Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Missouri

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 2023, at 87.1%. St. Louis city had the lowest, at 24.4%. The median was 71.8%. Source: EPA.

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Highest87.1Monroe County
Lowest24.4St. Louis city
Median71.821 counties

Map of counties, 2023

Andrew County: 72.1 %Boone County: 79.9 %Buchanan County: 54 %Callaway County: 80.4 %Cass County: 72.9 %Cedar County: 70.5 %Clay County: 65.1 %Clinton County: 68.6 %Greene County: 51.5 %Jackson County: 46.8 %Jasper County: 78.9 %Jefferson County: 62.2 %Lincoln County: 72.2 %Monroe County: 87.1 %Perry County: 73.1 %St. Charles County: 63.7 %Ste. Genevieve County: 79.6 %St. Louis County: 59.7 %Stoddard County: 71.8 %Taney County: 83.8 %St. Louis city: 24.4 %
  • Under 60
  • 60 to 69
  • 69 to 72
  • 72 to 80
  • 80 and over
  • No data
%, 2023. 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, 2023

Monroe County: 87.1 %Monroe County87.1Taney County: 83.8 %Taney County83.8Callaway County: 80.4 %Callaway County80.4Boone County: 79.9 %Boone County79.9Ste. Genevieve County: 79.6 %Ste. Genevieve County79.6Jasper County: 78.9 %Jasper County78.9Perry County: 73.1 %Perry County73.1Cass County: 72.9 %Cass County72.9Lincoln County: 72.2 %Lincoln County72.2Andrew County: 72.1 %Andrew County72.1Stoddard County: 71.8 %Stoddard County71.8Cedar County: 70.5 %Cedar County70.5Clinton County: 68.6 %Clinton County68.6Clay County: 65.1 %Clay County65.1St. Charles County: 63.7 %St. Charles County63.7Jefferson County: 62.2 %Jefferson County62.2St. Louis County: 59.7 %St. Louis County59.7Buchanan County: 54 %Buchanan County54Greene County: 51.5 %Greene County51.5Jackson County: 46.8 %Jackson County46.8St. Louis city: 24.4 %St. Louis city24.4Monroe County: 87.1 %Monroe County87.1Taney County: 83.8 %Taney County83.8Callaway County: 80.4 %Callaway County80.4Boone County: 79.9 %Boone County79.9Ste. Genevieve County: 79.6 %Ste. Genevieve County79.6Jasper County: 78.9 %Jasper County78.9Perry County: 73.1 %Perry County73.1Cass County: 72.9 %Cass County72.9Lincoln County: 72.2 %Lincoln County72.2Andrew County: 72.1 %Andrew County72.1Stoddard County: 71.8 %Stoddard County71.8Cedar County: 70.5 %Cedar County70.5Clinton County: 68.6 %Clinton County68.6Clay County: 65.1 %Clay County65.1St. Charles County: 63.7 %St. Charles County63.7Jefferson County: 62.2 %Jefferson County62.2St. Louis County: 59.7 %St. Louis County59.7Buchanan County: 54 %Buchanan County54Greene County: 51.5 %Greene County51.5Jackson County: 46.8 %Jackson County46.8St. Louis city: 24.4 %St. Louis city24.4
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2023 (%)Change on 2022
1Monroe County87.1-12.6 pts
2Taney County83.8-6 pts
3Callaway County80.4-10.6 pts
4Boone County79.9-16 pts
5Ste. Genevieve County79.6-8.5 pts
6Jasper County78.9+0.9 pts
7Perry County73.1-13 pts
8Cass County72.9-6.8 pts
9Lincoln County72.2-15.1 pts
10Andrew County72.1-14.8 pts
11Stoddard County71.8-9.8 pts
12Cedar County70.5-8 pts
13Clinton County68.6-17.5 pts
14Clay County65.1-13.3 pts
15St. Charles County63.7-20.4 pts
16Jefferson County62.2-3.4 pts
17St. Louis County59.7-12.4 pts
18Buchanan County54-10.9 pts
19Greene County51.5-3.8 pts
20Jackson County46.8+3 pts
21St. Louis city24.4-10.4 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. 13 counties with data in other periods have no value for 2023 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), 2023) [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), 2023. 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=2023. 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), 2023. 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=2023.

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), 2023 [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=2023 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_missouri_by_2023,
  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), 2023}},
  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=2023. 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), 2023
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=2023
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/missouri-counties?period=2023.
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.
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Questions

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

Monroe County, with 87.1% in 2023, according to EPA.

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

St. Louis city, with 24.4% in 2023.

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 2023 and are not ranked.

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

Counties in Missouri: more rankings