Denver vs Fort Collins Air Quality Comparison
Which city has cleaner air right now, from the latest EPA AirNow AQI
As of November 8, 2026, Denver, CO has cleaner air than Fort Collins, CO — AQI 39 (Good) vs 40 (Good), a gap of 1 AQI points in the latest EPA AirNow observations. Lower AQI means cleaner air. Denver's reading is driven by O3 and Fort Collins's by O3.
Denver, CO
Good
Fort Collins, CO
Good
Summary
Denver has 1 points better air quality
Denver has an AQI of 39 compared to 40
Reduce Indoor Ozone in Fort Collins
Today's main pollutant in Fort Collins is ground-level ozone (AQI 40). 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.
Compare activated-carbon purifiers (for gases & ozone):
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