Bad Air Days in Marquette County, Michigan: 9 a Year
9 bad air days a year
Among the worst tenth of monitored US counties. Ranked 95 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (100% particle days).
When the bad days come in Marquette
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in July and August. Averaged over 2016 to 2025.
What to buy, and what not to
- Particles (wildfire smoke, dust) cause enough bad days here to matter. A HEPA purifier sized to your bedroom removes them; run it with windows shut on bad days.
- Upgrade the furnace or AC filter to MERV 13 so the whole house is filtered, not just one room.
Better or worse than it was
The worst recent year was 2025, with 13 bad days on 307 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2025-07-30 | 193 | PM2.5 |
| 2025-06-03 | 183 | PM2.5 |
| 2025-07-31 | 168 | PM2.5 |
| 2025-07-13 | 163 | PM2.5 |
| 2025-08-02 | 156 | PM2.5 |
The air on a normal day
Across 531 monitored days from 2024 to 2025, the air in Marquette County rated Good on 86% of them, more often than the 72% typical of monitored counties, and Moderate on 12%. The median day sat at AQI 19; one day in ten went above 56.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)100%531 days
Year by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 307 | 253 | 41 | 13 | 6 | 19 | 193 |
| 2024 | 224 | 202 | 22 | 0 | 0 | 19 | 67 |
*2025 may be a partial year in EPA's file.
Elsewhere in Michigan
- Wayne County11/yr
- Muskegon County9/yr
- Allegan County9/yr
- Berrien County8/yr
- Macomb County7/yr
- Cass County6/yr
- Oakland County6/yr
- St. Clair County5/yr
How this is counted
A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day.