# Counties in Idaho by median Air Quality Index (US EPA), 2005

All 23 values come from U.S. Environmental Protection Agency for 2005, so the places are comparable. 8 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/idaho-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | Kootenai County | 51 |
| 2 | Power County | 50 |
| 3 | Shoshone County | 48 |
| 4 | Elmore County | 47 |
| 5 | Ada County | 44 |
| 5 | Canyon County | 44 |
| 7 | Boise County | 43 |
| 8 | Valley County | 39 |
| 9 | Benewah County | 38 |
| 9 | Gem County | 38 |
| 9 | Lemhi County | 38 |
| 12 | Twin Falls County | 36 |
| 13 | Franklin County | 31 |
| 14 | Boundary County | 28 |
| 15 | Bonneville County | 27 |
| 15 | Nez Perce County | 27 |
| 17 | Idaho County | 22 |
| 18 | Latah County | 20 |
| 19 | Bannock County | 19 |
| 19 | Bingham County | 19 |
| 21 | Bonner County | 14 |
| 22 | Butte County | 11 |
| 22 | Custer County | 11 |