Bad Air Days in Lenawee County, Michigan: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 413 of 996 monitored counties, where 1 is worst.
What makes them bad: a mix of particles and ozone (50% particle days).
When the bad days come in Lenawee
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in June and May and July. Averaged over 2016 to 2025.
Is a purifier worth it here?
- Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
- On the odd bad day, check AirNow and keep windows shut.
Better or worse than it was
In 2000 to 2009 this county averaged 25 bad days a year; in 2016 to 2025, 3. The air has improved. The worst recent year was 2023, with 10 bad days on 364 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-06-08 | 165 | PM2.5 |
| 2023-06-07 | 154 | PM2.5 |
| 2025-06-06 | 147 | PM2.5 |
| 2023-06-09 | 144 | PM2.5 |
| 2023-06-29 | 143 | Ozone |
The air on a normal day
Across 3,575 monitored days from 2016 to 2025, the air in Lenawee County rated Good on 65% of them, less often than the 72% typical of monitored counties, and Moderate on 34%. The median day sat at AQI 44; one day in ten went above 64.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)60%2,148 days
- ozone40%1,427 days
Year by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 365 | 253 | 105 | 7 | 0 | 41 | 147 |
| 2024 | 366 | 253 | 113 | 0 | 0 | 43 | 97 |
| 2023 | 364 | 188 | 166 | 10 | 2 | 50 | 165 |
| 2022 | 365 | 250 | 115 | 0 | 0 | 43 | 97 |
| 2021 | 322 | 188 | 134 | 0 | 0 | 46 | 93 |
| 2020 | 366 | 248 | 116 | 2 | 0 | 42 | 122 |
| 2019 | 358 | 233 | 125 | 0 | 0 | 44 | 91 |
| 2018 | 344 | 246 | 94 | 4 | 0 | 43 | 115 |
| 2017 | 364 | 248 | 115 | 1 | 0 | 44 | 101 |
| 2016 | 361 | 223 | 136 | 2 | 0 | 44 | 119 |
| 2015 | 348 | 201 | 147 | 0 | 0 | 47 | 92 |
| 2014 | 345 | 174 | 168 | 3 | 0 | 50 | 129 |
| 2013 | 245 | 173 | 71 | 1 | 0 | 43 | 105 |
| 2012 | 243 | 124 | 94 | 25 | 4 | 50 | 187 |
| 2011 | 241 | 145 | 85 | 11 | 1 | 46 | 154 |
| 2010 | 216 | 133 | 82 | 1 | 0 | 46 | 103 |
*2025 may be a partial year in EPA's file.
Nearby counties on file
- Wayne County11/yr
- Marquette County9/yr
- Muskegon County9/yr
- Allegan County9/yr
- Berrien County8/yr
- Macomb County7/yr
- Cass County6/yr
- Oakland County6/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, and on why a purifier does not touch ozone in smoke vs ozone.