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

Custer County had the highest share of days with good air quality (US EPA AQI) of 26 counties in 2003, at 100%. Tulsa County had the lowest, at 29.6%. The median was 65.2%. Source: EPA.

Highest100Custer County

Lowest29.6Tulsa County

Median65.226 counties

Map of counties, 2003

Under 46
46 to 63
63 to 70
70 to 73
73 and over
No data

%, 2003. 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, 2003

%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2003 (%)	Change on 2002
1	Custer County	100	+34.3 pts
1	Payne County	100	+43.3 pts
3	Cleveland County	79.2	-1 pts
4	McClain County	77.5	-2.2 pts
5	Muskogee County	75.3	+1.9 pts
6	Adair County	72.5	-0.1 pts
7	Dewey County	72.3	-13.8 pts
8	Johnston County	72	n/a
9	Canadian County	71.8	-1.8 pts
10	Comanche County	71.2	0 pts
11	Cherokee County	69.9	-5.2 pts
12	Creek County	68.9	n/a
13	Pittsburg County	66.1	+5.7 pts
14	Ellis County	64.2	-8.5 pts
15	Ottawa County	63.5	-10.6 pts
16	Cotton County	63.4	n/a
17	Kay County	54.2	-11.6 pts
18	Caddo County	53.7	-10.6 pts
19	Carter County	49.5	-14.1 pts
20	Garfield County	47.6	-9.9 pts
21	Pawnee County	46.3	-31.3 pts
22	Lincoln County	45.6	-16.9 pts
23	Seminole County	41.4	-18.9 pts
24	Oklahoma County	35.6	-7.4 pts
25	Mayes County	33.3	-8.4 pts
26	Tulsa County	29.6	-0.5 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. 19 counties with data in other periods have no value for 2003 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), 2003) [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), 2003. 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?period=2003. 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), 2003. 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?period=2003.

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), 2003 [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?period=2003 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_oklahoma_by_2003,
  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), 2003}},
  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?period=2003. 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), 2003
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?period=2003
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/oklahoma-counties?period=2003.
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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Rank Counties in Oklahoma by share of days with good air quality (US EPA AQI) using official data, and cite the source.

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Questions

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

Custer County, with 100% in 2003, according to EPA.

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

Tulsa County, with 29.6% in 2003.

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. 19 counties have no value for 2003 and are not ranked.