Skip to content
lung.com

Air quality in Michigan

EPA monitors report from 28 of Michigan’s 83 counties. That is the honest limit of this page: the other 55 are not measured, not clean. In 2025 the most affected monitored county was Allegan County, with 14 days above the moderate category.

28
Counties with monitors
55
Counties without
150
Days above moderate, 2025
Summed across monitored counties
11.5%
Adults with asthma
Population-weighted county estimate

County by county

Monitored Michigan counties

GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
County90th %ile AQIAbove moderateMax AQI2025 days by category
Allegan County7514151
Marquette County6213193
St. Clair County6711152
Wayne County7511156
Macomb County6810166
Kent County729163
Manistee County659167
Oakland County679166
Ingham County628153
Ottawa County688159
Washtenaw County688152
Kalamazoo County717156
Lenawee County667147
Schoolcraft County645167
Missaukee County584133
Bay County603139
Berrien County673147
Genesee County573126
Cass County612115
Huron County512108
Muskegon County612140
Clinton County501119
Tuscola County491112
Benzie County50080
Keweenaw County16031
Mason County51087
Monroe County41077
Wexford County48093

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

55 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