Denver vs Phoenix Air Quality Comparison
Which city has cleaner air right now, from the latest EPA AirNow AQI
As of September 16, 2026, Denver, CO has cleaner air than Phoenix, AZ — AQI 43 (Good) vs 47 (Good), a gap of 4 AQI points in the latest EPA AirNow observations. Lower AQI means cleaner air. Denver's reading is driven by O3 and Phoenix's by O3.
Denver, CO
Good
Phoenix, AZ
Good
Summary
Denver has 4 points better air quality
Denver has an AQI of 43 compared to 47
Reduce Indoor Ozone in Phoenix
Today's main pollutant in Phoenix is ground-level ozone (AQI 47). 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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