The Engine Manufacturers Association says major revisions are needed to improve the accuracy and usefulness of the Multiple Air Toxics Exposure Study before its final release by the South Coast Air Quality Management District.

"Our main concern is that the public will be misled," said Glenn Keller, EMA Executive Director. "The methods used in the draft MATES II report incorrectly estimate cancer risks and describe them as 'average risks' to the public. That's simply not true."
EMA says researchers have identified significant uncertainties and errors in the way South Coast staff determined the health risks associated with toxic air contaminants in the report. "The MATES II report inaccurately estimates ambient levels of diesel particulates since the calculation is based on outdated and incomplete data from the early 80's," Keller said. "In addition, the unit risk factor for diesel particulate that drives the results of the study is an invalid measure of the potency of diesel particulate. What's more, risk levels reported as 'average' in the report are based on hypothetical, maximum predicted, outdoor exposure concentrations and not real-life exposure levels."
EMA advocates major revisions to the MATES II report before its official release, including using up-to-date data on the role of diesel particulates, realistic exposure estimates, and inclusion of an analysis of the uncertainties inherent in the results.