Air pollutant

Nitrogen dioxide

Nitrogen dioxide (NO2) is one of a group of highly reactive gases known as nitrogen oxides. NO2 reacts with other chemicals in the air to form other pollutants, such as ozone, particulate matter, acid rain, and other toxic chemicals that can cause lung irritation and diminish immune responses to respiratory infections.

Sources

These gases, especially nitrogen dioxide, are products of vehicle, power plant, and off-road equipment emissions caused by fuels burning at high heat. Nitrogen dioxide and other nitrogen oxides react with other chemicals in the air to form other pollutants, such as ozone, particulate matter, acid rain, and other toxic chemicals. At high enough concentrations, NO2 can cause a reddish-brown haze.

Human health and environmental concerns

On its own, nitrogen dioxide can cause lung irritation and diminish immune responses to respiratory infections. Individuals with pre-existing conditions such as asthma, young children, and the elderly are particularly susceptible. Exposure can cause coughing, wheezing, or difficulty breathing, and can send affected individuals to the hospital. Secondary pollutants formed with nitrogen dioxide — including ozone and particulate matter — also have negative health impacts.

Monitoring, reporting, and regulations

Nitrogen dioxide is one of six common air pollutants called criteria pollutants. Criteria pollutants are subject to primary and secondary National Ambient Air Quality Standards under the Federal Clean Air Act. Primary standards define the air quality required to prevent adverse effects on human health; secondary standards are set to prevent adverse impacts on the environment.

Minnesota is currently in compliance with national standards for all six criteria pollutants.