[Federal Register: June 6, 2005 (Volume 70, Number 107)]
[Rules and Regulations]
[Page 32867-32968]
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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; Final Rule
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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: Final rule.
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SUMMARY: This final rule revises MSHA's existing standards addressing
diesel particulate matter (DPM) exposure in underground metal and
nonmetal (M/NM) mines. In this final rule, MSHA changes the 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. Also, this
final rule increases flexibility of compliance for mine operators by
requiring MSHA's longstanding hierarchy of controls for its other
exposure-based health standards at M/NM mines, but retains the
prohibition on rotation of miners for compliance. Furthermore, this
final rule: Requires MSHA to consider economic as well as technological
feasibility in determining if operators qualify for an extension of
time in which to meet the final DPM limit; deletes the requirement for
a control plan; and makes conforming changes to existing provisions
concerning compliance determinations, environmental monitoring and
recordkeeping.
DATES: Effective Date: The final rule is effective on July 6, 2005.
FOR FURTHER INFORMATION CONTACT: Office of Standards, Regulations, and
Variances, MSHA, 1100 Wilson Blvd., Room 2350, Arlington, Virginia
22209-3939; 202-693-9440 (telephone); or 202-693-9441 (facsimile).
You may obtain copies of this final rule and the Regulatory
Economic Analysis (REA) in alternative formats by calling 202-693-9440.
The alternative formats available are either a large print version of
these documents or electronic files that can be sent to you either on a
computer disk or as an attachment to an e-mail. The documents also are
available on the Internet at http://www.msha.gov/REGSINFO.HTM.
SUPPLEMENTARY INFORMATION:
Outline of Preamble
This outline will assist the mining community in finding
information in this preamble.
I. List of Common Terms
II. Rulemaking Background
A. First Partial Settlement Agreement
B. Second Partial Settlement Agreement
III. The Final PEL
IV. The 31-Mine Study
A. Summary
B. Subsequent Activities
V. Compliance Assistance
A. Baseline Sampling
B. DPM Control Technology
VI. DPM Exposures and Risk Assessment
A. Introduction
B. DPM Exposures in Underground M/NM Mines
C. Health Effects
D. Significance of Risk
VII. Feasibility
A. Background
B. Technological Feasibility
C. Economic Feasibility
VIII. Summary of Costs and Benefits
IX. Section-by-Section Analysis
X. Distribution Table
XI. Regulatory Impact Analysis
XII. References Cited
I. List of Common Terms
Listed below are the common terms used in the preamble.
Commission........................ Federal Mine Safety and Health
Review Commission.
CV................................ coefficient of variation.
DE................................ diesel exhaust.
DOCs.............................. diesel oxidation catalysts.
DPF............................... diesel particulate filter.
DPM............................... diesel particulate matter.
EC................................ elemental carbon.
ETS............................... environmental tobacco smoke.
Filter Selection Guide............ Diesel Particulate Filter. Selection
Guide for Diesel-powered Equipment
in Metal and Nonmetal Mines.
First Partial Settlement Agreement 66 FR 35518 (2001) & 66 FR 35521
(2001): basis for July 5, 2001
NPRM.
HEI............................... Health Effects Institute.
HWE............................... healthy worker effect.
MARG.............................. Methane Awareness Resource Group.
M/NM.............................. metal/non-metal.
MSHA.............................. Mine Safety and Health
Administration.
NIOSH............................. National Institute for Occupational
Safety and Health.
NTP............................... National Toxicology Program.
OC................................ organic carbon.
PAPR.............................. powered air-purifying respirator.
PEL............................... permissible exposure limit.
PPM............................... parts per million.
QRA............................... quantitative risk assessment.
REA............................... Regulatory Economic Analysis.
Second Partial Settlement 67 FR 47296 (2002): basis for August
Agreement. 14, 2003 NPRM.
SD................................ standard deviation.
SKC............................... SKC, Inc.
TC................................ total carbon.
USWA.............................. United Steelworkers of America.
[mu]g/cm \2\...................... micrograms per square centimeter.
[mu]g/m \3\....................... micrograms per cubic meter.
2001 final rule................... January 19, 2001 DPM final rule.
Amended 2001 final rule........... 2001 final rule amended on February
27, 2002.
2002 final rule................... February 27, 2002 final rule.
2002 ANPRM........................ Advance Notice of Proposed
Rulemaking published on September
25, 2002.
2003 NPRM......................... Notice of Proposed Rulemaking
published on August 14, 2003.
II. Rulemaking Background
On January 19, 2001, MSHA published a final rule (2001 final rule)
addressing DPM exposure in underground M/NM mines (66 FR 5706), amended
on February 27, 2002 at 67 FR 9180 (2002 final rule). The 2001 final
rule established new health standards for underground M/NM mines that
use equipment powered by diesel engines. The effective date of the 2001
final 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 2001 final rule in the District of
Columbia Circuit Court of Appeals. On February 7, 2001, the Georgia
Mining Association, the National Mining Association (NMA), 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
2001 final rule and for postponement of the effective date of the 2001
final rule pending judicial review. The Georgia Mining Association
petitioners similarly filed with MSHA a request for an administrative
stay or postponement of the effective date of the 2001 final rule. On
March 15, 2001, MSHA delayed the effective date of the 2001 final 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 document in the Federal Register
delaying the effective date of the 2001 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 the 2001 final rule.
A. First Partial DPM 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 2001 final 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 2001 final rule; and included correcting amendments.
The second document (66 FR 35521) proposed a rule to clarify Sec.
57.5066(b)(1) and (b)(2) regarding maintenance and to add a new
paragraph (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) (2002 final rule), 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 M/NM mines to
determine existing concentration levels of DPM; to assess the
performance of the SKC, Inc., Eighty Four, PA (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 M/NM underground mining environment before the limits
established in the final rule became effective. The final report was
issued on January 6, 2003.
B. Second Partial Settlement Agreement
Settlement negotiations continued on the remaining unresolved
issues in the litigation. On July 15, 2002, the parties signed an
agreement (second partial settlement agreement) that formed the basis
for MSHA's August 14, 2003 proposed rule (68 FR 48668) (2003 NPRM). On
July 18, 2002, MSHA published a document in the Federal Register (67 FR
47296) announcing, among other things, that the following provisions of
the 2001 final rule would become effective on July 20, 2002:
Sec. 57.5060(a), Addressing the interim concentration
limit of 400 micrograms of TC per cubic meter of air;
Sec. 57.5061, Compliance determinations; and
Sec. 57.5071, Environmental monitoring.
The document also announced that the following provisions of the
rule would continue in effect:
Sec. 57.5065, Fueling practices;
Sec. 57.5066, Maintenance standards;
Sec. 57.5067, Engines;
Sec. 57.5070, Miner training; and
Sec. 57.5075, Diesel particulate records, as they relate
to the requirements of the rule that went into effect on July 20, 2002.
The document also stayed the effectiveness of the following
provisions pending completion of this final rule:
Sec. 57.5060(d), Permitting miners to work in areas where
the level of DPM exceeds the applicable concentration limit with
advance approval from the Secretary;
Sec. 57.5060(e), Prohibiting the use of personal
protective equipment (PPE) to comply with the concentration limits;
Sec. 57.5060(f) Prohibiting the use of administrative
controls to comply with the concentration limits; and
Sec. 57.5062, DPM control plan.
Finally, the July 18, 2002, document 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 (2002 ANPRM) (67 FR 60199) to amend certain provisions of
the 2001 DPM rule.
The comment period closed on November 25, 2002. MSHA received
comments from underground M/NM mine operators, trade associations,
organized labor, public interest groups and individuals. On August 14,
2003, MSHA published the 2003 NPRM in the Federal Register (68 FR
48668) recommending certain revisions to the DPM rule as part of a
settlement agreement reached in response to a legal challenge to the
DPM standard. Public hearings were held in Salt Lake City, Utah; St.
Louis, Missouri; Pittsburgh, Pennsylvania; and Arlington, Virginia in
September and October 2003. The comment period closed on October 14,
2003. On February 20, 2004, MSHA published a document in the Federal
Register announcing a limited reopening of the comment period on the
2003 NPRM. This document reopened the comment period to obtain public
input on three new documents related to the August 14, 2003 rulemaking
(69 FR 7881). The three documents were as follows:
(1) United States (U.S.) Department of Health and Human Services,
Center for Disease Control, National Institute of Occupational Safety
and Health, ``The Effectiveness of Selected Technologies in Controlling
Diesel Emissions in an Underground Mine--Isolated Zone Study at
Stillwater Mining Company's Nye Mine,'' January 5, 2004.
(2) U.S. Department of Labor, Bureau of Labor Statistics, and U.S.
Department of Health and Human Services, Center for Disease Control,
National Institute of Occupational Safety and Health, ``Respirator
Usage in Private Sector Firms, 2001,'' September, 2003.
(3) Chase, Gerald, ``Characterizations of Lung Cancer in Cohort
Studies and a NIOSH Study on Health Effects of Diesel Exhaust in
Miners,'' undated, received January 5, 2004.
The subsequent comment period closed on April 5, 2004. MSHA
received and reviewed written and oral statements on the 2003 NPRM from
all segments of the mining community.
MSHA informed the mining community in both its 2002 ANPRM and its
2003 NPRM of its intentions to incorporate into the record of the
current rulemaking the existing rulemaking record, including the risk
assessment to the 2001 final rule. Commenters were encouraged to submit
additional evidence of new scientific data related to health risks to
underground M/NM miners from exposure to DPM.
