CASAC Endorses Stricter Fine Particle Standards
EPA’s panel of independent science reviewers have endorsed adoption of more stringent annual average and daily standards for fine particles.
The 22-member EPA Clean Air Scientific Advisory Committee (CASAC) sent a letter to EPA Administrator Stephen L. Johnson on June 6, 2005 requesting that “the primary PM2.5 24-hour and annual NAAQS should be modified to provide increased public health protection.” The panel is recommending a more stringent set of standards than contemplated in the draft Staff Paper that they were commenting on.
Specifically, the letter states that “most Panel members favored the option of setting a 24-hour PM2.5 NAAQS at concentrations in the range of 35 to 30 ug/m3 with the 98th percentile form, in concert with an annual NAAQS in the range of 14 to 13 ug/m3. The curent standards are 15 ug/m3 annual average and 65 ug/m3 24-hour average.
This range is narrower than the EPA staff-recommended ranges of (Option A )15 ug/m3 annual average combined with 35 to 25 ug/m3 daily; or (Option B) 14 to 12 ug/m3 annual averaged combined with 35 to 40 ug/m3 daily.
The CASAC recommendation lowers the upper end of the range for Option B by 5 ug/m3, potentially providing increased public health protection for 16 million additional Americans.
In addition, the CASAC panel endorsed establishment of a 24-hour average coarse particle standard (PM10-PM2.5) with implementation to be focused on urban areas. The letter states: “…most of the Panel members felt that the evidence that exists supports a causal role for health effects for PM10-2.5.” The panel will review the final staff paper’s recommmendations on ways to focus the implementation of the standard on urban areas at a teleconference in July.
The panel also endorsed establishment of a secondary standard to protect against visibility impairment in urban areas.
The full letter is available from EPA online.
