Fort Collins Air Quality in 2023
In 2023, Fort Collins's air quality (Fort Collins, CO area) had a median daily AQI of 51 (Moderate) across 365 monitored days. 5 days (1.4%) reached Unhealthy for Sensitive Groups or worse, 175 were Good, and the year's peak AQI was 156 (Unhealthy). Ground-level ozone set the daily AQI on 304 of those days. The cleanest month of 2023 was December (median AQI 44, 0 days above 100) and the worst was May (median 67, 2 days above 100, peak 105).
- Good: 47.9%
- Moderate: 50.7%
- Unhealthy for Sensitive Groups: 1.1%
- Unhealthy or worse: 0.3%
Reduce Indoor Ozone in Fort Collins
Today's main pollutant in Fort Collins is ground-level ozone (AQI 48). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How was Fort Collins's air quality in 2023?
Moderate on a typical day: median AQI 51, with 5 days above AQI 100 out of 365 monitored — the 1st cleanest of 7 years on record for the area.
- ✓Peak AQI in 2023: 156 (Unhealthy).
- ✓Ground-level ozone was the main pollutant on 304 days.
- ✓Cleanest month: December; worst: May.
Frequently asked questions
What was the average AQI in Fort Collins in 2023?▾
EPA's Air Quality System puts Fort Collins's (Fort Collins, CO) median daily AQI for 2023 at 51, which is Moderate. 5 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 156.
Which month had the worst air quality in Fort Collins in 2023?▾
The cleanest month of 2023 was December (median AQI 44, 0 days above 100) and the worst was May (median 67, 2 days above 100, peak 105).
Was 2023 a good or bad year for Fort Collins's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2023 ranks 1st cleanest by days above AQI 100 — the best year on record here. 2023's median of 51 is in line with the area's typical annual median of 51.
Fort Collins month by month in 2023
Fort Collins air quality month by month, 2023 (Fort Collins, CO, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 51 | 0 | 78 | PM2.5 |
| February | 28 | 50 | 0 | 76 | O3 |
| March | 31 | 51 | 0 | 84 | O3 |
| April | 30 | 63 | 0 | 90 | O3 |
| Mayworst | 31 | 67 | 2 | 105 | O3 |
| June | 30 | 53 | 0 | 97 | O3 |
| July | 31 | 61 | 1 | 101 | O3 |
| August | 31 | 64 | 2 | 156 | O3 |
| September | 30 | 54 | 0 | 90 | O3 |
| October | 31 | 45 | 0 | 73 | O3 |
| November | 30 | 47 | 0 | 56 | O3 |
| Decembercleanest | 31 | 44 | 0 | 67 | O3 |
How 2023 compares
Among the 7 years EPA has published for the area (2019–2025), 2023 ranks 1st cleanest by days above AQI 100 — the best year on record here.
2023's median of 51 is in line with the area's typical annual median of 51.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Fort Collins
The latest EPA AirNow observation puts Fort Collins's AQI at 48 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Fort Collins air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Fort Collins, CO), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.