Skip to content
lung.com

Air quality in Maine

EPA monitors report from 11 of Maine’s 16 counties. That is the honest limit of this page: the other 5 are not measured, not clean. In 2025 the most affected monitored county was Penobscot County, with 6 days above the moderate category.

11
Counties with monitors
5
Counties without
28
Days above moderate, 2025
Summed across monitored counties
12.6%
Adults with asthma
Population-weighted county estimate

County by county

Monitored Maine counties

GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
County90th %ile AQIAbove moderateMax AQI2025 days by category
Penobscot County586170
Cumberland County625136
Aroostook County574131
Hancock County494133
Oxford County603135
York County453169
Androscoggin County542112
Sagadahoc County471108
Kennebec County55096
Knox County44077
Washington County490100

EPA Air Quality System annual summaries by county, 2025. The 90th percentile AQI describes a day worse than nine out of ten, which is a steadier measure than the annual maximum a single wildfire can set.

Not measured

5 counties without a monitor

No EPA monitor reported from these counties, so there is no air quality record to publish. Their radon zone is known, and radon is measured in the building rather than the air outside it.

Other states

Air quality elsewhere