SmogRank / World / North America / United States / Massachusetts
Most polluted cities in Massachusetts, United States
17 measured cities, this year; 17 above the WHO annual guideline. Worst: Springfield at 6.9 µg/m³, #2,220 in the world.
About 2.95K people in these 3 cities breathed unhealthy air on an average day so far this year.
Ranked by people: each city's population times its share of unhealthy days, those with a daily mean over 35.4 µg/m³ (US AQI 101+). That is how many people living there breathed unhealthy air on an average day. Only cities measured at 2 or more places at least 3 km apart are ranked: one monitor shouldn't speak for a whole city. Population is the city itself, not its wider metro area.
Cities coloured by their PM2.5 over the last 24 hours. Fires, smoke and ash: Oct 5, the newest UTC day mapped.
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
Estimated: cities without a monitor
Massachusetts 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 |
|---|---|
| Cambridge | ≈ 6 µg/m³ |
| New Bedford | ≈ 5 µg/m³ |
| Dorchester | ≈ 6 µg/m³ |
| Newton | ≈ 6 µg/m³ |
| Somerville | ≈ 6 µg/m³ |
| Lawrence | ≈ 5 µg/m³ |
| Framingham Center | ≈ 5 µg/m³ |
| Waltham | ≈ 6 µg/m³ |
| Malden | ≈ 6 µg/m³ |
| Brookline | ≈ 6 µg/m³ |
| Medford | ≈ 6 µg/m³ |
| Taunton | ≈ 6 µg/m³ |
| Chicopee | ≈ 5 µg/m³ |
| Weymouth | ≈ 6 µg/m³ |
| Revere | ≈ 6 µg/m³ |
| Peabody | ≈ 6 µg/m³ |
| Methuen | ≈ 5 µg/m³ |
| South Peabody | ≈ 6 µg/m³ |
| Barnstable | ≈ 4 µg/m³ |
| Everett | ≈ 6 µg/m³ |
| Brighton | ≈ 6 µg/m³ |
| Attleboro | ≈ 6 µg/m³ |
| East Boston | ≈ 6 µg/m³ |
| Salem | ≈ 6 µg/m³ |
| Arlington | ≈ 6 µg/m³ |
| Westfield | ≈ 5 µg/m³ |
| Leominster | ≈ 5 µg/m³ |
| Beverly | ≈ 6 µg/m³ |
| Holyoke | ≈ 4 µg/m³ |
| Fitchburg | ≈ 4 µg/m³ |
| Beverly Cove | ≈ 6 µg/m³ |
| Billerica | ≈ 7 µg/m³ |
| Amherst | ≈ 5 µg/m³ |
| Marlborough | ≈ 5 µg/m³ |
| Woburn | ≈ 7 µg/m³ |
| Chelsea | ≈ 6 µg/m³ |
| Braintree | ≈ 6 µg/m³ |
| Mattapan | ≈ 6 µg/m³ |
| Chelmsford | ≈ 7 µg/m³ |
| Shrewsbury | ≈ 5 µg/m³ |
Bad-air episodes in Massachusetts
- Northern United States and Canada, July 202614 to 21 July 2026, 8 days327 cities548 µg/m³peak, Superior
- North-eastern United States and Canada, 14 to 19 February 20266 days108 cities54 µg/m³peak, Lancaster
- North-eastern United States, January 202618 January 2026, 1 day16 cities37 µg/m³peak, New Holland
- 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, June 202510 to 14 June 2025, 5 days134 cities71 µg/m³peak, Wilmington
Times when many cities around here had PM2.5 at twice their usual or more on the same days.
Use this board
SmogRank, most polluted cities in Massachusetts, United States, PM2.5, this year to 6 Oct 2026, 23:00 UTC, smogrank.com/us/region/massachusetts?w=year.
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 23:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.