Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Minnesota

Counties in Minnesota by share of days with good air quality (US EPA AQI)

Cook County had the highest share of days with good air quality (US EPA AQI) of 21 counties in 2015, at 96.1%. Hennepin County had the lowest, at 42.5%. The median was 84.3%. Source: EPA.

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Highest96.1Cook County
Lowest42.5Hennepin County
Median84.321 counties

Map of counties, 2015

Anoka County: 76.2 %Becker County: 81.8 %Beltrami County: 90.1 %Carlton County: 86.5 %Cook County: 96.1 %Crow Wing County: 81.9 %Dakota County: 72.3 %Goodhue County: 94.4 %Hennepin County: 42.5 %Lake County: 91 %Lyon County: 84.9 %Mille Lacs County: 96 %Olmsted County: 75.1 %Ramsey County: 58.9 %Rock County: 84 %St. Louis County: 79.2 %Scott County: 90.9 %Stearns County: 86.2 %Washington County: 55.6 %Winona County: 90 %Wright County: 84.3 %
  • Under 75
  • 75 to 82
  • 82 to 86
  • 86 to 91
  • 91 and over
  • No data
%, 2015. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2015

Cook County: 96.1 %Cook County96.1Mille Lacs County: 96 %Mille Lacs County96Goodhue County: 94.4 %Goodhue County94.4Lake County: 91 %Lake County91Scott County: 90.9 %Scott County90.9Beltrami County: 90.1 %Beltrami County90.1Winona County: 90 %Winona County90Carlton County: 86.5 %Carlton County86.5Stearns County: 86.2 %Stearns County86.2Lyon County: 84.9 %Lyon County84.9Wright County: 84.3 %Wright County84.3Rock County: 84 %Rock County84Crow Wing County: 81.9 %Crow Wing County81.9Becker County: 81.8 %Becker County81.8St. Louis County: 79.2 %St. Louis County79.2Anoka County: 76.2 %Anoka County76.2Olmsted County: 75.1 %Olmsted County75.1Dakota County: 72.3 %Dakota County72.3Ramsey County: 58.9 %Ramsey County58.9Washington County: 55.6 %Washington County55.6Hennepin County: 42.5 %Hennepin County42.5Cook County: 96.1 %Cook County96.1Mille Lacs County: 96 %Mille Lacs County96Goodhue County: 94.4 %Goodhue County94.4Lake County: 91 %Lake County91Scott County: 90.9 %Scott County90.9Beltrami County: 90.1 %Beltrami County90.1Winona County: 90 %Winona County90Carlton County: 86.5 %Carlton County86.5Stearns County: 86.2 %Stearns County86.2Lyon County: 84.9 %Lyon County84.9Wright County: 84.3 %Wright County84.3Rock County: 84 %Rock County84Crow Wing County: 81.9 %Crow Wing County81.9Becker County: 81.8 %Becker County81.8St. Louis County: 79.2 %St. Louis County79.2Anoka County: 76.2 %Anoka County76.2Olmsted County: 75.1 %Olmsted County75.1Dakota County: 72.3 %Dakota County72.3Ramsey County: 58.9 %Ramsey County58.9Washington County: 55.6 %Washington County55.6Hennepin County: 42.5 %Hennepin County42.5
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2015 (%)Change on 2014
1Cook County96.1+3.8 pts
2Mille Lacs County96-1.7 pts
3Goodhue County94.4+2.7 pts
4Lake County91+6.1 pts
5Scott County90.9+7.6 pts
6Beltrami County90.1+7.1 pts
7Winona County90+19.8 pts
8Carlton County86.5-11.8 pts
9Stearns County86.2+6.6 pts
10Lyon County84.9+5.2 pts
11Wright County84.3+4.7 pts
12Rock County84+1.1 pts
13Crow Wing County81.9-2.8 pts
14Becker County81.8+2.9 pts
15St. Louis County79.2+20 pts
16Anoka County76.2+3.4 pts
17Olmsted County75.1+1.1 pts
18Dakota County72.3-4.1 pts
19Ramsey County58.9+6.3 pts
20Washington County55.6-7.1 pts
21Hennepin County42.5-1.9 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. 19 counties with data in other periods have no value for 2015 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 Minnesota by share of days with good air quality (US EPA AQI), 2015) [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 Minnesota by share of days with good air quality (US EPA AQI), 2015. 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/minnesota-counties?period=2015. 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 Minnesota by share of days with good air quality (US EPA AQI), 2015. 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/minnesota-counties?period=2015.

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 Minnesota by share of days with good air quality (US EPA AQI), 2015 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/minnesota-counties?period=2015 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_minnesota_by_2015,
  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 Minnesota by share of days with good air quality (US EPA AQI), 2015}},
  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/minnesota-counties?period=2015. 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 Minnesota by share of days with good air quality (US EPA AQI), 2015
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/minnesota-counties?period=2015
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/minnesota-counties?period=2015.
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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Questions

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

Cook County, with 96.1% in 2015, according to EPA.

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

Hennepin County, with 42.5% in 2015.

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. 19 counties have no value for 2015 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in Minnesota: more rankings