SmogRank / World / United States / Pennsylvania / December 2025
Most polluted cities in Pennsylvania, United States, December 2025
35 cities in Pennsylvania, United States ranked by their average PM2.5 over the 31 days. Worst: York at 15.7 µg/m³, #697 of 2,960 cities in the world. Cleanest: Warren at 5.7. A city needs measurements on 70% of the days to be ranked.
Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.
- 1York 3%
- 2New Holland 0%
- 3Abingtonlow-cost sensors 0%
- 4Lancaster 0%
- 5Bensalem 0%
- 6Lebanon 0%
- 7Harrisburg 0%
- 8Hershey 0%
- 9Wyomissing 0%
- 10Philadelphia 0%
- 11Schlusser 0%
- 12Bethlehem 0%
- 13Beaver Falls 0%
- 13Norristown 0%
- 15Kennett Square 0%
- 15Allentown 0%
- 17West Mifflin 0%
- 18Kennedy Township 0%
- 19Scranton 0%
- 20New Brighton 0%
- 20Wilkinsburg 0%
- 22Hermitage 0%
- 23Canonsburg 0%
- 24Johnstown 0%
- 24Natrona Heights 0%
- 24Pittsburgh 0%
- 27Jefferson Hills 0%
- 27Monessen 0%
- 27State College 0%
- 30Greensburg 0%
- 31Bridgeville 0%
- 32Uniontown 0%
- 32Altoona 0%
- 34Erie 0%
- 35Warren 0%
Low-cost sensors: consumer units, counted only in cities with no government-grade monitor; they read close to reference monitors on the whole, but 15 to 25% high in humid air. How we use them.
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
All cities in the world, December 2025 · All cities in United States, December 2025 · Pennsylvania now
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SmogRank, most polluted cities in Pennsylvania, United States, PM2.5, December 2025, smogrank.com/us/region/pennsylvania/history/2025-12 (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.