Bad Air Days in Moffat County, Colorado: under 1 a Year
under 1 bad air days a year
Rare: among the cleanest-air counties EPA monitors. Ranked 863 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 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 2018, with 1 bad day on 331 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2018-06-11 | 108 | Ozone |
| 2018-08-01 | 93 | Ozone |
| 2017-09-07 | 84 | Ozone |
| 2017-07-23 | 80 | Ozone |
| 2017-09-04 | 80 | Ozone |
The air on a normal day
Across 1,025 monitored days from 2016 to 2018, the air in Moffat County rated Good on 84% of them, more often than the 72% typical of monitored counties, and Moderate on 16%. The median day sat at AQI 42; one day in ten went above 57.
The pollutant setting the AQI on an ordinary day here:
- ozone100%1,025 days
Year by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2018 | 331 | 262 | 68 | 1 | 0 | 42 | 108 |
| 2017 | 349 | 282 | 67 | 0 | 0 | 44 | 84 |
| 2016 | 345 | 316 | 29 | 0 | 0 | 41 | 67 |
| 2015 | 141 | 137 | 4 | 0 | 0 | 36 | 77 |
| 2014 | 270 | 236 | 34 | 0 | 0 | 43 | 90 |
| 2013 | 357 | 290 | 67 | 0 | 0 | 44 | 90 |
| 2012 | 361 | 266 | 94 | 1 | 0 | 44 | 105 |
| 2011 | 135 | 119 | 16 | 0 | 0 | 40 | 84 |
Elsewhere in Colorado
- Jefferson County28/yr
- Teller Countythin data
- Douglas County20/yr
- Larimer County18/yr
- Boulder County13/yr
- Weld County12/yr
- Arapahoe County12/yr
- Denver County12/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.