WASHINGTON, D.C. -- The U.S. Environmental Protection Agency on Jan. 25 announced a new national air-quality standard for nitrogen dioxide (NO2), a pollutant that can be generated from vehicle emissions. 

The EPA said the new one-hour standard will "protect millions of Americans from peak short-term exposures, which primarily occur near major roads." 

Short-term exposure to NO2 has been linked to impaired lung function and increased respiratory infections, especially in people with asthma. This is the first new NO2 standard in 35 years. The agency set the new one-hour standard for NO2 at a level of 100 parts per billion (ppb). EPA also is retaining the existing annual average standard of 53 ppb. NO2 is formed from vehicle, power plant and other industrial emissions.

"This new one-hour standard is designed to protect the air we breathe and reduce health threats for millions of Americans. For the first time ever, we are working to prevent short-term exposures in high-risk NO2 zones like urban communities and areas near roadways," said EPA Administrator Lisa P. Jackson.

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. Larger cities and areas with major roadways will have additional monitors. Community-wide monitoring will continue in cities with at least 1 million residents.