# Counties in Kentucky by median Air Quality Index (US EPA), 2004

All 36 values come from U.S. Environmental Protection Agency for 2004, so the places are comparable. 19 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/kentucky-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | Jefferson County | 61 |
| 2 | Laurel County | 58 |
| 3 | Madison County | 56 |
| 4 | Franklin County | 55 |
| 5 | Christian County | 50 |
| 6 | Kenton County | 48 |
| 7 | Hardin County | 46 |
| 8 | Bell County | 44 |
| 8 | Edmonson County | 44 |
| 8 | Livingston County | 44 |
| 8 | McLean County | 44 |
| 8 | Oldham County | 44 |
| 8 | Perry County | 44 |
| 8 | Warren County | 44 |
| 15 | Boyd County | 43 |
| 15 | Campbell County | 43 |
| 15 | Carter County | 43 |
| 18 | Greenup County | 42 |
| 18 | Hancock County | 42 |
| 18 | McCracken County | 42 |
| 18 | Simpson County | 42 |
| 18 | Trigg County | 42 |
| 23 | Bullitt County | 41 |
| 23 | Fayette County | 41 |
| 23 | Henderson County | 41 |
| 23 | Pulaski County | 41 |
| 27 | Boone County | 40 |
| 27 | Daviess County | 40 |
| 27 | Jessamine County | 40 |
| 30 | Graves County | 39 |
| 31 | Morgan County | 38 |
| 31 | Pike County | 38 |
| 33 | Washington County | 37 |
| 34 | Scott County | 33 |
| 35 | Harlan County | 19 |
| 36 | Marshall County | 17 |