AIR POLLUTION: EPA scientists recommend tougher soot standards (03/12/2010)
Robin Bravender, E&E reporter
The latest science supports substantially tightening U.S. EPA's air quality standards for soot in order to safeguard public health and the environment, according to a draft report from agency scientists.
Current evidence "calls into question whether the current suite" of health-based standards for fine particulate matter, or soot, "protects public health with an adequate margin of safety from effects associated with long- and short-term exposures," says the draft report issued this month.
EPA last revised its soot standard in 2006 under the George W. Bush administration, when the agency tightened the allowable concentrations of fine particulate matter from 65 micrograms per cubic meter to 35 micrograms when measured over a 24-hour period. EPA also opted to retain the annual soot standard at 15 micrograms per cubic meter, even though EPA's staff and scientific advisers had recommended a standard between 13 and 14 micrograms. EPA set an identical welfare-based standard at 15 micrograms...
In the draft report, the EPA staff suggests that the agency consider setting the annual and 24-hour standards so that the annual standard would provide long-term protection against long- and short-term exposures in conjunction with a tighter 24-hour standard to protect against high peak concentrations.
The report suggests two ranges to provide such protections that involve tightening the annual standard. One would tighten the annual standard to between 12 and 13 micrograms per cubic meter while either retaining or revising the 24-hour standard in a range of 30 to 35 micrograms.
The second scenario would involve tightening the annual standard to between 10 and 11 micrograms per cubic meter, coupled with lowering the 24-hour standard within a range of 25 to 30 micrograms.
EPA staff also reached the preliminary conclusion that the available data calls into question the adequacy of the agency's current welfare-based standards that aim in part to protect visibility. The draft assessment urges EPA to consider alternative standards to provide further protection, particularly in urban areas.
Frank O'Donnell, president of the advocacy group Clean Air Watch, welcomed the draft report. "The agency's own experts argue that the science calls for much stricter limits on the public's annual exposure to deadly particle soot," O'Donnell said. "This could have big implications for some of the major sources of fine particle soot, especially coal burning and diesel engines."
O'Donnell added that the EPA staff recommendations are noteworthy because there have been preliminary indications that the Obama EPA is inclined to adopt its scientific advisers' recommendations. "They may not go to the lowest end of it, but they want to respect what the science advisers are putting forward," he said.