The U.S. EPA has finalized a settlement with environmentalists and some states to issue final revisions to its fine particulate matter (PM2.5) national ambient air quality standards (NAAQS) by Dec. 14, despite concerns from industry, a GOP senator and others that the deadline is too tight to allow for adequate public comment on the rule.
The final consent decree lodged Aug. 31 with the U.S. District Court for the District of Columbia resolves litigation filed by two environmental groups and 11 states -- including New York and Oregon -- seeking to force issuance of a revised PM NAAQS.
Under a district court order in the deadline suit, EPA signed a June 14 proposal to tighten the PM2.5 annual standard down to 12-13 micrograms per cubic meter (ug/m3), while taking comment on a stricter 11 ug/m3 limit -- the level many environmentalists and public health groups endorse. As part of the rulemaking, the agency is also proposing a new, separate PM2.5 standard of either 28 or 30 “deciviews,” a measure of haze, aimed at improving visibility.
EPA last updated its standard in 2006, retaining the annual limit of 15 ug/m3 set in 1997, and tightening the 24-hour limit to address short-term exposures down from the 1997 limit of 65 ug/m3 to 35 ug/m3.