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 2024, at 97.5%. St. Louis city had the lowest, at 37.4%. The median was 84.6%. Source: EPA.

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Highest97.5Monroe County
Lowest37.4St. Louis city
Median84.621 counties

Map of counties, 2024

Andrew County: 86 %Boone County: 94.3 %Buchanan County: 59.8 %Callaway County: 95.1 %Cass County: 76.5 %Cedar County: 85.6 %Clay County: 78.1 %Clinton County: 85.5 %Greene County: 63.4 %Jackson County: 59.3 %Jasper County: 80.9 %Jefferson County: 81.1 %Lincoln County: 84.6 %Monroe County: 97.5 %Perry County: 86.9 %St. Charles County: 73.2 %Ste. Genevieve County: 90.9 %St. Louis County: 73.5 %Stoddard County: 87.6 %Taney County: 88.9 %St. Louis city: 37.4 %
  • Under 73
  • 73 to 81
  • 81 to 86
  • 86 to 89
  • 89 and over
  • No data
%, 2024. 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, 2024

Monroe County: 97.5 %Monroe County97.5Callaway County: 95.1 %Callaway County95.1Boone County: 94.3 %Boone County94.3Ste. Genevieve County: 90.9 %Ste. Genevieve County90.9Taney County: 88.9 %Taney County88.9Stoddard County: 87.6 %Stoddard County87.6Perry County: 86.9 %Perry County86.9Andrew County: 86 %Andrew County86Cedar County: 85.6 %Cedar County85.6Clinton County: 85.5 %Clinton County85.5Lincoln County: 84.6 %Lincoln County84.6Jefferson County: 81.1 %Jefferson County81.1Jasper County: 80.9 %Jasper County80.9Clay County: 78.1 %Clay County78.1Cass County: 76.5 %Cass County76.5St. Louis County: 73.5 %St. Louis County73.5St. Charles County: 73.2 %St. Charles County73.2Greene County: 63.4 %Greene County63.4Buchanan County: 59.8 %Buchanan County59.8Jackson County: 59.3 %Jackson County59.3St. Louis city: 37.4 %St. Louis city37.4Monroe County: 97.5 %Monroe County97.5Callaway County: 95.1 %Callaway County95.1Boone County: 94.3 %Boone County94.3Ste. Genevieve County: 90.9 %Ste. Genevieve County90.9Taney County: 88.9 %Taney County88.9Stoddard County: 87.6 %Stoddard County87.6Perry County: 86.9 %Perry County86.9Andrew County: 86 %Andrew County86Cedar County: 85.6 %Cedar County85.6Clinton County: 85.5 %Clinton County85.5Lincoln County: 84.6 %Lincoln County84.6Jefferson County: 81.1 %Jefferson County81.1Jasper County: 80.9 %Jasper County80.9Clay County: 78.1 %Clay County78.1Cass County: 76.5 %Cass County76.5St. Louis County: 73.5 %St. Louis County73.5St. Charles County: 73.2 %St. Charles County73.2Greene County: 63.4 %Greene County63.4Buchanan County: 59.8 %Buchanan County59.8Jackson County: 59.3 %Jackson County59.3St. Louis city: 37.4 %St. Louis city37.4
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2024 (%)Change on 2023
1Monroe County97.5+10.4 pts
2Callaway County95.1+14.7 pts
3Boone County94.3+14.4 pts
4Ste. Genevieve County90.9+11.3 pts
5Taney County88.9+5.1 pts
6Stoddard County87.6+15.8 pts
7Perry County86.9+13.8 pts
8Andrew County86+13.9 pts
9Cedar County85.6+15.1 pts
10Clinton County85.5+16.9 pts
11Lincoln County84.6+12.4 pts
12Jefferson County81.1+18.9 pts
13Jasper County80.9+2 pts
14Clay County78.1+13 pts
15Cass County76.5+3.6 pts
16St. Louis County73.5+13.8 pts
17St. Charles County73.2+9.5 pts
18Greene County63.4+11.9 pts
19Buchanan County59.8+5.8 pts
20Jackson County59.3+12.5 pts
21St. Louis city37.4+13 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 2024 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), 2024) [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), 2024. 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=2024. 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), 2024. 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=2024.

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), 2024 [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=2024 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_missouri_by_2024,
  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), 2024}},
  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=2024. 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), 2024
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=2024
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/missouri-counties?period=2024.
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 97.5% in 2024, according to EPA.

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

St. Louis city, with 37.4% in 2024.

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 2024 and are not ranked.

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

Counties in Missouri: more rankings