sample review 
and chain of custody procedures, that MSHA retain a portion of each 
sample for further analysis by the operator, and that the Agency 
institute inter- and intra-lab analysis of spiked EC samples, along the 
lines of an AIHA PAT (American Industrial Hygiene Association 
Proficiency Analytical Testing) program, in order ``to obtain reliable, 
reproducible information.''
    The MSHA Analytical Laboratory is AIHA (ISO 17025) accredited. As 
such, the Laboratory is required to develop and follow specified 
measurement assurance procedures. These procedures include calibration, 
assessing limits of detection, and determining sampling and analytical 
errors. These are done by standard laboratory methods, which are 
outside the scope of this rulemaking. MSHA would encourage the 
laboratories that would perform NIOSH 5040 analysis to develop and 
institute a PAT-like round-robin program. However, establishing such a 
program is not only outside the scope of this rulemaking but also 
outside MSHA's mandate.
    MSHA will be extracting and analyzing a second punch from any 
sample filter that indicates an overexposure (the two punch results 
will be averaged for purposes of determining noncompliance). As a 
result, sufficient sample will not be available to send to other 
laboratories for analysis. The inter-laboratory paired punch 
comparison, conducted on data from the 31-Mine Study, provided a 
rigorous evaluation of intra- and inter-laboratory variability in EC 
analysis. Based on 642 matched pairs of punches analyzed at four 
laboratories, the coefficient of variation in analytical EC measurement 
error, reflecting the combination of intra- and inter-laboratory 
imprecision, was estimated to be 6.5 percent at filter loadings 
corresponding to an EC concentration at or above the proposed interim 
limit of 308EC [mu]g/m3. This is considered an 
excellent degree of agreement for an inter-laboratory comparison.
    Sample collection procedures and chain of custody, along with other 
sampling issues, are addressed in the MSHA Metal and Nonmetal Health 
Inspection Procedures Handbook. Operators are aware that MSHA inspects 
without prior notice. Therefore, operators who wish to collect side-by-
side samples should have filter cassettes and other sampling equipment 
and supplies available.

Final Concentration Limit

B. Section 57.5060(c)

    Existing Sec.  57.5060(c) addresses application and approval 
requirements for an extension of time for mine operators to reduce the 
concentration of DPM to the final TC concentration limit of 160 
micrograms per cubic meter of air. Mine operators seeking an extension 
must apply to the Secretary. Only consider technological constraints 
can be considered as a basis for approving an extension. The current 
rule allows only one special extension per mine, and this extension is 
limited to two years. Operators must certify that one copy of the 
application was posted at the mine site for at least 30 days prior to 
the date of application. Operators also must give the authorized 
representative of miners a copy of the plan. The current rule does not 
apply to the interim concentration limit.
    In the settlement agreement, MSHA agreed to propose to adapt this 
provision to the interim limit, include consideration of economic 
feasibility, and allow for annual renewals of special extensions. 
Proposed Sec.  57.5060(c) would apply to both the interim and the final 
DPM limits. The proposed section would add consideration of economic 
feasibility in weighing whether operators qualify for an extension. 
Economic constraints as well as technological constraints may limit a 
mine operator's ability to come into compliance with either the interim 
or the final DPM concentration limit. An example of such an economic 
limitation is the case where the cost of modification to a piece of 
diesel-powered equipment that would be required to bring the equipment 
operator's exposure into compliance with the PEL would exceed the value 
of the equipment. In such an instance, additional time may be required 
to purchase and implement other effective controls, such as newer 
equipment with engines that emit less DPM or changes in the ventilation 
system of the mine.
    The proposed section would remove the limit on the number of 
extensions that may be granted to each mine, but would limit each each 
extension to one year. The MSHA district manager, rather than the 
Secretary, could grant extensions. The application for an extension 
would include information that demonstrates how the economic or 
technological feasibility issues affect the mine operator's ability to 
comply with

[[Page 48709]]

the standard. The application would also include the most recent DPM 
monitoring results.
    Section 57.5060(c)(vi) would require the mine operator to specify 
the actions that the operator intends to take during the extension 
period to minimize miner's exposures to DPM. These actions may include 
maintaining existing controls, conducting periodic monitoring of 
miner's exposures, and providing appropriate respiratory protection and 
requiring miners to use such respirators. MSHA does not intend that 
personal protective equipment be permitted during the extension as a 
substitute for engineering and administrative controls that can be 
implemented immediately. In these circumstances, MSHA would consider 
such controls to be feasible and would require mine operators to 
implement them prior to granting an extension.
    Finally, the proposed rule would retain the requirement that 
operators certify to MSHA that one copy of the application was posted 
at the mine site for at least 30 days prior to the date of application, 
and another copy was provided to the authorized representative of 
miners. This record would continue to be subject to records 
requirements under Sec.  57.5075 of the existing standard.
    Existing Sec.  57.5060 requires the mine operator to comply with 
the terms of any approved application for a special extension, and post 
a copy of the approved application for a special extension at the mine 
site for the duration of the special extension period. MSHA's proposed 
rule also would require operators to provide a copy of the approved 
application to the authorized representative of miners.
    The ANPRM solicited comments on circumstances that would 
necessitate an extension of time to come into compliance with the PEL 
and the final concentration limit. Some commenters stated that there 
were no circumstances that would necessitate an extension of time. 
Various commenters stated that there should be no extensions. Some 
commenters also said that the Mine Act does not require a feasibility 
determination for each mine. Others stated that the technology is 
available and referenced in the 1998 Verminderung der Emissionen von 
Realmaschinen en Tunnelbau (VERT) study.
    Some commenters favored granting extensions based on operators' 
good faith efforts to reduce DPM. One commenter said that the 31-Mine 
Study showed that many mines would be unable to comply with either the 
interim or final limit. Some commenters said that extensions would be 
necessary when technological or economic feasibility precludes 
compliance and that granting extensions should be site-specific.
    MSHA also solicited comments on the duration of the extension. Some 
commenters wanted one-year, renewable extensions. A few commenters 
stated that extensions should be granted automatically until control 
technology is feasible, while others felt that extensions should be 
granted liberally and renewed as long as the mine is making good faith 
efforts. Several commenters also stated that in-mine applications of 
control technology can differ from lab results and that manufacturers 
are developing new technology for EPA compliance, thus research and 
development for control technology on existing engines is not cost 
effective.
    MSHA asked for comments on what actions mine operators must take to 
minimize DPM exposures if they are operating under an extension. Some 
commenters stated that a detailed compliance plan specifying how the 
limit would be met should be required. These same commenters said that 
a public hearing on granting an extension should be held at the 
operator's or union's request. Use of administrative controls and PPE 
were recommended by several commenters. Commenters also said that 
research on respiratory protective devices such as PAPRs (powered air 
purifying respirators) is needed.
    MSHA agrees that applications for extension should include the 
actions a mine operator will take during the extension to reduce the 
miner's exposure level to the interim PEL or the final concentration 
limit such as monitoring, ordering controls, adjusting ventilation, 
respiratory protection, and other good faith actions of the mine 
operator. The circumstances under which MSHA would propose to require 
respiratory protection are in new Sec.  57.5060(d).
    MSHA is proposing to revise Sec.  57.5060(c) as agreed to in the 
DPM settlement agreement. MSHA has further reviewed and analyzed the 
effect of this standard and is concerned that it would duplicate the 
regulatory objectives addressed under new Sec.  57.5060(d) and the 
intended hierarchy of controls for the DPM rule. In the preamble to the 
existing rule at page 5861, MSHA stated:

    Extension application. Sec.  57.5060(c)(1) provides that if an 
operator of an underground metal or nonmetal mine can demonstrate 
that there is no combination of controls that can, due to 
technological constraints, be implemented within five years to 
reduce the concentration of DPM to the limit, MSHA may approve an 
application for an extension of time to comply.

    The Agency intended for the existing provision to address 
circumstances where mine operators would need additional time to 
implement a technological solution to controlling DPM in their 
individual mines. When MSHA promulgated the DPM rule, it intended for 
this provision to give flexibility to a regulatory scheme that 
prohibited use of administrative controls and respiratory protection.
    MSHA requests comments on whether the proposed provision for the 
extension of time to comply with the interim PEL and the final 
concentration limit would be necessary, and examples of how this 
requirement would benefit mine operators if included in the final 
regulatory framework. MSHA is interested in avoiding duplication and 
requiring additional paperwork from the mining industry in order to 
resolve feasibility issues at individual mining operations. The Agency 
needs further input from the public on the effectiveness of proposed 
Sec.  57.5070(c) and how this provision fits within the comprehensive 
structure of this rulemaking.

C. Section 57.5060(d)

    Existing Sec.  57.5060(d) permits miners engaged in specific 
activities involving inspection, maintenance, or repair activities, to 
work in concentrations of DPM that exceed the interim and final limits, 
with advance approval from the Secretary. MSHA specifies in the 
standard that advance approval is limited to activities conducted as 
follows:

    (i) For inspection, maintenance or repair activities to be 
conducted:
    (A) In areas where miners work or travel infrequently or for 
brief periods of time;
    (B) In areas where miners otherwise work exclusively inside of 
enclosed and environmentally controlled cabs, booths and similar 
structures with filtered breathing air; or
    (C) In shafts, inclines, slopes, adits, tunnels and similar 
workings that the operator designates as return or exhaust air 
courses and that miners use for access into the mine or egress from 
the mine;

    Operators must meet the conditions set forth in the standard for 
protecting miners when they engage in the specified activities in order 
to qualify for approval of the Secretary to use respiratory protection 
and work practices. MSHA considers work practices a component of 
administrative controls.
    In tandem with this requirement is existing Sec.  57.5060(e) which 
prohibits