This final rule for DPM exposure at M/NM mines is based on
consideration of the entire rulemaking record, including all written
comments and exhibits received related to the 2001 final rule as well
as all related data received to the close of this rulemaking record. To
serve the interest of the mining community, MSHA is revising Sec. Sec.
57.5060, 57.5061, 57.5071, and 57.5075 and republishing Sec. Sec.
57.5065, 57.5066, 57.5067, and 57.5070 of the DPM standards at 30 CFR
part 57 in order to present all sections in their entirety in this
document. What follows is a discussion of the specific revisions to the
2001 DPM standard:
Sec. 57.5060(a) addressing the interim limit on
concentration of DPM. MSHA has changed the 2001 final rule's interim
concentration limit of 400 micrograms of TC per cubic meter of air
(400TC [mu]g/m3) to a comparable permissible
exposure limit of 308 micrograms of EC per cubic meter of air
(308EC [mu]/m3);
Sec. 57.5060(c) addressing application and approval
requirements for an extension of time in which to reduce the final DPM
limit. MSHA has changed the 2001 final rule by requiring MSHA to
consider economic feasibility along with technological feasibility
factors in weighing whether to grant special extensions; has deleted
the limit on the number of special extensions that may be granted to
each mine; has limited each extension to a period of one year; has
allowed for annual renewals of special extensions; and has allowed the
MSHA District Manager, rather than the Secretary, to grant extensions.
This final rule retains the scope of the 2001 provision for operators
to apply for extensions to the final DPM limit;
Sec. 57.5060(d) addressing certain exceptions to the
concentration limits;
Sec. 57.5060(e) prohibiting use of PPE to comply with the
concentration limits;
Sec. 57.5060(f) prohibiting use of administrative
controls to comply with the concentration limits. MSHA has changed the
2001 final rule by implementing the current hierarchy of controls as
adopted in MSHA's other exposure-based health standards for M/NM mines.
MSHA's hierarchy includes primacy of engineering and administrative
controls to the extent feasible to reduce a miner's exposure to the
PEL, but MSHA continues to prohibit rotation of miners for compliance
purposes. If a miner's exposure cannot be reduced to the PEL with use
of feasible controls, controls are infeasible, or do not produce
significant reductions in DPM exposures, the new final rule requires
mine operators to supplement a miner's protection with respirators and
implement a respiratory protection program. This respiratory protection
program must meet the requirements in existing 30 CFR 57.5005, but
miners may only use the respirator filters specified by MSHA for DPM in
this section. Therefore, MSHA removes the 2001 prohibition against use
of respiratory protection without approval by the Secretary and
clarifies that use of administrative controls other than rotation of
miners is allowed;
Sec. 57.5062, addressing the diesel particulate control
plan. This final rule removes the existing requirement for a DPM
control plan; and
conforming changes to the following existing standards
that were proposed on August 14, 2003:
[cir] Sec. 57.5061, addressing compliance determinations;
[cir] Sec. 57.5071, addressing exposure monitoring; and,
[cir] Sec. 57.5075, addressing recordkeeping requirements.
This final rule does not include provisions for written procedures
for administrative controls, a written respiratory protection program,
medical examination of miners before they are required to wear
respiratory protection, and medical transfer of miners who are unable
to wear respiratory protection for medical and psychological reasons.
III. The Final Concentration Limit
In the 2002 ANPRM, 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 2001 final rule. 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. In the 2003 NPRM, MSHA agreed with these
commenters and solicited other information from the mining community
that would lead to an appropriate final DPM standard. Moreover, MSHA
announced its intentions to publish a separate rulemaking to amend the
existing final concentration limit in Sec. 57.5060(b). To assist MSHA
in achieving this purpose, MSHA requested comments on an appropriate
final permissible exposure limit rather than a concentration limit; and
asked for information on an appropriate surrogate for measuring miners'
DPM exposures. MSHA concluded its request for information by clarifying
that revisions to the final DPM concentration limit would not be a part
of this rulemaking.
In their comments to the 2003 NPRM, organized labor requested that
MSHA lower the final DPM limit below 160 micrograms based on
feasibility data and the significance of the health risks from exposure
to DPM. Industry trade associations and individual mine operators
recommended that MSHA repeal the final limit based on issues related to
health effects, inability of the mining industry to meet a lower limit
than 400 micrograms per cubic meter of air, and the need for MSHA to
have the results from the National Institute for Occupational Safety
and Health/National Cancer Institute (NIOSH/NCI) study and exposure-
response data.
MSHA believes that evidence in the current DPM rulemaking record is
inadequate for MSHA to make determinations regarding revision to the
final DPM limit.
IV. The 31-Mine Study
A. Summary
On January 19, 2001, MSHA published a final standard addressing
exposure of underground metal and nonmetal miners to diesel particulate
matter (DPM). The standard contained staggered effective dates for
interim and final concentration limits. The standard was challenged by
industry trade associations and several mining companies, and the
United Steelworkers of America (USWA) intervened in the litigation. The
parties agreed to resolve their differences through settlement
negotiations with MSHA. Thereafter, MSHA delayed the effective date of
certain provisions of the standard. As part of the settlement
negotiations, MSHA agreed to conduct joint sampling with the litigants
at 31 metal and nonmetal underground mines covered by the standard 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.
(Executive Summary, Report on the 31-Mine Study)
MSHA requested that NIOSH peer review the draft Report on the 31-
Mine Study, and NIOSH's conclusions were as follows:
1. Most mines have DPM concentrations higher than
400TC [mu]g/m\3\.
2. The impactor was effective in eliminating mineral dust from
collecting onto the filter analyzed for carbon by NIOSH Method 5040.
3. The ANFO data was inconclusive.
4. Oil mist from the stoper drill is a sub-micron aerosol and a
potential interference. Oil mist contamination from the driller can
be avoided by sampling upstream of stope or far enough downstream
that the oil mist has been diluted enough to give minimal TC
concentrations (if this type of sampling is possible).
5. No information about the interference of environmental
tobacco smoke is present in this report.
6. The inter-laboratory comparison of the NIOSH method 5040 of
paired punches from the same filter showed reasonable agreement
between MSHA results and commercial laboratory results and excellent
agreement between MSHA and NIOSH laboratory results. (Summary of
Findings of this Report in ``NIOSH Comments and recommendations on
the MSHA DRAFT report: Report on the Joint MSHA/Industry Study:
Determination of DPM Levels in Underground Metal and Nonmetal
Mines,'' dated June 3, 2002)
On January 6, 2003, MSHA issued its final report entitled, ``MSHA's
Report on Data Collected During a Joint MSHA/Industry Study of DPM
Levels in Underground Metal And Nonmetal Mines'' (Report on the 31-Mine
Study). MSHA's 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 * * * (Executive Summary, Report on the
31-Mine Study)
MSHA's complete report on the 31-Mine Study is contained in the
rulemaking record.
MSHA and NIOSH have reviewed the performance characteristics of the
SKC sampler, and are satisfied that it accurately measures exposures to
DPM. NIOSH found in laboratory and field data that the SKC DPM cassette
collected DPM efficiently. In a side protocol of the 31-Mine Study,
MSHA tested the efficiency of the SKC DPM cassette to avoid mineral
dust in four different mines and did not measure any mineral dust on
the filter when the SKC DPM cassette was used. This was confirmed by
laboratory results at NIOSH. (Noll, J. D., Timko, R. J., McWilliams,
L., Hall, P., Haney, R., ``Sampling Results of the Improved SKC Diesel
Particulate Matter Cassette,'' JOEH, 2005 Jan; 2(1):29-37.)
Results of the 31-Mine Study and the MSHA baseline compliance
assistance sampling demonstrated that the SKC submicron impactor
removed potential interferences from mineral dust from the collected
sample.
Interference from drill oil mist was found on personal samples
collected on the stoper and jackleg 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 an
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.
MSHA has found that the use of EC eliminates potential sampling
interference from drill oil mist, tobacco smoke, and organic solvents,
and that EC 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 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.
As part of the 31-Mine Study, representatives from MSHA, NIOSH, and
SKC met to address the following issues:
The quality of manufactured SKC DPM cassettes;
The feasibility of adding a dynamic blank filter to the
SKC DPM cassette; and
The possibility of putting a number on each SKC DPM
cassette.
Also, in its October 16, 2001 letter, MSHA informed SKC about the
problems that MSHA and the industry encountered using the SKC DPM
sampling cassette with the submicron impactor. These problems included:
dark flecks, alleged leaks, loose fitting nozzles and connectors, and
difficulty in shipping the sampler. As discussed in the report on the
31-Mine Study, SKC was responsive in addressing those concerns.
B. Subsequent Activities
Some industry commenters continued to state that the sampling and
analytical processes for DPM are too new for regulatory use. Other
commenters questioned the availability and reliability of the SKC
impactor.
MSHA moved expeditiously to help resolve the back-order and
manufacturing delays for samplers reported in the 31-Mine Study.
However, operators who sample alongside MSHA continued to request 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.
Some commenters stated that SKC changed the impactor, and that
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 organic carbon (OC) from the polystyrene assembly onto the
filter media and increasing TC measurement. These commenters questioned
MSHA's changes to the SKC sampler following completion of the 31-Mine
Study, and suggested that a defect to the sampler could have affected
the results of the study. 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.
