# Counties in Kentucky by share of days unhealthy for sensitive groups or worse (US EPA AQI), 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_unhealthy_sensitive_or_worse_days_share`
- Unit: %
- Definition: Days with a daily Air Quality Index above 100 (unhealthy for sensitive groups, unhealthy, very unhealthy or hazardous) 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; the counts are stored with each value.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: days with an AQI above 100 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: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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.
- Web page: https://invokely.ai/rankings/unhealthy-air-quality-days-share/kentucky-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Oldham County | 4.5 |
| 2 | Kenton County | 4 |
| 3 | Campbell County | 3.3 |
| 4 | Christian County | 2.5 |
| 5 | Jefferson County | 2.2 |
| 6 | McLean County | 1.7 |
| 7 | Greenup County | 1.6 |
| 7 | Hancock County | 1.6 |
| 9 | Trigg County | 1.4 |
| 10 | Simpson County | 1.2 |
| 11 | Hardin County | 1.1 |
| 11 | Morgan County | 1.1 |
| 13 | Bell County | 0.8 |
| 13 | Boone County | 0.8 |
| 13 | Henderson County | 0.8 |
| 13 | Livingston County | 0.8 |
| 17 | Boyd County | 0.6 |
| 17 | Bullitt County | 0.6 |
| 19 | Edmonson County | 0.5 |
| 20 | Graves County | 0.4 |
| 20 | Jessamine County | 0.4 |
| 20 | Perry County | 0.4 |
| 23 | Daviess County | 0.3 |
| 23 | McCracken County | 0.3 |
| 23 | Pike County | 0.3 |
| 23 | Warren County | 0.3 |
| 23 | Washington County | 0.3 |
| 28 | Carter County | 0 |
| 28 | Fayette County | 0 |
| 28 | Franklin County | 0 |
| 28 | Harlan County | 0 |
| 28 | Laurel County | 0 |
| 28 | Madison County | 0 |
| 28 | Marshall County | 0 |
| 28 | Pulaski County | 0 |
| 28 | Scott County | 0 |