Bad Air Days in Coconino County, Arizona: 2 a Year
2 bad air days a year
Fewer bad air days than most monitored US counties. Ranked 573 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (25% 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 April and May and July and June and October. 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
In 2000 to 2009 this county averaged 8 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2024, with 5 bad days on 366 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-11-02 | 203 | PM2.5 |
| 2023-10-21 | 178 | PM2.5 |
| 2023-10-18 | 153 | PM2.5 |
| 2024-06-14 | 136 | Ozone |
| 2018-04-17 | 126 | Ozone |
An ordinary day in Coconino
Across 3,653 monitored days from 2016 to 2025, the air in Coconino 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 45; one day in ten went above 68.
The pollutant setting the AQI on an ordinary day here:
- ozone97%3,535 days
- fine particles (PM2.5)3%118 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 365 | 256 | 107 | 2 | 0 | 46 | 113 |
| 2024 | 366 | 250 | 111 | 5 | 0 | 46 | 136 |
| 2023 | 365 | 243 | 118 | 4 | 3 | 46 | 203 |
| 2022 | 365 | 279 | 85 | 1 | 0 | 44 | 101 |
| 2021 | 365 | 265 | 100 | 0 | 0 | 46 | 93 |
| 2020 | 366 | 302 | 64 | 0 | 0 | 44 | 93 |
| 2019 | 365 | 280 | 85 | 0 | 0 | 45 | 80 |
| 2018 | 365 | 236 | 126 | 3 | 0 | 45 | 126 |
| 2017 | 365 | 253 | 111 | 1 | 0 | 46 | 105 |
| 2016 | 366 | 298 | 68 | 0 | 0 | 44 | 97 |
| 2015 | 365 | 258 | 103 | 4 | 0 | 44 | 108 |
| 2014 | 357 | 247 | 105 | 5 | 0 | 44 | 126 |
| 2013 | 364 | 257 | 104 | 3 | 0 | 46 | 115 |
| 2012 | 366 | 230 | 121 | 15 | 0 | 47 | 133 |
| 2011 | 365 | 227 | 128 | 10 | 0 | 47 | 129 |
| 2010 | 363 | 230 | 129 | 4 | 0 | 47 | 136 |
*2025 may be a partial year in EPA's file.
Arizona compared
- Maricopa County89/yr
- Pinal County53/yr
- Gila County14/yr
- Pima County9/yr
- Yuma County9/yr
- Santa Cruz County3/yr
- Cochise County3/yr
- La Paz County2/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.