# Counties in Kentucky by highest daily 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_max`
- Unit: index
- Definition: Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: highest 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: highest daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/highest-daily-air-quality-index/kentucky-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | Bullitt County | 192 |
| 2 | Jefferson County | 169 |
| 3 | Hancock County | 150 |
| 4 | Campbell County | 147 |
| 5 | Hardin County | 143 |
| 6 | Kenton County | 136 |
| 6 | Trigg County | 136 |
| 8 | Simpson County | 133 |
| 9 | Boyd County | 129 |
| 9 | Christian County | 129 |
| 11 | Oldham County | 126 |
| 12 | Boone County | 122 |
| 12 | Livingston County | 122 |
| 14 | McLean County | 119 |
| 15 | Bell County | 115 |
| 15 | Greenup County | 115 |
| 15 | Morgan County | 115 |
| 18 | Daviess County | 112 |
| 18 | Henderson County | 112 |
| 18 | McCracken County | 112 |
| 21 | Graves County | 108 |
| 21 | Jessamine County | 108 |
| 23 | Edmonson County | 105 |
| 23 | Warren County | 105 |
| 25 | Pike County | 103 |
| 26 | Perry County | 101 |
| 26 | Washington County | 101 |
| 28 | Fayette County | 100 |
| 29 | Laurel County | 97 |
| 29 | Madison County | 97 |
| 31 | Pulaski County | 93 |
| 32 | Franklin County | 88 |
| 33 | Carter County | 87 |
| 34 | Scott County | 67 |
| 35 | Harlan County | 40 |
| 36 | Marshall County | 26 |