Prior to the 31-Mine Study, MSHA had determined the deposit area of
the sample filter to be 9.12 square centimeters (cm\2\) with a standard
deviation of 3.1 percent (%). During the initial phases of the sampling
analysis 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
(measured in cm\2\) is multiplied by the results of the analysis
(micrograms per cm\2\) 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. With the cooperation of MSHA and the technical recommendations
and extensive experimental verification by NIOSH, SKC was able to
modify their cassette design to produce a consistent and regular DPM
deposit area, satisfactorily resolving the problem. 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 millimeter (32-mm) ring. This was done to give a more uniform
deposit area (8.04 cm\2\) with negligible variability, 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 38-mm filters also eliminate cassette leakage around
the filters. These modifications were completed and incorporated into
units manufactured after November 1, 2002.
The results of this project were prepared into a scientific
publication, ``Sampling Results of the Improved SKC Diesel Particulate
Matter Cassette,'' referenced above. This paper has been peer reviewed
and was published in January 2005. The following abstract was prepared
for the study results:
Diesel particulate matter (DPM) samples from underground metal/
non-metal mines are collected on quartz fiber filters and measured
for carbon content using National Institute for Occupational Safety
and Health Method 5040. If size selective samplers are not used to
collect DPM in the presence of carbonaceous ore dust, both the ore
dust and DPM will collect on the quartz filters, causing the carbon
attributed to DPM to be artificially high. Because the DPM particle
size is much smaller than that of mechanically generated mine dust
aerosols, it can be separated from the larger mine dust aerosol by a
single stage impactor. The SKC DPM cassette is a single stage
impactor designed to collect only DPM aerosols in the presence of
carbonaceous mine ore aerosols, which are commonly found in
underground nonmetal mines. However, there is limited data on how
efficiently the SKC DPM cassette can collect DPM in the presence of
ore dust. In this study, we investigated the ability of the SKC DPM
cassette to collect DPM while segregating ore dust from the sample.
We found that the SKC DPM cassette accurately collected DPM. In the
presence of carbon-based ore aerosols having an average
concentration of 8 mg/m3, no ore dust was detected on SKC
DPM cassette filters. We did discover a problem: the surface areas
of the DPM deposits on SKC DPM cassettes, manufactured prior to
August 2002, were inconsistent. To correct this problem, SKC
modified the cassette. The new cassette produced, with 99%
confidence, a range of DPM deposit areas between 8.05 and 8.28
cm2, a difference of less than 3%.
Because the design of the inlet cyclone, impaction nozzles, and 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 during the 31-Mine Study. 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 use of EC 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 OC measurements. These two issues do not apply to an EC
measurement. Once the cassettes have been preheated during
manufacturing, there is no source, other than sampling, to add EC to
the sealed cassette filters.
MSHA discussed in the preamble to the 2003 NPRM issues related to
interferences, field blanks and the error factor. Some comments on the
2003 NPRM still expressed concerns on interferences and further stated
that the MSHA industrial hygiene studies, conducted to verify the
magnitude of the interference problem, were not published or peer
reviewed and should be removed from the rulemaking record. However,
MSHA, organized labor, and the mining industry, through the
negotiations process, jointly developed the protocol for conducting the
31-Mine Study. All of the parties agreed on the protocol following
numerous discussions among industry, labor, and government experts, and
had an opportunity to comment and make changes to the document.
Thereafter, MSHA conducted the study, following the agreed upon
protocol, and published its results. Before publication, the report was
peer reviewed by NIOSH. Industry was given an opportunity to publish
their separate results simultaneously with the government. During this
rulemaking, industry submitted to MSHA through the notice and comment
process their conclusions on the 31-Mine Study in a report titled,
``Technical and Economic Feasibility of DPM Regulations.'' The industry
report is contained in the rulemaking record, and was considered by
MSHA in reaching determinations for this final rule.
(1) Interferences
In response to the question on whether there are interferences when
EC is used as the surrogate, some commenters stated that interferences
were thoroughly discussed in the preamble to the 2001 final rule, 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.
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. These commenters then
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. However, no data
were presented to support this claim or conclusion. Commenters
submitted no new information relative to interferences in response to
the 2003 NPRM.
(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 filter, which provides
a separate control filter for each sample. This is a much more flexible
method of sampling for the mining industry, since it eliminates the
need to send a separate control filter to the analytical lab. MSHA
informed the public of its intentions to adjust the EC result obtained
for each sample by the result obtained for the corresponding media
blank when MSHA measures for compliance purposes. When MSHA conducts
compliance measurements, MSHA will adjust the result obtained for each
corresponding sample by the field blank (tandem filter) result. No
comments or information related to field blanks were submitted to MSHA
in response to the 2003 NPRM.
In its comments on the 2002 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 (such as oils) during handling. However, such
contamination is irrelevant when EC is the surrogate.
(3) Error Factor
MSHA intends to cite a violation of the DPMEC exposure
limit only when MSHA has valid evidence that a violation actually
occurred. As with all other measurement-based M/NM compliance
determinations, MSHA will issue a citation only if a measurement
demonstrates noncompliance with at least 95% confidence. MSHA will
achieve this 95% confidence level by comparing each EC measurement to
the EC exposure limit multiplied by an appropriate error factor.
Generally, an error factor is used to compensate for certain known
inaccuracies in the sampling and analytical process, including such
things as the reliability of sampling equipment and precision of
analytical instrumentation. MSHA will continue to determine that an
overexposure has occurred when a sample exceeds the interim limit times
the error factor.
In this rulemaking, MSHA is discussing the procedure used to obtain
the error factor. This procedure is further discussed on the MSHA web
site at http://www.msha.gov under, ``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 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
involved in making an eight-hour equivalent full-shift measurement of
EC concentration using NIOSH 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. Variability of the filter deposit
area was represented by a 3.1% 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% (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, but
not by enough to be of any practical significance.
MSHA's error factor model accounts for the joint and related
variability in laboratory analysis, and combines that variability with
pump flow rate, sample collection size, and other sampling and analytic
variables. MSHA was then able to determine the appropriate error factor
for EC samples based on a statistically strong database.
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. 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 compared
two punches taken from different locations on the same filter to
evaluate the accuracy of the analytical method. Therefore, variability
between punch results due to their location on the filter is also
included in the error factor as calculated by MSHA.
Commenters to the 2003 NPRM further questioned whether the NIOSH
Method 5040 has been commercially tested. As in the preamble to the
2003 NPRM, MSHA has discussed in detail its findings regarding the
NIOSH Method 5040 in this section. NIOSH's peer review of the 31-Mine
Study also concludes that the analytical method specified by the diesel
standard gives an accurate measure of the TC content of a filter
sample. NIOSH confirmed this position by letter of February 8, 2002, in
which NIOSH stated that,
MSHA is following the procedures of NIOSH Method 5040, based on our
review of MSHA P13 (MSHA's protocol for sample analysis by NIOSH
Method 5040) and a visit to the MSHA laboratory.
V. Compliance Assistance
A. Baseline Sampling Summary
Under the second partial DPM settlement agreement, MSHA agreed to
provide compliance assistance to the M/NM underground mining industry
for a one-year period from July 20, 2002 through July 19, 2003. As part
of its compliance assistance activities, MSHA agreed to conduct
baseline sampling of miners' personal exposures at every underground
mine covered by the 2001 final rule.
Our baseline sampling began in October 2002 and continued through
October 2003. During this period a total of 1,194 valid baseline
samples were collected. A total of 183 underground M/NM mines are
represented by this analysis. The number of samples per mine range from
one to twenty. All 874 valid baseline sampling results in the analysis
published in the preamble of the 2003 NPRM are included in this updated
analysis. MSHA is including 320 additional valid samples because MSHA
decided to continue to conduct baseline sampling after July 19, 2003 in
response to mine operators' concerns. MSHA has analyzed all baseline
samples, and updated its analysis. Some of these mines were either not
in operation or were implementing major changes to ventilation systems
during the original baseline period. MSHA is including supplementary
samples from seasonal and intermittent mines, mines that were under-
represented, and mines that were not represented in the analysis
published in the preamble to the 2003 NPRM. Sixty mines included in the
former analysis had additional samples taken during the extended
assistance period. There are 12 mines in this updated analysis that
were not represented in the 2003 analysis. The results of this sampling
were used by MSHA in this preamble to estimate current DPM exposure
levels in underground M/NM mines using diesel equipment. These sampling
results also assist mine operators in developing compliance strategies
based on actual exposure levels.
This section summarizes analytical results of personal sampling for
DPM collected during compliance assistance. There are a total of 1,206
samples. However, 12 samples are invalid due to abnormal sample
deposits, broken cassettes or filters, contaminated backup pads,
instrument failure 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 or nonmetal ores. These commodities were grouped
into 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 with the average number of valid samples per mine ranging from
6.0 to 8.2 (average across all mines is 6.5 samples per mine). The
average number of samples per mine classified as ``Gold Ore Mining,
N.E.C.'' increased from an average of 2.0 samples per mine published in
the 2003 NPRM preamble to an average of 4.6 samples in this data set.
Approximately 79% of all mines sampled during the assistance period
have four or more results from DPM sampling in this analysis. Table V-3
lists the number of samples for each category of specific commodity.
Average number of samples for more general commodity groups is listed
in Table V-2.
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 in the miner's breathing zone and
for the miner's full shift regardless of the number of hours worked.
For the 1,194 valid personal samples, 85% were collected for at least
eight hours. TC and EC levels, as well as DPM levels, are reported in
units of micrograms per cubic meter for an 8-hour full shift
equivalent.
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 TC content. Each sample was analyzed for organic,
elemental, and carbonaceous carbon and calculated TC. Raw analytical
results from both laboratories as well as administrative information
about the sample were 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 tandem blank was also tested for the same
analyses. Otherwise, an unexposed filter from the same manufacturer's
lot was used to correct for background levels. In the event the initial
TC result was greater than 100TC [mu]g/cm2, a
smaller punch of the same exposed filter (in duplicate and with the
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.
