Air Quality Alert: EPA Proposes Stricter Particulate Matter Standard

On June 15, 2012, U.S. EPA proposed stricter standards to the National Ambient Air Quality Standards (NAAQS) under the Clean Air Act for fine particulate matter. The proposed rule, which is the result of a lawsuit in the U.S. Court of Appeals in the Washington D.C Circuit brought by environmental groups and certain states, proposes to tighten the annual standard for particulate matter under 2.5 microns (PM 2.5) from 15 micrograms per cubic meter (ug/m3) (the 2006 standard) to between 12 and 13 ug/m3. The rule also proposes a new separate standard for improving visibility in urban areas of either 28 to 30 "deciviews," a measurement of visibility. The proposed rule and "fact sheets" provided by the Agency make clear that EPA is not proposing a change to the existing 24-hour and secondary standards for fine and course particulate matter set in 2006.