Nitrogen Dioxide

National Trends in Nitrogen Dioxide Levels
Local Trends in Nitrogen Dioxide Levels

National Trends in Nitrogen Dioxide Levels

Using a nationwide network of monitoring sites, EPA has developed ambient air quality trends for nitrogen dioxide (NO2). Trends from 1980-2007 and from 1990-2007 are shown here. Under the Clean Air Act, EPA sets and reviews national air quality standards for NO2. 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. For information on NO2 standards, sources, health effects, and programs to reduce NO2, please see www.epa.gov/air/urbanair/nox.

Nitrogen dioxide air quality between 1980 and 2007, based on the annual arithmetic average. Chart shows a range of concentrations in 81 monitoring sites nationwide, with the average decreasing 43% from 1980 to 2007. Most of the sites have had concentrations below the national standard since the early 1980s.

Nitrogen dioxide air quality between 1980 and 2007, based on the annual arithmetic average. Chart shows a range of concentrations in 81 monitoring sites nationwide, with the average decreasing 43% from 1980 to 2007. Most of the sites have had concentrations below the national standard since the early 1980s.

How to Interpret the Graphs
View the chart data in Microsoft Excel (Download Excel Viewer)
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Nitrogen dioxide air quality between 1990 and 2007, based on the annual arithmetic average. Chart shows a range of concentrations in 160 monitoring sites nationwide, with the average decreasing 35% from 1990 to 2007.

How to Interpret the Graphs
View the chart data in Microsoft Excel (Download Excel Viewer)
View the chart data in HTML (New window opens)

Local Trends in Nitrogen Dioxide Levels

Air quality trends can vary from one area to another. Local trends are available at individual monitoring locations with an adequate record of historical data.

Nitrogen Dioxide

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