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)

Mille Lacs County had the highest share of days with good air quality (US EPA AQI) of 22 counties in 2024, at 98.6%. Olmsted County had the lowest, at 63.9%. The median was 79.8%. Source: EPA.

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Highest98.6Mille Lacs County
Lowest63.9Olmsted County
Median79.822 counties

Map of counties, 2024

Anoka County: 78.1 %Becker County: 83.3 %Beltrami County: 84.2 %Blue Earth County: 63.9 %Carlton County: 89.1 %Cass County: 86.5 %Cook County: 92.2 %Crow Wing County: 81.4 %Dakota County: 70.5 %Goodhue County: 93.5 %Hennepin County: 66.4 %Lake County: 90.2 %Lyon County: 75.4 %Mille Lacs County: 98.6 %Olmsted County: 63.9 %Ramsey County: 72.7 %St. Louis County: 78.1 %Scott County: 70.5 %Stearns County: 77 %Washington County: 98 %Winona County: 93.4 %Wright County: 75.7 %
  • Under 71
  • 71 to 77
  • 77 to 84
  • 84 to 92
  • 92 and over
  • No data
%, 2024. 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, 2024

Mille Lacs County: 98.6 %Mille Lacs County98.6Washington County: 98 %Washington County98Goodhue County: 93.5 %Goodhue County93.5Winona County: 93.4 %Winona County93.4Cook County: 92.2 %Cook County92.2Lake County: 90.2 %Lake County90.2Carlton County: 89.1 %Carlton County89.1Cass County: 86.5 %Cass County86.5Beltrami County: 84.2 %Beltrami County84.2Becker County: 83.3 %Becker County83.3Crow Wing County: 81.4 %Crow Wing County81.4Anoka County: 78.1 %Anoka County78.1St. Louis County: 78.1 %St. Louis County78.1Stearns County: 77 %Stearns County77Wright County: 75.7 %Wright County75.7Lyon County: 75.4 %Lyon County75.4Ramsey County: 72.7 %Ramsey County72.7Dakota County: 70.5 %Dakota County70.5Scott County: 70.5 %Scott County70.5Hennepin County: 66.4 %Hennepin County66.4Blue Earth County: 63.9 %Blue Earth County63.9Olmsted County: 63.9 %Olmsted County63.9Mille Lacs County: 98.6 %Mille Lacs County98.6Washington County: 98 %Washington County98Goodhue County: 93.5 %Goodhue County93.5Winona County: 93.4 %Winona County93.4Cook County: 92.2 %Cook County92.2Lake County: 90.2 %Lake County90.2Carlton County: 89.1 %Carlton County89.1Cass County: 86.5 %Cass County86.5Beltrami County: 84.2 %Beltrami County84.2Becker County: 83.3 %Becker County83.3Crow Wing County: 81.4 %Crow Wing County81.4Anoka County: 78.1 %Anoka County78.1St. Louis County: 78.1 %St. Louis County78.1Stearns County: 77 %Stearns County77Wright County: 75.7 %Wright County75.7Lyon County: 75.4 %Lyon County75.4Ramsey County: 72.7 %Ramsey County72.7Dakota County: 70.5 %Dakota County70.5Scott County: 70.5 %Scott County70.5Hennepin County: 66.4 %Hennepin County66.4Blue Earth County: 63.9 %Blue Earth County63.9Olmsted County: 63.9 %Olmsted County63.9
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2024 (%)Change on 2023
1Mille Lacs County98.6+8.7 pts
2Washington County98+17.2 pts
3Goodhue County93.5+10.3 pts
4Winona County93.4+13.6 pts
5Cook County92.2+6.1 pts
6Lake County90.2+12.9 pts
7Carlton County89.1+15.6 pts
8Cass County86.5+14.1 pts
9Beltrami County84.2+15.6 pts
10Becker County83.3+21.9 pts
11Crow Wing County81.4+14.6 pts
12Anoka County78.1+18.6 pts
12St. Louis County78.1+17.6 pts
14Stearns County77+22.5 pts
15Wright County75.7+23.3 pts
16Lyon County75.4+18.3 pts
17Ramsey County72.7+21.2 pts
18Dakota County70.5+20.1 pts
18Scott County70.5+23.1 pts
20Hennepin County66.4+19 pts
21Blue Earth County63.9n/a
21Olmsted County63.9+12.1 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. 18 counties with data in other periods have no value for 2024 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), 2024) [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), 2024. 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=2024. 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), 2024. 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=2024.

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), 2024 [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=2024 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_minnesota_by_2024,
  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), 2024}},
  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=2024. 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), 2024
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=2024
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/minnesota-counties?period=2024.
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)?

Mille Lacs County, with 98.6% in 2024, according to EPA.

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

Olmsted County, with 63.9% in 2024.

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. 18 counties have no value for 2024 and are not ranked.

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

Counties in Minnesota: more rankings