[[Page 48710]]

use of respiratory protection to comply with the concentration limits, 
except as specified in an approved extension under Sec.  57.5060(c) and 
as specified in approved conditions related to inspection, repair, or 
maintenance activities. Section 57.5060(f) prohibits use of 
administrative controls to comply with the concentration limits.
    MSHA agreed under the DPM settlement agreement to propose a 
revision of the existing Sec.  57.5060(d) and implement the current 
hierarchy of controls as adopted in the Agency's other exposure-based 
health standards for metal and nonmetal mines, and consider requiring 
application to the Secretary before respirators could be used to comply 
with the DPM standard. The settlement agreement further specifies that 
employee rotation would not be allowed as an administrative control for 
compliance with this standard.
    When a miner's exposure exceeds the PEL or the concentration limit, 
proposed Sec.  57.5060(d) would require that operators reduce the 
miner's exposure by installing, using and maintaining feasible 
engineering and administrative controls; except operators would then be 
prohibited from rotating a miner to meet the DPM limits. Under its 
current policy, MSHA allows mine operators to abate a citation for an 
overexposure to airborne contaminants (air quality) by using feasible 
engineering or administrative controls to reduce the miner's exposure 
to the contaminant's enforcement level (See MSHA Program Policy Manual, 
Volume IV, Parts 56 and 57, Subpart D, Section .5001(a)/.5005, 08/30/
1990). When controls do not reduce a miner's exposure to the DPM 
limits, controls are infeasible, or controls do not produce significant 
reductions in DPM exposures, operators would have to continue to use 
all feasible controls and supplement them with a respiratory protection 
program, the details of which are discussed below in this preamble.
    Therefore, MSHA is proposing to remove current Sec.  57.5060(e) 
prohibiting respiratory protection as a method of compliance in the DPM 
rule, and Sec.  57.5060(f) which prohibits the use of administrative 
controls for compliance. Administrative controls, however, were 
uniquely defined in the existing rule as ``worker rotation.'' MSHA has 
historically considered other types of controls, besides worker 
rotation, to be administrative controls.
    Administrative controls, such as work practice controls, were 
permitted. In the context of the existing rule, engineering controls 
were intended to refer to controls that remove the DPM hazard by 
applying such methods as substitution, isolation, enclosure, and 
ventilation.
    Work practice controls were referred to as specified changes in the 
manner work tasks are performed in order to reduce or eliminate a 
hazard. The Agency strongly believes that these types of administrative 
controls do not compromise miners' health and safety and would not 
reduce the level of their protection as provided under the existing 
final rule. Moreover, mine operators should be given the flexibility to 
use them to control miners' exposures under a revised DPM rule. 
Commenters should submit information and supporting data on appropriate 
administrative controls for a final rule.
    At the present time, operators are not required to develop written 
administrative control procedures, nor a written respiratory protection 
program when using these control methods to reduce miners' exposures to 
airborne contaminants in MSHA's air quality standards at 30 CFR 
57.5001/57.5005.
    In the ANPRM, MSHA asked commenters for information and data on the 
appropriate role for administrative controls and respirators in 
underground metal and nonmetal mines in a proposed rule. Most 
commenters supported removing the prohibition in order to have greater 
compliance flexibility.
    MSHA asked the mining community whether it should require written 
administrative control procedures when operators are required to use 
controls to reduce miners' exposures. Commenters were divided on this 
issue.
    MSHA received some objections from the public as to written 
administrative control strategies. The commenters stated that such a 
requirement would increase compliance costs and reduce efficiency and 
personnel availability. Other commenters recommended that MSHA require 
operators to have written administrative control strategies and post 
them on the mine's bulletin board. Commenters should submit to MSHA any 
information on the benefits and cost implications of including in a 
final rule a requirement to develop written administrative control 
procedures and post the procedures on the mine's bulletin board.
    The proposed changes to Sec.  57.5060(d) described above might 
appear to alter the way mine operators will be required to control DPM 
exposures compared to the requirements contained in the existing rule. 
However, in most cases, the proposed changes and the existing rule 
impose similar requirements. The mining community will find that these 
proposed changes are largely intended to simplify understanding of the 
rule's requirements for controlling DPM exposures and to reduce 
unnecessary paperwork.
    MSHA would consider an engineering or administrative control to be 
effective in reducing DPM exposure if credible scientific or 
engineering studies or analysis using similar diesel equipment operated 
under similar conditions have demonstrated the capability, either by 
itself or in combination with other controls, to achieve significant 
DPM exposure reductions, in either laboratory or field trials. MSHA 
believes that a 25% or greater reduction in DPM exposure should be 
considered significant. MSHA, however, requests further comments on 
what would constitute a significant reduction in a miner's DPM 
exposure.
    MSHA considers an engineering control to be technologically 
achievable if through reasonable application of existing products, 
devices, or work methods, with human skills and abilities, a workable 
engineering control can be applied. The control does not have to be 
``off the shelf,'' but it must have a realistic basis in present 
technical capabilities.
    As discussed elsewhere in this preamble (Feasibility), MSHA would 
consider, for example, a ceramic DPM filter to be a technologically 
feasible control for a piece of diesel equipment if there was evidence 
that the filter had been successfully applied to a similar engine 
subjected to similar operating conditions. The fact that a ceramic DPM 
filter had not been previously applied to that particular make and 
model of engine, or to that particular make and model of mining 
equipment would not, by itself, constitute a basis for determining that 
the application would be technologically infeasible.
    Also, the fact that the duty cycle of a particular piece of mining 
equipment might not be sufficient for passive controlled regeneration 
of a ceramic DPM filter would not, by itself, constitute a basis for 
determining that the application of that filter to that piece of mining 
equipment is technologically infeasible.
    In this example, unless additional substantive information 
establishing the technological infeasibility of the application is 
presented, MSHA would consider the filter to be a technologically 
feasible engineering control. Furthermore, MSHA would consider the 
filter to be technologically feasible even though a certain amount of 
applications engineering might be required to produce a workable or 
optimal system, including the need to re-locate, re-route or otherwise 
modify exhaust system components to facilitate

[[Page 48711]]

filter installation, and the possible need for either on-board or off-
board active or active/passive filter regeneration.
    MSHA would also consider certain traditional methods for control of 
exposure to airborne contaminants to be technologically feasible for 
controlling exposures to DPM, such as improved ventilation (main and/or 
auxiliary) and enclosed cabs with filtered breathing air. Improving 
ventilation may involve upgrading main fans, use of booster fans, and 
use of auxiliary fans that may or may not be connected to flexible or 
rigid ventilation duct, as well as installation of ventilation control 
structures such as air walls, stoppings, brattices, doors, and 
regulators. At most mines, cabs with filtered breathing air are 
technologically feasible for many newer model trucks, loaders, scalers, 
drills, and other similar equipment. However, use of enclosed cabs with 
filtered breathing air may not be feasible as a retrofit to certain 
older equipment or where the function performed by miners using a 
particular piece of equipment is inconsistent with any type of cab 
(e.g., loading blastholes from a powder truck, installing utilities 
from a scissors-lift truck) or where the height of the mine roof is not 
sufficient for cab clearance. Other examples of engineering controls 
that MSHA would consider to be technologically feasible include certain 
alternative fuels, fuel blends, fuel additives, and fuel pre-treatment 
devices, and replacement of older, high-emission engines with modern, 
low-emission engines.
    In determining economic feasibility, MSHA would consider whether 
the costs of implementing the control are disproportionate to the 
expected DPM concentration or exposure reduction, and whether the costs 
are so great that it would be unreasonable to require its use to 
achieve those results. MSHA would, for example, expect ceramic DPM 
filters ranging in cost from $5,000 for smaller engines to $20,000 for 
larger engines to be economically feasible, particularly given the 
significant reduction these filters can achieve.
    In the ANPRM, MSHA asked for comments on the appropriate role for 
respirators. Most commenters indicated that respirators with some 
restriction on their use should be permitted as a means of compliance 
with the DPM limits. Some commenters disagree on the types of 
restrictions that MSHA should place on their use, while other 
commenters believe that PPE may be far more effective in protecting 
miners from suspected DPM health effects than any available and 
feasible engineering control technology. According to still other 
commenters, respirators are uncomfortable and difficult to properly use 
over an extended period of time. They restrict visibility and create 
breathing resistance, thereby causing an additional hazard to miners. 
Finally, MSHA was notified that if the final rule allows respirators at 
all, such respirators should only be used with approval of the 
Secretary, and only as a supplemental control for other feasible 
controls.
    Generally, commenters agreed with proposing MSHA's current 
hierarchy of controls for reducing miners' exposures to DPM. Some 
commenters to the ANPRM stated that MSHA properly prohibited the use of 
PPE in the current rule and no change should be made to this provision. 
Others stated that MSHA should state and enforce its preference for 
engineering controls rather than personal protective equipment, and 
that standard industrial hygiene practice supports this position. In 
response to these commenters, MSHA agrees that engineering controls 
should be included in the first tier of the agency's methods of 
compliance. The proposed rule reflects this position but does not place 
preference for engineering controls over use of administrative controls 
for reducing miners' exposure to DPM. Mine operators would be required 
to use all feasible engineering and administrative controls as a first 
response to miners' overexposures. MSHA intends for mine operators to 
have the flexibility to choose to start with engineering or 
administrative controls, or a combination of both, as the control 
method that best suits their circumstances.
    Engineering controls are very effective in altering the sources of 
miners' DPM exposures in the underground mining environment, thereby 
decreasing DPM exposures. Unlike respiratory protection, engineering 
controls do not depend upon individual performance or direct human 
involvement to function. Based on its observations and experience in 
underground metal and nonmetal mines, MSHA continues to believe that 
feasible engineering and administrative controls exist to adequately 
address most DPM overexposures to the interim limit. However, MSHA is 
not persuaded that all DPM overexposures can be eliminated through 
implementation of feasible engineering and administrative controls 
alone, and that extra protective measures should be taken to protect 
miners in such circumstances.
    Some commenters suggested that various commercially available 
respirators, including those with filtering facepieces, were suitable 
for protection against particles smaller than DPM, and would therefore 
be suitable for DPM as well. NIOSH recommended that respirators used 
for protection against DPM have an R-100 or P-100 certification per 42 
CFR part 84. NIOSH recommended against using N-rated respirators since 
diesel exhaust contains oil, and aerosols containing oil can degrade 
the performance of N-rated filters. MSHA agrees.
    Proposed Sec.  57.5060(d)(1) would require that respirators be 
NIOSH certified as a high-efficiency particulate air (HEPA) filter, 
certified per 42 CFR part 84 (approval of Respiratory Protection 
Devices) as 99.97% efficient, or certified by NIOSH for diesel 
particulate matter. Proposed Sec.  57.5060(d)(2) would require that 
non-powered, negative-pressure, air purifying, particulate-filter 
respirators shall use an R- or P-series filter or any filter certified 
by NIOSH for diesel particulate matter. The proposal further specifies 
that R- series filters shall not be used for longer than one work 
shift.
    NIOSH also recommended that combination filters capable of removing 
both particulates and organic vapor be specified, since organic vapors 
and gases can be adsorbed onto DPM. The proposal does not require 
respirators to be certified for organic vapor because MSHA does not 
have data substantiating that a DPM overexposure would necessarily 
indicate an associated overexposure to organic vapors. If simultaneous 
sampling for DPM and organic vapors indicate overexposure to both 
contaminants, any subsequent citation(s) relating to the overexposures 
would require that respirators be used and equipped with a filter or 
combination of filters rated for both DPM and organic vapors.
    MSHA also asked for information as to whether mine operators should 
be required to implement a written respiratory protection program when 
miners must wear respiratory protection. Commenters were divided on 
this issue. Some commenters stated that MSHA should require that the 
respiratory protection program be in writing. NIOSH recommended in its 
comments that ``mine operators be required to have a written 
respiratory protection program, analogous to that required by OSHA for 
general industry in 29 CFR 1910.134 Respiratory protection, that is 
work-site specific and includes administration by a trained program 
administrator, respirator selection criteria, worker training, a 
program to determine that the workers are medically able to use 
respiratory protective equipment, and provisions for regular evaluation 
of the program's effectiveness.''

