# Counties in Wisconsin by median Air Quality Index (US EPA), 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_median`
- Unit: index
- Definition: Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries. The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide). Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: median daily AQI (https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual)
- Publisher page: https://invokely.ai/en/publishers/environmental-protection-agency
- Retrieved: 2026-10-12
- Citation: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/median-air-quality-index/wisconsin-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | Milwaukee County | 53 |
| 2 | Dane County | 51 |
| 2 | Kenosha County | 51 |
| 4 | La Crosse County | 49 |
| 5 | Dodge County | 47 |
| 5 | Waukesha County | 47 |
| 7 | Outagamie County | 46 |
| 8 | Brown County | 44 |
| 9 | Sheboygan County | 43 |
| 10 | Grant County | 42 |
| 10 | Ozaukee County | 42 |
| 10 | Rock County | 42 |
| 10 | Sauk County | 42 |
| 14 | Columbia County | 41 |
| 14 | Eau Claire County | 41 |
| 14 | Jefferson County | 41 |
| 14 | Kewaunee County | 41 |
| 14 | Manitowoc County | 41 |
| 14 | Taylor County | 41 |
| 20 | Fond du Lac County | 39 |
| 20 | Marathon County | 39 |
| 20 | Walworth County | 39 |
| 23 | Door County | 38 |
| 23 | Forest County | 38 |
| 23 | Racine County | 38 |
| 26 | Vilas County | 37 |
| 27 | Ashland County | 33 |
| 28 | Barron County | 19 |
| 29 | Chippewa County | 14 |
| 30 | Monroe County | 13 |
| 31 | Trempealeau County | 12 |
| 32 | Jackson County | 8 |