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 2019, at 97.8%. St. Louis city had the lowest, at 37%. The median was 83.2%. Source: EPA.

Keep it in a collection in your library.
Highest97.8Monroe County
Lowest37St. Louis city
Median83.221 counties

Map of counties, 2019

Andrew County: 92.7 %Boone County: 97.6 %Buchanan County: 61.1 %Callaway County: 97.1 %Cass County: 79.2 %Cedar County: 67.5 %Clay County: 72.9 %Clinton County: 86.9 %Greene County: 71.8 %Jackson County: 52.6 %Jasper County: 88.8 %Jefferson County: 69.8 %Lincoln County: 91 %Monroe County: 97.8 %Perry County: 91.4 %St. Charles County: 82.8 %Ste. Genevieve County: 93.9 %St. Louis County: 53.2 %Stoddard County: 83.2 %Taney County: 93.3 %St. Louis city: 37 %
  • Under 68
  • 68 to 79
  • 79 to 89
  • 89 to 93
  • 93 and over
  • No data
%, 2019. 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, 2019

Monroe County: 97.8 %Monroe County97.8Boone County: 97.6 %Boone County97.6Callaway County: 97.1 %Callaway County97.1Ste. Genevieve County: 93.9 %Ste. Genevieve County93.9Taney County: 93.3 %Taney County93.3Andrew County: 92.7 %Andrew County92.7Perry County: 91.4 %Perry County91.4Lincoln County: 91 %Lincoln County91Jasper County: 88.8 %Jasper County88.8Clinton County: 86.9 %Clinton County86.9Stoddard County: 83.2 %Stoddard County83.2St. Charles County: 82.8 %St. Charles County82.8Cass County: 79.2 %Cass County79.2Clay County: 72.9 %Clay County72.9Greene County: 71.8 %Greene County71.8Jefferson County: 69.8 %Jefferson County69.8Cedar County: 67.5 %Cedar County67.5Buchanan County: 61.1 %Buchanan County61.1St. Louis County: 53.2 %St. Louis County53.2Jackson County: 52.6 %Jackson County52.6St. Louis city: 37 %St. Louis city37Monroe County: 97.8 %Monroe County97.8Boone County: 97.6 %Boone County97.6Callaway County: 97.1 %Callaway County97.1Ste. Genevieve County: 93.9 %Ste. Genevieve County93.9Taney County: 93.3 %Taney County93.3Andrew County: 92.7 %Andrew County92.7Perry County: 91.4 %Perry County91.4Lincoln County: 91 %Lincoln County91Jasper County: 88.8 %Jasper County88.8Clinton County: 86.9 %Clinton County86.9Stoddard County: 83.2 %Stoddard County83.2St. Charles County: 82.8 %St. Charles County82.8Cass County: 79.2 %Cass County79.2Clay County: 72.9 %Clay County72.9Greene County: 71.8 %Greene County71.8Jefferson County: 69.8 %Jefferson County69.8Cedar County: 67.5 %Cedar County67.5Buchanan County: 61.1 %Buchanan County61.1St. Louis County: 53.2 %St. Louis County53.2Jackson County: 52.6 %Jackson County52.6St. Louis city: 37 %St. Louis city37
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2019 (%)Change on 2018
1Monroe County97.8+5.7 pts
2Boone County97.6+12.7 pts
3Callaway County97.1+11.4 pts
4Ste. Genevieve County93.9+8.2 pts
5Taney County93.3+8.4 pts
6Andrew County92.7+16.8 pts
7Perry County91.4+6.5 pts
8Lincoln County91+5.7 pts
9Jasper County88.8+5.5 pts
10Clinton County86.9+8.5 pts
11Stoddard County83.2+4.6 pts
12St. Charles County82.8+5.2 pts
13Cass County79.2+6.1 pts
14Clay County72.9+3.8 pts
15Greene County71.8+5.5 pts
16Jefferson County69.8-2.8 pts
17Cedar County67.5+2.5 pts
18Buchanan County61.1+5.7 pts
19St. Louis County53.2+4.4 pts
20Jackson County52.6-8.5 pts
21St. Louis city37+1.7 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 2019 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), 2019) [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), 2019. 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=2019. 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), 2019. 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=2019.

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), 2019 [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=2019 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_missouri_by_2019,
  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), 2019}},
  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=2019. 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), 2019
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=2019
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/missouri-counties?period=2019.
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 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}
GET https://invokely.ai/api/v1/rank?indicator=aqi_good_days_share&level=province&within=Missouri&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)?

Monroe County, with 97.8% in 2019, according to EPA.

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

St. Louis city, with 37% in 2019.

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 2019 and are not ranked.

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

Counties in Missouri: more rankings