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Diesel engines are widely and increasingly frequently used in mining operations because of their high power output and mobility. Diesel-powered machines, from bobcats to loaders, are more powerful than most battery-powered equipment and can be used without electrical trailing cables which can restrict equipment mobility. The downside, especially in the underground mining environment, is the potential health effects -- both acute and long-term -- of exposure to various constituents of diesel exhaust, which consists of noxious gases and very small particles. The Center for Disease Control and Prevention (CDC) has determined that diesel exhaust is a potential human carcinogen.
In addition, acute exposures to diesel exhaust have been linked to health problems such as eye and nose irritation, headaches, nausea, and asthma. Currently, underground miners can be exposed to over 100 times the typical environmental concentration of diesel exhaust and over 10 times that measured in other workplaces. In addition, miner exposure to diesel emissions promises to become more widespread as diesel equipment becomes more popular within the mining community.
MSHA sets limits on miner exposure to a number of the gases in diesel emission (see Title 30 CFR Sect. 75.322 and Sect. 71.700 for underground and surface coal mines and Sect. 57.5001 and Sect. 56.5001 for underground and surface metal and nonmetal mines).
MSHA also addresses the particles in diesel emissions. Diesel particulate matter is small enough to be inhaled and retained in the lungs. Each particle has hundreds of chemicals from the exhaust adsorbed (attached) onto its surface. Accordingly, MSHA proposed a June 6 rule to limit workers' exposure to diesel exhaust particles by requiring mine operators to remain under a Total Carbon (TC) limit of 160 micrograms per cubic meter of air. MSHA had been working on the rule for years and had carried out extensive negotiations with the mining industry, which has long argued the rule is unnecessary and unenforceable. The TC limit was identical to provision originally proposed by MSHA in a 2001 rule, when the agency first attempted to address the issue.
MARG Diesel, an informal group of mining companies and trade associations, filed a data quality challenge on Aug. 10, arguing that the TC rule fails to meet the data quality standards laid out in the Data Quality Act and the Department of Labor's guidelines for implementing that law. The group claims the rule is based on data that is not transparent or reproducible and that it underwent a flawed peer review process. MARG Diesel claims that the only "correction" possible is for MSHA to either stay or entirely overturn the 160 TC limit rule until these issues can be resolved.
This challenge represents another industry abuse of the Data Quality Act, in order to impede the processes of government agencies. While the petition raises issues and concerns about the studies and data used to produce the new TC rule, the studies are not listed as the challenged information. Instead, MARG identifies the rule as the target of its challenge.
Transparency and Reproducibility
MARG Diesel claims that the two main studies heavily relied upon in the rulemaking (called the 31-Mine Study and the Estimator) fail to meet the reproducibility and transparency standards of Labor's data quality guidelines, which indicate that the research process should be transparent enough that another entity could conduct the study and reach the same outcomes. The group asserts that MSHA's study makes incorrect assumptions, regarding, among other things, air ventilation, that "continue to contradict reality, even if input emission measurements were representative, which they are not." Among the specific assumptions MARG disagrees with is the effectiveness of filters required to become compliant with the 160 TC limit, arguing that some pieces of equipment cannot be fitted with filters, and therefore the particle limit is not achievable.
MARG clearly fails to raise a legitimate data transparency or reproducibility concern. Data is reproducible if it "is capable of being substantially reproduced, subject to an acceptable degree of imprecision," according to the data quality guidelines. Data is transparent if the source of the data is revealed along with the supporting data and models. The issues raised by MARG Diesel are not issues of reproducibility or transparency. The problems do not concern a hidden assumption or any undisclosed data or models. In fact, MARG Diesel, in an effort to disprove the MSHA results, conducted its own version of the study, thereby proving that the study was transparent.
Independent Peer Review
MARG Diesel also argues in its petition that the 31-Mine Study and the Estimator were not independently peer-reviewed, because the reviewers were "self selected personnel in its sister agency the National Institute for Occupational Safety and Health (NIOSH)," a division of the CDC. Additionally, MARG claims that, "a review of the Estimator for publication in a mining magazine does not constitute the needed independent peer review for use of the Estimator to determine feasibility of compliance for a mine or for the industry, due to the incorrect assumption in the Estimator described therein."
While MARG Diesel makes several assertions about the biased peer review, the group fails to provide any specific evidence or proof that the peer review process was not conducted objectively. The Department of Labor Information Quality Guidelines defines peer review as the "independent assessment of the technical and scientific merit of research by individuals knowledgeable in the particular subject interest and with no unresolved conflict of interest." NIOSH employees were clearly selected for their extensive knowledge of the material. The petition makes no mention of any specific conflict of interest or bias for the reviewers at NIOSH. It also makes little sense to claim that an independent peer review done by a mining magazine is insufficient, because the material they reviewed was flawed. The purpose of the review is to determine the merit of material and discover such flaws if they exist. MARG is challenging the peer review of the Estimator study, simply because it disagrees with its conclusions and the rule MSHA is basing on it.
The MSHA has not yet issued a formal reply to the MARG Diesel Coalition's challenge. However, the agency has already published a modification to the TC Rule. On Sept. 5, about one month after receiving the data quality challenge, the agency proposed to phasing in the 160 TC limit over six years, instead of requiring compliance next year.
The MARG Diesel coalition has failed to make a valid reproducibility, transparency, or independent peer review complaint. The other claims of the MARG Diesel challenge fall even further from the mark: the "feasibility" of complying with the TC rule, the "regulatory confusion" that the rule would cause, and the "significant loss of jobs" that instituting the rule would cause. None of these charges have anything to do with data quality, nor is the data quality mechanism the appropriate forum for MARG to make these complaints, which should be raised during the rulemaking process. Instead, MARG is misusing the data quality process to disagree with the policy of instituting the 160 TC rule.
The MARG Diesel petition does not constitute a valid data quality challenge, but rather a disingenuous complaint that divert agency resources and wastes agency time. The Department of Labor's own Data Quality Act guidelines acknowledge that, "Program efficiency must be a critical goal as DOL agencies carry out their responsibilities under these guidelines," MSHA, as the division of DOL responsible of miner safety, in the interest of program efficiency should reject such spurious industry tactics.