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

Monroe County had the highest share of days with good air quality (US EPA AQI) of 21 counties in 2022, at 99.7%. St. Louis city had the lowest, at 34.8%. The median was 81.6%. Source: EPA.

Highest99.7Monroe County

Lowest34.8St. Louis city

Median81.621 counties

Map of counties, 2022

Under 66
66 to 79
79 to 86
86 to 88
88 and over
No data

%, 2022. 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, 2022

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

Full ranking

Rank	Counties	2022 (%)	Change on 2021
1	Monroe County	99.7	+1.3 pts
2	Boone County	95.9	+0.8 pts
3	Callaway County	91	-2.5 pts
4	Taney County	89.8	+3.4 pts
5	Ste. Genevieve County	88.1	-4.6 pts
6	Lincoln County	87.3	-4.9 pts
7	Andrew County	86.9	-4.9 pts
8	Clinton County	86.1	-4.1 pts
8	Perry County	86.1	-1.2 pts
10	St. Charles County	84.1	-1.2 pts
11	Stoddard County	81.6	+4.5 pts
12	Cass County	79.7	+6.5 pts
13	Cedar County	78.5	+9.4 pts
14	Clay County	78.4	+1.3 pts
15	Jasper County	78	-4.8 pts
16	St. Louis County	72.1	+3.3 pts
17	Jefferson County	65.6	-1.2 pts
18	Buchanan County	64.9	+0.5 pts
19	Greene County	55.3	-26.9 pts
20	Jackson County	43.8	+7.6 pts
21	St. Louis city	34.8	+3.6 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. 13 counties with data in other periods have no value for 2022 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 Missouri by share of days with good air quality (US EPA AQI), 2022) [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 Missouri by share of days with good air quality (US EPA AQI), 2022. 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/missouri-counties?period=2022. 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 Missouri by share of days with good air quality (US EPA AQI), 2022. 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/missouri-counties?period=2022.

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 Missouri by share of days with good air quality (US EPA AQI), 2022 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/missouri-counties?period=2022 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_missouri_by_2022,
  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 Missouri by share of days with good air quality (US EPA AQI), 2022}},
  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/missouri-counties?period=2022. 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 Missouri by share of days with good air quality (US EPA AQI), 2022
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/missouri-counties?period=2022
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/missouri-counties?period=2022.
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 Missouri 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":"Missouri","limit":10}
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Questions

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

Monroe County, with 99.7% in 2022, according to EPA.

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

St. Louis city, with 34.8% in 2022.

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. 13 counties have no value for 2022 and are not ranked.