Smoke: keep one room clean
Shut the windows and run an air purifier sized for the room.
Wildfire smoke guide →Air quality in Minnesota, county by county
20 Minnesota counties have enough EPA monitor data to count bad-air days. Weighted by population, they averaged about 6 days a year from 2021 to 2025 when the air was unhealthy for sensitive groups or worse.
CDC's model, which estimates every county from monitors and satellites, gives the average Minnesota county, weighted by population, about 1 smoky day (fine particles over 35.4 µg/m³, mostly wildfire smoke) and almost no high-ozone days a year at its worst spot (2018 to 2022). See every county on the map.
Every Minnesota county with monitors
Most bad-air days first. 16 have a full report. Compare with the worst and the cleanest counties in the US.
| County | Bad-air days a year | |
|---|---|---|
| St. Louis CountyDuluthSummer smoke | 8.8 | |
| Wright CountyOtsegoOzone and particles | 7.8 | |
| Beltrami CountyBemidjiSummer smoke | 7.2 | |
| Anoka CountyBlaineOzone and particles | 6.8 | |
| Hennepin CountyMinneapolisSummer smoke | 6.8 | |
| Becker CountyDetroit LakesSummer smoke | 6.6 | |
| Cass CountySmokeozone not measured | 6.2 | |
| Stearns CountySt. CloudSummer smoke | 6.2 | |
| Crow Wing CountyBrainerdSummer smoke | 5.8 | |
| Lyon CountyMarshallSummer smoke | 5.8 | |
| Olmsted CountyRochesterSummer smoke | 5.4 | |
| Scott CountyShakopeeOzone and particles | 5.2 | |
| Dakota CountyLakevilleSmokeozone not measured | 4.8 | |
| Ramsey CountySt. PaulSmokeozone not measured | 4.6 | |
| Carlton CountyCloquetSummer smoke | 4.4 | |
| Lake CountySummer smoke | 4.4 | |
| Cook CountySmokeozone not measured | 4.0 | |
| Washington CountyWoodburyOzoneparticles not measured | 1.8 | |
| Mille Lacs CountyOzoneparticles not measured | 1.7 | |
| Goodhue CountyRed WingOzoneparticles not measured | 1.0 | |
| No Minnesota county with a monitor matches “”. Counties without a monitor aren't listed; a neighbor's numbers are a fair guide, or find it on the map. | ||
Counties without a monitor aren't listed. Air doesn't stop at the county line, so a neighbor's numbers are a fair guide.
What helps on a bad-air day
Check AirNow for today's reading and tomorrow's forecast, then match the step to the pollutant.
Upgrade the furnace filter
MERV 13 catches far more smoke than thin fiberglass filters.
Furnace filters →Questions people ask about air quality in Minnesota
Which county in Minnesota has the worst air?
Among Minnesota counties with EPA monitors, St. Louis County had the most bad-air days from 2021 to 2025: about 9 bad-air days a year with an AQI over 100. That's about 1 day in 41.
How often is the air bad in Minnesota?
Weighted by population, Minnesota counties with monitors averaged about 6 bad-air days a year from 2021 to 2025 with an AQI over 100, when children, older adults and people with asthma should cut back outdoors. That's about 1 day in 63.
Which county in Minnesota has the cleanest air?
Of the 20 counties with enough monitor data, Goodhue County had the fewest: 1.0 a year from 2021 to 2025. Counties without monitors aren't ranked.
Where can I check today's air quality in Minnesota?
AirNow, run by the EPA and its partners, shows current readings and forecasts by ZIP code, and its fire and smoke map adds smoke plumes and low-cost sensors.
Sources: EPA AirData county AQI summaries, 2021 to 2025; CDC Environmental Public Health Tracking Network modeled PM2.5 and ozone, 2018 to 2022. Updated November 8, 2026.