Median AQI
80
Moderate
California · County air quality · 2025
Riverside County, California
Median AQI 80 (Moderate). 10.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 80
- Median AQI
- 10.7%
- Good-air days
- 34
- Unhealthy days
- 0%
- Cleaner than US counties
Riverside County's 2025 annual median AQI is 80 (Moderate), with 10.7% Good days
According to the U.S. EPA Air Quality System, Riverside County, California posted a 2025 median AQI of 80 (Moderate) across 365 monitored days, with 10.7% rated Good and 34 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Riverside County's 10.7% Good-day share places it cleaner than 0% of US counties in 2025.
- Closest median-AQI peer
- San Bernardino County (12.6% Good, median AQI 77) is the closest nationwide median-AQI peer to Riverside County.
- 2020–2025 trend
- Riverside County's floor-qualifying Good-day share is improving from 2020 to 2025 (11.8% → 10.7%).
- Median AQI
- Median AQI: 80
The verdict
According to EPA Air Quality System monitoring data, Riverside County's air is moderate on balance, among the most polluted counties nationally, a median AQI of 80 with 10.7% of 365 monitored days in the Good band, driven mainly by Ozone.
- 80
- median AQI · Moderate
- 10.7%
- days rated Good
- Ozone
- main pollutant
- 0%
- cleaner than US counties
34 days reached Unhealthy or worse; the worst single reading hit AQI 365.
Annual release change
What changed in the 2025 EPA annual release
- Riverside County's Unhealthy-category days fell from 60 to 33 between the 2024 and 2025 EPA annual releases, a change of -27 days.
- Riverside County's peak single-day AQI rose from 213 to 365 between the 2024 and 2025 EPA annual releases, a change of +152 points.
- Riverside County's median AQI fell from 87 to 80 between the 2024 and 2025 EPA annual releases, a change of -7 points.
- Riverside County's Good-day share fell from 11.7% to 10.7% between the 2024 and 2025 EPA annual releases, a change of -1.1 percentage points.
Data updated August 2026
- Good · 39 d · 10.7%
- Moderate · 217 d · 59.5%
- USG · 75 d · 20.5%
- Unhealthy · 33 d · 9.0%
- Hazardous · 1 d · 0.3%
How did Riverside County's air break down in 2025?
Across 365 monitored days, 39 fell in the Good band (AQI 0–50) and 34 reached Unhealthy or worse. The worst single day peaked at AQI 365 (Hazardous).
EPA AQS →Air quality data from EPA Air Quality System (2025). 365 days monitored. Median AQI: 80 (Moderate).
Insights: Riverside County, California. EPA monitors recorded a median Air Quality Index of 80 across 365 measured days in 2025, earning a Moderate classification and a Very Poor health grade. Of those days, 39 (11%) fell in the Good band (AQI 0–50), 217 (59%) registered Moderate readings, and 75 (21%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 150, while the worst single-day peak hit 365 (Hazardous). Residents averaged about 3.2 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (207 days), PM2.5 (121 days), PM10 (37 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -0.8 points and the median AQI moved -7 points, placing the multi-year trajectory at improving. The annual record contains 34 days at Unhealthy or worse. On those days, the EPA recommends that sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Alameda (53.0% good, AQI 49); Amador (87.4% good, AQI 38); Butte (65.2% good, AQI 46); Calaveras (82.2% good, AQI 40); Colusa (79.2% good, AQI 40); Contra Costa (53.5% good, AQI 48).
Air Quality Summary
Good Days
10.7%
39 of 365 monitored days
-64.3pp vs 75% target
Max AQI Recorded
365
Hazardous
Health Grade
Very Poor
90th-pct AQI 150
Riverside County, Good days share 10.7%
National avg
Share of monitored days at AQI 0-50 (Good band).
Riverside County, Unhealthy-or-worse share 93.2%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
39
11%
Moderate
217
59%
USG
75
21%
Unhealthy
33
9%
Very Unhealthy
0
0%
Hazardous
1
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Riverside County.
