Bad Air Days in Routt County, Colorado: under 1 a Year
under 1 bad air days a year
Rare: among the cleanest-air counties EPA monitors. Ranked 943 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (100% 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. 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 Routt
In 2000 to 2009 this county averaged 0 bad days a year; in 2016 to 2025, under 1. Not much has changed. The worst recent year was 2019, with 1 bad day on 356 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2019-04-01 | 137 | PM10 |
| 2025-08-05 | 87 | PM2.5 |
| 2025-08-04 | 80 | PM2.5 |
| 2025-09-06 | 77 | PM2.5 |
| 2025-08-06 | 71 | PM2.5 |
The air on a normal day
Across 3,556 monitored days from 2016 to 2025, the air in Routt County rated Good on 98% of them, more often than the 72% typical of monitored counties, and Moderate on 2%. The median day sat at AQI 15; one day in ten went above 29.
The pollutant setting the AQI on an ordinary day here:
- coarse dust (PM10)90%3,215 days
- fine particles (PM2.5)10%341 days
Routt County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 365 | 342 | 23 | 0 | 0 | 22 | 87 |
| 2024 | 365 | 364 | 1 | 0 | 0 | 12 | 53 |
| 2023 | 353 | 348 | 5 | 0 | 0 | 13 | 58 |
| 2022 | 356 | 356 | 0 | 0 | 0 | 13 | 43 |
| 2021 | 354 | 347 | 7 | 0 | 0 | 15 | 68 |
| 2020 | 358 | 353 | 5 | 0 | 0 | 14 | 68 |
| 2019 | 356 | 353 | 2 | 1 | 0 | 13 | 137 |
| 2018 | 355 | 354 | 1 | 0 | 0 | 15 | 51 |
| 2017 | 342 | 333 | 9 | 0 | 0 | 15 | 62 |
| 2016 | 352 | 343 | 9 | 0 | 0 | 15 | 60 |
| 2015 | 364 | 357 | 7 | 0 | 0 | 13 | 58 |
| 2014 | 346 | 334 | 12 | 0 | 0 | 15 | 65 |
| 2013 | 349 | 336 | 13 | 0 | 0 | 15 | 64 |
| 2012 | 353 | 346 | 7 | 0 | 0 | 15 | 85 |
| 2011 | 343 | 331 | 12 | 0 | 0 | 15 | 91 |
| 2010 | 351 | 331 | 20 | 0 | 0 | 16 | 73 |
*2025 may be a partial year in EPA's file.
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.