Department of
Environmental Quality

Nitrogen dioxide is a brownish, highly reactive gas present in all urban atmospheres. Nitrogen dioxide is a criteria pollutant that can irritate the lungs, cause bronchitis and pneumonia, and lower resistance to respiratory infections. Nitrogen oxides contribute to formation of both ozone and acid rain and may affect both terrestrial and aquatic ecosystems. The major mechanism for the formation of nitrogen dioxide in the atmosphere is the oxidation of the primary air pollutant nitric oxide. Nitrogen oxide forms when fuel is burned at high temperatures.

The two major emission sources of nitrogen oxides are automobiles and stationary fuel combustion sources such as electric utility and industrial boilers.

Health Impacts of Exposure

Health effects of exposure to nitrogen dioxide include:

• In children and adults with respiratory disease such as asthma, nitrogen dioxide can cause coughing, wheezing, and shortness of breath. Even short exposures to nitrogen dioxide can affect lung function.

• In children, short-term exposure can increase the risk of respiratory illness.

• Animal studies suggest that long-term exposure to nitrogen dioxide may increase susceptibility to respiratory infection and may cause permanent structural changes in the lungs.