The equation used to calculate a 480-minute (8-hour) full shift
equivalent (FSE) exposure of TC is Total Carbon Concentration =
[GRAPHIC] [TIFF OMITTED] TR06JN05.014
Where:
EC = The corrected elemental carbon concentration measured in the
thermal/optical carbon analyzer, [mu]g/cm\2\,
OC = The corrected organic carbon concentration measured in the
thermal/optical carbon analyzer, [mu]g/cm\2\,
A = The surface area of the deposit on the filter media used to collect
the sample, cm\2\,
Flow Rate = Flow rate of the air pump used to collect the sample
measured in Liters per minute, and
480 minutes = Standardized eight-hour work shift.
All levels of carbon or DPM are reported in 8-hour full shift
equivalent TC concentrations measured in [mu]g/m\3\.
Because personal sampling was conducted and no attempt was made to
avoid interference from cigarette smoke or other OC sources, TC was
also calculated using the formula prescribed in the second partial 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.
The electronic records of the 1,194 samples 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, 12
samples (1.0%) 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. These samples were subjected to the same
laboratory quality assessments as samples collected for compliance
purposes. Accordingly, MSHA has included 1,194 samples from miners in
the analyses. Table V-2 is a list of the number of valid samples by
commodity group.
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 4 0 0 5
------------------------------------------------
Total...................................... 3 8 0 1 12
----------------------------------------------------------------------------------------------------------------
Table V-2.--Number of Mines and Valid Samples, by Commodity Group.
----------------------------------------------------------------------------------------------------------------
Average number of
Commodity group Number of mines Number of valid valid samples by
samples mine
----------------------------------------------------------------------------------------------------------------
Metal.................................................. 40 284 7.1
Stone.................................................. 115 689 6.0
Trona.................................................. 4 25 6.3
Other N/M.............................................. 24 196 8.2
--------------------------------------------------------
Total.............................................. 183 1,194 6.5
----------------------------------------------------------------------------------------------------------------
Table V-3 lists the number of samples collected by specific
commodities and sorted by average number of samples per mine. Although
MSHA made efforts to sample all underground M/NM mines covered by this
rulemaking within the specified time frame, several mines have few or
no samples for DPM in this analysis. Some M/NM 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 extended its period of baseline sampling especially to
incorporate into its analysis those mines with a low sampling frequency
or where no samples were collected as of March 26, 2003.
Table V-3.--Number of Valid Samples per Mine for Specific Commodities
----------------------------------------------------------------------------------------------------------------
Average
Specific commodity No. of mines No. of samples per
samples mine
----------------------------------------------------------------------------------------------------------------
Gemstones Mining, N.E.C......................................... 2 5 2.5
Dimension Marble Mining......................................... 3 9 3.0
Limestone....................................................... 2 6 3.0
Talc Mining..................................................... 1 3 3.0
Uranium-Vanadium Ore Mining, N.E.C.............................. 1 3 3.0
Gold Ore Mining, N.E.C.......................................... 19 87 4.6
Construction Sand & Gravel 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
Copper Ore Mining, N.E.C........................................ 2 11 5.5
Dimension Limestone Mining...................................... 3 18 6.0
Crushed & Broken Limestone Mining, N.E.C........................ 90 550 6.1
Crushed & Broken Marble Mining.................................. 4 25 6.3
Trona Mining.................................................... 4 25 6.3
Crushed & Broken Stone Mining, N.E.C............................ 4 28 7.0
Gypsum Mining................................................... 4 29 7.3
Salt Mining..................................................... 14 122 8.7
Clay, Ceramic & Refractory Minerals, N.E.C...................... 1 9 9.0
Miscellaneous Metal Ore Mining, N.E.C........................... 1 9 9.0
Lead-Zinc Ore Mining, N.E.C..................................... 10 96 9.6
Platinum Group Ore Mining....................................... 2 20 10.0
Potash Mining................................................... 3 30 10.0
Molybdenum Ore Mining........................................... 2 22 11.0
Silver Ore Mining, N.E.C........................................ 3 36 12.0
Miscellaneous Nonmetallic Minerals, N.E.C....................... 1 16 16.0
-----------------
Average of all samples...................................... 183 1,194 6.5
----------------------------------------------------------------------------------------------------------------
There are 63 different occupations in underground M/NM 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 group. Only occupations with 14 or
more total samples are listed individually. Occupations with fewer
samples were aggregated into a combined group for this table.
Table V-4.--Valid Samples, by Occupation and Mine Category.
----------------------------------------------------------------------------------------------------------------
Occupation Metal Stone Trona Other N/M Total
----------------------------------------------------------------------------------------------------------------
Truck Driver................................... 87 152 0 13 252
Front-end Loader Operator...................... 40 149 6 19 214
Blaster, Powder Gang........................... 12 98 0 24 134
Scaling (mechanical)........................... 1 66 0 13 80
Drill Operator, Rotary......................... 3 63 0 9 75
Drill Operator, Jumbo Perc..................... 10 19 0 9 38
Mechanic....................................... 7 15 0 12 34
Complete Load-Haul-Dump........................ 7 2 0 23 32
Utility Man.................................... 6 4 15 4 29
Scaling (hand)................................. 4 20 0 2 26
Mucking Mach. Operator......................... 19 1 0 3 23
Roof Bolter, Rock.............................. 5 9 0 7 21
Drill Operator, Rotary Air..................... 1 19 0 1 21
Miner, Drift................................... 16 1 0 0 17
Crusher Oper/Worker............................ 0 13 0 2 15
Miner, Stope................................... 14 0 0 0 14
All Others Combined............................ 52 58 4 55 169
--------------
Totals..................................... 284 689 25 196 1,194
----------------------------------------------------------------------------------------------------------------
TC levels calculated by EC x 1.3 were lower than TC levels
calculated by OC + EC in 858 (72%) of the 1,194 baseline samples. Of
the 336 samples where TC = OC + EC was the lower value, 68% 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 6.4% of the
paired results did not concur with respect to the 400TC
[mu]g/m\3\ standard when measuring TC by the two calculations (OC + EC
vs. EC x 1.3). Approximately 19.3% of the samples were above the
400TC [mu]g/m\3\ interim concentration limit when using TC =
EC x 1.3 and approximately 22.7% were above the concentration limit
when using TC = OC + EC. There is 93.6% concurrence between the two
methods of calculating TC and comparing the calculations to the
400TC [mu]g/m\3\ 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
--------------------------------
All valid samples < 400TC [mu]g/ > 400TC [mu]g/ Total
m\3\ m\3\
----------------------------------------------------------------------------------------------------------------
OC+EC...........................................................
< 400TC [mu]g/m\3\.......................................... 905 18 923
(75.8%) (1.5%) (77.3%)
> 400TC [mu]g/m\3\.......................................... 59 212 271
(4.9%) (17.8%) (22.7%)
-----------------
Total....................................................... 964 230 1,194
(80.7%) (19.3%) (100.0%)
----------------------------------------------------------------------------------------------------------------
Table V-6 lists the 26 occupations found to have at least one
sample in which the level of TC was over the 400TC [mu]g/
m\3\ interim concentration limit (TC = EC x 1.3). Table V-6 is sorted
by the median (middle) TC result. The median is reported because it is
a more robust measure of the middle value. Changing a single value
won't change the median very much. In contrast, the value of the mean
can be strongly affected by a single value that is very low or very high. The table also lists the minimum value, maximum 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 (TC = ECx 1.3)
----------------------------------------------------------------------------------------------------------------
TC, [mu]g/m\3\
Occupation Total -----------------------------------
samples Minimum Median Maximum
----------------------------------------------------------------------------------------------------------------
Diamond Drill Operator.......................................... 1 2,030 2,030 2,030
Ground Control/Timberman........................................ 2 368 545 722
Washer Operator................................................. 4 353 438 808
Engineer........................................................ 1 438 438 438
Roof Bolter, Mounted............................................ 12 98 335 1,063
Mucking Mach. Operator.......................................... 23 15 334 872
Miner, Stope.................................................... 14 100 283 622
Cleanup Man..................................................... 2 66 283 499
Scoop-Tram Operator............................................. 7 14 272 583
Drill Operator, Rotary Air...................................... 21 0 240 1,353
Miner, Drift.................................................... 17 16 228 1,459
Blaster, Powder Gang............................................ 134 6 227 1,340
Belt Crew....................................................... 8 26 225 502
Roof Bolter, Rock............................................... 21 63 223 1,310
Truck Driver.................................................... 252 0 211 1,581
Shuttle Car Operator (diesel)................................... 3 95 201 419
Complete Load-Haul-Dump......................................... 32 19 189 824
Drill Operator, Jumbo Perc...................................... 38 5 179 1,098
Drill Operator, Rotary.......................................... 75 3 171 1,109
Motorman........................................................ 8 59 168 419
Front-end Loader Operator....................................... 214 0 158 2,979
Scaling (mechanical)............................................ 80 0 139 1,246
Supervisor, Co. Official........................................ 13 1 130 856
Utility Man..................................................... 29 29 94 991
Scaling (hand).................................................. 26 18 87 2,013
Mechanic........................................................ 34 0 84 420
----------------------------------------------------------------------------------------------------------------
Table V-7 and Chart V-1 provide the percent of overexposures among
the four commodity groups. Chart V-2 provides the number of
overexposures among the four commodity groups. The metal mines have the
highest percent of overexposures followed by stone, then other non-
metal mines. For all samples combined, 19.3% were above
400TC [mu]g/m\3\.
