Is the Air Quality Good in Riverside, California?
No — air quality in Riverside, California is below the U.S. average. The city earns a Grade of D (poor) on a 5-year median AQI of 82 (Moderate), with 643 unhealthy-air days over five years (about 129 per year). Residents with asthma, heart disease, or young children should treat daily AQI forecasts as a real input.
Who Can Safely Breathe the Air in Riverside, California?
Treat daily AQI forecasts as essential input. On flagged days, sensitive groups (asthma, COPD, heart disease, pregnancy, young children, older adults) should limit outdoor exertion and keep windows closed. A HEPA air cleaner sized to a bedroom or family room can cut indoor PM2.5 by 80%+ during smoke or pollution events. Because ozone peaks in the afternoon on hot sunny days, plan outdoor exercise for early morning or after sunset on bad-air days.
Across the past five years, this area has logged 643 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 129 days per year, or roughly one in three days on the calendar. That count places this area in the worst tier nationally and is the dominant driver of the D grade.
Riverside, California Air Quality Snapshot
| Air Quality Grade | D36/100 |
| 5-Year Median AQI | 82 (Moderate) |
| Most Recent Median AQI (2023) | 79 (Moderate) |
| Dominant Pollutant | Ground-Level Ozone |
| 10-Year Trend | Improving (-1.11 AQI/yr) |
| Unhealthy Days (last 5 yr) | 643 |
| National Rank (cleanest = #1) | #1018 of 1,020 (100th most polluted percentile) |
| California Rank | #52 of 53 |
What Does the D Grade Mean?
Riverside, California earns a D — air quality falls below the U.S. average, with a 5-year median AQI of 82. Residents with asthma, COPD, heart disease, or young children should watch daily AQI forecasts and limit outdoor exertion when alerts go out.
Riverside, California's 5-year median AQI of 82 is 41 points above the national average of 41 — meaningfully more polluted than the typical U.S. metro tracked here. Within California, Riverside, California runs more polluted than the state average of 49 — local sources or geography are concentrating pollution above the state's typical reading.
For context within California: Humboldt, California currently holds the state's cleanest grade (A, AQI 28), while Inyo, California sits at the bottom (F, AQI 57).
What's in Riverside, California's Air?
The dominant pollutant in Riverside, California is Ground-Level Ozone. Ground-level ozone forms when sunlight reacts with vehicle exhaust and industrial emissions. It is worst on hot, sunny, stagnant summer days. Ozone irritates the lungs, triggers asthma attacks, and reduces lung function — even healthy adults can feel chest tightness and shortness of breath after exercising in elevated ozone.
Days by Dominant Pollutant (2023)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Ground-Level Ozone | 207 | 57% |
| Fine Particulate Matter (PM2.5) | 98 | 27% |
| Coarse Particulate Matter (PM10) | 59 | 16% |
| Nitrogen Dioxide | 1 | 0% |
Is the Air Getting Better or Worse?
Air quality in Riverside, California has been improving over the past decade, with median AQI dropping by roughly 1.1 points per year. That is consistent with the broader national pattern — most U.S. metros have seen steady reductions in particulate and ozone pollution since the 2010s as cleaner vehicles and power plants come online.
In 2014, Riverside, California posted a median AQI of 93. By 2023 that figure was 79 — a drop of 14 AQI points cleaner across 10 years of EPA records.
Year-by-Year AQI in Riverside, California
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 93 | 11 | 156 | Ozone |
| 2015 | 88 | 19 | 140 | Ozone |
| 2016 | 83 | 23 | 129 | Ozone |
| 2017 | 87 | 26 | 151 | Ozone |
| 2018 | 87 | 32 | 140 | Ozone |
| 2019 | 77 | 53 | 120 | Ozone |
| 2020 | 87 | 42 | 145 | Ozone |
| 2021 | 89 | 19 | 136 | Ozone |
| 2022 | 77 | 41 | 126 | Ozone |
| 2023 | 79 | 62 | 116 | Ozone |
How This Grade Is Calculated
The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.
More about Riverside, California
Riverside, California has an Air Quality Grade of D (poor) with a 5-year median AQI of 82. The dominant pollutant is Ground-Level Ozone, and air quality has been improving over the past decade.
The data source behind this answer is the EPA Air Quality System (AQS). Every figure on the page traces back to that source; the methodology page describes the inputs and the refresh cadence in full detail.
A practical caveat: the headline answer above reflects the most recent the EPA Air Quality System (AQS) vintage; underlying data is often revised for months after first publication, and the right reference for any specific decision is whichever vintage is current at the time of the decision. The as-of date is stamped on every page.
Source: EPA Outdoor Air Quality Data, 2026.