Median AQI
50
Good
California · County air quality · 2025
Ventura County, California
Median AQI 50 (Good). 52.8% of monitored days rated Good, direct from EPA Air Quality System stations.
- 50
- Median AQI
- 52.8%
- Good-air days
- 0
- Unhealthy days
- 8%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Ventura County's air is good on balance, among the most polluted counties nationally, a median AQI of 50 with 52.8% of 273 monitored days in the Good band, driven mainly by Ozone.
- 50
- median AQI · Good
- 52.8%
- days rated Good
- Ozone
- main pollutant
- 8%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 131.
Data updated July 2026
- Good · 144 d · 52.7%
- Moderate · 121 d · 44.3%
- USG · 8 d · 2.9%
How did Ventura County's air break down in 2025?
Across 273 monitored days, 144 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 131 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 50 (Good).
Insights: Ventura County, California. EPA monitors recorded a median Air Quality Index of 50 across 273 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 144 (53%) fell in the Good band (AQI 0–50), 121 (44%) registered Moderate readings, and 8 (3%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 71, while the worst single-day peak hit 131 (USG). Residents averaged about 15.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (160 days), PM2.5 (107 days), PM10 (6 days). Across the 2020–2025 trend window, good days shifted by -41 and the median AQI moved +0 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 131, usg but never Unhealthy. Nearby counties show comparable readings: Amador (84.8% good, AQI 40); Butte (66.1% good, AQI 47); Calaveras (73.9% good, AQI 43); Colusa (84.9% good, AQI 39); Del Norte (81.0% good, AQI 33); El Dorado (85.8% good, AQI 39).
Air Quality Summary
Good Days
52.8%
144 of 273 monitored days
-22.3pp vs 75% target
Max AQI Recorded
131
USG
Health Grade
Moderate
90th-pct AQI 71
Ventura County, Good days share 52.8%
National avg
Share of monitored days at AQI 0-50 (Good band).
Ventura County, Unhealthy-or-worse share 0.0%
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 273 monitored days across EPA AQI categories.
Good
144
53%
Moderate
121
44%
USG
8
3%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Ventura County.
- Ozone · 160 days · 58.6%
- PM2.5 · 107 days · 39.2%
- PM10 · 6 days · 2.2%
Health Impact Assessment
Moderate
Ventura County's air quality is rated Moderate based on 52.8% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 52.8% of monitored days in 2025, with a median AQI of 50. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 160 of 273 monitored days.
5-Year Air Quality Trend
Air quality is stable in Ventura County. Best year: 2023 (220 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 185 | 155 | 21 | 5 | 50 | 174 |
| 2021 | 157 | 198 | 10 | 0 | 53 | 122 |
| 2022 | 171 | 183 | 11 | 0 | 52 | 140 |
| 2023 | 220 | 133 | 12 | 0 | 46 | 136 |
| 2024 | 191 | 160 | 14 | 1 | 50 | 176 |
| 2025 | 144 | 121 | 8 | 0 | 50 | 131 |
How does Ventura County compare?
How Ventura County compares
Good-day share worse than US avg
Ventura County 52.8%
Amador County, California 84.8%
US average 76.5%
Median AQI worse than US avg
Ventura County 50
Amador County, California 40
US average 38
Unhealthy days / yr about average
Ventura County 0
Amador County, California 0
US average 0
Other Counties in California
Air quality comparison for nearby counties in California.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Ventura County.
Adams County, Colorado
AQI 50 · 50.2% good
Albany County, Wyoming
AQI 50 · 51.9% good
Boulder County, Colorado
AQI 50 · 50.9% good
Davidson County, North Carolina
AQI 50 · 50.2% good
Davidson County, Tennessee
AQI 50 · 51.8% good
Gila County, Arizona
AQI 50 · 52.0% good
What Ventura County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 50 means for exposure. Health guidance
- See how Ventura County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Ventura County with its California neighbours before drawing a conclusion about the region. All of California
Based on 273 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Ventura County, California? ▼
Ventura County has a median Air Quality Index (AQI) of 50, rated "Good." 52.8% of monitored days (144 out of 273) had good air quality in 2025.
What is the main pollutant in Ventura County? ▼
The primary pollutant in Ventura County is Ozone (O3), which was the main AQI driver on 160 days (59% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Ventura County have? ▼
In 2025, Ventura County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 131.
Is the air quality in Ventura County getting better or worse? ▼
Air quality in Ventura County is stable based on 5-year trends (2020-2025). Best year: 2023 with 220 good days. Worst year: 2025 with 144 good days.
What does AQI 50 mean for health? ▼
Ventura County's median AQI of 50 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Ventura County compare to other counties in California? ▼
Ventura County has 52.8% good air days. Nearby counties in California: Amador (84.8% good), Butte (66.1% good), Calaveras (73.9% good), Colusa (84.9% good), Del Norte (81.0% good), El Dorado (85.8% good).
What is the 90th percentile AQI in Ventura County? ▼
The 90th percentile AQI for Ventura County is 71, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 131 (USG).
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.
Every figure on PlainAir 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.