SmogRank / United States / Pennsylvania / Lancaster
Lancaster, month by month
Lancaster, Pennsylvania has a measured daily mean on 1,364 days since 1 January 2023. Its worst month was June 2023, at 93 US AQI (31.9 µg/m³), 66th of 1,603 cities on that month's world ranking. Its cleanest was October 2025, at 28 US AQI (5.1 µg/m³). 2025 averaged 46 US AQI (8.2 µg/m³), against 44 US AQI (7.9 µg/m³) in 2024.
Every month since 2023
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
Lancaster's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| June 2023 | 9331.9 µg/m³ | 66thof 1,603 | Eastern United States and Canada, June and July 2023 United States and Canada, June 2023and 1 more |
| July 2026 | 7320.9 µg/m³ | 302ndof 2,784 | Northern United States and Canada, July 2026 |
| February 2026 | 6516.6 µg/m³ | 710thof 2,866 | North-eastern United States and Canada, 14 to 19 February 2026 Pennsylvania, United States, February 2026 |
| July 2023 | 6014.1 µg/m³ | 197thof 1,432 | United States and Canada, July 2023 North-eastern United States, 19 July 2023and 1 more |
| December 2023 | 5611.7 µg/m³ | 458thof 2,247 | Pennsylvania, New Jersey and Massachusetts, United States, December 2023 North-eastern United States, December 2023 |
| January 2023 | 5611.6 µg/m³ | 363rdof 1,261 | – |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Lancaster's worst days
| Day | US AQI | Episode |
|---|---|---|
| 8 Jun 2023 | 247172.0 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 17 Jul 2026 | 221146.0 µg/m³ | Northern United States and Canada, July 2026 |
| 7 Jun 2023 | 217142.0 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 29 Jun 2023 | 17792.2 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 16 Jul 2026 | 16778.7 µg/m³ | Northern United States and Canada, July 2026 |
| 18 Jul 2026 | 16373.2 µg/m³ | Northern United States and Canada, July 2026 |
| 30 Jun 2023 | 16372.8 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 15 Feb 2026 | 14754.3 µg/m³ | North-eastern United States and Canada, 14 to 19 February 2026 |
| 6 Jun 2023 | 14051.2 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 10 Feb 2024 | 12143.6 µg/m³ | Pennsylvania and New Jersey, United States, February 2024 |
Daily means, the highest since 1 Jan 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Lancaster, Pennsylvania, United States, 1 Jan 2023 – 12 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/lancaster-pennsylvania/history (accessed 13 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.
Lancaster now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 05:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).