SmogRank / World / North America / United States / Maine
Most polluted cities in Maine, United States
5 measured cities, last 30 days; 0 above the WHO 24-hour guideline. Worst: Presque Isle at 4.9 µg/m³, #2,298 in the world.
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.
- 1Presque Isle 0%
- 2Portland 0%
- 3Augusta 0%
- 4Lewiston 0%
- 5Bangor 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
Estimated: cities without a monitor
Maine cities we can't measure, with model estimates for the last 7 days. Listed by population, not ranked: estimates aren't precise enough to rank. Model estimates from the Copernicus Atmosphere Monitoring Service (CAMS), adjusted to measured cities nearby where there are any. Adjusted, a single day lands within ×1.5 of what a monitor would read about two times in three; unadjusted, it can be off by half or double. Treat them as a guide, not a measurement.
| City | 7-day estimate |
|---|---|
| West Scarborough | ≈ 4 µg/m³ |
| South Portland | ≈ 4 µg/m³ |
| South Portland Gardens | ≈ 4 µg/m³ |
| Auburn | ≈ 4 µg/m³ |
| Biddeford | ≈ 4 µg/m³ |
| Sanford | ≈ 3 µg/m³ |
| Saco | ≈ 4 µg/m³ |
| Westbrook | ≈ 4 µg/m³ |
| Waterville | ≈ 3 µg/m³ |
| Brunswick | ≈ 3 µg/m³ |
Bad-air episodes in Maine
- Northern United States and Canada, July 202614 to 21 July 2026, 8 days327 cities548 µg/m³peak, Superior
- North-eastern United States and Canada, 29 July to 9 August 202512 days292 cities112 µg/m³peak, Marquette
- North-eastern United States and Canada, 24 to 28 July 20255 days113 cities88 µg/m³peak, Sorel-Tracy
- Northern United States and Canada, July 202511 to 16 July 2025, 6 days139 cities143 µg/m³peak, Virginia
- Northern United States and Canada, May and June 202531 May to 9 June 2025, 10 days247 cities116 µg/m³peak, Nepean
- Eastern Canada and United States, August 202416 to 17 August 2024, 2 days16 cities44 µg/m³peak, Saguenay
Times when many cities around here had PM2.5 at twice their usual or more on the same days.
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SmogRank, most polluted cities in Maine, United States, PM2.5, last 30 days to 6 Oct 2026, 22:00 UTC, smogrank.com/us/region/maine?w=30d.
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.
Updated 2026-10-06 22:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.