- Ozone · 207 days · 56.7%
- PM2.5 · 121 days · 33.2%
- PM10 · 37 days · 10.1%
Health Impact Assessment
Very Poor
Riverside County's air quality is rated Very Poor based on 10.7% good air days. There were 34 unhealthy days in 2025 when outdoor activity should be limited.
Air quality posed significant health risk in 2025. Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, pregnant women, and adults over 65, should monitor AirNow.gov alerts and limit outdoor activity on Unhealthy (AQI 151+) and Very Unhealthy (201+) days. Peak readings reached AQI 365, well into the Hazardous range.
Sensitive group advisory
People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.
The dominant pollutant is Ozone, driving AQI on 207 of 365 monitored days.
5-Year Air Quality Trend
Air quality is improving in Riverside County. Highest Good-day share: 2023 (17.5%, 62 of 365 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 42 | 179 | 98 | 36 | 87 | 584 |
| 2021 | 19 | 210 | 89 | 44 | 89 | 329 |
| 2022 | 41 | 198 | 86 | 31 | 77 | 1683 |
| 2023 | 62 | 187 | 73 | 33 | 79 | 660 |
| 2024 | 43 | 176 | 80 | 60 | 87 | 213 |
| 2025 | 39 | 217 | 75 | 33 | 80 | 365 |
How does Riverside County compare?
How Riverside County compares
Good-day share worse than typical
Riverside County 10.7%
San Bernardino County, California 12.6%
Typical US county 76.0%
Median AQI worse than typical
Riverside County 80
San Bernardino County, California 77
Typical US county 39
Unhealthy days / yr worse than typical
Riverside County 34
San Bernardino County, California 43
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Riverside County (80), not geographic neighbors.
San Bernardino County, California
Median AQI 77 · 12.6% Good-day share
Los Angeles County, California
Median AQI 74 · 10.7% Good-day share
Maricopa County, Arizona
Median AQI 73 · 8.8% Good-day share
El Paso County, Texas
Median AQI 70 · 18.1% Good-day share
Kern County, California
Median AQI 70 · 17.5% Good-day share
Pinal County, Arizona
Median AQI 67 · 17.0% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Tulare County, California
24.1% Good-day share · median AQI 64
Bernalillo County, New Mexico
26.6% Good-day share · median AQI 58
Dona Ana County, New Mexico
27.4% Good-day share · median AQI 61
Imperial County, California
27.7% Good-day share · median AQI 64
Fresno County, California
28.8% Good-day share · median AQI 61
Clark County, Nevada
31.0% Good-day share · median AQI 61
California counties on the map
Geographic containment only, other monitored counties in California, independent of AQI or pollutant match.
What Riverside County's air means for you
On most days the air here is fine, but Ozone drives 34 unhealthy-or-worse days a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 80 means for exposure. Health guidance
- See how Riverside County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Riverside County with its California neighbours before drawing a conclusion about the region. All of California
Based on 365 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Riverside County, California? ▼
Riverside County has a median Air Quality Index (AQI) of 80, rated "Moderate." 10.7% of monitored days (39 out of 365) had good air quality in 2025.
What is the main pollutant in Riverside County? ▼
The primary pollutant in Riverside County is Ozone (O3), which was the main AQI driver on 207 days (57% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Riverside County have? ▼
In 2025, Riverside County recorded 34 unhealthy air days (33 Unhealthy, 0 Very Unhealthy, 1 Hazardous). The maximum AQI reached 365.
Is the air quality in Riverside County getting better or worse? ▼
Air quality in Riverside County is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2023 at 17.5% (62 of 365 days). Lowest qualifying Good-day share: 2021 at 5.2% (19 of 365 days).
What does AQI 80 mean for health? ▼
Riverside County's median AQI of 80 falls in the "Moderate" category. See the AQI category guide for what each range means for health.
How does Riverside County compare to other counties in California? ▼
Riverside County has 10.7% good air days. Nearby counties in California: Alameda (53.0% good), Amador (87.4% good), Butte (65.2% good), Calaveras (82.2% good), Colusa (79.2% good), Contra Costa (53.5% good).
What is the 90th percentile AQI in Riverside County? ▼
The 90th percentile AQI for Riverside County is 150, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 365 (Hazardous).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Riverside County, California · 2020–2025
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Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.