Current Wisconsin statewide air quality notices

No Air Quality Notices As of 4:33 pm CT Monday, September 21, 2020 there are no DNR Air Quality Notices for Wisconsin.

Air Quality Status County Selection Form All Wisconsin Adams County Ashland County Barron County Bayfield County Brown County Buffalo County Burnett County Calumet County Chippewa County Clark County Columbia County Crawford County Dane County Dodge County Door County Douglas County Dunn County Eau Claire County Florence County Fond du Lac County Forest County Grant County Green County Green Lake County Iowa County Iron County Jackson County Jefferson County Juneau County Kenosha County Kewaunee County La Crosse County Lafayette County Langlade County Lincoln County Manitowoc County Marathon County Marinette County Marquette County Menominee County Milwaukee County Monroe County Oconto County Oneida County Outagamie County Ozaukee County Pepin County Pierce County Polk County Portage County Price County Racine County Richland County Rock County Rusk County St. Croix County Sauk County Sawyer County Shawano County Sheboygan County Taylor County Trempealeau County Vernon County Vilas County Walworth County Washburn County Washington County Waukesha County Waupaca County Waushara County Winnebago County Wood County

The DNR uses weather forecasts and data from air monitoring sites to determine air quality in the state, and notifies residents when pollutants reach unhealthy levels based on the Air Quality Index (AQI). The AQI corresponds to the national ambient air quality standard for several air pollutants regulated by the Clean Air Act. To protect public health, as resources allow, DNR may issue an air quality advisory for a county when the AQI exceeds, or is expected to exceed, the level of the ozone or fine particle (PM 2.5 ) standard.

How AQI ranges correspond to ozone and PM 2.5 concentrations

The ozone AQI is calculated from 8-hour rolling average concentrations. The PM 2.5 AQI is calculated using the 24-hour rolling average concentrations from the continuous monitors.

Color coded chart showing ozone and PM 2.5 concentration ranges for each AQI level AQI Levels

of Health Concern Numerical Value 8-hr Ozone (ppb) 24-hr PM 2.5 (ug/m3) Good 0-50 0-54 0.0 to 12.0 Moderate 51-100 55-70 12.1 to 35.4 Unhealthy for Sensitive Groups 101-150 71-85 35.5 to 55.4 Unhealthy 151-200 86-105 55.5 to 140.4 Very Unhealthy 201-300 106-200 140.5 to 210.4 Hazardous > 300 > 201 > 210.4

Changes to the AQI for ozone

The U.S. Environmental Protection Agency (EPA) establishes the national air quality standards at levels that protect human health, and reviews and updates the standards periodically based on the latest available science. In 2015, EPA strengthened the ozone standard from 75 parts per billion (ppb) to 70 ppb.

The AQI for ozone was adjusted in 2016 to reflect the updated ozone standard. In general, the level of the standard corresponds to an AQI value of 100. Values up to 100 are typically considered protective of human health. Under the new 2015 ozone standard, an AQI value of 100 corresponds to an ozone concentration of 70 ppb. Under the previous standard, an AQI value of 100 corresponded to a concentration of 75 ppb.

Air quality advisories are issued when the AQI reaches, or is expected to reach, a value of 100. Because the ozone standard has been lowered to 70 ppb, the department may issue air quality advisories more often and for a greater number of counties than in previous years, even if the air quality itself has not changed.

For this reason, a more frequent issuance of air quality advisories does not necessarily mean the air quality in any particular county is worse than before. In fact, air quality has been improving across the state. For more information, visit Wisconsin's air quality trends. For more information about the 2015 ozone standard, visit Ozone.

Color coded chart showing differences between 2008 and 2015 ozone standards AQI Levels

of Health Concern Numerical Value 8-hr Ozone Concentration (ppb) 2008 Ozone Standard 2015 Ozone Standard Good 0-50 0-59 0-54 Moderate 51-100 60-75 55-70 Unhealthy for Sensitive Groups 101-150 76-95 71-85 Unhealthy 151-200 96-115 86-105 Very Unhealthy 201-300 116-374 106-200 Hazardous > 300 > 375 > 201

Current air quality resources