On Feb. 9, the U.S. Court of Appeals for the District of Columbia Circuit concluded that MSHA demonstrated that DPM presents a significant risk to the health and safety of miners and that the agency provided more than enough evidence that mine operators can feasibly comply with the new standards.
"Exposure to diesel particulate matter is a significant public health concern, and the court determined that all aspects of MSHA's standard were supported," MSHA Administrator Richard Stickler said. "This decision ensures that we can move forward with enhanced protection for miners who work with diesel equipment underground."
Mining Firms, Other Stakeholders Challenged DPM Rule
The DPM rule, first promulgated in 2001, set an interim exposure limit of 400 micrograms per cubic of air, which was to become effective in July 2002. It set a final limit of 160 micrograms per cubic meter of air, which was to become effective in January 2006.
The rule was challenged by the Anglogold Corp. and Kennecott Greens Creek Mining Co.; the Georgia Mining Association; the National Mining Association; the Salt Institute; the Methane Awareness Resource Group ("MARG") Diesel Coalition; and Getchell Gold Corp.
MSHA examined the rule and agreed to undertake further rulemaking. In 2005, MSHA changed the surrogate metric used to measure DPM from "total carbon" to "elemental carbon" for the interim limit. In addition, the rule was amended to allow the use of respirators when engineering controls could not feasibly meet the DPM limits.
The National Mining Association alleged that the agency should not have based the rule on a calculation that allowed industry to comply with the new limits by using new clean-diesel engines, as the trade association noted that use of such engines could actually increase exposure to dangerous nanoparticles.
The court, however, held that it was reasonable for MSHA to regulate for the known risks of DPM while conducting research into the potential health effects of nanoparticles.
2006 Rule Retained Final Limit Set in 2001
The 2006 rule retained the final limit set in 2001, and gave the mining industry until May 20, 2008, to comply with that limit. Additionally, the 2006 rule provided medical evaluations for miners required to wear respirators and transfer rights to other existing jobs for miners unable to wear a respirator.
MSHA also stated that it would change the surrogate metric from total carbon to elemental carbon for the final limit.
