Santa Rosa Air Quality in 2021
In 2021, Santa Rosa's air quality (Santa Rosa, CA area) had a median daily AQI of 37 (Good) across 365 monitored days. 0 days (0.0%) reached Unhealthy for Sensitive Groups or worse, 283 were Good, and the year's peak AQI was 89 (Moderate). Fine particulate matter (PM2.5) set the daily AQI on 203 of those days. The cleanest month of 2021 was July (median AQI 27, 0 days above 100) and the worst was November (median 46, 0 days above 100, peak 61).
- Good: 77.5%
- Moderate: 22.5%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Santa Rosa
Today's main pollutant in Santa Rosa is ground-level ozone (AQI 15). 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.
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How was Santa Rosa's air quality in 2021?
Good on a typical day: median AQI 37, with 0 days above AQI 100 out of 365 monitored — the 5th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 89 (Moderate).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 203 days.
- ✓Cleanest month: July; worst: November.
Frequently asked questions
What was the average AQI in Santa Rosa in 2021?▾
EPA's Air Quality System puts Santa Rosa's (Santa Rosa, CA) median daily AQI for 2021 at 37, which is Good. 0 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 89.
Which month had the worst air quality in Santa Rosa in 2021?▾
The cleanest month of 2021 was July (median AQI 27, 0 days above 100) and the worst was November (median 46, 0 days above 100, peak 61).
Was 2021 a good or bad year for Santa Rosa's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 5th cleanest by days above AQI 100. 2021's median of 37 is in line with the area's typical annual median of 36.
Santa Rosa month by month in 2021
Santa Rosa air quality month by month, 2021 (Santa Rosa, CA, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 46 | 0 | 71 | PM2.5 |
| February | 28 | 35 | 0 | 49 | PM2.5 |
| March | 31 | 37 | 0 | 50 | O3 |
| April | 30 | 39 | 0 | 58 | PM2.5 |
| May | 31 | 34 | 0 | 59 | O3 |
| June | 30 | 29 | 0 | 59 | O3 |
| Julycleanest | 31 | 27 | 0 | 52 | PM2.5 |
| August | 31 | 31 | 0 | 89 | PM2.5 |
| September | 30 | 40 | 0 | 65 | PM2.5 |
| October | 31 | 34 | 0 | 77 | O3 |
| Novemberworst | 30 | 46 | 0 | 61 | PM2.5 |
| December | 31 | 41 | 0 | 66 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 5th cleanest by days above AQI 100.
2021's median of 37 is in line with the area's typical annual median of 36.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Santa Rosa
The latest EPA AirNow observation puts Santa Rosa's AQI at 15 (O3). The figures above are multi-year annual statistics, not today's reading.
View current Santa Rosa air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Santa Rosa, CA), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.