[[Page 48712]]

    Other commenters opposed a written program. MSHA requests the 
mining community to submit further information for justifying a written 
respiratory protection program, including cost data and benefits to 
miners' health.
    The proposed standard is based on the 1969 ANSI documentation that 
has been updated several times since the air quality standards were 
promulgated in 1973 (30 CFR 56/57.5005). The ANSI, nevertheless, 
recommended in its 1969 version, as well as in subsequent versions, 
that a standard respiratory protection program should include written 
procedures that address implementation information such as respirator 
selection, fit testing procedures, cleaning and sanitizing procedures, 
all of which are critical to an appropriate program. MSHA invites 
further comments on whether the final DPM rule should include 
provisions for a written respiratory protection program. Comments 
should address health benefits for miners, projected paperwork burden 
and compliance costs to the metal and nonmetal underground mining 
industry, and should include supporting data.
    MSHA also received comments on the need for including a requirement 
for operators to have a miner medically examined before that miner 
could be required to work in an area where respiratory protection would 
be required. In addition, some commenters asked the agency to protect 
miners' jobs by implementing the requirements of Sec.  101(a)(7) of the 
Mine Act. Section 101(a)(7) of the Mine Act establishes the statutory 
authority for MSHA to promulgate medical surveillance and transfer of 
miner requirements in order to prevent the miner from being exposed to 
health hazards. This provision of the Mine Act states, in pertinent 
part:

    Where appropriate, such mandatory standard shall also prescribe 
suitable protective equipment and control or technological 
procedures to be used in connection with such hazards and shall 
provide for monitoring or measuring miner exposure at such locations 
and intervals, and in such manner so as to assure the maximum 
protection of miners. In addition, where appropriate, any such 
mandatory standard shall prescribe the type and frequency of medical 
examinations or other tests which shall be made available, by the 
operator at his cost, to miners exposed to such hazards in order to 
most effectively determine whether the health of such miners is 
adversely affected by such exposure. Where appropriate, the 
mandatory standard shall provide that where a determination is made 
that a miner may suffer material impairment of health or functional 
capacity by reason of exposure to the hazard covered by such 
mandatory standard, that miner shall be removed from such exposure 
and reassigned. Any miner transferred as a result of such exposure 
shall continue to receive compensation for such work at no less than 
the regular rate of pay for miners in the classification such miner 
held immediately prior to his transfer. In the event of the transfer 
of a miner pursuant to the preceding sentence, increases in wages of 
the transferred miner shall be based upon the new work 
classification.

    Currently, MSHA standards do not require medical transfer of metal 
and nonmetal miners. Existing standards at 30 CFR 56/57.5005(b) for 
control of miners' exposure to airborne contaminants require that mine 
operators establish a respiratory protection program consistent with 
the ANSI Z88.2-1969 ``American National Standard for Respiratory 
Protection'' which includes medical determinations for potential 
respirator wearers. MSHA standards at 30 CFR part 90 address medical 
removal for coal miners and provide miners with a medical examination 
and an opportunity to transfer to an area of the mine having lower dust 
levels, at the same level of pay, when the miner has x-ray evidence of 
the development of pneumoconiosis.
    OSHA acknowledges within its current standards addressing 
respiratory protection at 29 CFR 1910.134(e) that use of a respirator 
may place a physiological burden on workers while using them. At a 
minimum, OSHA requires employers to provide medical evaluations before 
an employee is fit tested or required to use respiratory protection. 
Employers are required to have a physician or other licensed health 
care professional have the worker complete a questionnaire, or in the 
alternative, conduct an initial medical examination in order to make 
the determination. If the worker has a positive response to certain 
specified questions, the employer must provide a follow-up medical 
examination. The questionnaire is contained in the body of the OSHA 
rule. The preamble to the OSHA final rule states:

    Specific medical conditions can compromise an employee's ability 
to tolerate the physiological burdens imposed by respirator use, 
thereby placing the employee at increased risk of illness, injury, 
and even death (Exs. 64-363, 64-427). These medical conditions 
include cardiovascular and respiratory diseases (e.g., a history of 
high blood pressure, angina, heart attack, cardiac arrhythmias, 
stroke, asthma, chronic bronchitis, emphysema), reduced pulmonary 
function caused by other factors (e.g., smoking or prior exposure to 
respiratory hazards), neurological or musculoskeletal disorders 
(e.g., ringing in the ears, epilepsy, lower back pain), and impaired 
sensory function (e.g., a perforated ear drum, reduced olfactory 
function). Psychological conditions, such as claustrophobia, can 
also impair the effective use of respirators by employees and may 
also cause, independent of physiological burdens, significant 
elevations in heart rate, blood pressure, and respiratory rate that 
can jeopardize the health of employees who are at high risk for 
cardiopulmonary disease (Ex. 22-14). One commenter (Ex. 54-429) 
emphasized the importance of evaluating claustrophobia and severe 
anxiety, noting that these conditions are often detected during 
respirator training. [See 63 FR 1152, 01/08/1998]

    MSHA seeks information from the public as to whether the final rule 
should include requirements for medical examination and transfer of 
miners under the proposed DPM respiratory protection standard. 
Commenters should also submit cost implications of such a program and 
other related data.
    The Agency also considered whether mine operators should be 
required to apply in writing to the Secretary for approval to use 
respiratory protection. Some commenters recommended requiring approval 
by the Secretary before respiratory protection should be permitted as a 
means of compliance with the applicable DPM limit, but MSHA was not 
persuaded that such a step would be necessary and MSHA's proposed Sec.  
57.5060(d) does not include this recommendation. Respiratory protection 
functions as a supplemental control. Operators must have ready access 
to respirators when they must be used as is the case where the agency 
has allowed metal and nonmetal mine operators to do so for many years 
under MSHA's air quality standards. Moreover, the proposed control plan 
requirements in Sec.  57.5062 and the application for extension in 
Sec.  57.5060(c) would effectively require that mine operators specify 
when they plan to use respirators to control a miner's DPM exposure. 
MSHA, therefore, would know when mine operators intend to use 
respirators as an interim measure until compliance can be achieved 
through the application of engineering and administrative controls. 
Further, when a mine operator is issued a citation under proposed Sec.  
57.5060(d) for a miner's exposure exceeding the applicable DPM limit, 
and the mine operator intends to use respiratory protection as an 
interim control measure, MSHA would make certain that a respiratory 
protection program is established and appropriate respirators are used 
in accordance with Sec.  57.5005(a), (b) and proposed paragraphs Sec.  
57.5060(d)(1) and (d)(2) concerning filter selection for air-purifying 
respirators. Accordingly, this requirement can be deleted from the

[[Page 48713]]

existing rule without reducing protection to the miners.

D. Section 57.5060(e)

    Existing Sec.  57.5060(e) prohibits mine operators from using 
personal protective equipment (respirators) to comply with the DPM 
concentration limit except under specific circumstances and only with 
the advance approval of the Secretary based on an application submitted 
by the mine operator. The effect of this provision would be to require 
mine operators, in most situations, to control DPM concentrations by 
implementing engineering and work practice controls, with limited 
respirator usage as provided under Sec.  57.5060(d).
    MSHA emphasizes that the hierarchy of controls presupposes that 
certain types of industrial hygiene controls are inherently superior to 
other types of controls in reducing or eliminating hazardous exposures. 
Preference is given to controls that remove or eliminate the hazard 
from the work place. Engineering controls and changes in work practices 
that remove or eliminate the hazard are therefore the preferred methods 
for controlling hazardous exposures, and in accordance with the 
principle of hierarchy of controls, must be implemented first before 
resorting to the use of personal protective equipment as a means of 
compliance. Personal protective equipment is considered an acceptable 
control option only after all feasible engineering and administrative 
controls have been fully implemented. Under the hierarchy of controls 
concept, if engineering and administrative controls alone are not 
capable of reducing exposures to the applicable limit, these controls 
would need to be used and maintained, but in addition, the mine 
operator would be required to provide appropriate personal protective 
equipment to affected miners and would have to ensure the equipment is 
properly used.
    Engineering controls, in both the existing rule and the proposal, 
are meant to refer to controls that reduce or remove the DPM hazard 
from the workplace by applying such methods as substitution, isolation, 
interception, enclosure, and ventilation. In the existing rule, 
administrative controls were uniquely defined as ``worker rotation'' 
and prohibited as an acceptable DPM control method because it fails to 
eliminate the exposure hazard and results in placing more miners at 
risk. In the proposal, this unique definition is removed and 
administrative controls are meant to refer to the historically 
recognized controls such as specified changes in the way work tasks are 
performed that reduce or eliminate the hazard. Worker rotation is then 
specifically prohibited as an administrative control in proposed Sec.  
57.5060(e).
    Since existing Sec.  57.5060(e) provided certain exceptions to the 
prohibition on the use of personal protective equipment, MSHA does not 
believe that its proposed revisions will result in significantly 
greater respirator usage or decrease the level of protection afforded 
to miners. The Agency's proposal, therefore, serves primarily to 
simplify the understanding of the rule's requirements for controlling 
DPM exposures, to achieve consistency with MSHA's other exposure-based 
rules for metal and nonmetal mines, and to reduce unnecessary 
paperwork.

