The U.S. Environmental Protection Agency (EPA) has announced a new one-hour national air quality standard for nitrogen dioxide (NO2) of 100 parts per billion (ppb). The EPA is also retaining the existing annual average standard of 53 ppb.

The EPA is establishing new monitoring requirements in urban areas that will measure NO2 levels around major roads and across the community. Monitors must be located near roadways in cities with at least 500,000 residents, while larger cities and areas with major roadways will have additional monitors. Community-wide monitoring will continue in cities with at least 1 million residents.

Working with the states, the EPA will site at least 40 monitors in locations that are susceptible to elevated levels of NO2. The agency expects to identify or designate areas not meeting the new standard, based on the existing community-wide monitoring network, by January 2012. New monitors must begin operating no later than January 1, 2013. When three years of air quality data are available from the new monitoring network, the EPA intends to redesignate areas as appropriate.

Additional information is available at www.epa.gov/air/nitrogenoxides.

Links

• U.S. Environmental Protection Agency -- Nitrogen Dioxide