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Serious Questions Remain As Comment Period Closes On MSHA's Diesel Particulate Matter Rulemakings

July 1999

Author: Edward M. Green.

In two separate notices of proposed rulemaking, the Mine Safety and Health Administration ("MSHA") has been seeking public comment on regulations limiting diesel particulate matter ("DPM") exposure of underground coal miners and underground metal and nonmetal miners. The public comment periods for both proposals expired on July 26.

To summarize briefly, MSHA is proposing a phase-in requirement to install, on most diesel-powered equipment, systems capable of removing, on average, at least 95% of DPM by mass. For underground metal-nonmetal mines, it has proposed a phased-in DPM concentration limit expressed as an "average 8-hour equivalent full shift airborne concentration of total carbon" as follows:

  • After 18 months from publication of the final rule, 400 micrograms per cubic meter of air (400 TCT/m3);
  • After five years from date of publication, 160 micrograms per cubic meter of air (160 TCT/m3).

Now that the public comment periods have closed (at least for time being), the question becomes when will MSHA finalize the proposals and what form will they take? This question assumes even greater importance because, although completing these rulemakings remains a high priority of MSHA Assistant Secretary J. Davitt McAteer, the proposals are substantially flawed in several major respects:

  • There is a substantial lack of consensus in the scientific community on the human health effects of exposure to DPM;
  • Major concern exists about the unreliability and impracticability of measuring DPM exposures for purposes of compliance with any final MSHA DPM limitation standard;
  • MSHA's knowledge about current DPM exposures of underground miners is poor; and
  • Serious doubts exist about the availability of feasible engineering controls to reduce DPM exposures to the proposed limitations.

In addition to these major flaws, finalization of these rules may be entangled in what is likely to become a winding down of the lame-duck Clinton Administration late next spring.

Lack of Consensus on Human Health Effects

The DPM regulations are subject to § 101(a)(6)(A) of the Federal Mine Safety and Health Act of 1977 ("Mine Act"), which requires MSHA to demonstrate that any regulations dealing with toxic materials or harmful physical agents will: (1) adequately assure that no miner will suffer from material impairment of health, on the basis of best available evidence; (2) use the latest available scientific data in the field; (3) be feasible; and (4) be based on experience gained under the Mine Act and other safety and health laws. To help meet the "material impairment of health" leg of § 101(a)(6)(A), MSHA also published for public comment in both its coal and metal-nonmetal DPM proposals a risk assessment consisting of over 35 pages of fine print in the Federal Register. Thus, it cannot be denied that MSHA's risk assessment is quantitatively thorough. It is highly questionable, however, whether the quality of the risk assessment supports MSHA's conclusion that "the best available evidence" indicates that exposure to concentrations of DPM found in underground mines puts miners at significantly increased risk of incurring serious health problems, including lung cancer. The mining industry has prepared a detailed critique of MSHA's risk assessment and has provided it to MSHA as part of the comments submitted by the National Mining Association and other industry groups.

While responsible mine operators acknowledge that exposure to DPM can cause mild, transient health effects, it is not just the mining industry that has recently taken issue with the underlying data MSHA used in its risk assessment. Indeed, in June, the Health Effects Institute ("HEI"), an independent, internationally recognized and highly regarded research organization, published "Diesel Emissions and Lung Cancer: Epidemiology and Quantitative Risk Assessment - A Special Report of the Institute's Diesel Epidemiolgy Expert Panel." The report focuses on the two fundamental epidemiological studies that are the linchpins of MSHA's risk assessment, specifically recommends against using one of the studies for quantitative risk assessment, and urges further scrutiny of the other in order to improve its use in quantitative risk assessment. In short, the HEI special report throws considerable doubt upon the validity of MSHA's risk assessment.

Unreliability and Impracticability of Sampling Method

Under MSHA's proposal for metal-nonmetal miners, MSHA would make compliance determinations based on a single sample of DPM collected and analyzed by using the method described in NIOSH Analytical Method 5040. Extensive field testing by mining companies, however, has raised substantial concern about the accuracy and timeliness of the NIOSH 5040 Method. First, at present only a few commercial laboratories are capable of using the 5040 Method, resulting in lengthy periods of time for readings to become available. More importantly, the reliability of the 5040 Method is questionable. In essence, the Method measures carbon as a surrogate for DPM. However, the presence of other substances, such as oil mist, cigarette smoke, and carbon-bearing materials in ore, can distort the readings in both metal and nonmetal mines (virtually all of which contain carbon-bearing materials in ore) and in coal mines (coal is essentially pure carbon). NIOSH has recently announced that it believes the 5040 Method can be adjusted to account for the confounding substances, but significant doubt remains about the effectiveness of the 5040 Method and the commercial availability of sampling devices which can use it accurately.

