18 January 2001

The US Mine Safety and Health Administration has announced two final rules to protect underground miners from emissions of diesel exhaust particulate matter (DPM). One of the rules regulates PM emissions in coal mines, the other in metal/nonmetal mines (i.e., noncoal mines). Both rules are scheduled for publication in the Federal Register on Friday, January 19.

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.

Many underground miners are exposed to DPM levels that are many times higher than those encountered in all other occupational environments. According to MSHA, 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 Secretary of Labor Alexis M. Herman. “We want to work with industry to encourage the use of newer, cleaner engines currently on the market”.

The regulations take different approaches to reduce DPM exposure in coal and in noncoal mines. The final rule to protect underground metal and nonmetal miners will establish an “interim” DPM concentration limit of 400 µg/m3 (micrograms per cubic meter of air) and, after five years, that level must be reduced to 160 µg/m3. In the metal/nonmetal mine rule, DPM is defined as total carbon (TC), i.e., it includes elemental and organic carbon, but excludes metal ash or sulfates.

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 g/hr (grams per hour) of DPM for permissible and non-permissible equipment. This emission limit replaces the explicit requirement to install 95% efficient particulate filters, which was criticized during the public discussion on the proposed rules. 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.

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.

Considering the current level of DPM exposure in North American mines, which typically ranges between 200 and 500 µg/m3, but levels as high as 1700 µg/m3 have been measured in some locations, the adopted regulations are expected to force a widespread use of diesel particulate filters in US underground mining.

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. MSHA accepted public comments on the coal rule for 15 months and on the metal and nonmetal rule for nine months.

For more information contact: Rodney Brown, MSHA, 703-235-1452.

Regulatory documents from MSHA server

Source: MSHA