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“We’re updating these standards to build on the latest scientific data and meet changing health protection needs,” said EPA Administrator Lisa P. Jackson. “In addition to limiting annual average concentrations, we’re preventing high NO2 levels for shorter periods of time and adding stronger monitoring in areas near roadways, where the highest levels of NO2 are often found. This will fill gaps in the current standard and provide important additional protections where they are needed most.”
The EPA’s proposed revisions apply to the primary NO2 standard and would:
- establish a one-hour NO2 standard at a level between 80-100 parts per billion (ppb)
- retain the current annual average NO2 standard of 53 ppb
- add NO2 monitoring within 50 meters of major roads in cities with at least 350,000 residents
- continue monitoring “area-wide” NO2 concentrations in cities with at least 1 million residents
The EPA first set standards for NO2 in 1971, establishing both a primary standard to protect health and a secondary standard to protect the public welfare at 53 ppb, averaged annually. Annual average NO2 concentrations have decreased by more than 40% since 1980. All areas in the U.S. are well below the current (1971) NO2 standards with annual averages ranging from approximately 10-20 ppb.
The EPA will accept public comments for 60 days after the proposal is published in the Federal Register. The agency will hold two public hearings in August 2009: one in Los Angeles and one in the Washington, D.C. area. The EPA will provide details on the public hearings in a separate notice issued later this summer, and the agency must issue a final decision on the NO2 standard by January 22, 2010.
Details about the proposal are available at www.epa.gov/air/nitrogenoxides.