# Counties in Arizona by highest daily Air Quality Index (US EPA), 2025

All 13 values come from U.S. Environmental Protection Agency for 2025, so the places are comparable. 2 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/arizona-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | Pinal County | 1,215 |
| 2 | Maricopa County | 366 |
| 3 | Pima County | 357 |
| 4 | Mohave County | 331 |
| 5 | Cochise County | 328 |
| 6 | La Paz County | 253 |
| 7 | Yuma County | 211 |
| 8 | Gila County | 196 |
| 9 | Santa Cruz County | 187 |
| 10 | Coconino County | 113 |
| 11 | Apache County | 100 |
| 12 | Yavapai County | 97 |
| 13 | Navajo County | 54 |