SmogRank / World / United States / Pennsylvania / May 2026
Most polluted cities in Pennsylvania, United States, May 2026
34 cities in Pennsylvania, United States ranked by their average PM2.5 over the 31 days. Worst: Philadelphia at 9.5 µg/m³, #868 of 2,852 cities in the world. Cleanest: Johnstown at 3.8. 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.
- 1Philadelphia 0%
- 2Bensalem 0%
- 3York 0%
- 4Wyomissing 0%
- 5Lancaster 0%
- 5West Mifflin 0%
- 7Lebanon 0%
- 8Harrisburg 0%
- 9Hershey 0%
- 10Kennett Square 0%
- 11Beaver Falls 0%
- 11Norristown 0%
- 11Scranton 0%
- 11Kennedy Township 0%
- 15Schlusser 0%
- 16Allentown 0%
- 16Natrona Heights 0%
- 16Wilkinsburg 0%
- 19New Holland 0%
- 20Warren 0%
- 21Bethlehem 0%
- 21Jefferson Hills 0%
- 23Canonsburg 0%
- 23New Brighton 0%
- 25Uniontown 0%
- 25Greensburg 0%
- 25Monessen 0%
- 25State College 0%
- 29Erie 0%
- 30Bridgeville 0%
- 30Hermitage 0%
- 32Pittsburgh 0%
- 33Altoona 0%
- 34Johnstown 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 2026, smogrank.com/us/region/pennsylvania/history/2026-05 (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.