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

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

Hennepin County had the highest median Air Quality Index (US EPA) of 21 counties in 2015, at 52. Beltrami County had the lowest, at 23. The median was 37. Source: the U.S. Environmental Protection Agency.

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Highest52Hennepin County
Lowest23Beltrami County
Median3721 counties

Map of counties, 2015

Anoka County: 41 indexBecker County: 36 indexBeltrami County: 23 indexCarlton County: 37 indexCook County: 26 indexCrow Wing County: 37 indexDakota County: 39 indexGoodhue County: 37 indexHennepin County: 52 indexLake County: 32 indexLyon County: 33 indexMille Lacs County: 33 indexOlmsted County: 41 indexRamsey County: 44 indexRock County: 29 indexSt. Louis County: 40 indexScott County: 34 indexStearns County: 37 indexWashington County: 46 indexWinona County: 24 indexWright County: 37 index
  • Under 32
  • 32 to 36
  • 36 to 37
  • 37 to 41
  • 41 and over
  • No data
index, 2015. 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, 2015

Hennepin County: 52 indexHennepin County52Washington County: 46 indexWashington County46Ramsey County: 44 indexRamsey County44Anoka County: 41 indexAnoka County41Olmsted County: 41 indexOlmsted County41St. Louis County: 40 indexSt. Louis County40Dakota County: 39 indexDakota County39Carlton County: 37 indexCarlton County37Crow Wing County: 37 indexCrow Wing County37Goodhue County: 37 indexGoodhue County37Stearns County: 37 indexStearns County37Wright County: 37 indexWright County37Becker County: 36 indexBecker County36Scott County: 34 indexScott County34Lyon County: 33 indexLyon County33Mille Lacs County: 33 indexMille Lacs County33Lake County: 32 indexLake County32Rock County: 29 indexRock County29Cook County: 26 indexCook County26Winona County: 24 indexWinona County24Beltrami County: 23 indexBeltrami County23Hennepin County: 52 indexHennepin County52Washington County: 46 indexWashington County46Ramsey County: 44 indexRamsey County44Anoka County: 41 indexAnoka County41Olmsted County: 41 indexOlmsted County41St. Louis County: 40 indexSt. Louis County40Dakota County: 39 indexDakota County39Carlton County: 37 indexCarlton County37Crow Wing County: 37 indexCrow Wing County37Goodhue County: 37 indexGoodhue County37Stearns County: 37 indexStearns County37Wright County: 37 indexWright County37Becker County: 36 indexBecker County36Scott County: 34 indexScott County34Lyon County: 33 indexLyon County33Mille Lacs County: 33 indexMille Lacs County33Lake County: 32 indexLake County32Rock County: 29 indexRock County29Cook County: 26 indexCook County26Winona County: 24 indexWinona County24Beltrami County: 23 indexBeltrami County23
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2015
index		Change on 2014
1Hennepin County520
2Washington County46+2
3Ramsey County44-4
4Anoka County410
4Olmsted County410
6St. Louis County40-7
7Dakota County39+7
8Carlton County37+6
8Crow Wing County37+2
8Goodhue County37-1
8Stearns County370
8Wright County370
13Becker County360
14Scott County34-2
15Lyon County33-4
15Mille Lacs County33+2
17Lake County32+1
18Rock County290
19Cook County26+3
20Winona County24-16
21Beltrami County230

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. 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: 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), 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: median daily AQI, Counties in Minnesota by median Air Quality Index (US EPA), 2015. 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?period=2015. 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), 2015. 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?period=2015.

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), 2015 [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?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: median daily AQI: Counties in Minnesota by median Air Quality Index (US EPA), 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/median-air-quality-index/minnesota-counties?period=2015. 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), 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/median-air-quality-index/minnesota-counties?period=2015
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/minnesota-counties?period=2015.
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 52 in 2015, according to the U.S. Environmental Protection Agency.

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

Beltrami County, with 23 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: median daily AQI. Retrieved 2026-10-12. 19 counties have no value for 2015 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Minnesota: more rankings