Engine Manufacturers Challenge Validity of Air Toxics Study
8 November 1999
Engine Manufacturers Challenge Validity of Air Toxics Study
CHICAGO--Nov. 5, 1999--The Engine Manufacturers Association (EMA) challenged the validity of the air quality report issued in California today indicating that it is "rushed, not ready for public review, and contains unreliable information."Questioning the accuracy and validity of the Multiple Air Toxics Exposure Study (MATES II) released by the South Coast Air Quality Management District (SCAQMD), Glenn Keller, EMA Executive Director, warned that the public will be misinformed as a result of the released study.
"There are significant uncertainties and flaws in the way South Coast staff determined the health risks from diesel in the report," said Keller. "The report was rushed out before undergoing technical and scientific peer reviews, misinforming people on serious issues affecting air quality and their health."
"The study takes a lot of shortcuts in its methodologies and assumptions used to make its findings," explained Keller. "Perhaps the report's most critical flaw is that it uses air data from 1986-1989, and neglects to account for the reduced toxicity of CARB-spec diesel fuel used since 1993 as well as the evolution of diesel engine technology to produce reduced emissions of particles and other harmful chemical compounds."
"Particulate emissions from diesel-fueled engines have been reduced by 90% over the past decade, and even greater reductions are in the works," cited Keller. "Reformulated diesel fuel in California also has led to significant reductions in toxic emissions. However, the report does indicate that the risk of exposure to air toxics in the South Coast basin has been reduced to one-third of the level that they were in the mid-1980s."
The relative contribution of diesel engines to the total inventory of particulates reported in the MATES II study also is suspect, according to EMA. The South Coast findings conflict with results from more thorough, state-of-the-art studies (e.g., the Denver Northern Front Range Air Quality Study) which indicate that the majority of fine particulate matter emissions may come from sources other than diesel trucks.
In addition, the unit risk factor (URF) for diesel particulate that drives the results of the MATES II study is a highly controversial and possibly invalid measure of the potency of diesel particulate, according to EMA. Recently, the Health Effects Institute and the Environmental Protection Agency's own Clean Air Scientific Advisory Committee found that there are insufficient data linking diesel exhaust to cancer to derive a quantitative unit risk factor. Current scientific knowledge does not corroborate SCAQMD's use of that URF to calculate increased cancer incidence reported in the draft MATES II study.
EMA is a trade association representing worldwide manufacturers of internal combustion engines for all application except passenger cars and aircraft. The EMA continues to work with government and industry stakeholders to help the nation achieve its goals of cleaner fuels, more efficient engines and cleaner air. For more information contact Anne Rukavina at (312) 644-6610 x3393 or visit our website at www.engine-manufacturers.org