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Health Assessment Document for Diesel Engine Exhaust

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Environmental Protection Agency.


Notice of availability of a final report.


The U.S. Environmental Protection Agency (EPA) is announcing the availability of the final Health Assessment Document for Diesel Engine Exhaust (EPA/600/8-90/057F, May 2002). The document was prepared by the Office of Research and Development's National Center for Environmental Assessment (NCEA). The assessment evaluates the health effects literature to identify the most important exposure hazards to humans. Secondly, the assessment evaluates the exposure-response characteristics of the key health effects so that information is available for understanding the possible impact on an exposed population.


The final document is available electronically on NCEA's Web site today.


The document is available electronically on NCEA's Web site (​ncea) under the What's New and Publications menus. A limited number of CDs and paper copies will be available from EPA's National Service Center for Environmental Publications (NSCEP). To obtain copies, please contact NSCEP by telephone (1-800-490-9198 or 513-489-8190), by facsimile (513-489-8695), or by mail (PO Box 42419, Cincinnati, OH 45242-0419). Please provide your name and mailing address and the title and EPA number of the Health Assessment Document for Diesel Engine Exhaust (EPA/600/8-90/057F, May 2002).

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The Technical Information Staff, NCEA-Washington Office (8623D), U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW., Washington, DC 20460; telephone: 202-564-3261; facsimile: 202-565-0050.

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The diesel engine has been a vital workhorse in the United States, powering many of its large trucks, buses, farm, railroad, marine and construction equipment. Expectations are that the use of diesel engines will increase due to the superior performance characteristics of the engine. Diesel engine exhaust, however, contains large quantities of harmful pollutants in a complex mixture of gases and particulates. Human exposure to this exhaust comes from both highway uses (on-road) as well as from the nonroad uses of the diesel engine.

EPA started regulating the gaseous emissions from the heavy duty highway uses of diesel engines in the 1970s and particles in the 1980s. The reduction of harmful exhaust emissions has taken a large step forward because of standards issued in 2000 which will bring about very large reductions in exhaust emissions for model year 2007 heavy duty engines used in trucks, buses and other on-road uses. EPA anticipates developing similarly stringent regulations for other diesel engine uses, including those used in nonroad applications.

Until these regulations take effect, EPA is partnering with state and local agencies to retrofit older, dirtier, engines to make them run cleaner and to develop model programs to reduce emissions from idling engines. In addition, EPA and local authorities are working to ensure early introduction of effective technologies for particulate matter control and low sulfur fuel where possible in advance of the 2007 requirements. Today, at least one engine manufacturer is producing new engines with particulate traps that when coupled with low-sulfur fuel meet 2007 particulate emission levels. The Agency expects significant environmental and public health benefits as the environmental performance of diesel engines and diesel fuels improve.

A draft of this assessment, along with the peer review comments of the Clean Air Scientific Advisory Committee, was part of the scientific basis for EPA's regulation of heavy-duty highway engines completed in December 2000. The information provided by this assessment was useful in developing EPA's understanding of the public health implications of exposure to diesel engine exhaust and the public health benefits of taking regulatory action to control diesel emissions.

The health assessment concludes that long-term (i.e., chronic) exposure to diesel exhaust is likely to pose a lung cancer hazard, as well as damage the lung in other ways depending on exposure. The health assessment's conclusions are based on exposure to exhaust from diesel engines built prior to the mid-1990s. Short-term (i.e., acute) exposures can cause transient irritation and inflammatory symptoms, although the nature and extent of these symptoms are highly variable across the population. The assessment also states that evidence is emerging that diesel exhaust exacerbates existing allergies and asthma symptoms. The assessment recognizes that diesel engine exhaust emissions, as a mixture of many constituents, also contribute to ambient concentrations of several criteria air pollutants including nitrogen oxides, sulfur oxides, fine particles, as well as other hazardous air pollutants.

The particulate fraction of diesel exhaust and its composition is a key element in EPA's present understanding of the health issues and formulation of the conclusions in the health assessment. The amount of exhaust particulate from on-road engines has been decreasing in recent years and is expected to decrease 90% from today's levels with the engines designed to meet the 2007 regulations. The composition of the exhaust particulate matter and the gases also will change. While EPA believes that the assessment's conclusions apply to the general use of diesels today, as cleaner diesel engines replace a substantial number of existing engines, the general applicability of the conclusions in this Health Assessment Document will need to be reevaluated.

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Dated: July 1, 2002.

Paul Gilman,

Assistant Administrator for Research and Development.

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[FR Doc. 02-22368 Filed 8-30-02; 8:45 am]