The Environmental Protection Agency (EPA) recently proposed to tighten the annual national ambient air quality standard for fine particulate matter. My colleague Daren Bakst and I submitted comments on behalf of CEI. We challenge the proposal as arbitrary and capricious. Daren’s blog post of April 5 calls out the EPA’s rush to scrap the current NAAQS only 13 months into the five-year period such standards normally remain in effect. He also deplores the EPA’s purge of its Clean Air Scientific Advisory Committee (CASAC) to ensure agreement with the agency’s agenda. The present post discusses the weakness of the EPA’s core scientific premise that fine particle pollution kills tens of thousands of Americans every year.