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

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

Kay County had the highest median Air Quality Index (US EPA) of 25 counties in 2016, at 52. Grady County had the lowest, at 9. The median was 39. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest52Kay County
Lowest9Grady County
Median3925 counties

Map of counties, 2016

Adair County: 43 indexCaddo County: 33 indexCanadian County: 36 indexCarter County: 42 indexCherokee County: 38 indexCleveland County: 44 indexComanche County: 42 indexCotton County: 39 indexCreek County: 39 indexCuster County: 15 indexDewey County: 42 indexGrady County: 9 indexJohnston County: 39 indexKay County: 52 indexLincoln County: 39 indexMcClain County: 37 indexMayes County: 38 indexMuskogee County: 17 indexOklahoma County: 46 indexOsage County: 38 indexOttawa County: 47 indexPittsburg County: 43 indexSequoyah County: 38 indexTulsa County: 52 indexWashington County: 45 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

Kay County: 52 indexKay County52Tulsa County: 52 indexTulsa County52Ottawa County: 47 indexOttawa County47Oklahoma County: 46 indexOklahoma County46Washington County: 45 indexWashington County45Cleveland County: 44 indexCleveland County44Adair County: 43 indexAdair County43Pittsburg County: 43 indexPittsburg County43Carter County: 42 indexCarter County42Comanche County: 42 indexComanche County42Dewey County: 42 indexDewey County42Cotton County: 39 indexCotton County39Creek County: 39 indexCreek County39Johnston County: 39 indexJohnston County39Lincoln County: 39 indexLincoln County39Cherokee County: 38 indexCherokee County38Mayes County: 38 indexMayes County38Osage County: 38 indexOsage County38Sequoyah County: 38 indexSequoyah County38McClain County: 37 indexMcClain County37Canadian County: 36 indexCanadian County36Caddo County: 33 indexCaddo County33Muskogee County: 17 indexMuskogee County17Custer County: 15 indexCuster County15Grady County: 9 indexGrady County9Kay County: 52 indexKay County52Tulsa County: 52 indexTulsa County52Ottawa County: 47 indexOttawa County47Oklahoma County: 46 indexOklahoma County46Washington County: 45 indexWashington County45Cleveland County: 44 indexCleveland County44Adair County: 43 indexAdair County43Pittsburg County: 43 indexPittsburg County43Carter County: 42 indexCarter County42Comanche County: 42 indexComanche County42Dewey County: 42 indexDewey County42Cotton County: 39 indexCotton County39Creek County: 39 indexCreek County39Johnston County: 39 indexJohnston County39Lincoln County: 39 indexLincoln County39Cherokee County: 38 indexCherokee County38Mayes County: 38 indexMayes County38Osage County: 38 indexOsage County38Sequoyah County: 38 indexSequoyah County38McClain County: 37 indexMcClain County37Canadian County: 36 indexCanadian County36Caddo County: 33 indexCaddo County33Muskogee County: 17 indexMuskogee County17Custer County: 15 indexCuster County15Grady County: 9 indexGrady County9
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2016
index		Change on 2015
1Kay County52-1
1Tulsa County520
3Ottawa County47-3
4Oklahoma County460
5Washington County45n/a
6Cleveland County44-1
7Adair County43-1
7Pittsburg County43+2
9Carter County42n/a
9Comanche County42-2
9Dewey County420
12Cotton County390
12Creek County39+3
12Johnston County39-2
12Lincoln County39-2
16Cherokee County38+1
16Mayes County380
16Osage County38n/a
16Sequoyah County38+2
20McClain County37+1
21Canadian County36-1
22Caddo County33+2
23Muskogee County17-2
24Custer County150
25Grady County9n/a

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. 20 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 Oklahoma 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 Oklahoma 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/oklahoma-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 Oklahoma 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/oklahoma-counties?period=2016.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in Oklahoma 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/oklahoma-counties?period=2016 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_oklahoma_by_2016,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in Oklahoma 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/oklahoma-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 Oklahoma 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/oklahoma-counties?period=2016
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/oklahoma-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 Oklahoma by median Air Quality Index (US EPA) using official data, and cite the source.
rank_places {"indicator":"aqi_median","level":"province","within":"Oklahoma","limit":10}
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Questions

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

Kay County, with 52 in 2016, according to the U.S. Environmental Protection Agency.

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

Grady County, with 9 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. 20 counties have no value for 2016 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Oklahoma: more rankings