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 2016, at 96.4%. St. Louis city had the lowest, at 38.3%. The median was 80.8%. Source: EPA.

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Highest96.4Monroe County
Lowest38.3St. Louis city
Median80.821 counties

Map of counties, 2016

Andrew County: 87.9 %Boone County: 92.5 %Buchanan County: 63.1 %Callaway County: 93.5 %Cass County: 80.8 %Cedar County: 77.1 %Clay County: 75.6 %Clinton County: 82.2 %Greene County: 71.6 %Jackson County: 58.2 %Jasper County: 88.4 %Jefferson County: 59.8 %Lincoln County: 85 %Monroe County: 96.4 %Perry County: 80.8 %St. Charles County: 72 %Ste. Genevieve County: 86.4 %St. Louis County: 56 %Stoddard County: 78.5 %Taney County: 89.4 %St. Louis city: 38.3 %
  • Under 63
  • 63 to 77
  • 77 to 82
  • 82 to 88
  • 88 and over
  • No data
%, 2016. 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, 2016

Monroe County: 96.4 %Monroe County96.4Callaway County: 93.5 %Callaway County93.5Boone County: 92.5 %Boone County92.5Taney County: 89.4 %Taney County89.4Jasper County: 88.4 %Jasper County88.4Andrew County: 87.9 %Andrew County87.9Ste. Genevieve County: 86.4 %Ste. Genevieve County86.4Lincoln County: 85 %Lincoln County85Clinton County: 82.2 %Clinton County82.2Cass County: 80.8 %Cass County80.8Perry County: 80.8 %Perry County80.8Stoddard County: 78.5 %Stoddard County78.5Cedar County: 77.1 %Cedar County77.1Clay County: 75.6 %Clay County75.6St. Charles County: 72 %St. Charles County72Greene County: 71.6 %Greene County71.6Buchanan County: 63.1 %Buchanan County63.1Jefferson County: 59.8 %Jefferson County59.8Jackson County: 58.2 %Jackson County58.2St. Louis County: 56 %St. Louis County56St. Louis city: 38.3 %St. Louis city38.3Monroe County: 96.4 %Monroe County96.4Callaway County: 93.5 %Callaway County93.5Boone County: 92.5 %Boone County92.5Taney County: 89.4 %Taney County89.4Jasper County: 88.4 %Jasper County88.4Andrew County: 87.9 %Andrew County87.9Ste. Genevieve County: 86.4 %Ste. Genevieve County86.4Lincoln County: 85 %Lincoln County85Clinton County: 82.2 %Clinton County82.2Cass County: 80.8 %Cass County80.8Perry County: 80.8 %Perry County80.8Stoddard County: 78.5 %Stoddard County78.5Cedar County: 77.1 %Cedar County77.1Clay County: 75.6 %Clay County75.6St. Charles County: 72 %St. Charles County72Greene County: 71.6 %Greene County71.6Buchanan County: 63.1 %Buchanan County63.1Jefferson County: 59.8 %Jefferson County59.8Jackson County: 58.2 %Jackson County58.2St. Louis County: 56 %St. Louis County56St. Louis city: 38.3 %St. Louis city38.3
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2016 (%)Change on 2015
1Monroe County96.4-0.9 pts
2Callaway County93.5+6.6 pts
3Boone County92.5+0.4 pts
4Taney County89.4-0.3 pts
5Jasper County88.4+4.3 pts
6Andrew County87.9+1.5 pts
7Ste. Genevieve County86.40 pts
8Lincoln County85-2.9 pts
9Clinton County82.2+4.2 pts
10Cass County80.8+19.5 pts
10Perry County80.8-2.4 pts
12Stoddard County78.5+5.4 pts
13Cedar County77.1+6.9 pts
14Clay County75.6+15.7 pts
15St. Charles County72-9.3 pts
16Greene County71.6+6.2 pts
17Buchanan County63.1+13.9 pts
18Jefferson County59.8+20.9 pts
19Jackson County58.2+3.4 pts
20St. Louis County56+8.9 pts
21St. Louis city38.3+4.9 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 2016 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), 2016) [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), 2016. 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=2016. 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), 2016. 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=2016.

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), 2016 [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=2016 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_missouri_by_2016,
  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), 2016}},
  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=2016. 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), 2016
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=2016
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/missouri-counties?period=2016.
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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Questions

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

Monroe County, with 96.4% in 2016, according to EPA.

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

St. Louis city, with 38.3% in 2016.

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 2016 and are not ranked.

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

Counties in Missouri: more rankings