Bad Air Days in Brown County, Indiana: under 1 a Year
under 1 bad air days a year
Rare: among the cleanest-air counties EPA monitors. Ranked 870 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (0% particle days).
The bad-air season here
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in May and June. Averaged over 2016 to 2025.
What to buy, and what not to
- 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
The worst recent year was 2016, with 1 bad day on 138 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-05-24 | 126 | Ozone |
| 2023-06-02 | 112 | Ozone |
| 2016-05-23 | 101 | Ozone |
| 2016-05-24 | 100 | Ozone |
| 2018-06-07 | 97 | Ozone |
The air on a normal day
Across 3,252 monitored days from 2016 to 2025, the air in Brown County rated Good on 94% of them, more often than the 72% typical of monitored counties, and Moderate on 6%. The median day sat at AQI 35; one day in ten went above 48.
The pollutant setting the AQI on an ordinary day here:
- ozone100%3,252 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 364 | 349 | 15 | 0 | 0 | 34 | 77 |
| 2024 | 359 | 339 | 20 | 0 | 0 | 37 | 77 |
| 2023 | 347 | 313 | 32 | 2 | 0 | 37 | 126 |
| 2022 | 358 | 348 | 10 | 0 | 0 | 35 | 97 |
| 2021 | 361 | 341 | 20 | 0 | 0 | 33 | 84 |
| 2020 | 364 | 349 | 15 | 0 | 0 | 33 | 80 |
| 2019 | 365 | 349 | 16 | 0 | 0 | 35 | 74 |
| 2018 | 363 | 339 | 24 | 0 | 0 | 33 | 97 |
| 2017 | 233 | 207 | 26 | 0 | 0 | 39 | 90 |
| 2016 | 138 | 123 | 14 | 1 | 0 | 36 | 101 |
| 2015 | 181 | 166 | 14 | 1 | 0 | 38 | 101 |
| 2014 | 119 | 112 | 7 | 0 | 0 | 39 | 71 |
*2025 may be a partial year in EPA's file.
Nearby counties on file
- Marion County8/yr
- Porter County8/yr
- Lake County7/yr
- LaPorte County7/yr
- St. Joseph County5/yr
- Clark County3/yr
- Elkhart County3/yr
- Floyd County3/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.