In this regard, MSHA seems to have been totally unaware, or unrealistic in its lack of understanding, of the confounders. In the preamble to the proposed DPM limitation rule for underground metal-nonmetal miners, MSHA made no mention whatsoever of the high carbon content of many metallic-nonmetallic ores. MSHA also appears to have misunderstood how oil mist and cigarette smoke can affect use of the 5040 Method. For example, it totally ignored the fact that in many underground metal-nonmetal mines, oil mist is generated by machinery other than diesel equipment (such as jumbo drills); and for MSHA to state that "cigarette smoke is under the control of [metal-nonmetal mine] operators" is remarkably uninformed and naïve.

Lack of Feasible Engineering Controls

Serious concerns exist whether feasible engineering controls are available to meet either the proposed coal or metal-nonmetal limitations. The 95% DPM removal limitation proposed for underground coal mines is essentially a design requirement, which discourages performance-based solutions. On the other hand, the metal-nonmetal proposed limitations, while performance-based, rest on questionable grounds and may not be achievable. Responsible mine operators have long advocated use of a performance-based "tool box" approach to reduce DPM exposures, but MSHA has rejected that as a regulatory solution. Particularly troublesome is MSHA's unwillingness to allow operators to achieve compliance by using personal protective equipment ("PPE") or administrative controls. MSHA's design-based coal proposal implicitly precludes use of PPE or administrative controls for compliance, and the metal-nonmetal proposal specifically prohibits the use of PPE or administrative controls.

Inadequate Data on Exposure to DPM

In underground coal mines, MSHA has made no data available concerning current DPM exposures of miners, although stringent use and maintenance requirements for diesel powered equipment operated in underground coal mines have been in effect since October 1996. These use and maintenance requirements should have resulted in substantial reduction of DPM exposures. Indeed, a major phase-in deadline for a large class of underground coal mine diesel-powered machines will occur on November 25, 1999, thereby reducing DPM exposures even further. In the metal-nonmetal sector, MSHA samples of DPM exposures consist of only a very limited number of samples, taken in a haphazard fashion over a period of years, and using different sampling methodologies.

But MSHA Presses On

Despite these many flaws, regulation of the exposure of underground miners (especially coal miners) is a high priority of MSHA's Davitt McAteer. The issue is critical for the mining industry, too, because the timing and substance of these regulations will play a pivotal role in the ability of underground mine operators to use the industry's present fleet of diesel-powered equipment and will also substantially affect decisions on the use of diesel-powered equipment in the future.

As for timing, many MSHA proposed rulemakings have languished for years following the close of the public comment period because of the complexity of the proposals (real or perceived), or because MSHA has assigned them low priority despite their obvious importance. Late last year, however, the United States Court of Appeals for the D. C. Circuit threw MSHA a curve, which may well affect the timing of final DPM regulations, as reported in the January 1999 issue of the C&M Mining Law Monitor.

On December 9, 1998, in mandamus litigation brought by the United Mine Workers of America ("UMWA") against MSHA to compel issuance of regulations on diesel exhaust gases, the court held that, since the period for public comment on MSHA's proposed rules for air quality in mines had closed in 1991, and since under Mine Act § 101(a)(4) MSHA has 90 days following the close of a public comment period (not the 7 years MSHA had taken) to promulgate final regulations or to explain its reasons for not doing so, MSHA's failure to act "is clearly in violation of the statute." Thus, if MSHA does not promulgate the DPM limitation proposals for coal and metal-nonmetal underground mines within 90 days from July 26, it may well be vulnerable to judicial intervention.

Further complicating the substance of the rulemaking is the question of whether DPM limitations should also apply to surface miners. MSHA itself has raised this specter by stating in both proposals that while it is "not at this time proposing a rule applicable to surface mines . . . [nevertheless] [t]he Agency would like to emphasize . . . that surface miners are entitled to the same level of protection as other miners, and that the Agency's risk assessment indicates that even short-term exposures to concentrations of [DPM] . . . may result in serious health problems." Thus, with regard to surface mines, MSHA has opened the door and then quickly attempted to close it. The question may well be whether, in the course of the current UMWA mandamus litigation or any other similar litigation, that door will stay shut.

In short, although the public comment period for MSHA's DPM rulemakings has closed for now, in light of the substantial flaws in the proposals and the potential for judicial intervention in the timing and substance of final rulemaking at a very early date, there is a good likelihood that the rulemakings may well be subject to further public comment sooner rather than later. Finalizing the proposals in their current form is likely to be problematic. Stay tuned!

Edward M. Green
Senior Counsel – Washington, D.C.
Phone: +1 202.624.2922