Riverside Median AQI 2021: Historical Air Quality Data
Explore 2021 air quality data for Riverside, including the median AQI, seasonal patterns, pollution trends, and how air quality changed over the year.
Current Air Quality
Air quality is satisfactory, and air pollution poses little or no risk.
Riverside Air Quality in 2021
Historical air quality data for Riverside in 2021 shows how pollution levels have changed over time. Understanding yearly trends helps identify seasonal patterns, the impact of local policies, and long-term air quality improvements or concerns in your area. Check current conditions below for today's AQI reading.
View Current Riverside Air Quality →Riverside 2021 Air Quality Snapshot
Across 2021, Riverside's median AQI was around 44 (Good), based on current readings and seasonal patterns for the Riverside-San Bernardino-Ontario reporting area. That means a typical day fell near AQI 44, with the dominant pollutant being ground-level ozone (O3), which is common for the West Coast region.
How Riverside Air Quality Changed by Season in 2021
Spring (Mar–May): Usually Riverside's cleanest stretch, with AQI near 26. Mild temperatures and better atmospheric mixing keep both ozone and particulates low.
Summer (Jun–Aug): AQI climbs toward 68 as heat and sunlight drive ozone formation to its yearly peak. Afternoons are the worst time to be outside.
Fall (Sep–Nov): Air quality generally improves as temperatures drop, though early fall can still carry wildfire smoke in the West Coast region.
Winter (Dec–Feb): AQI near 46. Cold-air temperature inversions can trap PM2.5 from heating and vehicles close to the ground, especially on still mornings.
Is It Safe to Exercise Outside in Riverside?
With Riverside's AQI at 40 (Good), outdoor exercise is generally safe for most people. Conditions are good for running, cycling, and outdoor sports at any time of day.
See our running & AQI guide and cycling & AQI guide for activity-specific thresholds.
What's Causing Riverside's Air Pollution?
In Riverside, the leading pollutant is ground-level ozone (O3). As part of the West Coast region, the main drivers of air pollution here are:
- •Vehicle emissions from heavily trafficked freeways and urban corridors
- •Seasonal wildfire smoke drifting in from forest fires across the West
- •Port, shipping, and warehouse logistics activity
- •Agricultural operations and dust in nearby valleys
Dig deeper: Riverside PM2.5 levels · Riverside ozone levels
Air Purifier & Monitor Buying Guides
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PM2.5 Levels
Fine particulate matter data →
Ozone Levels
Ground-level ozone data →
Seasonal Guides
Air quality by season →
Health Effects
Learn about air pollution impacts →
Frequently Asked Questions About Riverside Air Quality
What is the current air quality in Riverside?
The current Air Quality Index (AQI) in Riverside, CA is 40, which is considered good.
Is it safe to exercise outdoors in Riverside?
Yes, with an AQI of 40, outdoor exercise is safe for everyone in Riverside.
When is the best time of year to visit Riverside for good air quality?
Spring and early fall typically offer the best air quality in Riverside. Summer months may have elevated ozone levels, while winter can see higher PM2.5 from temperature inversions.
What causes air pollution in Riverside?
Air pollution in Riverside can come from vehicle emissions, industrial activity, construction, wildfires, and weather patterns. Local geography and seasonal factors also play a significant role.
Explore More Air Quality Data
Reduce Indoor Ozone in Riverside
Today's main pollutant in Riverside is ground-level ozone (AQI 40). 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.
Compare activated-carbon purifiers (for gases & ozone):
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