SmogRank / World / United States / Pennsylvania / April 2026
Most polluted cities in Pennsylvania, United States, April 2026
34 cities in Pennsylvania, United States ranked by their average PM2.5 over the 30 days. Worst: Philadelphia at 9.5 µg/m³, #1,040 of 2,914 cities in the world. Cleanest: Altoona at 4.9. 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 April 2026.
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
- 2West 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, April 2026, smogrank.com/us/region/pennsylvania/history/2026-04 (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.