Study shows air quality improving in the dairy state

Wisconsin Department of Natural Resources

Report confirms decreasing concentrations of most pollutants across the state

Wisconsin’s air quality is improving. The Wisconsin Department of Natural Resources (DNR) 2020 Air Quality Trends Report has been released and confirms decreasing concentrations of most pollutants across the state.

The report, which includes air quality data through 2019, finds that concentrations of most pollutants for which the Environmental Protection Agency (EPA) has set national air quality standards have decreased in all regions of the state since monitoring began. Due in part to these significant reductions, 95% of Wisconsin’s population lives in areas meeting all federal air quality standards.





The state’s air quality improved along the Lake Michigan shoreline, an area historically impacted by elevated ozone concentrations. The lakeshore areas have experienced an average reduction in ground-level ozone concentrations of 25% since 2001.

This notable decrease in ozone concentrations allowed the EPA to recently determine that several lakeshore areas are now meeting federal ozone standards, including parts of Door and Sheboygan counties.

The report also includes updated emissions data, which shows that air pollutant emissions in Wisconsin decreased substantially from 2002 to 2017. Some highlights include:

  • A 63% drop in emissions of nitrogen oxides (NOx) and a 58% drop in volatile organic compounds (VOCs), the compounds that form ground-level ozone;
  • An 89% drop in sulfur dioxide (SO2) emissions; and
  • A nearly 60% reduction in carbon monoxide emissions.

The 2020 report also includes updated maps of nitrogen dioxide (NO2) densities in the atmosphere, derived from National Aeronautics and Space Administration (NASA) satellite data. From 2006 to 2019, the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite observed reductions of NOacross the entire state, with the largest reductions found in the Milwaukee area.

The DNR Air Program attributes the decrease in pollutant concentrations to the implementation of a variety of federal and state pollution control programs. The greatest reductions are the result of cleaner burning and more efficient fuel combustion from highway vehicles and electric utilities.





“State and federal air pollution control programs, as well as voluntary actions taken by companies and citizens, are responsible for the improvements in air quality in Wisconsin,” said DNR air program director Gail Good. “The Air Management Program will continue to work with our partners to study and resolve remaining air quality concerns.”

The 2020 Air Quality Trends Report, along with historic reports are available on DNR’s Air Quality webpage. Current Wisconsin air quality conditions can be found on the Wisconsin Air Quality Monitoring data webpage.

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