Sulfur Dioxide
National Trends in Sulfur Dioxide Levels
Local Trends in Sulfur Dioxide Levels
National Trends in Sulfur Dioxide Levels
Using a nationwide network of monitoring sites, EPA has developed ambient air quality trends for sulfur dioxide (SO2). Trends from 1980-2008 and from 1990-2008 are shown here. Under the Clean Air Act, EPA sets and reviews national air quality standards for SO2. Air quality monitors measure concentrations of SO2 throughout the country. EPA, state, tribal and local agencies use that data to ensure that SO2 in the air is at levels that protect public health and the environment. Nationally, average SO2 concentrations have decreased substantially over the years. For information on SO2 standards, sources, health effects, and programs to reduce SO2, please see www.epa.gov/air/urbanair/so2.How to Interpret the Graphs
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How to Interpret the Graphs
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Local Trends in Sulfur 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.
![Map of the United States](images/us-states.gif)