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Wisconsin's Air Quality Trends

There is a statewide network of 30 ozone monitoring sites and 18 fine particle (PM2.5) monitoring sites to measure ambient air quality in Wisconsin. In addition, the DNR monitoring network measures sulfur dioxide, nitrogen dioxide, carbon monoxide and inhalable particles (PM10). The DNR monitoring network is operated under a federally approved network plan, submitted and reviewed annually to ensure appropriate monitoring in all locations required by federal regulations.

Under the Clean Air Act (CAA), the U.S. EPA sets National Ambient Air Quality Standards for pollutants. Data from Wisconsin’s monitoring network is validated and reported to the EPA to demonstrate how well air pollution controls and programs are working to improve air quality and meet the federal standards. In addition, using continuous monitoring data, the DNR quickly informs the public when air pollution reaches unhealthy levels.

2021 Wisconsin Air Quality Trends Report

As part of its effort to meet CAA requirements, the DNR released the 2021 Wisconsin Air Quality Trends Report - data through 2020 (AM-599). The report shows that the overall air quality in Wisconsin continues to improve, building on a 20-year trend in the state.

To view charts that show the air quality trends in each county, see the 2021 Wisconsin Air Quality Trends by County (AM-600).

We continue to work toward attainment in all counties and ensure compliance with all federal air requirements.

Previous Reports