Front Porch Blog


On September 29th, the seven permanent members of EPA’s Clean Air Science Advisory Committee (“CASAC”) sent a scathing letter to EPA’s top dog, Stephen Johnson, condemning his decision to ignore CASAC’s recommendations concerning recent revisions to the National Ambient Air Quality Standards (“NAAQS”) for particulate matter (“PM”).

Highlights of the letter attacking Johnson’s decision to retain the annual PM2.5 standard at 15µg/m3 include the following statements:

*”The CASAC recommended changes in the annual fine-particle standard because there is clear and convincing scientific evidence that significant adverse human-health effects occur in response to short-term and chronic particulate matter exposures at and below 1515µg/m3 the level of the current annual PM2.5 standard.”

*”While there is uncertainty associated with the risk assessment for the PM2.5 standard, this very uncertainty suggests a need for a prudent approach to providing an adequate margin of safety. It is the CASAC’s consensus scientific opinion that the decision to retain without change the annual PM2.5 standard does not provide an ‘adequate margin of safety … requisite to protect the public health’ (as required by the Clean Air Act), leaving parts of the population of this country at significant risk of adverse health effects from exposure to fine PM.”

“Significantly, we wish to point out that the CASAC’s recommendations were consistent with the mainstream scientific advice that EPA received from virtually every major medical association and public health organization that provided their input to the Agency, including the American Medical Association, the American Thoracic Society, the American Lung Association, the American Academy of Pediatrics, the American College of Cardiology, the American Heart Association, the American Cancer Society, the American Public Health Association, and the National Association of Local Boards of Health. Indeed, to our knowledge there is no science, medical or public health group that disagrees with this very important aspect of the CASAC’s recommendations. EPA’s recent ‘expert elicitation’ study (Expanded Expert Judgment Assessment of the Concentration-Response Relationship Between PM2.5 Exposure and Mortality, September 21, 2006) only lends additional support to our conclusions concerning the adverse human health effects of PM2.5.”

To view the entire letter, click here CASAC Letter





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