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MSHA News Release No. 2001-0118
Mine Safety and Health Administration
Contact: Amy Louviere/Rodney Brown
Phone: (703) 235-1452

Released Thursday, January 18, 2001

The Mine Safety and Health Administration has announced two final rules to protect all underground miners from diesel exhaust particulate matter, a serious health hazard created by diesel-powered equipment. The rules are scheduled for publication in the Federal Register on Friday, January 19.

   Diesel particulate matter, or DPM, consists of tiny particles present in diesel engine exhaust that can readily penetrate into the deepest recesses of the lungs. Despite ventilation, the confined underground mine work environment may contribute to significant concentrations of particles produced by equipment used in the mine. Underground miners are exposed to higher concentrations of DPM than any other occupational group. As a result, they face a significantly greater risk than other workers of developing such diseases as lung cancer, heart failure, serious allergic responses and other cardiopulmonary problems.

   The new diesel regulations will affect 145 underground coal mines employing nearly 15,000 miners and 196 underground metal and nonmetal mines employing nearly 19,000 miners.

   "Underground mines are unique workplaces where workers may be exposed to high concentrations of diesel emissions," said Secretary of Labor Alexis M. Herman. "These rules will not eliminate all of the health risks to miners working around diesel-powered equipment, but they will significantly reduce the level of risk."

   The new rules will ensure that miner exposures do not exceed those of other groups of workers regularly exposed to diesel exhaust, such as truck and bus drivers.

   "The use of diesel equipment is integral to mine production," said Herman. "We want to work with industry to encourage the use of newer, ‘cleaner' engines currently on the market."

   Since underground conditions vary between coal mines and metal and nonmetal mines, the regulations take different approaches to reduce DPM exposure to the same level. The final rule to protect underground metal and nonmetal miners will establish an "interim" DPM concentration limit of 400 micrograms of total carbon per cubic meter of air and, after five years, that level must be reduced to 160.

   Following publication of the regulation, metal and nonmetal mines have up to 18 months to reach compliance with the interim concentration limit in their underground operations. These operators have the option of using engineering controls and best practices to reduce DPM to the proper limit.

   In underground coal mines, the new rule sets a specific emission limit of 2.5 grams per hour of DPM for permissible and non-permissible equipment. These limits will be phased in for an operation's existing equipment inventory over a 48-month period, but new equipment must meet the emission limits sooner. Coal mine operators may use a combination of controls (cleaner engine, filter, etc.) to comply with the emission limit.

   Annual training is required for all underground miners exposed to diesel emissions. Workers will be trained on the health risks associated with DPM exposure, control methods being used at the mine, identification of personnel responsible for maintaining those controls, and actions miners must take to ensure the controls operate as intended.

   To assist mine operators in understanding the requirements of the rules, MSHA will offer compliance assistance and a series of informational workshops throughout the country (dates and locations to be announced). A compliance guide and tool-box also will be available on MSHA's web site at

   MSHA estimates that at least 8.5 cases of lung cancer per year will be avoided as a result of the metal and nonmetal rule, and at least 1.8 cases per year will be avoided as a result of the coal rule.

   MSHA first proposed regulations regarding diesel emissions in April 1998 for coal mines and October 1998 for metal and nonmetal mines. Public hearings were held in November and December for the coal rule and the following May for the metal and nonmetal rule. Public comments were accepted on the coal rule for 15 months and on the metal and nonmetal rule for nine months.