Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in Oklahoma

Counties in Oklahoma by share of days with good air quality (US EPA AQI), 2018

Custer County had the highest share of days with good air quality (US EPA AQI) of 25 counties in 2018, at 97.5%. Tulsa County had the lowest, at 32.1%. The median was 72.1%. Source: EPA.

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Highest97.5Custer County
Lowest32.1Tulsa County
Median72.125 counties

Map of counties, 2018

Adair County: 72.1 %Bryan County: 85.4 %Canadian County: 83.3 %Carter County: 63.8 %Choctaw County: 93.4 %Cleveland County: 43.6 %Comanche County: 65.8 %Creek County: 88.1 %Custer County: 97.5 %Dewey County: 58.6 %Jefferson County: 74.2 %Kay County: 49.6 %Le Flore County: 88.2 %Love County: 75.4 %McClain County: 82.2 %Mayes County: 87.4 %Muskogee County: 90.8 %Nowata County: 52.5 %Oklahoma County: 43.8 %Osage County: 84.4 %Ottawa County: 42.7 %Pittsburg County: 63.9 %Sequoyah County: 71.3 %Tulsa County: 32.1 %Washington County: 50 %
  • Under 50
  • 50 to 65
  • 65 to 78
  • 78 to 88
  • 88 and over
  • No data
%, 2018. 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, 2018

Custer County: 97.5 %Custer County97.5Choctaw County: 93.4 %Choctaw County93.4Muskogee County: 90.8 %Muskogee County90.8Le Flore County: 88.2 %Le Flore County88.2Creek County: 88.1 %Creek County88.1Mayes County: 87.4 %Mayes County87.4Bryan County: 85.4 %Bryan County85.4Osage County: 84.4 %Osage County84.4Canadian County: 83.3 %Canadian County83.3McClain County: 82.2 %McClain County82.2Love County: 75.4 %Love County75.4Jefferson County: 74.2 %Jefferson County74.2Adair County: 72.1 %Adair County72.1Sequoyah County: 71.3 %Sequoyah County71.3Comanche County: 65.8 %Comanche County65.8Pittsburg County: 63.9 %Pittsburg County63.9Carter County: 63.8 %Carter County63.8Dewey County: 58.6 %Dewey County58.6Nowata County: 52.5 %Nowata County52.5Washington County: 50 %Washington County50Kay County: 49.6 %Kay County49.6Oklahoma County: 43.8 %Oklahoma County43.8Cleveland County: 43.6 %Cleveland County43.6Ottawa County: 42.7 %Ottawa County42.7Tulsa County: 32.1 %Tulsa County32.1Custer County: 97.5 %Custer County97.5Choctaw County: 93.4 %Choctaw County93.4Muskogee County: 90.8 %Muskogee County90.8Le Flore County: 88.2 %Le Flore County88.2Creek County: 88.1 %Creek County88.1Mayes County: 87.4 %Mayes County87.4Bryan County: 85.4 %Bryan County85.4Osage County: 84.4 %Osage County84.4Canadian County: 83.3 %Canadian County83.3McClain County: 82.2 %McClain County82.2Love County: 75.4 %Love County75.4Jefferson County: 74.2 %Jefferson County74.2Adair County: 72.1 %Adair County72.1Sequoyah County: 71.3 %Sequoyah County71.3Comanche County: 65.8 %Comanche County65.8Pittsburg County: 63.9 %Pittsburg County63.9Carter County: 63.8 %Carter County63.8Dewey County: 58.6 %Dewey County58.6Nowata County: 52.5 %Nowata County52.5Washington County: 50 %Washington County50Kay County: 49.6 %Kay County49.6Oklahoma County: 43.8 %Oklahoma County43.8Cleveland County: 43.6 %Cleveland County43.6Ottawa County: 42.7 %Ottawa County42.7Tulsa County: 32.1 %Tulsa County32.1
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2018 (%)Change on 2017
1Custer County97.5-1.5 pts
2Choctaw County93.4-1.4 pts
3Muskogee County90.8-7.3 pts
4Le Flore County88.2n/a
5Creek County88.1-0.6 pts
6Mayes County87.4-4.2 pts
7Bryan County85.4-3.7 pts
8Osage County84.4-3.9 pts
9Canadian County83.3-1.5 pts
10McClain County82.2-2.7 pts
11Love County75.4+0.2 pts
12Jefferson County74.2-9.9 pts
13Adair County72.1+6.4 pts
14Sequoyah County71.3-11.9 pts
15Comanche County65.8-2.4 pts
16Pittsburg County63.9-1.4 pts
17Carter County63.8+0.3 pts
18Dewey County58.6-14.6 pts
19Nowata County52.5n/a
20Washington County50-7.8 pts
21Kay County49.6+8.2 pts
22Oklahoma County43.8-5 pts
23Cleveland County43.6-15.8 pts
24Ottawa County42.7-5.2 pts
25Tulsa County32.1-5.7 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. 20 counties with data in other periods have no value for 2018 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 Oklahoma by share of days with good air quality (US EPA AQI), 2018) [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 Oklahoma by share of days with good air quality (US EPA AQI), 2018. 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/oklahoma-counties. 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 Oklahoma by share of days with good air quality (US EPA AQI), 2018. 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/oklahoma-counties.

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 Oklahoma by share of days with good air quality (US EPA AQI), 2018 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/oklahoma-counties (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_oklahoma_by_2018,
  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 Oklahoma by share of days with good air quality (US EPA AQI), 2018}},
  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/oklahoma-counties. 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 Oklahoma by share of days with good air quality (US EPA AQI), 2018
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/oklahoma-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/oklahoma-counties.
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)?

Custer County, with 97.5% in 2018, according to EPA.

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

Tulsa County, with 32.1% in 2018.

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. 20 counties have no value for 2018 and are not ranked.

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

Counties in Oklahoma: more rankings