E. Section 57.5061(a)

    Under existing Sec.  57.5061(a), the Secretary would have 
determined compliance with ``an applicable limit on the concentration 
of diesel particulate matter pursuant to Sec.  57.5060.'' In accordance 
with the DPM settlement agreement, the Agency proposes that Sec.  
57.5061(a) be changed to specify that MSHA would determine compliance 
with ``the PEL''. MSHA is proposing to replace the term Aconcentration 
limit'' in this section with the term ``PEL'' to reflect that MSHA 
proposes to enforce a personal exposure limit to limit miners' exposure 
to DPM. These are conforming changes and do not result in a decrease of 
protection to the miners.

F. Section 57.5061(b)

    Compliance determinations under existing Sec.  57.5061(b) are based 
on total carbon measurements. MSHA is proposing that compliance 
determinations made under Sec.  57.5061(b) would be based on elemental 
carbon measurements instead of total carbon in accordance with the 
proposed change in the interim limit in Sec.  57.5060. Copies of the 
NIOSH 5040 Analytical Method can be obtained at www.cdc.gov/niosh, or 
by contacting MSHA's Pittsburgh Safety and the Health Technology 
Center, P.O. Box 18233, Cochrans Mill Road, Pittsburgh, PA 15236.

G. Section 57.5061(c)

    Under existing Sec.  57.5061(c), the Secretary would have 
determined the appropriate sampling strategy for conducting compliance 
sampling utilizing personal sampling, occupational sampling, or area 
sampling, based on the circumstances of a particular exposure. The 
Agency proposes that Sec.  57.5061(c) be changed to specify that only 
personal sampling would be utilized for compliance determination.
    The Agency believes that personal sampling alone will result in an 
accurate determination of miner exposure to DPM. Proposed Sec.  
57.5060(a) establishes a DPM limit that specifically relates to the 
exposure of miners to DPM. Since the proposed limit relates to the 
exposure of miners, the appropriate sampling method to determine 
compliance is personal sampling. In this respect, the proposed rule's 
sampling method for compliance determination is consistent with the 
Agency's longstanding practice of utilizing personal sampling to 
determine compliance with exposure limits for airborne contaminants in 
the metal and nonmetal sector.
    Under proposed Sec.  57.5061(b), MSHA would utilize elemental 
carbon as the surrogate for DPM sampling. This is a conforming change 
in the paragraph. Personal sampling allows for the accurate 
determination of DPM exposure when elemental carbon is utilized as the 
DPM surrogate.
    The Agency anticipates several benefits of standardizing personal 
sampling as the compliance sampling method. MSHA expects that mine 
operators and miners are already familiar with personal sampling, since 
MSHA utilizes it routinely when compliance sampling for noise, dust, 
and other airborne contaminants. Utilizing personal sampling eliminates 
possible disputes that could have arisen over whether an area sample 
was obtained ``where miners normally work or travel.'' Mine operators 
who choose to conduct environmental monitoring for DPM under Sec.  
57.5071 using MSHA's compliance sampling method will not need to 
anticipate which sampling method MSHA would most likely have selected, 
personal, area, or occupational, based on the circumstances of a 
particular exposure. Personal sampling avoids situations where area 
sampling is intended to capture the exposure of a particular miner for 
most or all of the work shift, but that miner moves to a new location 
during the shift. Personal sampling for elemental carbon avoids the 
problem of determining compliance for an equipment operator who is a 
smoker and who works inside an enclosed cab. Under the existing rule, 
this miner could not be sampled inside the cab due to interference from 
tobacco smoke, and area sampling outside the cab would not capture that 
miner's DPM exposure.
    MSHA received numerous comments in response to the ANPRM concerning 
the proposed elimination of area and occupational sampling. Most 
supported

[[Page 48714]]

the change for the reasons expressed above. One commenter observed:

    We agree that personal sampling more accurately measures 
personal exposure. However, area sampling can also be useful for 
checking the reliability of personal sampling, and the degree to 
which that sampling is representative. Area sampling can also 
provide important information about the quality of compliance plans. 
MSHA should retain the ability to collect area samples for such 
purposes, and to require that operators collect them, even if area 
samples cannot, in themselves, trigger a citation.

    The Agency agrees that personal sampling is more representative of 
personal exposure, which is why the change to personal sampling for 
compliance determinations is being proposed. The Agency also agrees 
that area sampling can be a useful tool for quantifying DPM 
concentrations at specific locations in a mine, which can greatly 
facilitate evaluation of DPM controls. MSHA has conducted extensive 
area sampling for DPM to assist Agency personnel, mine operators, and 
miners to better understand DPM baseline conditions in mines, and to 
evaluate the effectiveness of various DPM controls. MSHA intends to 
continue to conduct area sampling for DPM as necessary, but on a 
compliance assistance basis only, and not for compliance determinations 
or enforcement.
    A few commenters were opposed to the elimination of area and 
occupational sampling for compliance determination. Two commenters 
suggested that relying on personal sampling alone would enable a mine 
operator to influence the sampling result to the mine operator's 
advantage by re-assigning a miner being sampled to an area with lower 
DPM levels. MSHA believes that although a mine operator may attempt to 
defeat compliance sampling by re-assigning the miner being sampled, 
MSHA's existing enforcement authority is adequate to ensure a valid and 
representative sample can nonetheless be obtained.
    If the miner being sampled for DPM is re-assigned to a different 
workplace with lower DPM levels, or the miner's DPM exposure is 
deliberately manipulated by some other means, such as by withdrawing a 
``dirty'' piece of equipment from the area where the miner is working, 
the inspector has the authority to investigate the circumstances, and 
invalidate the sample if the inspector determines that the miner's 
workday was not ``normal.'' In egregious cases, where there is clear 
indication of intent and proof, the inspector may cite the mine 
operator under 103(a) of the Mine Act for impeding an inspection. In 
either case, sampling may be conducted subsequently to obtain a valid 
and representative sample of that miner's DPM exposure.
    One commenter suggested that personal sampling is not appropriate 
for miners who work inside enclosed cabs, because although they may be 
protected against DPM, other downstream miners who do not work inside 
enclosed cabs would not be protected. MSHA believes that the compliance 
status of any miner can be determined by personal sampling, whether 
they work in an enclosed cab or not. Personal sampling of the miner in 
an enclosed cab can determine whether the cab air filtration system or 
other DPM controls are adequate to maintain compliance for that miner. 
Downstream miners who do not work in enclosed cabs and who are 
suspected of high DPM exposures can also be sampled, and in accordance 
with MSHA's health sampling policy that targets miners with the highest 
exposures for sampling, the inspector would likely do so.
    Several comments were also received that responded specifically to 
the questions asked in the ANPRM relating to existing Sec.  57.5061(c) 
and proposed changes.
    (a) What would be the cost implications for mine operators to 
conduct personal sampling of miners' DPM exposures if EC is the 
surrogate?
    One commenter indicated that costs are secondary to whether the 
policy of conducting personal sampling for compliance determination is 
reasonable. Other comments suggested no change in expected costs 
because the NIOSH Method 5040 is in place at several commercial labs. 
Several commenters noted that costs may be lower if EC is the surrogate 
due to ``fewer false readings and contaminated samples.'' On the whole, 
MSHA believes valid and representative samples can be obtained through 
personal sampling, and MSHA does not expect differences in sampling 
cost, if any, to be significant.
    (b) What experience do mine operators have with DPM sampling and 
analysis?
    The commenters indicated that mine operators' experience with DPM 
sampling and analysis varies widely across the underground metal and 
nonmetal mining industry. Some mine operators, especially those that 
have been parties to the DPM litigation and/or involved in the 31-Mine 
Study, have acquired considerable experience, while many other 
operators have had little or no experience. Several commenters 
mentioned that mining company health and safety staff capable of 
conducting DPM sampling ``are overburdened with other MSHA initiatives 
(HazCom, noise, silica) and will not be able to complete the required 
DPM tasks.'' These commenters recommended that AMSHA should provide in-
mine training, sampling assistance [and] outreach meetings'' and that 
MSHA health staff should help mine operators that lack DPM sampling 
experience ``without enforcement, by providing comprehensive in-mine 
training and sampling assistance.''
    MSHA largely agrees that many mine operators are unfamiliar with 
MSHA's DPM sampling and analytical methods. Accordingly, MSHA intends 
to provide numerous opportunities for mine operators and miners to 
obtain training on DPM sampling. MSHA will target these compliance 
assistance training opportunities to small mine operators in 
particular. MSHA conducted a 3-day, in-mine, hands-on DPM sampling 
workshop at an underground limestone mine near Louisville, KY in 
December 2002, and other similar workshops are planned.
    MSHA has also posted information on its Web site relating to the 
specialized DPM sampling cassette with integral submicron impactor. 
Also posted on the MSHA web site are a Compliance Guide on the standard 
itself, which includes considerable information about sampling, the 
draft chapter from MSHA's Metal and Nonmetal Health Inspection 
Procedures Handbook detailing the compliance sampling procedures that 
MSHA inspectors will follow, and the field notes form that MSHA 
inspectors will use to document DPM compliance sampling. All of this 
information is also available in hardcopy form for mine operators and 
miners who do not have internet access. MSHA intends to develop and 
provide additional DPM sampling-related compliance assistance materials 
as needed to mine operators and miners in both hard-copy form and on 
its Web site.
    As a result of some of the changes in the rule language that have 
been proposed through this rulemaking, MSHA's DPM compliance sampling 
procedures will conform more closely to existing MSHA sampling 
practices for dust and other airborne contaminants. As a consequence, 
mine operators that have had no previous experience with DPM sampling, 
but have had experience with, or at least knowledge of, MSHA respirable 
dust sampling, will discover they have very little more to learn. 
Except for the sample filter cassette itself, the mechanics of DPM 
sampling will be almost identical to respirable

