Bad Air Days in Utah County, Utah: 10 a Year
10 bad air days a year
Among the worst tenth of monitored US counties. Ranked 83 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (39% 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 July and August and September. Averaged over 2016 to 2025.
Is a purifier worth it here?
- 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.
- Ozone drives many bad days here. Purifiers and filters do not remove ozone, so do not buy one for that. Ozone peaks on hot afternoons: exercise outside in the morning.
Better or worse than it was
In 2000 to 2009 this county averaged 30 bad days a year; in 2016 to 2025, 10. The air has improved. The worst recent year was 2018, with 32 bad days on 365 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2016-08-04 | 166 | Ozone |
| 2018-09-19 | 166 | PM2.5 |
| 2017-02-01 | 165 | PM2.5 |
| 2018-09-17 | 164 | PM2.5 |
| 2018-09-14 | 162 | PM2.5 |
An ordinary day in Utah
Across 3,653 monitored days from 2016 to 2025, the air in Utah County rated Good on 54% of them, less often than the 72% typical of monitored counties, and Moderate on 43%. The median day sat at AQI 49; one day in ten went above 80.
The pollutant setting the AQI on an ordinary day here:
- ozone64%2,354 days
- fine particles (PM2.5)32%1,180 days
- nitrogen dioxide2%89 days
- coarse dust (PM10)1%30 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 365 | 206 | 158 | 1 | 0 | 48 | 109 |
| 2024 | 366 | 210 | 147 | 9 | 1 | 47 | 151 |
| 2023 | 365 | 201 | 163 | 1 | 0 | 48 | 104 |
| 2022 | 365 | 206 | 154 | 5 | 0 | 49 | 119 |
| 2021 | 365 | 192 | 156 | 17 | 0 | 49 | 144 |
| 2020 | 366 | 199 | 162 | 5 | 0 | 48 | 150 |
| 2019 | 365 | 217 | 147 | 1 | 0 | 48 | 107 |
| 2018 | 365 | 190 | 143 | 32 | 7 | 50 | 166 |
| 2017 | 365 | 162 | 189 | 14 | 3 | 53 | 165 |
| 2016 | 366 | 189 | 158 | 19 | 2 | 50 | 166 |
| 2015 | 365 | 206 | 146 | 13 | 0 | 48 | 120 |
| 2014 | 365 | 216 | 137 | 12 | 0 | 46 | 140 |
| 2013 | 365 | 166 | 158 | 41 | 16 | 52 | 205 |
| 2012 | 366 | 142 | 212 | 12 | 1 | 54 | 156 |
| 2011 | 365 | 157 | 199 | 9 | 0 | 52 | 137 |
| 2010 | 365 | 147 | 204 | 14 | 2 | 54 | 300 |
*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
- Duchesne County10/yr
- Cache County8/yr
- Tooele County8/yr
- Box Elder County4/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.