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Air quality in Minnesota

EPA monitors report from 23 of Minnesota’s 87 counties. That is the honest limit of this page: the other 64 are not measured, not clean. In 2025 the most affected monitored county was St. Louis County, with 23 days above the moderate category.

23
Counties with monitors
64
Counties without
213
Days above moderate, 2025
Summed across monitored counties
9.9%
Adults with asthma
Population-weighted county estimate

County by county

Monitored Minnesota counties

GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
County90th %ile AQIAbove moderateMax AQI2025 days by category
St. Louis County7923216
Beltrami County6917191
Lake County6015191
Blue Earth County7014180
Crow Wing County6314174
Cass County5913177
Carlton County6212184
Cook County5412201
Becker County7311185
Stearns County6211165
Dakota County6210175
Hennepin County7110178
Wright County6710170
Anoka County649177
Ramsey County619170
Olmsted County658166
Scott County648172
Lyon County657161
Goodhue County51097
Mille Lacs County46097
Pine County45061
Washington County46084
Winona County55089

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

64 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