Contact Us


All News Releases By Date


New Studies Compare Composition and Toxicity of Diesel Exhaust

Release Date: 06/02/2004
Contact Information:

David Deegan, 617-918-1017 /

(06/02/04) The June issue of “Environmental Health Perspectives” has recently published two studies by EPA scientists which compare two different samples of diesel exhaust particles for composition, toxicity and mutagenicity (ability of a substance to cause a mutation). The two types of diesel exhaust samples, used for health effects studies for about the past 10 years, derive from emissions of a forklift and an automobile. The recent studies are the first to compare the two emission sources in this manner. The particular automobile sample has been used exclusively in experiments to test heart and lung effects, and the particular forklift sample has been used primarily to test for genotoxic effects (i.e., the ability to cause damaging effects at a cellular or DNA level). The new research shows that the two samples of diesel exhaust particles have different physical and chemical properties, as well as different mutagenic effects in bacteria and pulmonary toxicity effects in mice. Accompanying the studies is a commentary by Dr. Janet Arey of the University of California at Riverside calling for more cooperation among toxicologists, analytical chemists, atmospheric chemists, and automotive and combustion engineers to provide a comprehensive assessment of health risks to humans exposed to contemporary diesel emissions. The studies and commentary highlight the need for additional research to understand the composition of particles and potential health effects in all types of diesel sources.

EPA has previously concluded that diesel exhaust, as emitted from a variety of diesel engines, is harmful to human health. During the past several years, EPA has proposed and implemented a suite of measures to reduce harmful emissions from all types of diesel engines, including automobiles, school buses, trucks and heavy machinery such as construction equipment. On May 11, EPA signed a Clean Air Nonroad Diesel rule that will cut emission levels from construction, agricultural and industrial diesel-powered equipment by more than 90 percent. The new rule will also remove 99 percent of the sulfur in diesel fuel by 2010, resulting in dramatic reductions in soot from all diesel engines. More information on EPA’s efforts to limit harmful air emissions from diesel engines is available at: .