Air Quality Rankings for Maine 2026
Maine has 10 cities with EPA air quality data. Kennebec, Maine has the cleanest air with a 5-year average AQI of 33. Cumberland, Maine has the highest AQI at 40.
| # | City | 5yr Avg AQI | Current AQI | Worst Pollutant | Trend | Grade |
|---|---|---|---|---|---|---|
| 1 | Kennebec, Maine | 33 | 37 | Ozone | Worsening | B |
| 2 | Penobscot, Maine | 33 | 35 | PM2.5 | Improving | B |
| 3 | Androscoggin, Maine | 34 | 35 | PM2.5 | Improving | B |
| 4 | Knox, Maine | 34 | 33 | Ozone | Stable | B |
| 5 | Washington, Maine | 34 | 36 | Ozone | Stable | B |
| 6 | Oxford, Maine | 35 | 38 | PM2.5 | Stable | B |
| 7 | Aroostook, Maine | 36 | 37 | PM2.5 | Improving | B |
| 8 | Hancock, Maine | 37 | 38 | Ozone | Stable | B |
| 9 | York, Maine | 37 | 35 | Ozone | Improving | B |
| 10 | Cumberland, Maine | 40 | 40 | PM2.5 | Improving | B |
Air quality data for Maine is sourced from the EPA Air Quality System (AQS), which monitors outdoor air quality at thousands of stations nationwide.
Frequently Asked Questions
Kennebec, Maine has the best air quality in Maine with a 5-year average AQI of 33 and a grade of B.
Maine has 10 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."
Cities ranked by 5-year average AQI (lower is better). Grades factor in average AQI, trend direction, unhealthy days, and dominant pollutant.