August 20, 2003

Proposed Nonroad Diesel Engine and Fuel Standards

Key materials
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Nonroad Diesel Tier 4 and Nonroad Diesel Tier 3 Technology Review (OAR-2003-0012)

Stated Purpose:

"To reduce emissions of particulate matter (PM) and oxides of nitrogen (NOx) from nonroad diesel engines."

Summary of RSP Comment:

EPA proposes new emission standards for nonroad diesel engines and sulfur reductions in nonroad diesel fuel to significantly reduce emissions attributed to nonroad diesel engines. The rule focuses on nonroad diesel equipment that is self-propelled, land-based and portable but stationary when in use. EPA has already adopted three progressively tougher sets of emission standards for nonroad mobile equipment. These proposed standards will require an additional reduction of more than a 90 percent in allowable NOx and PM emissions requirements.

EPA should rethink not just the Proposed Rule, but also its regulatory context. The cost of attaining stringent National Ambient Air Quality standards for ozone and particulate matter will likely far exceed the benefits. Epidemiologic evidence suggests EPA can achieve its desired health results with less stringent standards.

Since EPA is unlikely to change course on the standards, it should consider more seriously if NOx reductions will increase ozone in some or many areas. The Proposed Rule will exacerbate an already problematic situation. EPA should likewise revisit the emission inventories used for modeling future air quality. The evidence suggests these inventories overstate future levels of ozone precursors.

The health benefit and cost analyses on which the proposal is based are seriously flawed, and should be revised before EPA proceeds. EPA was only able to achieve its large benefit estimates by ignoring shortcomings in its favored studies, and selectively excluding countervailing evidence. EPA’s regulatory cost accounting does not provide a meaningful estimate of the Proposed Rule’s societal cost—the standard against which an unbiased total benefit estimate should be compared.

Finally, EPA should place risk claims in context to give the public a realistic idea of both the harm from current air pollution levels and the potential benefits of a given emission reduction proposal.