# Counties in Idaho by highest daily 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_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/idaho-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | Shoshone County | 182 |
| 2 | Franklin County | 171 |
| 3 | Idaho County | 170 |
| 3 | Power County | 170 |
| 5 | Canyon County | 151 |
| 5 | Lemhi County | 151 |
| 7 | Ada County | 147 |
| 8 | Gem County | 134 |
| 9 | Valley County | 132 |
| 10 | Benewah County | 126 |
| 11 | Bannock County | 122 |
| 12 | Twin Falls County | 114 |
| 13 | Boise County | 109 |
| 14 | Kootenai County | 105 |
| 15 | Elmore County | 84 |
| 16 | Boundary County | 83 |
| 17 | Bonneville County | 81 |
| 18 | Latah County | 74 |
| 19 | Custer County | 71 |
| 19 | Nez Perce County | 71 |
| 21 | Bingham County | 62 |
| 21 | Bonner County | 62 |
| 23 | Butte County | 38 |