Table V-7.--Baseline Samples by Commodity (TC = EC x 1.3)
----------------------------------------------------------------------------------------------------------------
Percent >
Commodity Number < 400TC Number > 400TC Total Samples 400TC [mu]g/
[mu]g/m\3\ [mu]g/m\3\ m\3\
----------------------------------------------------------------------------------------------------------------
Metal........................................... 195 89 284 31.3
Stone........................................... 571 118 689 17.1
Other N/M....................................... 174 22 196 11.2
Trona........................................... 24 1 25 4.0
All Mines....................................... 964 230 1,194 19.3
----------------------------------------------------------------------------------------------------------------
BILLING CODE 4510-43-U
[GRAPHIC] [TIFF OMITTED] TR06JN05.001
[GRAPHIC] [TIFF OMITTED] TR06JN05.002
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 68 mines (37%) are in this category. There
were no mines with more than 12 samples > 400TC [mu]g/m\3\
for that mine.
[GRAPHIC] [TIFF OMITTED] TR06JN05.003
At four of the mines, all samples taken during the assistance
period were above 400TC [mu]g/m\3\. Between one and ten
samples were taken at each of these four mines. No overexposures were
found in 115 (63%) of the mines sampled. (See Chart V-4.)
BILLING CODE 4510-43-C
[GRAPHIC] [TIFF OMITTED] TR06JN05.004
Tables V-8 and V-9 summarize sample statistics by commodity for TC
calculated by TC = EC x 1.3 and TC = EC + OC respectively. Overall, the
mean TC as calculated by EC x 1.3 is 255 [mu]g/m\3\. The median level
is 174 [mu]g/m\3\. The mean TC level by OC + EC is 293 [mu]g/m\3\ and
the median level is 226 [mu]g/m\3\. Individual exposure levels of TC
vary widely within all commodities and most mines. The commodity
groupings reported in Tables V-8 and V-9 were chosen to be consistent
with those reported in the 31-Mine Study and the Quantitative Risk
Assessment (QRA) for this rule.
The mean and median TC values for each group, using EC x 1.3, are
lower than the interim compliance limit of 400 [mu]g/m3. The
mean (median) TC value for metal mines is 356(271) [mu]g/m3.
The mean (median) for stone mines is 236(149), other non-metal mines is
194(148), and trona mines is 105(82) [mu]g/m3. Table V-8
lists additional statistics for TC values compiled by commodity.
Table V-8.--Average Levels of TC by Commodity Measured in [mu]g/m3 (EC x 1.3)
[Estimated 8-hour Full Shift Equivalent TC Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
TC = EC x 1.3 Metal Stone Other N/M Trona All Mines
----------------------------------------------------------------------------------------------------------------
No. of Samples................................. 284 689 196 25 1,194
Maximum........................................ 2,026 2,979 960 407 2,979
Median......................................... 271 149 148 82 174
Mean........................................... 356 236 194 105 255
Std. Error................................. 19 10 12 16 8
95% CI Upper............................... 392 256 217 138 270
95% CI Lower............................... 319 216 172 73 239
----------------------------------------------------------------------------------------------------------------
The mean and median TC values for each group of mines as calculated
by OC + EC are also lower than the interim compliance limit of 400
[mu]g/m3. The mean (median) TC value for metal mines is
370(313) [mu]g/m3. The mean for stone mines is 282(209), other non-metal mines is 238(191) and for trona mines is 140(126) [mu]g/m3. Table V-9 lists additional
statistics for TC values compiled by commodity group.
Table V-9.--Average Levels of TC by Commodity Group Measured in [mu]g/m3 (OC + EC)
[Estimated 8-hour Full Shift Equivalent TC Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
TC = OC + EC Metal Stone Other N/M Trona All Mines
----------------------------------------------------------------------------------------------------------------
No. of Samples................................. 284 689 196 25 1,194
Maximum........................................ 2,045 2,796 1,230 344 2,796
Median......................................... 313 209 191 126 226
Mean........................................... 370 282 238 140 293
Std. Error................................. 17 11 12 12 8
95% CI Upper............................... 404 303 263 165 308
95% CI Lower............................... 336 261 214 115 278
----------------------------------------------------------------------------------------------------------------
Tables V-10, V-11, and V-12 show summary statistics for whole DPM
exposures for the baseline sampling and the 31-Mine Study. For baseline
sampling whole DPM was calculated by EC x 1.3 x 1.25 and by (OC + EC) x
1.25. The 1.25 factor represents the assumption that TC comprises 80%
of whole DPM. The other 20% includes the solid aerosols such as ash
particulates, metallic abrasion particles, sulfates and silicates. The
vast majority of these particulates are in the sub-micron range.
Section VI-B discusses the relationship between EC and TC. For
whole DPM concentrations, the mean (median) value is 444(339) [mu]g/
m3 for metal mines, 295(186) for stone mines, 243(185) for
other non-metal mines, and 132(102) [mu]g/m3 for trona
mines. The whole DPM exposures for Table V-11 were calculated as (OC +
EC) x 1.25.
Table V-10.--Baseline Whole DPM Concentrations (EC x 1.3 x 1.25, [mu]g/m3), by Mine Category
[Estimated 8-hour Full Shift Equivalent Whole DPM Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
DPM = EC x 1.3 x 1.25 Metal Stone Other N/M Trona All Mines
----------------------------------------------------------------------------------------------------------------
Number of Samples.............................. 284 689 196 25 1,194
Maximum........................................ 2,532 3,724 1,200 509 3,724
Median......................................... 339 186 185 102 218
Mean........................................... 444 295 243 132 318
Std. Error................................. 23 13 15 20 10
95% CI Upper............................... 490 320 272 173 338
95% CI Lower............................... 399 270 214 91 299
----------------------------------------------------------------------------------------------------------------
Table V-11.--Baseline Whole DPM Concentrations ((EC + OC) x 1.25, [mu]g/m 3), by Mine Category
[Estimated 8-hour Full Shift Equivalent Whole DPM Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
DPM = (EC + OC) x 1.25 Metal Stone Other N/M Trona All Mines
----------------------------------------------------------------------------------------------------------------
Number of Samples.............................. 284 689 196 25 1,194
Maximum........................................ 2,556 3,495 1,538 430 3,495
Median......................................... 392 262 238 158 283
Mean........................................... 463 353 298 175 366
Std. Error................................. 21 13 16 15 10
95% CI Upper............................... 505 379 329 206 385
95% CI Lower............................... 421 327 267 144 347
----------------------------------------------------------------------------------------------------------------
The mean whole DPM concentration for metal and stone mines (as
measured by (EC + OC) x 1.25) was significantly lower during baseline
compliance assistance sampling than the levels measured during the 31-
Mine Study.
Table V-12.--31-Mine Study Whole DPM Concentrations ([mu]g/m3) by Mine Category
[Estimated 8-hour Full Shift Equivalent Whole DPM Concentration ([mu]g/m3)]
----------------------------------------------------------------------------------------------------------------
DPM = (EC + OC) x 1.25 Metal Stone Other N/M Trona
----------------------------------------------------------------------------------------------------------------
Number of Samples........................................... 116 105 83 54
Maximum..................................................... 2,581 1,845 1,210 331
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 the study 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 DPM exposure. Workers inside equipment cabs were not
sampled during the 31-Mine Study due to possible interference from
cigarette smoke. During baseline compliance assistance sampling,
however, personal samples were taken on miners inside cabs.
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MSHA received several comments on the baseline sampling. Some
commenters stated that many mines were sampled in a manner that
rendered results exceedingly low and not representative of operating
conditions. Commenters also stated that the results of independent DPM
sampling conducted by operators indicate MSHA's results underestimate
DPM exposure. These commenters did not provide data or analyses from
mine operators' sampling programs to substantiate their claim.
MSHA compliance specialists collected baseline samples in the same
manner they have been instructed to use for collecting samples for
enforcement purposes. It is expected that personal exposure to DPM will
fluctuate due to variations in day to day operations in a mine.
Reported levels of DPM are representative of the exposures of the
highest risk miners identified during compliance assistance. In an
ideal situation, and with unlimited resources, every potentially
exposed miner would be individually sampled. It is not necessary or
practical, however, to sample all miners on a mine property in order to
evaluate personal exposures. Suspected and potential health hazards may
be reasonably and adequately evaluated by sampling the maximum risk
miner in a work area. The maximum risk miner is the one expected to
have the greatest exposure of all of the miners in the area. Other
miners in the same work area or area of common exposure sources may
reasonably be expected to experience lesser concentrations of
occupational hazards than the maximum risk miner. There may be more
than one maximum risk miner when activities, operations, and exposure
sources vary throughout the day. MSHA acknowledges that some samples
were not taken on the highest possible risk occupation at some mines.
As previously stated, we continued baseline sampling past the date of
July 19, 2003 in response to this concern.
A miner experiences high risk because of the location and type of
tasks performed relative to the source of the suspected hazard. The
miner's predicted environment or duties may change during the course of
the work shift. If the working conditions present during the exposure
assessment are not typical of the regular mining operation, the sample
results may not represent the typical exposure for that occupation.
Compliance specialists strive to characterize the higher exposure
levels during typical work shifts. The baseline samples are
representative of the conditions experienced on work shifts during the
defined compliance assistance period. MSHA has obtained the best
available information for characterizing recent activities at the relevant M/NM mines.
