Counties in Minnesota by share of days with good air quality (US EPA AQI)

Carlton County had the highest share of days with good air quality (US EPA AQI) of 21 counties in 2011, at 100%. Ramsey County had the lowest, at 48.8%. The median was 76%. Source: EPA.

Highest100Carlton County

Lowest48.8Ramsey County

Median7621 counties

Map of counties, 2011

Under 56
56 to 73
73 to 79
79 to 89
89 and over
No data

%, 2011. 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, 2011

%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2011 (%)	Change on 2010
1	Carlton County	100	+2.5 pts
2	Mille Lacs County	96.6	+0.2 pts
3	Washington County	93.8	+3.2 pts
4	Goodhue County	93	+2.6 pts
5	Cass County	89.2	-10.8 pts
6	Scott County	84.9	+6.8 pts
7	Rock County	83	+9.9 pts
8	Becker County	82.4	+4.2 pts
9	Lake County	79.2	-6.2 pts
10	Cook County	76.5	-4.1 pts
11	Crow Wing County	76	+0.2 pts
12	Lyon County	75	+31.3 pts
13	St. Louis County	73.4	+2.2 pts
14	Winona County	73.3	-2.1 pts
15	Stearns County	63.4	-4.6 pts
16	Dakota County	56.4	+4.1 pts
16	Olmsted County	56.4	+5.3 pts
18	Anoka County	54.8	+10.7 pts
19	Hennepin County	53.7	-4.4 pts
20	Wright County	49	+0.6 pts
21	Ramsey County	48.8	-1.3 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 2011 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), 2011) [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), 2011. 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=2011. 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), 2011. 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=2011.

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), 2011 [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=2011 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_minnesota_by_2011,
  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), 2011}},
  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=2011. 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), 2011
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=2011
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/minnesota-counties?period=2011.
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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Rank Counties in Minnesota by share of days with good air quality (US EPA AQI) using official data, and cite the source.

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Questions

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

Carlton County, with 100% in 2011, according to EPA.

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

Ramsey County, with 48.8% in 2011.

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 2011 and are not ranked.