# Counties in Wisconsin by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2013

All 32 values come from U.S. Environmental Protection Agency for 2013, so the places are comparable. 16 counties have no value for that period and are not ranked.

- Indicator id: `aqi_unhealthy_sensitive_or_worse_days_share`
- Unit: %
- Definition: Days with a daily Air Quality Index above 100 (unhealthy for sensitive groups, unhealthy, very unhealthy or hazardous) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; the counts are stored with each value.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts (https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual)
- Retrieved: 2026-10-12
- Citation: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/unhealthy-air-quality-days-share/wisconsin-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Sheboygan County | 5.3 |
| 2 | Manitowoc County | 2.9 |
| 3 | Kenosha County | 2.7 |
| 4 | Jefferson County | 1.6 |
| 5 | Ozaukee County | 1.1 |
| 6 | Door County | 1 |
| 7 | Columbia County | 0.5 |
| 7 | Dodge County | 0.5 |
| 7 | Kewaunee County | 0.5 |
| 7 | Rock County | 0.5 |
| 7 | Walworth County | 0.5 |
| 12 | Brown County | 0.3 |
| 12 | Milwaukee County | 0.3 |
| 12 | Outagamie County | 0.3 |
| 15 | Ashland County | 0 |
| 15 | Barron County | 0 |
| 15 | Chippewa County | 0 |
| 15 | Dane County | 0 |
| 15 | Eau Claire County | 0 |
| 15 | Fond du Lac County | 0 |
| 15 | Forest County | 0 |
| 15 | Grant County | 0 |
| 15 | Jackson County | 0 |
| 15 | La Crosse County | 0 |
| 15 | Marathon County | 0 |
| 15 | Monroe County | 0 |
| 15 | Racine County | 0 |
| 15 | Sauk County | 0 |
| 15 | Taylor County | 0 |
| 15 | Trempealeau County | 0 |
| 15 | Vilas County | 0 |
| 15 | Waukesha County | 0 |