Data / Rankings / Median Air Quality Index (US EPA) / Counties in Minnesota

Counties in Minnesota by median Air Quality Index (US EPA), 2025

Hennepin County had the highest median Air Quality Index (US EPA) of 23 counties in 2025, at 45. Cook County had the lowest, at 16. The median was 37. Source: the U.S. Environmental Protection Agency.

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Highest45Hennepin County
Lowest16Cook County
Median3723 counties

Map of counties, 2025

Anoka County: 38 indexBecker County: 38 indexBeltrami County: 36 indexBlue Earth County: 42 indexCarlton County: 33 indexCass County: 28 indexCook County: 16 indexCrow Wing County: 37 indexDakota County: 35 indexGoodhue County: 38 indexHennepin County: 45 indexLake County: 31 indexLyon County: 37 indexMille Lacs County: 34 indexOlmsted County: 39 indexPine County: 23 indexRamsey County: 34 indexSt. Louis County: 42 indexScott County: 38 indexStearns County: 37 indexWashington County: 34 indexWinona County: 21 indexWright County: 39 index
  • Under 32
  • 32 to 35
  • 35 to 37
  • 37 to 39
  • 39 and over
  • No data
index, 2025. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2025

Hennepin County: 45 indexHennepin County45Blue Earth County: 42 indexBlue Earth County42St. Louis County: 42 indexSt. Louis County42Olmsted County: 39 indexOlmsted County39Wright County: 39 indexWright County39Anoka County: 38 indexAnoka County38Becker County: 38 indexBecker County38Goodhue County: 38 indexGoodhue County38Scott County: 38 indexScott County38Crow Wing County: 37 indexCrow Wing County37Lyon County: 37 indexLyon County37Stearns County: 37 indexStearns County37Beltrami County: 36 indexBeltrami County36Dakota County: 35 indexDakota County35Mille Lacs County: 34 indexMille Lacs County34Ramsey County: 34 indexRamsey County34Washington County: 34 indexWashington County34Carlton County: 33 indexCarlton County33Lake County: 31 indexLake County31Cass County: 28 indexCass County28Pine County: 23 indexPine County23Winona County: 21 indexWinona County21Cook County: 16 indexCook County16Hennepin County: 45 indexHennepin County45Blue Earth County: 42 indexBlue Earth County42St. Louis County: 42 indexSt. Louis County42Olmsted County: 39 indexOlmsted County39Wright County: 39 indexWright County39Anoka County: 38 indexAnoka County38Becker County: 38 indexBecker County38Goodhue County: 38 indexGoodhue County38Scott County: 38 indexScott County38Crow Wing County: 37 indexCrow Wing County37Lyon County: 37 indexLyon County37Stearns County: 37 indexStearns County37Beltrami County: 36 indexBeltrami County36Dakota County: 35 indexDakota County35Mille Lacs County: 34 indexMille Lacs County34Ramsey County: 34 indexRamsey County34Washington County: 34 indexWashington County34Carlton County: 33 indexCarlton County33Lake County: 31 indexLake County31Cass County: 28 indexCass County28Pine County: 23 indexPine County23Winona County: 21 indexWinona County21Cook County: 16 indexCook County16
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2025
index		Change on 2024
1Hennepin County45+3
2Blue Earth County42-1
2St. Louis County42+3
4Olmsted County39-5
4Wright County39-2
6Anoka County38-3
6Becker County38+2
6Goodhue County380
6Scott County38-4
10Crow Wing County37-1
10Lyon County37-3
10Stearns County37-2
13Beltrami County360
14Dakota County35-3
15Mille Lacs County34-2
15Ramsey County34-2
15Washington County34-1
18Carlton County33-1
19Lake County31-1
20Cass County28+1
21Pine County23n/a
22Winona County21+1
23Cook County160

Other periods

About this ranking

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.

More on how it is measured
  • 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.

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. 17 counties with data in other periods have no value for 2025 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: median daily AQI. 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: median daily AQI (Counties in Minnesota by median Air Quality Index (US EPA), 2025) [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: median daily AQI, Counties in Minnesota by median Air Quality Index (US EPA), 2025. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/minnesota-counties. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Minnesota by median Air Quality Index (US EPA), 2025. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/minnesota-counties.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Minnesota by median Air Quality Index (US EPA), 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/minnesota-counties (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_minnesota_by_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Minnesota by median Air Quality Index (US EPA), 2025}},
  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/median-air-quality-index/minnesota-counties. Publisher attribution: 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.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: median daily AQI: Counties in Minnesota by median Air Quality Index (US EPA), 2025
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/median-air-quality-index/minnesota-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/minnesota-counties.
N1  - Publisher attribution: 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.
ER  -
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Rank Counties in Minnesota by median Air Quality Index (US EPA) using official data, and cite the source.
rank_places {"indicator":"aqi_median","level":"province","within":"Minnesota","limit":10}
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Questions

Which county has the highest median Air Quality Index (US EPA)?

Hennepin County, with 45 in 2025, according to the U.S. Environmental Protection Agency.

Which county has the lowest median Air Quality Index (US EPA)?

Cook County, with 16 in 2025.

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: median daily AQI. Retrieved 2026-10-12. 17 counties have no value for 2025 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Minnesota: more rankings