B. DPM Control Technology
MSHA participated in a number of compliance assistance activities
directed at improving sampling and assisting mine operators with
selecting and implementing appropriate DPM control technology. Some of
these activities were directed to either a segment of the mining
industry, or to the entire industry, while others were conducted on a
mine specific basis. In general, activities directed toward a large
number of mines included outreach programs, workshops, web site postings
and publications, while activities directed at an individual mine
included evaluation of a specific control technology, and review of the
technology in use by or available to a specific mine.
Regional DPM Seminars. During September and October, 2002, MSHA
conducted regional DPM seminars at the following locations: Ebensburg,
PA; Knoxville, TN; Lexington, KY; Des Moines, IA; Kansas City, MO;
Albuquerque, NM; Coeur d'Alene, ID; Green River, WY; and Elko, NV. MSHA
offered these full-day seminars free of charge in the major underground
M/NM 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, a computerized
program that calculates DPM concentration reduction.
NIOSH Diesel Emission and Control Technologies in Underground M/NM
Mines Workshops. MSHA participated in these two workshops in February,
2003 in Cincinnati, OH and March, 2003, in Salt Lake City, UT. The
workshops served several purposes. They provided technical
presentations and a forum for discussing control technology for
reducing exposure to particulate matter and gaseous emissions from the
exhaust of diesel-powered vehicles in underground mines. Additionally,
they intended to help mine managers, maintenance personnel, safety and
health professionals, and ventilation engineers select and apply
control technologies in their mines. Speakers, representing MSHA,
NIOSH, and several mining companies, provided ample time for questions
and in-depth technical discussion of issues raised by participants.
National Stone, Sand & Gravel Association (NSSGA)/MSHA DPM Sampling
Workshop. This three day seminar, hosted by the Rogers Group, Inc.'s
Jefferson County Stone and Underground in Louisville, Kentucky, was
held on December 11 through 13, 2002. On the first day, MSHA reviewed
DPM sampling procedures, and presented training on pump calibration,
sample train assembly and note taking. On the second day, participants
traveled to the Rogers Group Jefferson County Mine to conduct full
shift sampling on underground miners. Our technical support staff took
ventilation measurements and collected area samples to assess DPM
emissions in the mine. On the third day, MSHA reviewed engine emission
and ventilation measurements. Additionally, MSHA reviewed and discussed
DPM outreach material. Approximately 10 industry participants attended
the seminar.
Nevada Mining Association Safety Committee. In April, 2003, MSHA
discussed DPM control technologies at a meeting of the Nevada Mining
Association Safety Committee in Elko, NV. Discussion topics included
bio-diesel fuel blends, various fuel additives and fuel pre-treatment
devices, mine ventilation, environmental cabs, clean engines, and
diesel particulate filter (DPF) systems. Mining company representatives
discussed their experiences with and perspectives on these
technologies. MSHA discussed experiences and observations that it made
at various mines, and results of its laboratory and field testing.
MSHA South Central Joint Mine Safety and Health Conference. MSHA
presented a DPM workshop at this conference in April 2003, in New
Orleans, LA. The workshop included a detailed history and explanation
of the provisions of the DPM regulation, and a technical presentation
on feasible DPM engineering controls. At the April 2004 conference in
Albuquerque, NM, MSHA presented a review of DPM control strategies that
have generally been adopted in the underground M/NM mining industry.
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). MSHA presented a DPM workshop at this conference in
June 2003, in Reno, NV. The workshop included a detailed history and
explanation of the provisions of the regulation, and a technical
presentation on DPM sampling, analytical tools for identifying and
evaluating DPM sources in mines, and feasible DPM engineering controls.
DPM Sampling and Control Workshops. In March 2004, MSHA presented
full one day workshops in Bloomington, IN and Des Moines, IA. In these
workshops, MSHA reviewed the sampling procedures that MSHA inspectors
would use for DPM, and MSHA provided hands on instruction to the
participants in these procedures. MSHA also presented a review of DPM
control strategies that have generally been adopted in the underground
M/NM mining industry.
Equipment Manufacturers Association (EMA) DPM Workshop. In August
2003, MSHA conducted a DPM workshop for the EMA in Chicago, IL. At this
workshop, MSHA reviewed the M/NM DPM regulations, discussed the need
for clean engine technology, explained engine emission testing for
mines, reviewed the importance of environmental cabs and discussed
ventilation issues.
Web site. Our Web site, http://www.msha.gov, contains a single source page
for DPM rules for M/NM mines. The page has links to 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 Standard
Error Factor for TC Analysis.
MSHA Metal and Nonmetal DPM Standard Compliance Guide of
August 5, 2003, addressing the interim DPM limit.
NIOSH Listserver.
MSHA-NIOSH Diesel Particulate Filter Selection Guide for
Diesel-powered Equipment in Metal and Nonmetal Mines (Filter Selection
Guide), last updated February 20, 2003.
Baseline DPM Sample Results, updated October 2003.
Presentation from Compliance Assistance Workshop, October
16, 2002.
Summary of Requirements: MSHA Standard on Diesel
Particulate Matter Exposure of Underground Metal and Nonmetal Miners
that are in effect as of July 20, 2002.
Link to SKC Web site: SKC Diesel Particulate Matter
Cassette with Precision-jeweled Impactor.
Diesel Particulate Matter Control Technologies, last
updated January 14, 2004.
--Table I: Paper/Synthetic Filters.
--Table II: Non-Catalyzed Particulate Filters, Base Metal Particulate
Filters, Specially Catalyzed Particulate Filters, and High Temperature
Disposable Filters.
--Table III: Catalyzed (Platinum Based) Diesel Particulate Filters.
Work Place Emissions Control Estimator.
Federal Register documents concerning this and prior DPM
rulemakings.
Public comments on this rulemaking.
Economic analyses for this rule and prior DPM rules.
MSHA News Release: MSHA Rules Will Control Miners'
Exposure to Diesel Particulate, January 18, 2001.
Program Information Bulletins:
--PIB01-10 Diesel Particulate Matter Exposure of Underground Metal and
Nonmetal Miners, August 28, 2001.
--PIB02-04 Potential Health Hazard Caused by Platinum-Based Catalyzed
Diesel Particulate Matter Exhaust Filters, May 31, 2002.
--PIB02-08 Diesel Particulate Matter Exposure of Underground Metal and
Nonmetal Miners---Summary of Settlement Agreement, August 12, 2002.
Additionally, our diesel single source page for the coal industry
contains topics that may also be of interest to the M/NM mining
industry, particularly for those operations at gassy mines where
permissible equipment is required.
Specific control technology studies. Following the settlement
agreement, MSHA was invited by various mining companies to evaluate the
effectiveness of different control technologies for DPM, including
ceramic filters, alternative fuels and a fuel oxygenator. Company
participation was essential to the success of each test. MSHA evaluated
ceramic filters in two mines, one where MSHA was the only investigator
and one where NIOSH was the primary investigator. In our test, MSHA
evaluated DPM on a production unit 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.
MSHA evaluated bio-diesel fuel in two mines. In one, MSHA evaluated
a 20% and a 50% recycled bio-diesel fuel and a 50% new bio-diesel. In
the other, MSHA evaluated a 35% recycled bio-diesel fuel and a 35% new
bio-diesel.
MSHA evaluated the fuel catalyst system in one mine. MSHA sampled
the mine exhaust with fuel catalyst systems installed on all production
equipment, and also without the units installed.
MSHA evaluated water emulsion diesel fuel in four mines.
Following is a summary of the individual mine technology evaluation
studies:
Kennecott Greens Creek Mining Company: MSHA participated with
Kennecott Greens Creek Mining Company in a collaborative test to verify
the efficiency of catalyzed ceramic DPFs for reducing diesel
particulate emissions. The goal of the testing was to identify 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. MSHA also determined relative engine
gaseous and DPM emissions for the equipment under specific load
conditions.
MSHA conducted the tests over a two-week period. MSHA sampled three
shifts with ceramic after-filters installed; and three shifts without
the after-filters. MSHA also collected personal samples to assess
worker exposures, and area samples to assess engine emissions. MSHA
took both gaseous and diesel particulate measurements.
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 DPFs may have a significant impact on personal
exposures. The following findings and conclusions were obtained from
the test:
1. The results of the raw exhaust gas measurements conducted during
the test indicate that the engines were operating properly.
2. The ceramic filters installed on the machines used in this test
do not adversely affect 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% when after-
filters were used.
5. CO levels decreased by up to one-half while the catalyzed
filters were used. There appeared to be an increase in NO2
(Nitrous Dioxide) while catalyzed filters were being used; however, it
is 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 exposure by 75% when DPFs were in
use and by 80% when DPFs 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 DPFs reduced average engine DPM emissions by
96%.
9. The reduction in personal exposure was not attributed solely to
DPF 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 our
compliance assistance program, MSHA provided support to mining
operations to evaluate diesel particulate control technologies. The
test was initiated by the industry partner, and, along with NIOSH, MSHA
provided support for test design, data collection, and sample and data
analysis. The project was funded by Carmeuse and Kentucky Department of
Energy, through the Kentucky Clean Fuels Coalition.
The initial test was conducted in two phases, using a 20% and a 50%
bio-diesel blend of recycled vegetable oil (RVO), each mixed with 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
test, 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 method to
determine TC and EC 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
TC. Results for the 20% and 50% RVO indicated 33% and 69% reductions in
DPM emissions, respectively. Results for the tests on the 50% blend of
new soy bio-diesel fuel, showed about a 37% reduction in DPM emissions.