[[Page 48715]]

dust sampling. For example, the same pump and sampling train are used 
(sample pump, hose, cyclone holder, Dorr-Oliver 10 mm nylon cyclone), 
and the pumps must be pre- and post-calibrated at the same 1.7 liters 
per minute flow rate. Sampling for both respirable dust and DPM is for 
the full shift, and the same chain-of-custody procedures must be 
followed for handling the cassettes. For both respirable dust and DPM, 
the miners with the highest expected exposure will be targeted for 
sampling, and much of the same information will need to be documented 
in the sampler's field notes (mine, date, person conducting sampling, 
person being sampled, sources of exposure, controls used, etc.).
    As with respirable dust sampling, compliance sampling, for DPM 
would be personal rather than a combination of personal, area, and 
occupational. Also, since the surrogate for DPM would be EC instead of 
TC, the sampling complications associated with avoiding OC interferents 
are eliminated (e.g. sampling too close to smokers, sampling too close 
to sources of drill oil mist, etc.).
    Mine operators should already be familiar with MSHA's sampling 
procedures for respirable dust. Because respirable dust sampling and 
DPM sampling will be so similar, and because numerous DPM sampling 
training opportunities will be made available across the industry, MSHA 
expects few if any mines will be unable to conduct their own DPM 
sampling or to comply with the DPM sampling requirements of this 
standard. Regarding the issue of mine operator DPM sampling being an 
added burden on mine safety and health staff, MSHA acknowledges that it 
is almost unavoidable that some staff time will need to be allocated to 
DPM sampling. However, MSHA does not believe that this added burden 
will be significant for most mines. A specific DPM monitoring schedule 
is not included in the standard. Mine operators are required to monitor 
as often as necessary to verify continuing compliance. Once compliance 
has been verified, MSHA would not anticipate that extensive additional 
monitoring would be required. However, if conditions affecting DPM 
emissions or in-mine DPM concentrations change significantly, such as 
by the addition of new equipment or changes in the ventilation system, 
the mine operator would be expected to verify that these changes have 
not resulted in DPM overexposures.
    (c) Is there experience with DPM sampling in other industries and 
other countries?
    One commenter suggested that many coal mine operators know enough 
about sampling to influence the outcome, and that MSHA should therefore 
use a combination of personal, area and occupational sampling to 
properly evaluate the levels of DPM in the ambient atmosphere. However, 
as noted above, MSHA believes it has sufficient enforcement authority 
to appropriately deal with any incidents of deliberate sample 
tampering, should they arise.
    Other commenters were aware that a group in Canada (DEEP) has been 
researching technology to reduce DPM in occupational settings and 
mentioned the EPA studies on diesel exposure. They did not feel the EPA 
sampling was applicable to occupational exposure assessments. Some of 
them felt that MSHA should stay its DPM enforcement until the DEEP 
study and NIOSH research yielded more data.
    MSHA is also aware of these studies and considered them during this 
rulemaking. The Agency believes that there is sufficient information 
available to support feasibility of the proposed 308EC[mu]g/
m3 interim limit, as discussed previously in this preamble 
under Technological and Economic Feasibility. As a result of the 
settlement agreement, MSHA allowed mine operators to take an additional 
year after the effective date of the existing interim DPM concentration 
limit during which mine operators could begin to install appropriate 
controls to reduce DPM concentrations.

H. Section 57.5062 Diesel Particulate Matter Control Plan

    Existing Sec.  57.5062 requires mine operators to establish a DPM 
control plan, or modify the plan, upon receiving a citation for an 
overexposure to the concentration limit in Sec.  57.5060. A single 
citation triggers the plan. A violation of the plan is citable without 
consideration of the current DPM concentration level. The operator must 
demonstrate that the new or modified plan will be effective in 
controlling the DPM concentration to the limit. The existing rule also 
sets forth a number of other specific details about the plan, including 
a description of controls that the operator will use to maintain the 
DPM concentration; a list of diesel-powered units maintained by the 
mine operator; information about each unit's emission control device; 
demonstration of the plan's effectiveness; verification sampling; 
retention of a copy of the control plan at the mine site for the 
duration of the plan plus one year; and a plan duration of three years 
from the date of the violation resulting in establishment of the plan.
    In accordance with the DPM settlement agreement, MSHA agreed to 
publish a notice of proposed rulemaking to revise current Sec.  
57.5062. The settlement agreement, however, did not specify how MSHA 
should revise this section. In the ANPRM, MSHA requested comments and 
ideas from the mining community as to how the control plan requirements 
should be revised.
    Some commenters stated that there was no reason for MSHA to change 
this provision. These commenters emphasized that control plans are good 
industrial hygiene practice and should be the standard of practice for 
the mining industry. Other commenters felt strongly that the control 
plan was unnecessary in light of MSHA's intent to propose its long-
standing hierarchy of controls for metal and nonmetal exposure-based 
standards. Some commenters opposed to a control plan stated that the 
purpose of the existing control plan was to prevent chronic excursions 
above the allowable concentration limit rather than allowing these 
excursions as part of the daily DPM control scheme. These commenters 
believed that the controls in place are sufficient to protect miners 
from DPM overexposures without introducing a cumbersome plan approval 
process. They further stated that MSHA could accomplish this through 
existing mechanisms such as section 104(b) of the Federal Mine Safety 
and Health Act of 1977 (30 U.S.C. 814) sanctions currently employed for 
failure to abate violations.
    Other commenters opposing a control plan stated that not only was 
it unnecessary, but it also imposed upon mine operators unwarranted 
costs. They suggested that MSHA assess compliance by the operator's 
environmental monitoring and MSHA compliance sampling. Furthermore, 
following a hierarchy of controls approach would ensure miners' 
protection during non-compliance. They stated that formal plans would 
add little or nothing to established systems.
    Some other comments that MSHA received on its question of whether 
to retain the control plan in a final rule included two which stated 
that a control plan was not necessary if mine operators put forth good-
faith efforts in complying with the standard; and, that MSHA could 
monitor an operator's good faith efforts and obtain supporting 
documentation during regular inspections.
    MSHA also asked in its ANPRM whether there was any benefit derived 
from retaining the control plan since the Agency intended to propose 
its long-

[[Page 48716]]

standing hierarchy of controls for controlling miners' exposures to 
DPM. In response, some commenters felt that substituting the hierarchy 
of controls for a DPM control plan would be unacceptable.
    Commenters in favor of retaining the control plan stated that it 
requires mine operators to develop an organized written approach to 
controlling exposure and does not preclude developing a policy on the 
hierarchy of controls. The effectiveness of the standard depends on 
preparing and following a detailed control plan. Commenters believe 
that control plans are cost effective by forcing operators to control 
DPM efficiently. Control plans help MSHA determine if the company is 
acting in good faith. They help compliance assistance and provide 
information for the miners' representative to participate in safety and 
health programs. Commenters believe that an alternative would be a plan 
with more specific requirements for maintenance, vehicle inspection, 
emission controls, and fuel quality.
    Although some commenters believe that a control plan is 
unnecessary, MSHA is proposing to retain this requirement. As expressed 
in the preamble to the existing rule, MSHA's rationale for requiring a 
DPM control plan is derived from the rule's approach to setting control 
requirements. MSHA recognizes that every mine covered by this rule has 
unique conditions and circumstances that affect DPM exposures such as 
the number and sizes of diesel-powered engines, idling duration and 
frequency, emission controls, diesel maintenance practices, and 
ventilation.
    The Agency is interested in developing uniform DPM control 
requirements that are effective in protecting miners' health and 
practical for the mining industry to implement. MSHA acknowledges that 
there are numerous approaches in accomplishing this objective.
    Operators may choose to control DPM emissions by filtering the 
diesel-powered equipment; installing cleaner-burning engines; 
increasing ventilation; improving fleet management; utilizing 
administrative controls; or using a variety of other readily available 
controls, all without consulting with, or seeking approval from MSHA. 
Given the wide variety of options and alternatives available to 
operators for controlling DPM exposures, the Agency believes that it 
needs to know what strategy the operator will be utilizing to control 
DPM exposures, particularly if compliance cannot be achieved within a 
short period of time.
    Although MSHA is proposing to retain the control plan, the Agency, 
however, requests further comment on whether the control plan should be 
retained since MSHA is also proposing a DPM rule that includes 
hierarchy of controls. It is not MSHA's intent to duplicate compliance 
requirements in this rulemaking.
    In proposed Sec.  57.5062, MSHA would require an operator to 
establish a written control plan, or modify an existing control plan, 
if it will take the mine operator more than 90 calendar days from the 
date of a citation to achieve compliance. A single violation of the PEL 
would continue to be the basis for triggering the requirement for a 
control plan. The control plan would remain in effect for a one-year 
period following termination of the citation. Mine operators would also 
be required to include in the plan a description of the controls that 
will be used to reduce the miners' exposures to the PEL. MSHA intends 
to cite for a violation of the plan without regard for a miner's 
exposure to the PEL. MSHA believes that these requirements would prompt 
mine operators to properly maintain existing DPM controls at their 
mines.
    Existing Sec.  57.5062(e)(1) specifies that the control plan remain 
in effect for 3 years from the date of the violation which caused it to 
be established. MSHA asked the mining community for input regarding the 
appropriate duration of a revised control plan. Commenters responded 
that if the violation was minor and easily corrected, that the control 
plan could be simple in content and brief in duration.
    MSHA believes that it is important to maintain the plan as long as 
the operator is working to reduce DPM exposures to the applicable 
limits. However, once the operator achieves compliance, MSHA believes 
that the need for maintaining a plan decreases. Accordingly, MSHA is 
proposing in Sec.  57.5062(a) that a plan remain in effect for a period 
of one year after the citation is terminated.
    MSHA does not intend to include a monitoring provision under the 
control plan because generic monitoring provisions in Sec.  57.5071 
would continue to apply during the existence of a control plan. MSHA 
expects mine operators to monitor as frequently as necessary to confirm 
that controls are effective in reducing the miners' exposure to the 
PEL. MSHA seeks further comment on the duration of time that the 
control plan should continue in effect once a citation for overexposure 
to DPM is terminated.
    Existing Sec.  57.5062(b) requires that the operator include in the 
plan a description of the controls that will be used to maintain the 
concentration of diesel particulate matter to the applicable limit 
specified by Sec.  57.5060, a list of the diesel-powered units 
maintained by the mine operator, and information about each unit's 
emission control device. MSHA is proposing to simplify the contents of 
the plan and require that it only include a description of the controls 
the operator will use to reduce the miners' exposures to the PEL. MSHA 
believes that there could be a wide variety of information that 
operators may want to include in their plan, and that it is not 
beneficial to specify a few while leaving out many others. Therefore, 
MSHA intends to provide maximum flexibility of compliance for mine 
operators. This description should include all controls that the 
operator is using to reduce miners' exposures, including engineering 
controls, administrative controls, personal protective equipment, and 
maintenance procedures, to name a few.
    Existing Sec.  57.5062(e)(3) requires an operator to modify a DPM 
control plan during its duration as required to reflect changes in 
controls, mining equipment or circumstances. MSHA did not receive any 
comments in response to its ANPRM regarding modifications to the plan.
    MSHA is proposing to retain this particular requirement consistent 
with the existing rule, with one minor modification. Proposed Sec.  
57.5062(c) would require that the operator modify the plan to reflect 
changes in controls, mining equipment, or continuing noncompliance. 
This would require mine operators to modify their plan when the results 
of sampling conducted by MSHA or the mine operator indicates that a 
miner's exposure exceeds the PEL. MSHA does not believe that this 
change will result in an increase in compliance costs or paperwork. The 
change is intended to clarify the existing provision. MSHA did not 
receive comments to its ANPRM on this issue.
    Existing Sec.  57.5062(a)(2) requires that the operator demonstrate 
that the new or modified DPM control plan parameters control the 
concentration of DPM to the concentration limit specified in Sec.  
57.5060. Mine operators must demonstrate plan effectiveness by 
monitoring, using the measurement method specified by Sec.  57.5061(b) 
which addresses compliance determinations. Such monitoring must be 
sufficient to verify that the plan will control the concentration of 
DPM to the limit under conditions that can be reasonably anticipated in 
the mine. Further, the operator must retain a copy of each

