EPA Proposes Stronger Air Quality Standards for Nitrogen Dioxide

“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.”

EPA’s proposed revisions apply to the primary NO₂ standard and would:

* Establish, for the first time, 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, and
* Continue monitoring “area-wide” NO₂ concentrations in cities with at least 1 million residents.

These proposed standards and additional monitoring requirements would protect public health by reducing people’s exposure to high, short-term concentrations of NO₂, which generally occur near roadways. The proposal also would ensure that area-wide NO₂ concentrations remain below levels that can cause public health problems.

Current scientific evidence links short-term NO₂ exposures, ranging from 30 minutes to 24 hours, with increased respiratory effects, especially in people with asthma. These effects can lead to increased visits to emergency departments and hospital admissions for respiratory illnesses, particularly in at-risk populations such as children, the elderly and asthmatics.

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 percent since 1980. All areas in the United States are well below the current (1971) NO₂ standards, with annual averages ranging from approximately 10–20 ppb.

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. EPA will provide details on the public hearings in a separate notice issued later this summer. EPA must issue a final decision on the NO₂ standard by Jan. 22, 2010.

Details about the proposal can be found at http://www.epa.gov/air/nitrogenoxides.