Air Quality Rankings for Massachusetts 2026

Massachusetts has 13 cities with EPA air quality data. Barnstable, Massachusetts has the cleanest air with a 5-year average AQI of 36. Hampden, Massachusetts has the highest AQI at 44.

#	City	5yr Avg AQI	Current AQI	Worst Pollutant	Trend	Grade
1	Barnstable, Massachusetts	36	37	Ozone	Stable	B
2	Norfolk, Massachusetts	37	41	Ozone	Stable	B
3	Dukes, Massachusetts	37	38	Ozone	Worsening	C
4	Middlesex, Massachusetts	39	39	Ozone	Worsening	C
5	Hampshire, Massachusetts	39	38	Ozone	Stable	B
6	Bristol, Massachusetts	41	42	Ozone	Stable	B
7	Essex, Massachusetts	41	44	Ozone	Stable	B
8	Plymouth, Massachusetts	41	40	PM2.5	Stable	C
9	Berkshire, Massachusetts	42	41	PM2.5	Improving	B
10	Franklin, Massachusetts	42	43	PM2.5	Stable	C
11	Worcester, Massachusetts	43	39	Ozone	Stable	C
12	Suffolk, Massachusetts	44	44	PM2.5	Improving	B
13	Hampden, Massachusetts	44	46	PM2.5	Stable	C

Air quality data for Massachusetts is sourced from the EPA Air Quality System (AQS), which monitors outdoor air quality at thousands of stations nationwide.
— EPA Air Quality System

Frequently Asked Questions

Barnstable, Massachusetts has the best air quality in Massachusetts with a 5-year average AQI of 36 and a grade of B.

Massachusetts has 13 cities with EPA air quality monitoring data in our database, covering multiple years of AQI measurements.

The Air Quality Index (AQI) measures five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Lower AQI values indicate cleaner air — 0-50 is "Good," while 150+ is "Unhealthy."

Sources: EPA Air Quality System (AQS)

Cities ranked by 5-year average AQI (lower is better). Grades factor in average AQI, trend direction, unhealthy days, and dominant pollutant.

Cleanest Cities Nationwide →All Air Quality in Massachusetts →