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

All 45 values come from U.S. Environmental Protection Agency for 2025, so the places are comparable. 18 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/texas-counties

| Rank | Place | index |
|---:|---|---:|
| 1 | El Paso County | 2,122 |
| 2 | Dallas County | 304 |
| 3 | Ector County | 183 |
| 4 | Denton County | 179 |
| 4 | Galveston County | 179 |
| 6 | Harris County | 172 |
| 7 | Lubbock County | 167 |
| 8 | Brewster County | 164 |
| 9 | Tarrant County | 162 |
| 10 | Jefferson County | 160 |
| 11 | Culberson County | 159 |
| 12 | Collin County | 156 |
| 13 | Bexar County | 154 |
| 14 | Parker County | 147 |
| 15 | Brazoria County | 143 |
| 16 | McLennan County | 142 |
| 17 | Bell County | 140 |
| 17 | Hidalgo County | 140 |
| 19 | Cameron County | 139 |
| 20 | Nueces County | 137 |
| 21 | Montgomery County | 133 |
| 22 | Travis County | 129 |
| 23 | Kaufman County | 126 |
| 24 | Hood County | 122 |
| 25 | Webb County | 121 |
| 26 | Hunt County | 119 |
| 27 | Gregg County | 115 |
| 28 | Rockwall County | 108 |
| 29 | Bowie County | 107 |
| 29 | Kleberg County | 107 |
| 29 | Navarro County | 107 |
| 32 | Polk County | 105 |
| 33 | Johnson County | 101 |
| 34 | Harrison County | 100 |
| 34 | Victoria County | 100 |
| 36 | Randall County | 97 |
| 37 | Ellis County | 93 |
| 37 | Smith County | 93 |
| 39 | Atascosa County | 92 |
| 40 | Maverick County | 90 |
| 40 | Orange County | 90 |
| 42 | Potter County | 85 |
| 43 | Brazos County | 78 |
| 44 | Wilson County | 41 |
| 45 | Karnes County | 32 |