Saying No to NO2

Tailpipes are one source of the country"s harmful nitrogen dioxide emissions.©

On the heels of the House of Representatives passing the American Clean Energy and Security Act, the Environmental Protection Agency announced it is now seeking to tighten nitrogen dioxide air quality standards. The EPA considers nitrogen dioxide a public health threat, citing a link between exposure and respiratory problems. The new rule sets limits for the concentration humans can be exposed to for one hour, thus lowering the exposure to nitrogen dioxide at high concentrations. Additional revisions include monitoring NO2 within 50 meters of a major road in cities with a population greater than 350,000 and continuing extensive monitoring in cities with a population over 1 million.

Recent studies on the health effects of nitrogen dioxide exposure from vehicle and industrial emissions spurred the EPA to take a stricter stance on exposure limits. Nitrogen dioxide has been monitored under the National Ambient Air Quality Standard since 1971, and according to the EPA, has slowly decreased in concentration ever since. In 1971, the average annual standard was 53 parts per billons for nitrogen dioxide. Today, the EPA estimates that concentrations across the U.S. range from 10 to 20 ppb.

EPA Administrator Lisa Jackson said the changes reflect the EPA’s efforts to keep up with scientific data on public health. "In addition to limiting annual average concentrations, we’re preventing high nitrogen dioxide levels for shorter periods of time and adding stronger monitoring in areas near roadways, where the highest levels of nitrogen dioxide are often found," she said. "This will fill gaps in the current standard and provide important additional protections where they are needed most."

A final decision on the revisions will be made by January 22, 2010.

SOURCES: Environmental News Network; EPA