San Francisco vs San Diego Air Quality Comparison
Which city has cleaner air right now, from the latest EPA AirNow AQI
As of November 8, 2026, San Francisco, CA has cleaner air than San Diego, CA — AQI 13 (Good) vs 34 (Good), a gap of 21 AQI points in the latest EPA AirNow observations. Lower AQI means cleaner air. San Francisco's reading is driven by O3 and San Diego's by O3.
San Francisco, CA
Good
San Diego, CA
Good
Summary
San Francisco has 21 points better air quality
San Francisco has an AQI of 13 compared to 34
Reduce Indoor Ozone in San Diego
Today's main pollutant in San Diego is ground-level ozone (AQI 34). 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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5-Day Forecast Comparison
| Day | San Francisco | San Diego | Better |
|---|---|---|---|
| Today | AQI 55 | AQI 54 | San Diego |
| Sun, Nov 8 | AQI 56 | AQI 61 | San Francisco |