Chicago vs Houston Air Quality Comparison
Which city has cleaner air right now, from the latest EPA AirNow AQI
As of September 23, 2026, Chicago, IL has cleaner air than Houston, TX — AQI 31 (Good) vs 77 (Moderate), a gap of 46 AQI points in the latest EPA AirNow observations. Lower AQI means cleaner air. Chicago's reading is driven by O3 and Houston's by O3.
Chicago, IL
Good
Houston, TX
Moderate
Summary
Chicago has 46 points better air quality
Chicago has an AQI of 31 compared to 77
Reduce Indoor Ozone in Houston
Today's main pollutant in Houston is ground-level ozone (AQI 77). 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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