San Jose, California Air Quality
San Jose air quality today — the AQI, the main pollutant, and whether it’s safe to exercise outside right now
San Jose, CA · Air quality right now
The air quality index in San Jose, CA is 50 (Good) right now — safe for outdoor activity.
Is it safe to be outside in San Jose today?
AQI 50 Yes — air quality is Good
Air is clean — great for outdoor activity.Main pollutant: PM2.5Observed 7:00 AM PDT
Pollutants right now
- PM2.58.6 µg/m³Main pollutantfine particles — smoke, exhaust, soot
- PM1011 µg/m³coarse particles — dust, pollen, ash
- Ozone46 µg/m³smog — builds on hot, sunny days
- NO₂8.9 µg/m³nitrogen dioxide — traffic, combustion
ExerciseOK to run — no air-quality limits on outdoor exercise.
How to read San Jose’s air quality
Guides: The AQI Scale, Explained · Air Quality Alerts, Decoded · How to Read a Wildfire Smoke Map · Why Wildfire Smoke Travels 1,000 Miles.
Air quality over time in San Jose
Across the EPA’s county records from 2020 to 2024, San Jose’s cleanest year was 2023 (median AQI 43) and its most polluted was 2021 (median AQI 53); the typical (median) day has trended cleaner since 2020.
| Year | Median AQI | Unhealthy+ | Main pollutant | USG | Moderate | Good |
|---|---|---|---|---|---|---|
| 2020 | 52 | 9 | PM2.5 | 11 | 172 | 174 |
| 2021 | 53 | 0 | PM2.5 | 7 | 211 | 147 |
| 2022 | 49 | 0 | PM2.5 | 5 | 172 | 188 |
| 2023 | 43 | 0 | Ozone | 4 | 121 | 240 |
| 2024 | 47 | 0 | PM2.5 | 1 | 161 | 201 |
“USG” is Unhealthy for Sensitive Groups (AQI 101–150); “Unhealthy+” combines the Unhealthy, Very Unhealthy, and Hazardous days. In 2024 the EPA tightened the annual fine-particle (PM2.5) standard to 9 µg/m³ from the previous 12 µg/m³, so counties near the old limit read worse against the new one. Source: EPA AQS annual summaries, 2020–2024.
Frequently asked
- What was the worst year for air quality in San Jose?
- In the EPA's 2020–2024 county records, 2020 had the most days above AQI 100: 20 days (11 Unhealthy for Sensitive Groups, 9 Unhealthy or worse). The highest median AQI came in 2021 (53; 2020's was 52).
- How many unhealthy air days does San Jose have?
- Across 2020–2024, 2% of the days reported for San Jose's county had an AQI above 100 (37 of 1824), about 7 days a year. 2024 had 1 day.
- What's the main air pollutant in San Jose?
- PM2.5 drove San Jose's county AQI on the most days in 4 of 5 years (2020–2024); Ozone in 2023.