Riverside Air Quality in 2021
In 2021, Riverside's air quality (Riverside-San Bernardino-Ontario, CA area) had a median daily AQI of 97 (Moderate) across 365 monitored days. 166 days (45.5%) reached Unhealthy for Sensitive Groups or worse, 9 were Good, and the year's peak AQI was 486 (Hazardous). Ground-level ozone set the daily AQI on 185 of those days. The cleanest month of 2021 was January (median AQI 66, 1 day above 100) and the worst was July (median 156, 30 days above 100, peak 212).
- Good: 2.5%
- Moderate: 52.1%
- Unhealthy for Sensitive Groups: 22.7%
- Unhealthy or worse: 22.7%
Extra Protection for Riverside Homes
Air quality in Riverside is moderate (AQI 55), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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How was Riverside's air quality in 2021?
Moderate on a typical day: median AQI 97, with 166 days above AQI 100 out of 365 monitored — the 6th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 486 (Hazardous).
- ✓Ground-level ozone was the main pollutant on 185 days.
- ✓Cleanest month: January; worst: July.
Frequently asked questions
What was the average AQI in Riverside in 2021?▾
EPA's Air Quality System puts Riverside's (Riverside-San Bernardino-Ontario, CA) median daily AQI for 2021 at 97, which is Moderate. 166 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 486.
Which month had the worst air quality in Riverside in 2021?▾
The cleanest month of 2021 was January (median AQI 66, 1 day above 100) and the worst was July (median 156, 30 days above 100, peak 212).
Was 2021 a good or bad year for Riverside's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 6th cleanest by days above AQI 100. 2021's median of 97 is above the area's typical annual median of 89.
Riverside month by month in 2021
Riverside air quality month by month, 2021 (Riverside-San Bernardino-Ontario, CA, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| Januarycleanest | 31 | 66 | 1 | 133 | PM2.5 |
| February | 28 | 71 | 2 | 120 | PM2.5 |
| March | 31 | 65 | 3 | 196 | PM2.5 |
| April | 30 | 97 | 12 | 147 | O3 |
| May | 31 | 115 | 23 | 329 | O3 |
| June | 30 | 161 | 26 | 216 | O3 |
| Julyworst | 31 | 156 | 30 | 212 | O3 |
| August | 31 | 164 | 29 | 215 | O3 |
| September | 30 | 124 | 19 | 202 | O3 |
| October | 31 | 71 | 4 | 486 | O3 |
| November | 30 | 87 | 10 | 155 | PM2.5 |
| December | 31 | 80 | 7 | 187 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 6th cleanest by days above AQI 100.
2021's median of 97 is above the area's typical annual median of 89.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Riverside
The latest EPA AirNow observation puts Riverside's AQI at 55 (PM2.5). The figures above are multi-year annual statistics, not today's reading.
View current Riverside air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Riverside-San Bernardino-Ontario, 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.