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Statement of Need: As a result of the first partial settlement with the litigants, MSHA published two documents in the Federal Register on July 5, 2001. One document delayed the effective date of 57.5066(b) regarding the tagging provisions of the maintenance standard; clarified the effective dates of certain provisions of the final rule; and gave correction amendments (66 FR 35518). The second document was a proposed rule to clarify 57.5066(b)(1) and (b)(2) of the maintenance standards and to add a new paragraph (b)(3) to 57.5067 regarding the transfer of existing diesel equipment from one underground mine to another underground mine (66 FR 35518). The final rule on these issues was published February 27, 2002, and became effective March 29, 2002. As a result of the second partial settlement agreement, MSHA proposed specific changes to the 2001 DPM final rule. On September 25, 2002, MSHA published an ANPRM. In response to commenters, MSHA proposed changes only to the interim DPM standard of 400 micrograms per cubic meter of air. In a separate rulemaking, the Agency will propose a rule to revise the final concentration limit of 160 micrograms per cubic meter of air. The scope of both rulemakings is limited to the settlement agreement. The current rulemaking addresses the following provisions: 57.5060(a) - Whether to change the existing DPM surrogate for the interim limit from total carbon to elemental carbon; and change the concentration limit to a comparable permissible exposure limit. 57.5060(c) - Whether to adapt to the interim limit the existing provision that allows mine operators to apply to the Secretary for additional time to come into compliance with the final concentration limit. MSHA also agreed to propose to include consideration of economic feasibility, and to allow for annual renewals of such special extensions. 57.5060(d) – Whether to remove the existing provision permitting miners to engage in certain activities in concentrations exceeding the interim and final limits upon application and approval from the Secretary, since the Agency agreed to propose the current hierarchy of controls that MSHA applies in its existing metal and nonmetal exposure based health standards for abating violations. 57.5060(e) – Whether to remove the existing prohibition on the use of personal protective equipment. 57.5060(f) - Whether to remove the prohibition on the use of administrative controls. 57.5061(a) – Whether to change the reference from "concentration" to PEL. 57.5061(b) – Whether to change the reference from "total carbon" to "elemental carbon." 57.5061(c) - Whether to delete the references to "area" and "occupational" sampling for compliance. 57.5062 – Whether to revise the existing diesel control plan.

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: This rulemaking would amend and improve health protection from that afforded by the existing standard.

Anticipated Costs and Benefits: MSHA's preliminary economic analysis indicates that making the changes under consideration would result in a net cost savings to the mining industry.

Risks: A number of epidemiological studies have found that exposure to diesel exhaust presents potential health risks to miners. These potential adverse health effects range from headaches and nausea to respiratory disease and cancer. In the confined space of the underground mining 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 matter. Proceeding with rulemaking on the provisions discussed above will more effectively reduce miners' exposure to DPM.