Last week, EPA posted its draft Integrated Science Assessment for Particulate Matter. 
It’s the foundational document for EPA’s periodic review of its National Ambient Air Quality Standard for PM. The current standard for PM2.5, promulgated in 2012, is 12 ug/m3.
Section 109 of the Clean Air Act requires the Administrator to set the NAAQS “requisite to protect the public health” with “an adequate margin of safety.”
The new ISA states that:
Evidence from U.S.… More