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 2018, at 93.5%. Washington County had the lowest, at 43.3%. The median was 83.9%. Source: EPA.

Keep it in a collection in your library.
Highest93.5Cook County
Lowest43.3Washington County
Median83.921 counties

Map of counties, 2018

Anoka County: 61.1 %Becker County: 84.1 %Beltrami County: 87.8 %Carlton County: 90.1 %Cass County: 83.8 %Cook County: 93.5 %Crow Wing County: 83.9 %Dakota County: 70.4 %Goodhue County: 89.2 %Hennepin County: 47.9 %Lake County: 84.9 %Lyon County: 84.4 %Mille Lacs County: 90.5 %Olmsted County: 61.5 %Ramsey County: 59.5 %St. Louis County: 77.8 %Scott County: 85.7 %Stearns County: 77.5 %Washington County: 43.3 %Winona County: 85 %Wright County: 74.2 %
  • Under 62
  • 62 to 78
  • 78 to 84
  • 84 to 88
  • 88 and over
  • No data
%, 2018. 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, 2018

Cook County: 93.5 %Cook County93.5Mille Lacs County: 90.5 %Mille Lacs County90.5Carlton County: 90.1 %Carlton County90.1Goodhue County: 89.2 %Goodhue County89.2Beltrami County: 87.8 %Beltrami County87.8Scott County: 85.7 %Scott County85.7Winona County: 85 %Winona County85Lake County: 84.9 %Lake County84.9Lyon County: 84.4 %Lyon County84.4Becker County: 84.1 %Becker County84.1Crow Wing County: 83.9 %Crow Wing County83.9Cass County: 83.8 %Cass County83.8St. Louis County: 77.8 %St. Louis County77.8Stearns County: 77.5 %Stearns County77.5Wright County: 74.2 %Wright County74.2Dakota County: 70.4 %Dakota County70.4Olmsted County: 61.5 %Olmsted County61.5Anoka County: 61.1 %Anoka County61.1Ramsey County: 59.5 %Ramsey County59.5Hennepin County: 47.9 %Hennepin County47.9Washington County: 43.3 %Washington County43.3Cook County: 93.5 %Cook County93.5Mille Lacs County: 90.5 %Mille Lacs County90.5Carlton County: 90.1 %Carlton County90.1Goodhue County: 89.2 %Goodhue County89.2Beltrami County: 87.8 %Beltrami County87.8Scott County: 85.7 %Scott County85.7Winona County: 85 %Winona County85Lake County: 84.9 %Lake County84.9Lyon County: 84.4 %Lyon County84.4Becker County: 84.1 %Becker County84.1Crow Wing County: 83.9 %Crow Wing County83.9Cass County: 83.8 %Cass County83.8St. Louis County: 77.8 %St. Louis County77.8Stearns County: 77.5 %Stearns County77.5Wright County: 74.2 %Wright County74.2Dakota County: 70.4 %Dakota County70.4Olmsted County: 61.5 %Olmsted County61.5Anoka County: 61.1 %Anoka County61.1Ramsey County: 59.5 %Ramsey County59.5Hennepin County: 47.9 %Hennepin County47.9Washington County: 43.3 %Washington County43.3
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2018 (%)Change on 2017
1Cook County93.5-1.1 pts
2Mille Lacs County90.5-5.8 pts
3Carlton County90.1-1.4 pts
4Goodhue County89.2-5.1 pts
5Beltrami County87.8+0.8 pts
6Scott County85.7-2.7 pts
7Winona County85-2.4 pts
8Lake County84.9-5.5 pts
9Lyon County84.4-0.9 pts
10Becker County84.1-4.4 pts
11Crow Wing County83.9-0.2 pts
12Cass County83.8n/a
13St. Louis County77.8-6.3 pts
14Stearns County77.5-3 pts
15Wright County74.2-1.7 pts
16Dakota County70.4-2.8 pts
17Olmsted County61.5-8.1 pts
18Anoka County61.1-4.4 pts
19Ramsey County59.5-7.9 pts
20Hennepin County47.9+2.4 pts
21Washington County43.3-16.4 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 2018 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), 2018) [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), 2018. 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=2018. 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), 2018. 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=2018.

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), 2018 [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=2018 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_minnesota_by_2018,
  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), 2018}},
  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=2018. 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), 2018
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=2018
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/minnesota-counties?period=2018.
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  -
Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

Rank Counties in Minnesota by share of days with good air quality (US EPA AQI) using official data, and cite the source.
rank_places {"indicator":"aqi_good_days_share","level":"province","within":"Minnesota","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_good_days_share&level=province&within=Minnesota&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

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

Cook County, with 93.5% in 2018, according to EPA.

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

Washington County, with 43.3% in 2018.

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 2018 and are not ranked.

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

Counties in Minnesota: more rankings