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

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

Tulsa County had the highest median Air Quality Index (US EPA) of 25 counties in 2004, at 54. Custer County had the lowest, at 17. The median was 41. Source: the U.S. Environmental Protection Agency.

Keep it in a collection in your library.
Highest54Tulsa County
Lowest17Custer County
Median4125 counties

Map of counties, 2004

Adair County: 41 indexCaddo County: 47 indexCanadian County: 37 indexCarter County: 43 indexCherokee County: 39 indexCleveland County: 35 indexComanche County: 40 indexCotton County: 42 indexCreek County: 37 indexCuster County: 17 indexDewey County: 40 indexEllis County: 33 indexGarfield County: 47 indexJohnston County: 41 indexKay County: 44 indexLincoln County: 50 indexMcClain County: 33 indexMayes County: 43 indexMuskogee County: 25 indexOklahoma County: 51 indexOttawa County: 41 indexPittsburg County: 40 indexSeminole County: 52 indexSequoyah County: 49 indexTulsa County: 54 index
  • Under 37
  • 37 to 40
  • 40 to 42
  • 42 to 47
  • 47 and over
  • No data
index, 2004. 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, 2004

Tulsa County: 54 indexTulsa County54Seminole County: 52 indexSeminole County52Oklahoma County: 51 indexOklahoma County51Lincoln County: 50 indexLincoln County50Sequoyah County: 49 indexSequoyah County49Caddo County: 47 indexCaddo County47Garfield County: 47 indexGarfield County47Kay County: 44 indexKay County44Carter County: 43 indexCarter County43Mayes County: 43 indexMayes County43Cotton County: 42 indexCotton County42Adair County: 41 indexAdair County41Johnston County: 41 indexJohnston County41Ottawa County: 41 indexOttawa County41Comanche County: 40 indexComanche County40Dewey County: 40 indexDewey County40Pittsburg County: 40 indexPittsburg County40Cherokee County: 39 indexCherokee County39Canadian County: 37 indexCanadian County37Creek County: 37 indexCreek County37Cleveland County: 35 indexCleveland County35Ellis County: 33 indexEllis County33McClain County: 33 indexMcClain County33Muskogee County: 25 indexMuskogee County25Custer County: 17 indexCuster County17Tulsa County: 54 indexTulsa County54Seminole County: 52 indexSeminole County52Oklahoma County: 51 indexOklahoma County51Lincoln County: 50 indexLincoln County50Sequoyah County: 49 indexSequoyah County49Caddo County: 47 indexCaddo County47Garfield County: 47 indexGarfield County47Kay County: 44 indexKay County44Carter County: 43 indexCarter County43Mayes County: 43 indexMayes County43Cotton County: 42 indexCotton County42Adair County: 41 indexAdair County41Johnston County: 41 indexJohnston County41Ottawa County: 41 indexOttawa County41Comanche County: 40 indexComanche County40Dewey County: 40 indexDewey County40Pittsburg County: 40 indexPittsburg County40Cherokee County: 39 indexCherokee County39Canadian County: 37 indexCanadian County37Creek County: 37 indexCreek County37Cleveland County: 35 indexCleveland County35Ellis County: 33 indexEllis County33McClain County: 33 indexMcClain County33Muskogee County: 25 indexMuskogee County25Custer County: 17 indexCuster County17
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2004
index		Change on 2003
1Tulsa County54-5
2Seminole County52-1
3Oklahoma County51-5
4Lincoln County50-3
5Sequoyah County49n/a
6Caddo County470
6Garfield County47-5
8Kay County44-4
9Carter County43-8
9Mayes County43-12
11Cotton County42-4
12Adair County41-1
12Johnston County41-2
12Ottawa County41-3
15Comanche County40-4
15Dewey County40-2
15Pittsburg County40-3
18Cherokee County39-3
19Canadian County37-3
19Creek County37-7
21Cleveland County35-3
22Ellis County33-5
22McClain County33-6
24Muskogee County25-1
25Custer County17-2

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 2004 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), 2004) [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), 2004. 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=2004. 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), 2004. 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=2004.

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), 2004 [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=2004 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_oklahoma_by_2004,
  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), 2004}},
  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=2004. 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), 2004
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=2004
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/oklahoma-counties?period=2004.
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)?

Tulsa County, with 54 in 2004, according to the U.S. Environmental Protection Agency.

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

Custer County, with 17 in 2004.

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 2004 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in Oklahoma: more rankings