Bad Air Days in Big Horn County, Wyoming: under 1 a Year
under 1 bad air day a year
Rare: among the cleanest-air counties EPA monitors. Ranked 792 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (0% particle days).
When the bad days come in Big Horn
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in August and July. Averaged over 2016 to 2025.
What actually helps 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.
The record for Big Horn
The worst recent year was 2024, with 2 bad days on 353 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2020-08-22 | 126 | Ozone |
| 2024-07-22 | 119 | Ozone |
| 2020-08-21 | 108 | Ozone |
| 2021-08-02 | 101 | Ozone |
| 2024-07-23 | 101 | Ozone |
Most days, not the worst ones
Across 3,129 monitored days from 2016 to 2024, the air in Big Horn 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 38; one day in ten went above 48.
The pollutant setting the AQI on an ordinary day here:
- ozone100%3,129 days
Big Horn County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2024 | 353 | 315 | 36 | 2 | 0 | 39 | 119 |
| 2023 | 359 | 335 | 24 | 0 | 0 | 39 | 77 |
| 2022 | 362 | 356 | 6 | 0 | 0 | 38 | 64 |
| 2021 | 364 | 324 | 39 | 1 | 0 | 39 | 101 |
| 2020 | 359 | 349 | 8 | 2 | 0 | 38 | 126 |
| 2019 | 356 | 344 | 12 | 0 | 0 | 36 | 77 |
| 2018 | 348 | 311 | 37 | 0 | 0 | 39 | 84 |
| 2017 | 345 | 326 | 19 | 0 | 0 | 36 | 74 |
| 2016 | 283 | 277 | 6 | 0 | 0 | 38 | 84 |
| 2015 | 359 | 315 | 44 | 0 | 0 | 41 | 71 |
| 2014 | 352 | 306 | 46 | 0 | 0 | 41 | 74 |
| 2013 | 348 | 299 | 49 | 0 | 0 | 40 | 87 |
| 2012 | 363 | 355 | 8 | 0 | 0 | 36 | 84 |
| 2011 | 291 | 286 | 5 | 0 | 0 | 39 | 71 |
| 2010 | 292 | 286 | 6 | 0 | 0 | 38 | 67 |
Nearby counties on file
- Platte County9/yr
- Sweetwater County7/yr
- Albany County6/yr
- Campbell County5/yr
- Sublette County5/yr
- Sheridan County3/yr
- Laramie County3/yr
- Teton 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.