[[Page 48717]]

verification sample result at the mine site for five years. Monitoring 
must be conducted in addition to, and not in lieu of, any other 
sampling the Secretary performs.
    MSHA is proposing to delete the requirements for plan verification 
monitoring. The Agency believes that such monitoring is adequately 
addressed under Sec.  57.5071, which requires mine operators to monitor 
in order to determine, under conditions that can be reasonably 
anticipated in the mine, whether DPM exposures exceed the applicable 
limits specified in Sec.  57.5060. No monitoring frequency is specified 
under existing DPM monitoring requirements. MSHA believes that these 
requirements provide an effective alternative to the existing plan 
verification sampling requirements. Further, MSHA will conduct 
additional compliance sampling whenever the Agency suspects that 
miners' exposures to DPM are not being maintained to the PEL.
    The Agency also believes that operator sampling may not always be 
necessary to determine if controls are being used or maintained. The 
proposed control plan would require that mine operators specifically 
describe the controls being used to reduce the miners' exposures to the 
DPM limit. If MSHA finds during an inspection that specified controls 
were missing or not being maintained, MSHA has existing enforcement 
tools to require that mine operators correct the situation.
    MSHA is proposing to retain the requirement that mine operators 
keep a copy of the current control plan at the mine site for its 
duration. Existing Sec.  57.5062(f) specifies that an operator's 
failure to comply with the provisions of the diesel particulate matter 
control plan in effect at a mine, or to conduct required verification 
sampling is a violation of this part without regard for the 
concentration of diesel particulate matter that may be present at any 
time. MSHA intends to adopt this position and cite mine operators for a 
violation of the plan without consideration of a miner's exposure to 
the DPM limit. The Agency is proposing to delete this requirement in 
the rule language only and explain this enforcement position in the 
preamble.
    Existing Sec.  57.5062(d) requires the operator to provide access 
to records maintained under this section to specified individuals and 
agencies. The existing rule further requires the mine operator to 
maintain a copy of the plan and the plan verification monitoring 
results. As explained earlier in this preamble, MSHA does not believe 
that verification monitoring is justified in a proposed rule. Pursuant 
to Sec.  57.5071, MSHA has access to any record listed in the DPM rule, 
including an operator's control plan. This access, among other things, 
provides the Agency with the means to verify an operator's control plan 
without requiring additional compliance from mine operators. Therefore, 
MSHA intends to delete this requirement.
    MSHA believes that this proposal would provide an alternative 
method of protecting miners' health provided for under the existing 
standard. MSHA is interested in providing compliance flexibility to 
mine operators where such flexibility does not compromise miners' 
health or safety. The Agency is proposing to retain the current 
requirement for a control plan with modifications to eliminate 
unnecessary requirements.
    MSHA emphasizes that the proposed modifications do not compromise 
miners' health or safety under Sec.  101(a)(9) of the Mine Act. Section 
101(a)(9) provides: ``No mandatory health or safety standard 
promulgated under this title shall reduce the protection afforded 
miners by an existing mandatory health or safety standard.'' MSHA 
interprets this provision of the Mine Act to require that all of the 
health or safety benefits resulting from a new standard be at least 
equivalent to all of the health or safety benefits resulting from the 
existing standard when the two sets of benefits are evaluated as a 
whole. Int'l Union v. Federal Mine Safety and Health Admin., 920 F.2d 
960, 962-64 (D.C. Cir. 1990); Int'l Union v. Federal Mine Safety and 
Health Admin., 931 F.2d 908, 911 (D.C. Cir 1991). The Agency believes 
that the proposal meets this test.

I. Section 57.5071 Exposure Monitoring

    Proposed Sec.  57.5071 would make conforming changes to the 
existing requirements for mine operators to monitor DPM levels to be 
consistent with the other changes being proposed. While the existing 
rule limits DPM concentration in the mine, the proposed rule would 
limit a miner's DPM exposure. Therefore, existing paragraph (a) 
requiring the mine operator to monitor the concentration of DPM would 
be revised to require mine operators to monitor a miner's full-shift 
airborne exposure.
    Similarly, existing paragraph (c) requiring mine operators to take 
prompt corrective action when the concentration limit is exceeded would 
be revised to substitute ``PEL'' for ``concentration limit.''

J. Section 57.5075 Diesel Particulate Records

    Existing Sec.  57.5075(a) summarizes the recordkeeping requirements 
of the DPM standards contained in Sec. Sec.  57.5060 through 57.5071. 
Proposed Sec.  57.5075(a) would number the Diesel Particulate 
Recordkeeping Requirements table within the section without changing 
the requirements under existing Sec.  57.5075(a). MSHA intends to 
delete table entries for existing Sec.  57.5060(d), approved plan for 
miners to perform inspection, maintenance or repair activities in areas 
exceeding the concentration limit, and Sec.  57.5062(c), compliance 
plan verification sample results. MSHA intends to add the requirement 
for maintaining a copy of the control plan for the duration of the plan 
in accordance with proposed Sec.  57.5062(d). As a clarifying change to 
the table, MSHA also intends to add the existing requirement for 
posting notice of corrective action being taken under Sec.  57.5071(c).

X. Regulatory Impact Analysis

    This part of the preamble reviews several impact analyses which the 
Agency is required to provide in connection with its proposed 
rulemaking. The full text of these analyses can be found in the 
Agency's Preliminary Regulatory Economic Analysis (PREA).

A. Cost and Benefits: Executive Order 12866

    Executive Order 12866 requires regulatory agencies to assess both 
the costs and benefits of regulations. In making this assessment, MSHA 
determined that although this final rule will not have an annual effect 
of $100 million or more on the economy, and therefore is not a 
significant regulatory action as defined by 3(f)(1) of E.O. 12866, the 
rule meets the Sec.  3(f)(4) definition, that is, the rule may `` * * * 
raise novel legal or policy issues arising out of legal mandates, the 
President's priorities, or the principles set forth in this Executive 
Order.'' MSHA completed a Preliminary Regulatory Economic Analysis 
(PREA) which estimates both the costs and benefits of the rule. This 
PREA is available from MSHA and is summarized below.
    Table X-1 presents the total yearly compliance costs by provision 
and mine size for the proposed revisions. All MSHA cost estimates are 
presented in 2001 dollars. The proposed rule would result in a net cost 
of $4,539 per year for underground metal and nonmetal mine operators. 
This would be an average cost of $25 for each of the 182 underground

[[Page 48718]]

metal and non-metal mines that would be affected by this proposed rule. 
Of these 182 mines, 65 have fewer than 20 workers, 113 have 20 to 500 
workers; and 4 have more than 500 workers. The average cost per mine 
for mines in these three size classes would be -$34 (a cost savings), 
$58, and $58, respectively.

                                    Table X-1.--Total Yearly Compliance Costs
----------------------------------------------------------------------------------------------------------------
                                                                     Mine size
                    Provision                    ------------------------------------------------      Total
                                                        <20           20-500      500
----------------------------------------------------------------------------------------------------------------
Special Extensions 57.5060(c)...................          $6,179         $21,117            $748         $28,044
Respirator Protection 57.5060(d)................          -2,569          -4,466            -158          -7,192
DPM Control Plan 57.5062........................          -5,826         -10,128            -359         -16,313
                                                 -----------------
    Total.......................................          -2,215           6,523             231           4,539
----------------------------------------------------------------------------------------------------------------

B. Regulatory Flexibility Act Certification

    The Regulatory Flexibility Act (RFA) requires regulatory agencies 
to consider a rule's economic impact on small entities. Under the RFA, 
MSHA must use the Small Business Act definition of a small business 
concern in determining a rule's economic impact unless, after 
consultation with the SBA Office of Advocacy, and after opportunity for 
public comment, MSHA establishes a definition which is appropriate to 
the activities of the agency and publishes that definition in the 
Federal Register. For the mining industry, SBA defines ``small'' as 
having 500 or fewer workers. MSHA has traditionally considered small 
mines to be those with fewer than 20 workers. To ensure that the rule 
conforms with the RFA, MSHA analyzed the economic impact on mines with 
500 or fewer workers and also on mines with fewer than 20 workers. MSHA 
concluded that the rule will not have a significant economic impact on 
a substantial number of small entities under either definition.

C. Unfunded Mandates Reform Act of 1995

    For purposes of the Unfunded Mandates Reform Act of 1995, the rule 
does not include any Federal mandate that may result in increased 
expenditures of more than $100 million incurred by state, local, or 
tribal governments, or by the private sector.

