Bad Air Days in Wasatch County, Utah: 1 a Year
1 bad air day a year
Fewer bad air days than most monitored US counties. Ranked 600 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 Wasatch
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in June and August. 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
The worst recent year was 2024, with 1 bad day on 153 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2024-08-02 | 108 | Ozone |
| 2025-06-20 | 105 | Ozone |
| 2025-06-27 | 100 | Ozone |
| 2025-08-04 | 97 | Ozone |
| 2025-05-11 | 93 | Ozone |
The air on a normal day
Across 518 monitored days from 2024 to 2025, the air in Wasatch County rated Good on 73% of them, close to the 72% typical of monitored counties, and Moderate on 27%. The median day sat at AQI 43; one day in ten went above 67.
The pollutant setting the AQI on an ordinary day here:
- ozone85%441 days
- fine particles (PM2.5)14%75 days
Wasatch County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 365 | 240 | 124 | 1 | 0 | 45 | 105 |
| 2024 | 153 | 138 | 14 | 1 | 0 | 37 | 108 |
*2025 may be a partial year in EPA's file.
Elsewhere in Utah
- Salt Lake County30/yr
- Davis County15/yr
- Uintah County13/yr
- Weber County11/yr
- Utah County10/yr
- Duchesne County10/yr
- Cache County8/yr
- Tooele County8/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.