Santa Cruz, California Air Quality
Santa Cruz air quality today — the AQI, the main pollutant, and whether it’s safe to exercise outside right now
Santa Cruz, CA · Air quality right now
The air quality index in Santa Cruz, CA is 51 (Moderate) right now — acceptable for most people.
Is it safe to be outside in Santa Cruz today?
AQI 51 Yes — air quality is Moderate
Fine for most; unusually sensitive people can take it easy.Main pollutant: PM2.5Observed 1:00 AM PDT
Pollutants right now
- PM2.59.3 µg/m³Main pollutantfine particles — smoke, exhaust, soot
- PM1014 µg/m³coarse particles — dust, pollen, ash
- Ozone62 µg/m³smog — builds on hot, sunny days
- NO₂5.0 µg/m³nitrogen dioxide — traffic, combustion
ExerciseOK to run for most; sensitive athletes can ease the intensity.
How to read Santa Cruz’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 Santa Cruz
Across the EPA’s county records from 2020 to 2025, Santa Cruz’s cleanest year was 2022 (median AQI 35) and its most polluted was 2020 (median AQI 39); the typical (median) day has held roughly steady since 2020.
| Year | Median AQI | Unhealthy+ | Main pollutant | USG | Moderate | Good |
|---|---|---|---|---|---|---|
| 2020 | 39 | 14 | PM2.5 | 6 | 85 | 261 |
| 2021 | 37 | 0 | Ozone | 0 | 67 | 298 |
| 2022 | 35 | 0 | PM2.5 | 0 | 78 | 287 |
| 2023 | 36 | 0 | PM2.5 | 1 | 64 | 300 |
| 2024 | 39 | 0 | PM2.5 | 0 | 73 | 293 |
| 2025 | 35 | 0 | Ozone | 0 | 45 | 320 |
“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, 2020–2025.
Frequently asked
- What was the worst year for air quality in Santa Cruz?
- In the EPA's 2020–2025 county records, 2020 had the most days above AQI 100: 20 days (6 Unhealthy for Sensitive Groups, 14 Unhealthy or worse). It also had the highest median AQI, 39.
- How many unhealthy air days does Santa Cruz have?
- Across 2020–2025, under 1% of the days reported for Santa Cruz's county had an AQI above 100 (21 of 2192), about 4 days a year. 2025 had 0 days.
- What's the main air pollutant in Santa Cruz?
- PM2.5 drove Santa Cruz's county AQI on the most days in 4 of 6 years (2020–2025); Ozone in 2021, 2025.