D. Paperwork Reduction Act of 1995 (PRA)

    This proposed rule contains changes to two information collection 
requirements, both of which were approved by the Office of Management 
and Budget (OMB) as part of Information Collection No. 1219-0135, which 
expires on September 30, 2004.
    The proposed changes were submitted to OMB for review pursuant to 
the PRA, as codified at 44 U.S.C. 3501-3520 and implemented by OMB in 
regulations at 5 CFR part 1320. The PRA defines collection of 
information as ``the obtaining, causing to be obtained, soliciting, or 
requiring the disclosure to third parties or the public of facts or 
opinions by or for an agency regardless of form or format.''
    The proposed paperwork requirement changes are contained in 
Sec. Sec.  57.5060 and 57.5062. There are burden hours and associated 
costs that will occur only in the first year that the provision is in 
effect, and there are burden hours and associated costs that will occur 
every year the rule is in effect, starting with the first year 
(``annual'' burden hours and costs). Due to different requirements in 
these provisions for the interim and final limits, the effective dates 
vary. In the first year, mine operators will incur a net of 1,047.78 
burden hours and associated costs of $2,479. in year one.
    In year two only, mine operators will incur 613.17 burden hours and 
associated annualized costs of $1,776. There is a reduction of 931.96 
burden hours occurring only in year three. The present value of the 
cost savings associated with these burden hours is $6,343. Starting in 
year three, there is a reduction in annual burden hours of 103.55. The 
discounted value of the cost savings associated with these burden hours 
is $3,738 annually. Mine operators will incur 613.17 annual burden 
hours starting in year four. The discounted value of the cost 
associated with these burden hours is $22,161 annually.
    Included in these estimates are the time for reviewing 
instructions, gathering and maintaining the data needed, and completing 
and reviewing the collection of information. MSHA invites comments on: 
(1) Whether any proposed collection of information presented here (and 
further detailed in the Agency's PREA) is necessary for proper 
performance of MSHA's functions, including whether the information will 
have practical utility; (2) the accuracy of MSHA's estimate of the 
burden of the proposed collection of information, including the 
validity of the methodology and assumptions used; (3) ways to enhance 
the quality, utility, and clarity of information to be collected; and 
(4) ways to minimize the burden of the collection of information on 
respondents, including through the use of automated collection 
techniques, when appropriate, and other forms of information 
technology.
    The Agency has submitted a copy of this proposed rule to OMB for 
its review and approval of these information collections. The complete 
paperwork submission is contained in the Preliminary Regulatory 
Economic Analysis and Preliminary Regulatory Flexibility Analysis 
(PREA/PRFA) and includes the estimated costs and assumptions for each 
proposed paperwork requirement (these costs are also included in the 
Agency's cost and benefit analyses for the proposed rule). A copy of 
the PREA/PRFA is available at http://www.msha.gov/regsinfo.htm. These 
paperwork requirements have been submitted to the Office of Management 
and Budget for review under section 3504(h) of the Paperwork Reduction 
Act of 1995. Respondents are not required to respond to any collection 
of information unless it displays a current valid OMB control number.

F. Executive Order 12630: Government Actions and Interference With 
Constitutionally Protected Property Rights

    This proposed rule is not subject to Executive Order 12630, 
Government Actions and Interference with Constitutionally Protected 
Property Rights, because it does not involve implementation of a policy 
with takings implications.

G. Executive Order 12988: Civil Justice Reform

    The Agency has reviewed Executive Order 12988, Civil Justice 
Reform, and determined that the proposed DPM rule

[[Page 48719]]

would not unduly burden the Federal court system. The proposed rule has 
been written so as to provide a clear legal standard for affected 
conduct and has been reviewed carefully to eliminate drafting errors 
and ambiguities.

H. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    In accordance with Executive Order 13045, MSHA has evaluated the 
environmental health and safety effects of the proposed DPM rule on 
children. The Agency has determined that the proposed rule would not 
have an adverse impact on children.

I. Executive Order 13132: Federalism

    MSHA has reviewed the proposed DPM rule in accordance with 
Executive Order 13132 regarding federalism and has determined that it 
would not have any federalism implications. The proposed rule would 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.

J. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    MSHA has determined that the proposed DPM rule would not impose 
substantial direct compliance costs on Indian tribal governments.

K. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    In accordance with Executive Order 13211, the Agency has reviewed 
proposed DPM rule for its energy impacts. The rule would have no effect 
on the supply, distribution or use of energy.

L. Executive Order 13272: Proper Consideration of Small Business 
Entities in Agency Rulemaking

    In accordance with Executive Order 13272, MSHA has thoroughly 
reviewed the proposed DPM rule to assess and take appropriate account 
of its potential impact on small businesses, small governmental 
jurisdictions, and small organizations. As discussed in Chapter V of 
the PREA, MSHA has determined that the proposed rule would not have a 
significant economic impact on a substantial number of small entities.

XI. References

Al-Humadi, N. H., et al., ``The Effect of Diesel Exhaust Particles 
(DEP) and Carbon Black (CB) on Thiol Changes in Pulmonary Ovalbumin 
Allergic Sensitized Brown Norway Rats'', Exp. Lung Res., 2002 Jul-
Aug; 28(5):333-49.
Boffetta, Paolo and Silverman, Debra T., ``A Meta-Analysis of 
Bladder Cancer and Diesel Exhaust Exposure'', Epidemiology, 
2001;12(1):125-130.
Biimlnger, J., et al., ``Mutagenicity of diesel exhaust particles 
from two fossil and two plant oil fuels'', Mutagenesis, 2000 
Sep;15(5):391-7.
Carero, Don Porto A., et al., ``Genotoxic Effects of Carbon Black 
Particles, Diesel Exhaust Particles, and Urban Air Particulates and 
Their Extracts on a Human Alveolar Epithelial Cell Line (A549) and a 
Human Monocytic Cell Line (THP-1).'' Environ. Mol. Mutagen., 
2001;37(2):155-63.
Castranova V., et al., ``Effect of Exposure to Diesel Exhaust 
Particles on the Susceptibility of the Lung to Infection'', Environ. 
Health. Perspect., 2001 Aug;109 Suppl 4:609-12.
Chambellan, A., et al., ``Diesel particles and allergy: cellular 
mechanisms'', Allerg. Immunol., 2000 Feb;32(2):43-8 (French).
Chow, et al., ``Comparison of IMPROVE and NIOSH Carbon 
Measurements'', Aerosol Science and Technology, 2001;(34):23-34.
Dominici, Francesca, ``A Report to the Health Effects Institute: 
Reanalyses of the NMMAPS Database'', October 31, 2002.
Frew A. J., Salvi S., Holgate S.T., Kelly F., Stenfors N., 
Nordenh[auml]ll C., Blomberg A., Sandstr[ouml]m T., ``Low 
concentrations of diesel exhaust induce a neutrophilic response and 
upregulate IL-8 mRNA in healthy subjects but not in asthmatic 
volunteers'', Int Arch Allergy Immunol., 2001;124:324-325.
Fujimaki, H., et al., ``Induction of the imbalance of helper T-cell 
functions in mice exposed to diesel exhaust'', Sci. Total Environ., 
2001 Apr 10;270(1-3):113-21.
Fusco D., et al., ``Air Pollution and Hospital Admissions for 
Respiratory Conditions in Rome, Italy'', Eur. Respir. J., 2001 
Jun;17(6):1143-50.
Gavett S. H., et al., ``The Role of Particulate Matter in 
Exacerbation of Atopic Asthma'', Int. Arch. Allergy. Immunol., 2001 
Jan-Mar;124(1-3):109-12.
Gilmour, M. I., et al., ``Air Pollutant-enhanced Respiratory Disease 
in Experimental Animals'', Environ. Health Perspect. 2001 Aug;109 
Suppl 4:619-22.
Gustavsson, P., et al., ``Occupational Exposure and Lung Cancer 
Risk: A Population-based Case-Referent Study in Sweden'', Am. J. 
Epidemiol., 2000;152(1):32-40.
Holgate et al., 2002.
Hsiao W. L., et al., ``Cytotoxicity of PM(2.5) and PM(2.5-10) 
Ambient Air Pollutants Assessed by the MTT and the Comet Assays'', 
Mutat. Res., 2000 Nov 20;471(l-2):45-55.
International Life Sciences Institute (ILSI) Risk Science Institute 
Workshop Participants, ``The Relevance of the Rat Lung Response to 
Particle Overload for Human Risk Assessment: A Workshop Consensus 
Report'', Inhal. Toxicol., 2000 Jan-Feb;12(l-2):1-17.
Kuljukka-Rabb, T., et al., ``Time- and Dose-Dependent DNA Binding of 
PAHs Derived from Diesel Particle Extracts, Benzo[a]pyrene and 5-
Methychrysene in a Human Mammary Carcinoma Cell Line (MCF-7)'', 
Mutagenesis, 2001 Jul;16(4):353-358.
Lippmann, Morton, et al., ``Association of Particulate Matter 
Components with Daily Mortality and Morbidity in Urban 
Populations'', Health Effects Institute Research Report No. 95, 
August 2000.
Magari, S. R., et al., ``Association of heart rate variability with 
occupational and environmental exposure to particulate air 
pollution'', Circulation, 2001 Aug 28;104(9):986-991.
Moyer C. F., et al., ``Systemic Vascular Disease in Male B6C3Fl Mice 
Exposed to Particulate Matter by Inhalation: Studies Conducted by 
the National Toxicology Program'', Toxicol. Pathol., 2002 Jul-
Aug;30(4):427-34.
Nikula K. J., ``Rat Lung Tumors Induced by Exposure to Selected 
Poorly Soluble Nonfibrous Particles'', Inhal. Toxicol., 2000 Jan-
Feb;12(1-2):97-119.
Oberdorster G., ``Toxicokinetics and Effects of Fibrous and 
Nonfibrous Particles'', Inhal. Toxicol., 2002 Jan;14(1):29-56.
Ojaj[auml]rvi, I. A., et al., ``Occupational exposures and 
pancreatic cancer: a meta-analysis'', Occup. Environ. Med., 2000; 
97:316-324.
Oliver L. C., et al., ``Respiratory symptoms and lung function in 
workers in heavy and highway construction: a cross-sectional 
study'', Am. J. Ind. Med., 2001 Jul;40(1):73-86.
Patton L., et al., ``Effects of Air Pollutants on the Allergic 
Response'', Allergy. Asthma. Proc., 2002 Jan-Feb;23(l):9-14.
Patton and Lopez, 2002.
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Environ. Health. Perspect., 2002 Aug;110 Suppl 4:565-8.
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Motor Vehicles: A Putative Proallergic Hazard?'', Can. Respir. J., 
1999;6(5):436-441.
Polosa, et al., 2002 (Italian).
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and Long-term Exposure to Fine Particulate Air Pollution'', JAMA, 
2002;287(9):1132-1141.
Saito, Y., et al., ``Long-Term Inhalation of Diesel Exhaust Affects 
Cytokine Expression in Murine Lung Tissues: Comparison Between Low- 
and High-Dose Diesel Exhaust Exposure'', Exp. Lung Res., 2002 Sep; 
28(6):493-506.
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Samet, Jonathan M., et al., ``The National Morbidity, Mortality, and 
Air Pollution Study-Part II: Morbidity and Mortality From Air 
Pollution in the United States'', Health Effects Institute Research 
Report No. 94, June 2000.
Salvi, S., et al., ``Acute exposure to diesel exhaust increases IL-8 
and GRO-alpha production in healthy human airways'', Am J. Respir. 
Crit Care Med., 2000Feb;161(2Pt1):550-7.

