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 2014, at 52. Cook County had the lowest, at 23. The median was 37. Source: the U.S. Environmental Protection Agency.

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Highest52Hennepin County
Lowest23Cook County
Median3721 counties

Map of counties, 2014

Anoka County: 41 indexBecker County: 36 indexBeltrami County: 23 indexCarlton County: 31 indexCook County: 23 indexCrow Wing County: 35 indexDakota County: 32 indexGoodhue County: 38 indexHennepin County: 52 indexLake County: 31 indexLyon County: 37 indexMille Lacs County: 31 indexOlmsted County: 41 indexRamsey County: 48 indexRock County: 29 indexSt. Louis County: 47 indexScott County: 36 indexStearns County: 37 indexWashington County: 44 indexWinona County: 40 indexWright County: 37 index
  • Under 31
  • 31 to 36
  • 36 to 37
  • 37 to 41
  • 41 and over
  • No data
index, 2014. 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, 2014

Hennepin County: 52 indexHennepin County52Ramsey County: 48 indexRamsey County48St. Louis County: 47 indexSt. Louis County47Washington County: 44 indexWashington County44Anoka County: 41 indexAnoka County41Olmsted County: 41 indexOlmsted County41Winona County: 40 indexWinona County40Goodhue County: 38 indexGoodhue County38Lyon County: 37 indexLyon County37Stearns County: 37 indexStearns County37Wright County: 37 indexWright County37Becker County: 36 indexBecker County36Scott County: 36 indexScott County36Crow Wing County: 35 indexCrow Wing County35Dakota County: 32 indexDakota County32Carlton County: 31 indexCarlton County31Lake County: 31 indexLake County31Mille Lacs County: 31 indexMille Lacs County31Rock County: 29 indexRock County29Beltrami County: 23 indexBeltrami County23Cook County: 23 indexCook County23Hennepin County: 52 indexHennepin County52Ramsey County: 48 indexRamsey County48St. Louis County: 47 indexSt. Louis County47Washington County: 44 indexWashington County44Anoka County: 41 indexAnoka County41Olmsted County: 41 indexOlmsted County41Winona County: 40 indexWinona County40Goodhue County: 38 indexGoodhue County38Lyon County: 37 indexLyon County37Stearns County: 37 indexStearns County37Wright County: 37 indexWright County37Becker County: 36 indexBecker County36Scott County: 36 indexScott County36Crow Wing County: 35 indexCrow Wing County35Dakota County: 32 indexDakota County32Carlton County: 31 indexCarlton County31Lake County: 31 indexLake County31Mille Lacs County: 31 indexMille Lacs County31Rock County: 29 indexRock County29Beltrami County: 23 indexBeltrami County23Cook County: 23 indexCook County23
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2014
index		Change on 2013
1Hennepin County52+9
2Ramsey County48+7
3St. Louis County47+3
4Washington County44-3
5Anoka County41-3
5Olmsted County41-3
7Winona County40+11
8Goodhue County38-2
9Lyon County37-4
9Stearns County37-2
9Wright County37-2
12Becker County36-3
12Scott County36-6
14Crow Wing County35+2
15Dakota County32-4
16Carlton County31-2
16Lake County31-2
16Mille Lacs County31-3
19Rock County29-1
20Beltrami County23n/a
20Cook County23-6

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 2014 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), 2014) [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), 2014. 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=2014. 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), 2014. 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=2014.

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), 2014 [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=2014 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_minnesota_by_2014,
  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), 2014}},
  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=2014. 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), 2014
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=2014
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/minnesota-counties?period=2014.
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 2014, according to the U.S. Environmental Protection Agency.

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

Cook County, with 23 in 2014.

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 2014 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Minnesota: more rankings