# Counties in Pennsylvania by share of days with good air quality (US EPA AQI), 2025

All 38 values come from U.S. Environmental Protection Agency for 2025, so the places are comparable. 6 counties have no value for that period and are not ranked.

- Indicator id: `aqi_good_days_share`
- Unit: %
- Definition: Days with a daily Air Quality Index of 0 to 50 (good) 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; both counts are stored with each value.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: good days 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: good days 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/good-air-quality-days-share/pennsylvania-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Elk County | 95.3 |
| 2 | Somerset County | 94.5 |
| 3 | Franklin County | 91.5 |
| 4 | Susquehanna County | 88.4 |
| 5 | Monroe County | 88.3 |
| 6 | Wyoming County | 86.5 |
| 7 | Bucks County | 86.2 |
| 8 | Tioga County | 82.1 |
| 9 | Bradford County | 81.6 |
| 10 | Fayette County | 78.9 |
| 11 | Warren County | 78.7 |
| 12 | Westmoreland County | 78.2 |
| 13 | Greene County | 77.8 |
| 14 | Lycoming County | 77.5 |
| 15 | Blair County | 76.9 |
| 16 | Erie County | 76.7 |
| 17 | Indiana County | 74.8 |
| 18 | Cambria County | 74.5 |
| 19 | Adams County | 74.4 |
| 20 | Centre County | 74.2 |
| 21 | Lackawanna County | 74 |
| 22 | Montgomery County | 73.4 |
| 23 | Mercer County | 72.6 |
| 24 | Northampton County | 72.1 |
| 25 | Lehigh County | 72 |
| 26 | Cumberland County | 71.5 |
| 27 | Chester County | 71.3 |
| 28 | Armstrong County | 70.5 |
| 29 | Berks County | 68.2 |
| 30 | Washington County | 67.7 |
| 31 | Delaware County | 65.2 |
| 32 | Lebanon County | 64.4 |
| 33 | Dauphin County | 62.5 |
| 34 | Lancaster County | 60.5 |
| 35 | York County | 59.5 |
| 36 | Beaver County | 55.6 |
| 37 | Philadelphia County | 50.4 |
| 38 | Allegheny County | 46 |