# Counties in Oklahoma by median Air Quality Index (US EPA), 2018

All 25 values come from U.S. Environmental Protection Agency for 2018, so the places are comparable. 20 counties have no value for that period and are not ranked.

- Indicator id: `aqi_median`
- Unit: index
- Definition: 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. 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.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: median daily AQI (https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual)
- Publisher page: https://invokely.ai/en/publishers/environmental-protection-agency
- Retrieved: 2026-10-12
- Citation: 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.
- Web page: https://invokely.ai/rankings/median-air-quality-index/oklahoma-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | Tulsa County | 56 |
| 2 | Washington County | 53 |
| 3 | Cleveland County | 52 |
| 3 | Oklahoma County | 52 |
| 3 | Ottawa County | 52 |
| 6 | Kay County | 51 |
| 7 | Nowata County | 48 |
| 8 | Dewey County | 47 |
| 9 | Pittsburg County | 46 |
| 10 | Comanche County | 44 |
| 11 | Jefferson County | 43 |
| 11 | Love County | 43 |
| 13 | Adair County | 42 |
| 14 | Carter County | 41 |
| 14 | Sequoyah County | 41 |
| 16 | Bryan County | 38 |
| 16 | McClain County | 38 |
| 18 | Choctaw County | 37 |
| 18 | Mayes County | 37 |
| 20 | Canadian County | 36 |
| 20 | Creek County | 36 |
| 20 | Osage County | 36 |
| 23 | Le Flore County | 34 |
| 24 | Muskogee County | 19 |
| 25 | Custer County | 16 |