Carmeuse North America, Inc., Black River Mine: Following the
success of the bio-diesel tests at Maysville Mine, Carmeuse requested
our assistance in continuing the bio-diesel optimization testing at
their Black River Mine. Two bio-diesel blends were tested, and a
baseline test was made. In each test personal exposures and the mine
exhaust were tested for two shifts. The two bio-diesel blends included a
35% RVO and a 35% blend of new soy oil. Results for the 35% RVO
showed a 32% reduction in DPM emissions.
Results of the 35% blend of new soy bio-diesel fuel showed an
approximate 16% reduction in DPM emissions.
Stone Creek Brick Company, Water Emulsion Fuel Tests: During the
Stone Creek Brick Company compliance assistance visit, MSHA identified
several control strategies that would reduce DPM emissions and
exposures. These strategies included: The installation of clean
engines, the use of alternative fuels, and an increase in mine
ventilation. The mine chose to implement alternative fuel use followed
by an engine replacement program. MSHA provided in-mine testing to
evaluate the impact of using an alternative fuel. The company chose to
use a water emulsion fuel. This fuel is an EPA approved fuel,
consisting of a 20% blend of water with No. 2 diesel fuel. A surfactant
is added to keep the water and diesel fuel from separating. MSHA
sampled at the mine before (using No. 2 diesel fuel) and after the
implementation of the fuel. MSHA collected personal samples to evaluate
the worker exposure and area samples to evaluate emissions.
Results of the testing showed that the highest exposure was reduced
from 823TC [mu]g/m3 to 321TC [mu]g/
m3 (61% reduction). EC emissions were reduced by 49% and TC
emissions were reduced by 3%. The lack of a reduction in TC emissions
was attributed to the lower combustion temperature resulting from the
water emulsion fuel and the older engine technology in use. The older
engines have larger injector nozzles which do not provide efficient
fuel burning. The mine has been using the fuel for approximately one
year, and continues to be satisfied with the results.
Carmeuse North American, Inc., Maysville Mine, Water Emulsion Fuel
Tests: MSHA provided assistance to Carmeuse North American, Inc., to
evaluate summer and winter blends of a water emulsion fuel at their
Maysville Mine. For the first test, emission reductions for a 10% blend
(winter blend) of water with No. 2 diesel fuel was compared to a 35%
blend of RVO. Emission reductions were compared to both a 35% blend of
RVO and standard No. 2 diesel fuel. MSHA collected personal samples to
evaluate the worker exposure and area samples to evaluate emissions.
Results of the testing showed that the highest average exposure
(high scaler working outside a cab) was reduced from 254TC
[mu]g/m3 to 145TC [mu]g/m3 (43%
reduction) when changing from RVO to the water emulsion. EC emissions
were reduced by 52% and TC emissions were reduced by 49% for the water
emulsion to 35% RVO fuel comparison. EC emissions were reduced by 77%
and TC emissions were reduced by 74% for the water emulsion to standard
diesel fuel comparison.
For the second test, emission reductions for a 20% blend (summer
blend) of water with No. 2 diesel fuel was compared to a 35% blend of
RVO. Emission reductions were compared to both a 35% blend of RVO and
standard No. 2 diesel fuel. The comparison to No. 2 diesel fuel was
obtained by combining the water emulsion to the 35% RVO results and
previously obtained 35% RVO to No. 2 diesel fuel results. MSHA
collected personal samples to evaluate the worker exposure and area
samples to evaluate emissions. For the summer blend, EC emissions were
reduced by 60% and TC emissions were reduced by 59% for the water
emulsion to 35% RVO fuel comparison. EC emissions were reduced by 81%
and TC emissions were reduced by 79% for the water emulsion to standard
diesel fuel comparison.
Carmeuse North American, Inc., Black River Mine, Water Emulsion
Fuel Tests: MSHA provided assistance to Carmeuse North American, Inc.
to evaluate summer and winter blends of a water emulsion fuel at their
Black River Mine. For these tests, emission reductions for 10% and 20%
blends (winter blend) of water with No. 2 diesel fuel was compared to a
35% blend of RVO. Emission reductions were compared to both a 35% blend
of RVO and standard No. 2 diesel fuel. MSHA collected personal samples
to evaluate the worker exposure and area samples to evaluate emissions.
For the winter blend (10%), EC emissions were reduced by 46% and TC
emissions were reduced by 45% for the water emulsion to 35% RVO fuel
comparison. EC emissions were reduced by 63% and TC emissions were
reduced by 62%, for the water emulsion to standard No. 2 diesel fuel
comparison.
For the summer blend (20%), EC emissions were reduced by 61% and TC
emissions were reduced by 54% for the water emulsion to 35% RVO fuel
comparison. EC emissions were reduced by 73% and TC emissions were
reduced by 68% for the water emulsion to standard diesel fuel
comparison.
Martin Marietta, Durham Mine, Water Emulsion Fuel Tests: MSHA
provided assistance to Martin Marietta to evaluate a summer blend of
water emulsion fuel at their Durham Mine. This was a multi-level mine,
with a 15% ramp between levels. For this test, emissions for a 20%
blend of water with No. 2 diesel fuel was compared to standard No. 2
diesel fuel. MSHA collected personal samples to evaluate the worker
exposure and area samples to evaluate emissions. Even with the 15%
ramps, the loss in horsepower due to the fuel did not adversely effect
the mine operations.
Results of the testing showed that the highest average exposure
(powder crew working outside a cab) was reduced from 372TC
[mu]g/m\3\ to 54TC [mu]g/m\3\ (85% reduction) when changing
from No. 2 diesel fuel to the water emulsion. EC emissions were reduced
by approximately 80% for the water emulsion compared to standard
diesel.
Rogers Group, Jefferson County Mine: MSHA was invited to this mine
to evaluate a fuel catalyst system that was installed in the fuel line
of the diesel equipment. The company had installed the units to
increase fuel economy, and sought to determine the effects of the units
on DPM. Prior to the units having been installed, MSHA had conducted
baseline sampling and had collected personal samples on production
workers and area samples in the mine exhaust airflow. After the units
were installed on loaders and trucks and the units had accumulated 100
hours of operation, sampling was repeated. Results indicated that the
use of the fuel catalyst had no measurable effect on either DPM
exposure or emissions.
Summary of DPM control technology: In addition to conducting
baseline sampling and providing assistance in developing DPM control
strategies at specific mines, MSHA assessed the effectiveness of
various DPM controls during and following the compliance assistance
period. These controls included alternative fuels, fuel oxygenators,
environmental cabs and ceramic DPFs. Alternative fuels evaluated
included various blends of bio-diesel fuels (including both Virgin Soy
Oil (VSO) and RVO), No. 1 diesel fuel, and water emulsion fuels.
The resulting reduction in DPM emissions for each of these controls
is given in Chart V-6. All reductions are compared to diesel emissions
with low sulfur No. 2 diesel fuel. All bio-diesel tests were conducted
at mines with relatively clean engines. The first water emulsion test
was conducted at a mine utilizing older engines. Subsequent water
emulsion tests were conducted at mines utilizing clean engines with
oxidation catalytic converters.
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Assistance for Developing Control Strategies
Martin Marietta Aggregates: MSHA provided compliance assistance
during full-day visits at the North Indianapolis Mine and the Parkville
Mine in March, 2003, and at the Kaskaskia Mine and the Manheim Mine in
May, 2003. MSHA reviewed each mine's DPM sampling history, current operating and
equipment maintenance practices, ventilation, diesel equipment
inventory, and steps taken to date and future plans to reduce DPM
exposures. MSHA discussed the full range of engineering controls,
demonstrated an exhaust temperature measurement and data logging
system, and presented a spreadsheet for using such data to select
appropriate filter systems. MSHA presented a simple approach for
measuring the effectiveness of cab air filtering and pressurization
systems, identified the highest DPM-emitting equipment (so future
equipment-specific DPM control efforts could be appropriately focused),
and discussed the likely effect of various ventilation system upgrades.
Rogers Group, Oldham County Mine: MSHA provided compliance
assistance at this mine during a full-day visit in November 2002. MSHA
conducted extensive DPM sampling at the mine, collecting both personal
exposure samples and area samples. Further, MSHA collected DPM samples
from both inside and outside of equipment cabs. No personal samples
exceeded 160TC [mu]g/m\3\. MSHA reviewed current operating
and equipment maintenance practices, ventilation, diesel equipment
inventory, and steps taken to date and future plans to reduce DPM
exposures. MSHA discussed the full range of engineering controls.
Results from this survey indicate the environmental cabs significantly
reduced the DPM exposure of equipment operators.
Rogers Group, Jefferson County Mine: MSHA provided compliance
assistance at this mine during a full-day visit in December 2002. MSHA
collected both personal exposure samples and area samples. The highest
personal sample, collected on the loader, was 468TC [mu]g/m
\3\. This loader was operated with the window open. MSHA reviewed
current operating and equipment maintenance practices, ventilation,
diesel equipment inventory, and steps taken to date and future plans to
reduce DPM exposures. Mechanical ventilation was provided for the mine.
MSHA discussed the full range of engineering controls, demonstrated an
exhaust temperature measurement and data logging system, and presented
a spreadsheet for using such data to select appropriate filter systems.
MSHA presented a simple approach for measuring the effectiveness of cab
air filtering and pressurization systems, identified the highest DPM-
emitting equipment (so future equipment-specific control efforts could
be appropriately focused), and discussed the likely effect of various
ventilation system upgrades.
