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Release Date: 10/07/97
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U.S. EPA Administrator Carol M. Browner today announced two, cost-effective clean air programs that will significantly reduce pollution from diesel engines. The new engine standards will provide substantial, long-term improvements in the nation’s air quality and public health and help the nation meet the EPA’s new air quality standards for smog and fine particles.
The agency said both new diesel programs, one, a final emission reduction standard for all diesel trucks and buses and the other a proposal to phase-in tighter emission limits for non-road diesel engines, like bulldozers, will reduce pollution by 2.7 million tons a year. The reduction is equivalent to taking six million heavy trucks off the road.
Browner said, “Air pollution poses a serious threat to the health and well-being of millions of Americans and diesel engines are a significant source of air pollution nationwide. New cost-effective standards will be a major step forward in reducing threats to public health and the environment from smog and particulate matter.”

Nitrogen oxides from diesel engines are a major contributor to the formation of ground-level ozone and particulate matter. Ozone reduces lung function and aggravates existing respiratory problems such as asthma. It can also cause a breakdown in a person's ability to fight off infectious bacteria. Particulates become lodged in the lungs’ most sensitive tissue and may result in premature death. In addition, ozone, particulate matter and nitrogen oxides cause crop damage, acid rain, and reduction in visibility.

In the first rule, EPA finalized a new, combined nitrogen oxides and hydrocarbon emission standard for heavy duty diesel engines used in trucks and buses that becomes effective with the 2004 model year. The nitrogen oxides reductions also will reduce nitrate particulate matter and acid rain. By 2020, when the new, cleaner engines dominate the fleet, nitrogen oxides will be reduced more than a million tons per year.
The agency in its second rule proposed standards for most non-road equipment with diesel engines. Over a half a million of the engines are sold each year and used in a wide variety of equipment, including bulldozers, logging equipment, forklifts and some marine vessels. The proposal includes progressively tighter standards that would be phased in between 1999-2008. When fully implemented, nitrogen oxides and particulate matter emissions from each engine would be reduced by up to two thirds from current standards.

EPA said the proposed standards are expected to be adopted by California which has the authority to set its own vehicle emission standards. They also are consistent with those proposed in Europe, so manufacturers will be able to use a single engine or machine design for all of these markets and avoid the added cost of multiple versions.

Both programs are cost-effective, costing only $300 or less per ton of nitrogen oxides reduced. The standards will add about two percent or less to the purchase price of new diesel-powered trucks and non-road equipment.

Despite the technological challenge, diesel engine manufacturers have demonstrated their ability to design new diesel engines that will achieve significant additional emission reductions to meet the more stringent standards for both programs. States, environmental organizations, small businesses, engine and equipment manufacturers and the trucking industry were involved with EPA in the development of both programs. Engine manufacturers, the state of California and EPA signed two separate “Statements of Principles” outlining a framework for the standards.

EPA will accept public comments on the non-road diesel proposal until Nov. 24, 1997.

Both rules will be published in the Federal Register and on the Office of Mobile Sources web page at

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