AQI 55 · PM2.5 · Trend: Improving
| Average AQI | 55 |
| Good Days / Year | 195 |
| Unhealthy Days / Year | 15 |
| Primary Pollutant | PM2.5 |
| PM2.5 Average | 10.2 µg/m³ |
| Trend | ↓ Improving |
| Monitoring Stations | 55 |
| Nonattainment Areas | 3 |
Pennsylvania's air quality is shaped by two urban centers with distinct challenges. Pittsburgh still battles legacy steel industry pollution, while Philadelphia faces refinery and vehicle emissions. The Marcellus Shale gas boom has introduced new emission sources in rural areas.
PA DEP Bureau of Air Quality manages standards. Vehicle emissions testing. Member of RGGI. Marcellus Shale air quality monitoring.
Pittsburgh — PM2.5 nonattainment. Philadelphia — ozone nonattainment. Liberty-Clairton area — SO2 nonattainment (coke plant). Three separate nonattainment areas.