Smoke: keep one room clean
Shut the windows and run an air purifier sized for the room.
Wildfire smoke guide →Air quality in Michigan, county by county
25 Michigan counties have enough EPA monitor data to count bad-air days. Weighted by population, they averaged about 7 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 Michigan county, weighted by population, almost no smoky days (fine particles over 35.4 µg/m³, mostly wildfire smoke) and about 4 high-ozone days a year at its worst spot (2018 to 2022). See every county on the map.
Every Michigan county with monitors
Most bad-air days first. 18 have a full report. Compare with the worst and the cleanest counties in the US.
| County | Bad-air days a year | |
|---|---|---|
| Wayne CountyDetroitOzone and particles | 12.2 | |
| Allegan CountyOzone | 9.0 | |
| St. Clair CountyPort HuronOzone | 7.2 | |
| Muskegon CountyMuskegonOzoneparticles not measured | 6.4 | |
| Macomb CountyWarrenOzone | 6.0 | |
| Kent CountyGrand RapidsOzone | 5.8 | |
| Manistee CountyOzone | 5.8 | |
| Ottawa CountyHollandOzone | 5.0 | |
| Berrien CountyNilesOzoneparticles not measured | 4.6 | |
| Washtenaw CountyAnn ArborOzone | 4.4 | |
| Oakland CountyTroyOzone | 4.2 | |
| Genesee CountyFlintOzone | 4.0 | |
| Ingham CountyLansingOzone and particles | 3.8 | |
| Kalamazoo CountyKalamazooOzone | 3.8 | |
| Lenawee CountyAdrianOzone and particles | 3.4 | |
| Cass CountyOzoneparticles not measured | 3.0 | |
| Schoolcraft CountyOzone | 2.4 | |
| Missaukee CountyOzone | 2.2 | |
| Huron CountyOzoneparticles not measured | 2.0 | |
| Bay CountyBay CitySmokeozone not measured | 1.8 | |
| Tuscola CountyOzoneparticles not measured | 1.8 | |
| Benzie CountyOzoneparticles not measured | 1.6 | |
| Wexford CountyCadillacOzoneparticles not measured | 1.6 | |
| Mason CountyLudingtonOzoneparticles not measured | 1.4 | |
| Clinton CountyOzoneparticles not measured | 0.8 | |
| No Michigan 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 Michigan
Which county in Michigan has the worst air?
Among Michigan counties with EPA monitors, Wayne County had the most bad-air days from 2021 to 2025: about 12 bad-air days a year with an AQI over 100. That's about 1 day in 30.
How often is the air bad in Michigan?
Weighted by population, Michigan counties with monitors averaged about 7 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 56.
Which county in Michigan has the cleanest air?
Of the 25 counties with enough monitor data, Clinton County had the fewest: 0.8 a year from 2021 to 2025. Counties without monitors aren't ranked.
Where can I check today's air quality in Michigan?
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.