SmogRank / World / United States / Pennsylvania / May 2025
Most polluted cities in Pennsylvania, United States, May 2025
31 cities in Pennsylvania, United States ranked by their average PM2.5 over the 31 days. Worst: Philadelphia at 6.1 µg/m³, #1,860 of 2,771 cities in the world. Cleanest: Canonsburg at 3.7. A city needs measurements on 70% of the days to be ranked.
About 0 people in these 2 cities breathed unhealthy air on an average day of May 2025.
Ranked by people: each city's population times its share of unhealthy days, those with a daily mean over 35.4 µg/m³ (US AQI 101+). That is how many people living there breathed unhealthy air on an average day. Only cities measured at 2 or more places at least 3 km apart are ranked: one monitor shouldn't speak for a whole city. Population is the city itself, not its wider metro area.
- 1Philadelphia 0
- 1West Mifflin 0
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
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SmogRank, most polluted cities in Pennsylvania, United States, PM2.5, May 2025, smogrank.com/us/region/pennsylvania/history/2025-05 (accessed 6 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.