Data / Rankings / Median Air Quality Index (US EPA) / Counties in Missouri

Counties in Missouri by median Air Quality Index (US EPA)

St. Louis city had the highest median Air Quality Index (US EPA) of 21 counties in 2016, at 53. Stoddard County had the lowest, at 32. The median was 41. Source: the U.S. Environmental Protection Agency.

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Highest53St. Louis city
Lowest32Stoddard County
Median4121 counties

Map of counties, 2016

Andrew County: 40 indexBoone County: 37 indexBuchanan County: 44 indexCallaway County: 38 indexCass County: 39 indexCedar County: 41 indexClay County: 41 indexClinton County: 42 indexGreene County: 42 indexJackson County: 47 indexJasper County: 34 indexJefferson County: 46 indexLincoln County: 39 indexMonroe County: 32 indexPerry County: 42 indexSt. Charles County: 44 indexSte. Genevieve County: 39 indexSt. Louis County: 48 indexStoddard County: 32 indexTaney County: 37 indexSt. Louis city: 53 index
  • Under 37
  • 37 to 39
  • 39 to 42
  • 42 to 44
  • 44 and over
  • No data
index, 2016. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2016

St. Louis city: 53 indexSt. Louis city53St. Louis County: 48 indexSt. Louis County48Jackson County: 47 indexJackson County47Jefferson County: 46 indexJefferson County46Buchanan County: 44 indexBuchanan County44St. Charles County: 44 indexSt. Charles County44Clinton County: 42 indexClinton County42Greene County: 42 indexGreene County42Perry County: 42 indexPerry County42Cedar County: 41 indexCedar County41Clay County: 41 indexClay County41Andrew County: 40 indexAndrew County40Cass County: 39 indexCass County39Lincoln County: 39 indexLincoln County39Ste. Genevieve County: 39 indexSte. Genevieve County39Callaway County: 38 indexCallaway County38Boone County: 37 indexBoone County37Taney County: 37 indexTaney County37Jasper County: 34 indexJasper County34Monroe County: 32 indexMonroe County32Stoddard County: 32 indexStoddard County32St. Louis city: 53 indexSt. Louis city53St. Louis County: 48 indexSt. Louis County48Jackson County: 47 indexJackson County47Jefferson County: 46 indexJefferson County46Buchanan County: 44 indexBuchanan County44St. Charles County: 44 indexSt. Charles County44Clinton County: 42 indexClinton County42Greene County: 42 indexGreene County42Perry County: 42 indexPerry County42Cedar County: 41 indexCedar County41Clay County: 41 indexClay County41Andrew County: 40 indexAndrew County40Cass County: 39 indexCass County39Lincoln County: 39 indexLincoln County39Ste. Genevieve County: 39 indexSte. Genevieve County39Callaway County: 38 indexCallaway County38Boone County: 37 indexBoone County37Taney County: 37 indexTaney County37Jasper County: 34 indexJasper County34Monroe County: 32 indexMonroe County32Stoddard County: 32 indexStoddard County32
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2016
index		Change on 2015
1St. Louis city53-2
2St. Louis County48-4
3Jackson County470
4Jefferson County46-7
5Buchanan County44-7
5St. Charles County44+2
7Clinton County420
7Greene County42-1
7Perry County42+1
10Cedar County41+1
10Clay County41-5
12Andrew County400
13Cass County39-6
13Lincoln County390
13Ste. Genevieve County390
16Callaway County38-3
17Boone County37-1
17Taney County37+3
19Jasper County34-1
20Monroe County32+1
20Stoddard County32-5

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

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: median daily AQI. 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: median daily AQI (Counties in Missouri by median Air Quality Index (US EPA), 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: median daily AQI, Counties in Missouri by median Air Quality Index (US EPA), 2016. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/missouri-counties?period=2016. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in Missouri by median Air Quality Index (US EPA), 2016. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/missouri-counties?period=2016.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Missouri by median Air Quality Index (US EPA), 2016 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/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: median daily AQI: Counties in Missouri by median Air Quality Index (US EPA), 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/median-air-quality-index/missouri-counties?period=2016. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. 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: median daily AQI: Counties in Missouri by median Air Quality Index (US EPA), 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/median-air-quality-index/missouri-counties?period=2016
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/missouri-counties?period=2016.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -
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Rank Counties in Missouri by median Air Quality Index (US EPA) using official data, and cite the source.
rank_places {"indicator":"aqi_median","level":"province","within":"Missouri","limit":10}
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Questions

Which county has the highest median Air Quality Index (US EPA)?

St. Louis city, with 53 in 2016, according to the U.S. Environmental Protection Agency.

Which county has the lowest median Air Quality Index (US EPA)?

Stoddard County, with 32 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: median daily AQI. Retrieved 2026-10-12. 13 counties have no value for 2016 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Missouri: more rankings