Nalley and Gibson, Georgetown Mine: MSHA provided compliance
assistance at this mine during a full-day visit in May 2003. MSHA
reviewed current operating and equipment maintenance practices,
ventilation, diesel equipment inventory, and steps taken to date and
future plans to reduce DPM exposures. MSHA collected DPM samples to
assess improvements since the baseline sampling. At that time,
mechanical ventilation provided airflow to the mine. MSHA discussed the
full range of engineering controls, demonstrated an exhaust temperature
measurement and data logging system, and presented a spreadsheet for
using such data to select appropriate filter systems. MSHA presented a
simple approach for measuring the effectiveness of cab air filtering
and pressurization systems, identified the highest DPM-emitting
equipment (so future equipment-specific DPM control efforts could be
appropriately focused), and discussed the likely effect of various
ventilation system upgrades.
Stone Creek Brick Company: MSHA provided compliance assistance at
this mine during a full-day visit in May 2003. MSHA reviewed current
operating and equipment maintenance practices, ventilation, diesel
equipment inventory, and steps taken to date and future plans to reduce
DPM exposures. MSHA collected DPM samples from underground miners. The
mine was using mechanical ventilation. None of the equipment had
environmental cabs. MSHA discussed the full range of engineering
controls, presented a spreadsheet for using such data to select
appropriate filter systems, identified the highest DPM-emitting
equipment (so future equipment-specific DPM control efforts could be
appropriately focused), and discussed the likely effect of various
ventilation system upgrades.
Wisconsin Industrial Sand Co., Maiden Rock Mine: MSHA provided
compliance assistance at this mine during a full-day visit in May 2003.
MSHA reviewed the mine's current operating and equipment maintenance
practices, ventilation, diesel equipment inventory, and steps taken to
date and future plans to reduce DPM exposures. MSHA discussed the full
range of engineering controls, presented a spreadsheet for using such
data to select appropriate filter systems, and identified the highest
DPM-emitting equipment so future equipment-specific DPM control efforts
could be appropriately focused.
Gouverneur Talc Company, Inc., No. 4 Mine: MSHA provided compliance
assistance at this mine during a full-day visit in May 2003. DPM
samples were collected on underground workers. MSHA reviewed then
current operating and equipment maintenance practices, ventilation,
diesel equipment inventory, and steps taken to date and future plans to
reduce DPM exposures. MSHA discussed the full range of engineering
controls, demonstrated an exhaust temperature measurement and data
logging system, and presented a spreadsheet for using such data to
select appropriate filter systems. MSHA presented a simple approach for
measuring the effectiveness of cab air filtering and pressurization
systems, identified the highest DPM-emitting equipment (so future
equipment-specific control efforts could be appropriately focused), and
discussed the likely effect of various ventilation system upgrades.
Additional specific mine compliance assistance: Following the
initial baseline sampling period, MSHA compiled a list of mines having
at least one DPM sample which exceeded the 400TC [mu]g/m\3\
limit. Of the 183 mines sampled, approximately 69 mines had at least
one sample over the 400TC [mu]g/m\3\ interim TC limit. Of
the 69 mines with one or more overexposures, 44 used room and pillar
mining methods. These include stone mines, salt mines and a potash
mine. Of the 44 room and pillar mines, MSHA provided specific
compliance assistance to 36 of these mines (two mines were closed and
two mines declined assistance). Although trona mines use room and
pillar mining methods, they were not visited because they were in
compliance with the 400TC [mu]g/m\3\ limit. The remaining 15
mines with overexposures were multilevel metal mines using a variety of
stoping mining methods. Industry seminars were provided to assist these
mines.
Typically, the high risk workers in the mines visited were the face
workers that worked outside an environmental cab. Production loader and
truck operators had elevated exposures when they either did not have an
environmental cab or when the cab was not being properly maintained.
Additional high risk workers include the blasting crew, drillers, and
roof bolters.
During each mine visit, DPM samples were collected unless the mine
had been recently sampled or the mine reported no additional DPM
controls had been implemented since MSHA's previous sampling was
conducted. The DPM controls, including engines, ventilation, cabs,
fuels and work practices, were reviewed with mine management. Specific
engine emission rates, mine ventilation rates, cab pressures and
work practices were determined. At some mines, a temperature trace of
an engine exhaust was made. The information was entered into a computer
spreadsheet model to assess the effect of control changes on DPM levels
and to assist the mine in developing a DPM control strategy.
Laboratory Compliance Assistance: In addition to the compliance
assistance field tests, our 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 M/NM or coal mines.
Evaluating paper/synthetic media as exhaust filters: MSHA has
evaluated paper/synthetic media as exhaust filters. These filters have
shown DPM removal efficiencies in excess of 90% in the laboratory when
tested on our test engine using the test specified in subpart E of part
7. The laboratory has tested approximately 20 different paper/synthetic
media from 10 different filter manufacturers. Although 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 M/NM 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. The 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
equipment in M/NM mines, particularly gassy mines where permissible
equipment is required.
Evaluating Ceramic Filter Systems: MSHA worked with six ceramic
filter manufacturers to evaluate the effects of their catalytic wash-
coats on NO2 production. As discussed under the
``Effectiveness of the DPM Estimator'' portion of this preamble,
catalytic wash-coats on the ceramic filters may cause increases in
NO2 levels. MSHA used our test engine (Caterpillar 3306
PCNA) and followed the test procedures in subpart E of 30 CFR part 7.
The DPM single source webpage lists the ceramic filters that have
significantly increased NO2 levels, as well as the ceramic
filters that are not known to increase NO2 levels. MSHA
tested the DPM removal efficiencies of these filters during the
laboratory tests. The efficiency results agree with the efficiencies
posted on our web site DPM Control Technologies with Percent Removal
Efficiency page (85% for cordierite and 87% for silicon carbide).
Finally, MSHA worked with NIOSH during these tests to collect DPM
samples for EC analysis using the NIOSH 5040 method. The laboratory
results showed that the filters removed EC at up to 99% efficiency.
Evaluation of Fuel Oxygenator System: MSHA'S laboratory completed
tests on the Rentar \TM\ in-line fuel catalyst. The Rentar \TM\ unit
was installed on a Caterpillar\TM\ 3306 ATAAC, which was coupled to a
generator. MSHA used an electrical load bank to load the engine under
various operating conditions. To establish a baseline, MSHA tested the
engine for gaseous and DPM emissions without the Rentar \TM\ unit. The
unit was then installed, and MSHA operated the engine for a 100 hour
break-in period. MSHA then repeated the gaseous and DPM emission
measurements. The test results of the one laboratory evaluation for
this control device to date showed no significant reductions in whole
diesel particulate, however, the data did not show any adverse effects
on the raw whole DPM exhaust emission. NIOSH's results were consistent
with MSHA's results, and showed no significant EC reductions and no
adverse effects on the engine's emissions. MSHA has discussed with
Rentar \TM\ further laboratory tests.
Evaluation of a Magnet System: MSHA performed laboratory tests for
Ecomax, a manufacturer of a magnet system installed on the fuel line,
oil filter, air intake and radiator. MSHA performed a preliminary field
test of this product at a surface aggregate operation. The magnetic
device demonstrated a 30% reduction in CO levels. The laboratory tests
were performed with the Ecomax system installed and compared to our
baseline engine data. The test results of the one laboratory evaluation
for this control device to date showed no significant reductions in
whole diesel particulate, however, the data did not show any adverse
effects on the raw DPM exhaust emissions.
Evaluation of the Fuel Preporator [reg] System: MSHA's
laboratory tested a fuel preparator system. The system is designed to
remove collected air from the fuel system for better fuel combustion.
The results of the system installed were compared to the baseline
engine. The test results of the one laboratory evaluation for this
control device to date showed no significant reductions in whole diesel
particulate, however, the data did not show any adverse effects on the
raw DPM exhaust emissions. NIOSH also conducted tests in our lab on the
Fuel Preporator [reg] and the results were consistent with
MSHA's results. There were no significant EC reductions and no adverse
effects on the engine's emissions.
VI. DPM Exposures and Risk Assessment
A. Introduction
In support of the 2001 final rule, MSHA published a comprehensive
risk assessment (66 FR at 5752-5855, with corrections at 35518-35520).
In the following discussion, we will refer to the risk assessment
published in conjunction with the 2001 final rule as the ``2001 risk
assessment.''
The 2001 risk assessment presented MSHA's evaluation of health
risks associated with DPM exposure levels encountered in the mining
industry. This was based on a review of the scientific literature
available through March 31, 2000, along with consideration of all
material submitted during the applicable public comment periods.
The 2001 risk assessment was divided into three main sections.
Section 1 (66 FR at 5753-5764) contained a discussion of U.S. miner
exposures based on field data collected through mid-1998. An important
conclusion of this section was that, prior to the 2001 final rule,
* * * median dpm concentrations observed in some underground mines
are up to 200 times as high as mean environmental exposures in the
most heavily polluted urban areas [footnote deleted] and up to 10
times as high as median exposures estimated for the most heavily
exposed workers in other occupational groups. [66 FR at 5764]
Section 2 of the 2001 risk assessment (66 FR at 5764-5822) reviewed
the available scientific literature on health effects associated with
DPM exposures. This review covered effects of both acute and chronic
exposures and also contained a discussion of potential mechanisms of
toxicity. The review of acute effects included anecdotal reports of
symptoms experienced by exposed miners, studies based on exposures to
diesel emissions, and studies based on exposures to particulate matter
in the ambient air. The review of chronic effects included studies
based specifically on exposures to diesel emissions and studies based
more generally on exposures to fine particulate matter in the ambient
air. As part of this discussion, MSHA evaluated 47 epidemiologic
studies examining the prevalence of lung cancer within groups of
workers occupationally exposed to DPM and discussed the criteria used
to evaluate and rank these studies (66 FR at 5774-5810). For both acut |
