Counties in Wisconsin by share of days with good air quality (US EPA AQI), 2013

Jackson County had the highest share of days with good air quality (US EPA AQI) of 32 counties in 2013, at 100%. Milwaukee County had the lowest, at 40%. The median was 77.6%. Source: EPA.

Highest100Jackson County

Lowest40Milwaukee County

Median77.632 counties

All counties, 2013

%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2013 (%)	Change on 2012
1	Jackson County	100	0 pts
1	Monroe County	100	0 pts
1	Trempealeau County	100	n/a
4	Chippewa County	98.4	-1.6 pts
5	Ashland County	95.6	+2.7 pts
6	Barron County	93.7	-6.3 pts
7	Vilas County	91.4	+4 pts
8	Fond du Lac County	88.4	+15.5 pts
9	Marathon County	85.2	+0.1 pts
10	Walworth County	85.1	+18.6 pts
11	Racine County	83.9	+16.5 pts
12	Forest County	82.9	-1.2 pts
13	Columbia County	81.7	+11.7 pts
14	Jefferson County	80.3	+12.9 pts
15	Door County	79.5	+3.5 pts
16	Kewaunee County	78.4	+2.6 pts
17	Rock County	76.8	+12.4 pts
18	Manitowoc County	73.2	-0.8 pts
19	Eau Claire County	71.2	+1.9 pts
19	Taylor County	71.2	-4.4 pts
21	Sauk County	67.3	+6.2 pts
22	Sheboygan County	66.8	-0.4 pts
23	Ozaukee County	65.3	+10.1 pts
24	Brown County	63	+5.6 pts
25	Grant County	61.5	+1 pts
26	Outagamie County	57.8	+4.8 pts
27	Dodge County	57.3	+4.6 pts
28	Waukesha County	53.3	+19.3 pts
29	La Crosse County	52.9	-4.4 pts
30	Dane County	49.9	+5.4 pts
31	Kenosha County	47.6	-3.9 pts
32	Milwaukee County	40	-4.8 pts

Other periods

About this ranking

Days with a daily Air Quality Index of 0 to 50 (good) 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; both counts are stored with each value.

United States counties with air quality monitors only, about 1,000 of some 3,100 in recent years; a county without monitors has no value. The number of days with an AQI differs between counties because some monitors run only in the ozone season.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. 16 counties with data in other periods have no value for 2013 and are left out rather than filled from another source. Equal values share a rank.

How to cite

U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days 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 styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts (Counties in Wisconsin by share of days with good air quality (US EPA AQI), 2013) [Data set]. Retrieved October 12, 2026, from https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual

MLA 9

EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in Wisconsin by share of days with good air quality (US EPA AQI), 2013. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/wisconsin-counties. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Counties in Wisconsin by share of days with good air quality (US EPA AQI), 2013. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/wisconsin-counties.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in Wisconsin by share of days with good air quality (US EPA AQI), 2013 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/wisconsin-counties (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_wisconsin_by_2013,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Counties in Wisconsin by share of days with good air quality (US EPA AQI), 2013}},
  year = {2026},
  howpublished = {Data set},
  url = {https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/wisconsin-counties. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days 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.},
}

RIS

TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Counties in Wisconsin by share of days with good air quality (US EPA AQI), 2013
PY  - 2026
DA  - 2026/07/13
PB  - U.S. Environmental Protection Agency
DB  - Invokely
UR  - https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual
L2  - https://invokely.ai/rankings/good-air-quality-days-share/wisconsin-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/wisconsin-counties.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days 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.
ER  -

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Rank Counties in Wisconsin by share of days with good air quality (US EPA AQI) using official data, and cite the source.

rank_places {"indicator":"aqi_good_days_share","level":"province","within":"Wisconsin","limit":10}
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Questions

Which county has the highest share of days with good air quality (US EPA AQI)?

Jackson County, with 100% in 2013, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Milwaukee County, with 40% in 2013.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 16 counties have no value for 2013 and are not ranked.