Most polluted cities in Pennsylvania, United States

25 measured cities ranked by PM2.5, last 7 days. Worst: Pittsburgh at 5.4 µg/m³, #1698 in the world.

#	City	µg/m³
1	Pittsburgh Pennsylvania	5.4
2	McKeesport Pennsylvania	5.3
3	West Mifflin Pennsylvania	5.2
4	Wilkinsburg Pennsylvania	4.9
5	Hermitage Pennsylvania	4.8
6	Johnstown Pennsylvania	4.6
7	Scranton Pennsylvania	4.6
8	Upper Saint Clair Pennsylvania	4.6
9	Erie Pennsylvania	4.5
10	Bensalem Pennsylvania	4.4
11	York Pennsylvania	4.3
12	Lancaster Pennsylvania	4.3
13	Philadelphia Pennsylvania	4.1
14	Harrisburg Pennsylvania	4.1
15	Chambersburg Pennsylvania	4.0
16	Reading Pennsylvania	3.4
17	Abington low-cost sensorsPennsylvania	3.3
18	Lebanon Pennsylvania	3.3
19	State College Pennsylvania	3.3
20	Allentown Pennsylvania	3.1
21	Carlisle Pennsylvania	3.1
22	Bethlehem Pennsylvania	3.0
23	Chester Pennsylvania	2.8
24	Norristown Pennsylvania	2.8
25	Altoona Pennsylvania	0.3

Good 0–9.0Moderate 9.1+Unhealthy for sensitive groups 35.5+Unhealthy 55.5+Very unhealthy 125.5+Hazardous 225.5+No data

Updated 2026-10-01 04:07 UTC. Values are PM2.5 in µg/m³ (fine particles), the median of each city's monitors.