Washington, D.C. – The U.S. Environmental Protection Agency (EPA) has proposed strengthening the country’s nitrogen dioxide (NO2) air quality standard for the first time in more than 35 years. The proposed changes reflect the latest science on the health effects of exposure to NO2, which is formed by emissions from cars, trucks, buses, power plants and industrial facilities, and which can lead to respiratory disease.
“We’re updating these standards to build on the latest scientific data and meet changing health protection needs,” said EPA Administrator Lisa 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 revisions would establish a 1-hour NO2 standard at a level between 80 and 100 parts per billion (ppb); retain the current average NO2 standard of 53 ppb; add NO2 monitoring within 50 metres 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.
The proposed standards and additional monitoring requirements would reduce people’s exposure to high, short-term concentrations of NO2, which generally occur near roadways. Current scientific evidence links short-term NO2 exposures, ranging from 30 minutes to 24 hours, with increased respiratory effects, especially in people with asthma.
The EPA first set standards for NO2 in 1971, establishing both a primary standard to protect health and a secondary standard to protect public welfare at 53 ppb, averaged annually. Annual average NO2 concentrations have decreased by more than 40 per cent since 1980, and all areas in the U.S. are well below the 1971 standards, with annual averages ranging from approximately 10 to 20 ppb. The agency must issue a final decision on the NO2 standard by January 22, 2010.