5 July 1999

The Engine Manufacturers Association (EMA) petitioned the California Environmental Protection Agency's Air Resources Board (ARB) to reconsider its proposed designation of diesel particulate emissions as a toxic air contaminant (TAC). The petition, filed on July 2, is based on new epidemiologic data, including the June 1999 HEI report.

"We have consistently said that the scientific data that have been reviewed so far are inadequate to support the designation of diesel particulate emissions as a toxic air contaminant," said Glenn Keller, executive director, EMA. "Now, new information from highly respected, independent scientists overwhelms the shaky foundation for the California Board's proposed designation and quantitative risk assessment. The TAC listing of diesel particulate is absolutely not justified."

Keller noted that today's truck engines emit nearly 70% less NOx and 90% less particulates than in 1987. Meanwhile, diesel offers improved mileage over gasoline, along with greatly reduced emissions of hydrocarbons, carbon monoxide and greenhouse gases (carbon dioxide).

"If this TAC listing goes forward despite the evidence that it is unwarranted, there is grave risk that the people of California and elsewhere will be denied the environmental and energy efficiency benefits of diesel engines," Keller stated. "Diesel technology is a crucial component of any national energy solution going forward, if the options for consideration are not unjustly limited by government action," he said.

The Air Resources Board on 27 August 1998, adopted a resolution classifying diesel particulate emissions as a toxic air contaminant, and is in the process of finalizing the listing. The EMA petition, in which several other petitioners joined, cites recent reports from the Health Effects Institute and the Environmental Protection Agency's Clean Air Science Advisory Committee that show the flaws of the science ARB relied on in making that decision. According to the petitioners, these reports include:

  • The October 1998 report of the Environmental Protection Agency's Clean Air Science Advisory Committee. CASAC was established under the Clean Air Act to provide independent scientific advice to the Administrator of the EPA. CASAC reported a preliminary finding of numerous flaws in a draft EPA diesel health assessment document that relies on many of the same studies used by ARB. The advisory group remanded the draft document back for further study and editing.
  • The June 1999 Special Report of the Health Effects Institute. HEI, founded in 1980 and jointly funded by EPA and industry, is charged with providing an independent and unbiased source of information on the health effects of motor vehicle emissions. HEI's new report concludes that key studies relied on by ARB are inadequate to provide a scientific basis for assessing risks related to diesel.

"ARB is obligated to review and act upon the new evidence that has come to light," Keller stated. "We believe that when ARB reviews these highly authoritative new reports, it will come to the conclusion we have reached: that the TAC listing of diesel particulate is not justified."

Source: EMA