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Statement of Need: The use of diesel-powered equipment in underground mines has increased significantly and rapidly during the past decade. We estimate that about 7,500 miners working in production or development areas are occupationally exposed to diesel exhaust emissions in underground metal and nonmetal mines. Several epidemiological studies have shown a positive carcinogenic risk associated with exposure to diesel exhaust. Other reported health effects associated with exposure to diesel exhaust include dizziness, drowsiness, headaches, nausea, decreased visual activity, and decreased forced expiratory volume. In addition, studies by MSHA and the former Bureau of Mines show that miners working in underground mining operations that use diesel equipment are probably the most heavily exposed workers of any occupational group. Based on the levels of diesel particulate measured in underground mining operations and the evidence of adverse health effects associated with exposure to diesel exhaust. We are concerned about the potential health risk to miners.

Summary of the Legal Basis: Promulgation of these regulations is authorized by sections 101 and 103 of the Federal Mine Safety and Health Act of 1977.

Alternatives: In the fall of 1995, we held a series of public workshops to gather suggestions for possible approaches to limit miners' exposure to diesel particulate. In addition, over the past 10 years, MSHA and the former Bureau of Mines have conducted research on methodologies for the measurement and control of diesel particulate in the mining environment. This research has demonstrated that the use of low sulfur fuel, good engine maintenance, exhaust after-treatment, new engine technology, and optimized application of ventilating air all play a role in reducing miners' exposure to diesel exhaust particulate matter.

Anticipated Costs and Benefits: We estimate that the compliance costs for underground metal and nonmetal operators would be approximately $19 million. The compliance costs to manufacturers are assumed to be passed through to underground metal and nonmetal operators and therefore, they would not incur any direct costs as a result of the rule. The proposed rule would reduce a significant health risk to underground miners, reducing the potential for acute sensory irritations and respiratory symptoms, lung cancer, and premature death, along with the attendant suffering and costs to the miners, their families, and society. In addition to savings related to acute health effects, we estimate that some lung cancer would also be avoided.

Risks: Several epidemiological studies have found that exposure to diesel exhaust presents potential health risks to workers. These potential adverse health effects range from headaches and nausea to respiratory disease and cancer. In the confined space of the underground mine environment, occupational exposure to diesel exhaust may present a greater hazard due to ventilation limitations and the presence of other airborne contaminants, such as toxic mine dusts or mine gases. We believe that the health evidence forms a reasonable basis for reducing miners' exposure to diesel particulate.