Air quality monitors measure concentrations of NO₂ throughout the country. EPA, state, tribal and local agencies use that data to ensure that NO₂ in the air is at levels that protect public health and the environment. Nationally, average NO₂ concentrations have decreased substantially over the years. The charts below show national and regional trends in NO₂ concentrations. For information on NO₂ standards, sources, health effects, and programs to reduce NO₂, please see our Nitrogen Dioxide Pollution page.

National Trends

Starting in  1980 | 1990 | 2000 | 2010

Regional Trends

Region: Central | Upper Midwest | Northeast | South | Southeast | Southwest | West | Northern Rockies and Plains