[[Page 48720]]

Sato H., et al., ``Increase in Mutation Frequency in Lung of Big 
Blue Rat by Exposure to Diesel Exhaust'',
Carcinogenesis, 2000 Apr;21(4):653-61.
Saverin R., et al., ``Diesel Exhaust and Lung Cancer Mortality in 
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Respir. J., 2000 Apr;15(4):716-24.
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Eur. Respir. J., 2001 Apr;17 (4):733-46.
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of Diesel Emission: An Epidemiological Review'', Med. Pr., 
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Particles Display Distinct Th1/Th2 Modulating Activity'', Toxicol. 
Appl. Pharmacol., 2000 Oct 15;168:131-139.
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Particulate Matter (PM) Air Pollutants'', Neurotoxicology, 2001 Dec; 
22(6):795-810.
Vincent, R., et al., ``Inhalation Toxicology of Urban Ambient 
Particulate Matter: Acute Cardiovascular Effects in Rats'', Res. 
Rep. Health Eff. Inst., 2001 Oct;(104):5-54; discussion 55-62.
Walters D. M., et al., ``Ambient Urban Baltimore Particulate-induced 
Airway Hyperresponsiveness and Inflammation in Mice'', Am. J. 
Respir. Crit. Care Med., 2001 Oct 15;164(8 Pt l):1438-43.
Wichmann, H. Erich, et al., ``Daily Mortality and Fine and Ultrafine 
Particles in Erfurt, Germany--Part I: Role of Particle Number and 
Particle Mass'', Health Effects Institute Research Report No. 98, 
November 2000.
Whitekus M. J., et al., ``Thiol Antioxidants Inhibit the Adjuvant 
Effects of Aerosolized Diesel Exhaust Particles in a Murine Model 
for Ovalbumin Sensitization'', Immunol., 2002 Mar l;168(5):2560-7.
Yu, J. Z., Xu, J. H. and Yang, H., ``Charring Characteristics of 
Atmospheric Organic Particulate Matter in Thermal Analysis'', 
Environmental Science & Technology,[deg] 2002;36(4):754-761.
Yang, Hong and Yu, Jian, ``Uncertainties in Charring Correction in 
the Analysis of Elemental and Organic Carbon in Atmospheric 
Particles by Thermal/Optical Methods'', Environmental Science and 
Technology, 2002;36:5199-5204
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Netherlands'', Occup. Environ. Med., 2001 Sep;58(9)V:590-6.

List of Subjects in 30 CFR Part 57

    Diesel particulate matter, Metals, Mine safety and health, 
Reporting and recordkeeping requirements.

    For the reasons set forth in the preamble, MSHA proposes to amend 
Chapter I of Title 30 as follows:
    1. The authority citation for part 57 continues to read as follows:


    Authority: 30 U.S.C. 811 and 813.

    2. Section 57.5060 is amended by revising paragraphs (a), (c)(1), 
(c)(2), (c)(3), (c)(4), (d), and (e) and removing paragraphs (c)(5) and 
(f) to read as follows:


Sec.  57.5060  Limit on concentration of diesel particulate matter.

    (a) A miner's personal exposure to diesel particulate matter (DPM) 
in an underground mine shall not exceed an average eight-hour 
equivalent full shift airborne concentration of 308 micrograms of 
elemental carbon per cubic meter of air (308EC [mu]g/
m3). [This interim permissible exposure limit (PEL) shall 
remain in effect until the final DPM exposure limit becomes effective.]
* * * * *
    (c)(1) If a mine requires additional time to come into compliance 
with the applicable limits established in paragraphs (a) and (b) of 
this section due to technological or economic constraints, the operator 
of the mine may file an application with the district manager for a 
special extension.
    (2) The mine operator must certify on the application that the 
operator has posted one copy of the application at the mine site for at 
least 30 days prior to the date of application, and has provided 
another copy to the authorized representative of miners.
    (3) No approval of a special extension shall exceed a period of one 
year from the date of approval. Mine operators may file for additional 
special extensions provided each extension does not exceed a period of 
one year. An application must include the following information:
    (i) A statement that diesel-powered equipment was used in the mine 
prior to October 29, 1998;
    (ii) Documentation supporting that controls are technologically or 
economically infeasible at this time to reduce the miner's exposure to 
the DPM limit.
    (iii) The most recent DPM monitoring results.
    (iv) The actions the operator will take during the extension to 
minimize exposure of miners to DPM.
    (4) A mine operator must comply with the terms of any approved 
application for a special extension, post a copy of the approved 
application for a special extension at the mine site for the duration 
of the special extension period, and provide a copy of the approved 
application to the authorized representative of miners.
    (d) The mine operator shall install, use, and maintain feasible 
engineering and administrative controls to reduce a miner's exposure to 
or below the DPM limit established in this section. When controls do 
not reduce a miner's DPM exposure to the limit, controls are 
infeasible, or controls do not produce significant reductions in DPM 
exposures, controls shall be used to reduce the miner's exposure to as 
low a level as feasible and shall be supplemented with respiratory 
protection in accordance with Sec.  57.5005(a), (b), and paragraphs 
(d)(1) and (d)(2) of this section.
    (1) Air purifying respirators shall be equipped with the following:
    (i) Filters certified by NIOSH under 30 CFR part 11 (appearing in 
the July 1, 1994 edition of 30 CFR, parts 1 to 199) as a high 
efficiency particulate air (HEPA) filter;
    (ii) Filters certified by NIOSH under 42 CFR part 84 as 99.97% 
efficient; or
    (iii) Filters certified by NIOSH for diesel particulate matter.
    (2) Nonpowered, negative-pressure, air purifying, particulate-
filter respirators shall use an R- or P-series filter or any filter 
certified by NIOSH for diesel particulate matter. An R-series filter 
shall not be used for longer than one work shift.
    (e) Rotation of miners shall not be considered an acceptable 
administrative control used for compliance with this section.
    3. Section 57.5061 is revised to read as follows:


Sec.  57.5061  Compliance determinations.

    (a) MSHA shall use a single sample collected and analyzed by the 
Secretary in accordance with the requirements of this section as an 
adequate basis for a determination of noncompliance with the DPM limit.
    (b) The Secretary will collect samples of diesel particulate matter 
by using a respirable dust sampler equipped with a submicrometer 
impactor and analyze the samples for the amount of elemental carbon 
using the method described in NIOSH Analytical Method 5040, except that 
the Secretary also may use any methods of collection and analysis 
subsequently determined by NIOSH to provide equal or improved accuracy 
for the measurement of diesel particulate matter.
    (c) The Secretary will use full-shift personal sampling for 
compliance determinations.
    4. Section 57.5062 is revised to read as follows:


Sec.  57.5062  Diesel particulate matter control plan.

    (a) When it will take the operator more than 90 calendar days from 
the

[[Page 48721]]

date of a citation for violating Sec.  57.5060 to achieve compliance, 
the operator shall establish and implement a written plan to control 
the miner's exposure. The plan shall remain in effect for a period of 
one year after the citation is terminated.
    (b) The plan must include a description of the controls the 
operator will use to reduce the miner's exposure to the DPM limit.
    (c) The operator must modify the plan to reflect changes in 
controls, mining equipment, or continuing noncompliance.
    (d) The operator must retain a copy of the plan at the mine site 
for the duration of the plan.
    5. Section 57.5071 is amended by revising the section heading and 
by revising paragraphs (a) and (c) to read as follows:


Sec.  57.5071  Exposure monitoring.

    (a) Mine operators must 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 specified in Sec.  
57.5060.
* * * * *
    (c) If any monitoring performed under this section indicates that a 
miner's exposure to diesel particulate matter exceeds the DPM limit 
specified in Sec.  57.5060, the operator must promptly post notice of 
the corrective action being taken on the mine bulletin board, initiate 
corrective action by the next work shift, and promptly complete such 
corrective action.
* * * * *
    6. Section 57.5075 is amended to revise paragraph (a) to read as 
follows:


Sec.  57.5075  Diesel particulate records.

    (a) Table 57.5075(a), ``Diesel Particulate Recordkeeping 
Requirements'' lists the records the operator must retain pursuant to 
Sec. Sec.  57.5060 through 57.5071, and the duration for which 
particular records need to be retained.

                        Table 57.5075(a).--Diesel Particulate Recordkeeping Requirements
----------------------------------------------------------------------------------------------------------------
                   Record                            Section reference                   Retention time
----------------------------------------------------------------------------------------------------------------
1. Approved application for extension of     Sec.   57.5060(c)................  Duration of extension.
 time to comply with exposure limits.
2. Control plan............................  Sec.   57.5062(a)................  Duration of plan.
3. Purchase records noting sulfur content    Sec.   57.5065(a)................  1 year beyond date of purchase.
 of diesel fuel.
4. Maintenance log.........................  Sec.   57.5066(b)................  1 year after date any equipment
                                                                                 is tagged.
5. Evidence of competence to perform         Sec.   57.5066(c)................  1 year after date maintenance
 maintenance.                                                                    performed.
6. Annual training provided to potentially   Sec.   57.5070(b)................  1 year beyond date training
 exposed miners.                                                                 completed.
7. Record of corrective action.............  Sec.   57.5071(c)................  Until the citation is
                                                                                 terminated.
8. Sampling method used to effectively       Sec.   57.5071(d)................  5 years from sample date.
 evaluate particulate concentration, and
 sample results.
----------------------------------------------------------------------------------------------------------------

* * * * *

    Dated: July 25, 2003.
Dave D. Lauriski,
Assistant Secretary of Labor for Mine Safety and Health.
[FR Doc. 03-20190 Filed 8-13-03; 8:45 am]
BILLING CODE 4510-43-P