Median AQI
41
Good
California · County air quality · 2025
San Benito County, California
Median AQI 41 (Good). 90.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 41
- Median AQI
- 90.6%
- Good-air days
- 0
- Unhealthy days
- 77%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, San Benito County's air is good on balance, cleaner than most US counties, a median AQI of 41 with 90.6% of 223 monitored days in the Good band, driven mainly by Ozone.
- 41
- median AQI · Good
- 90.6%
- days rated Good
- Ozone
- main pollutant
- 77%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 71.
Data updated July 2026
- Good · 202 d · 90.6%
- Moderate · 21 d · 9.4%
How did San Benito County's air break down in 2025?
Across 223 monitored days, 202 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 71 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 223 days monitored. Median AQI: 41 (Good).
Insights: San Benito County, California. EPA monitors recorded a median Air Quality Index of 41 across 223 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 202 (91%) fell in the Good band (AQI 0–50), 21 (9%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 50, while the worst single-day peak hit 71 (Moderate). Residents averaged about 27.2 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (197 days), PM2.5 (26 days). Across the 2020–2025 trend window, good days shifted by -69 and the median AQI moved +0 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 71, moderate 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
90.6%
202 of 223 monitored days
15.6pp vs 75% target
Max AQI Recorded
71
Moderate
Health Grade
Excellent
90th-pct AQI 50
San Benito County, Good days share 90.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
San Benito 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 223 monitored days across EPA AQI categories.
Good
202
91%
Moderate
21
9%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in San Benito County.
- Ozone · 197 days · 88.3%
- PM2.5 · 26 days · 11.7%
Health Impact Assessment
Excellent
San Benito County's air quality is rated Excellent based on 90.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 90.6% of monitored days in 2025, with a median AQI of 41. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 197 of 223 monitored days.
5-Year Air Quality Trend
Air quality is improving in San Benito County. Best year: 2023 (316 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 271 | 78 | 8 | 9 | 41 | 174 |
| 2021 | 295 | 70 | 0 | 0 | 41 | 100 |
| 2022 | 297 | 68 | 0 | 0 | 42 | 97 |
| 2023 | 316 | 48 | 1 | 0 | 40 | 111 |
| 2024 | 260 | 105 | 1 | 0 | 43 | 105 |
| 2025 | 202 | 21 | 0 | 0 | 41 | 71 |
How does San Benito County compare?
How San Benito County compares
Good-day share better than US avg
San Benito County 90.6%
Amador County, California 84.8%
US average 76.5%
Median AQI worse than US avg
San Benito County 41
Amador County, California 40
US average 38
Unhealthy days / yr about average
San Benito 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 San Benito County.
Albemarle County, Virginia
AQI 41 · 77.9% good
Anderson County, South Carolina
AQI 41 · 90.0% good
Berkshire County, Massachusetts
AQI 41 · 71.6% good
Berrien County, Michigan
AQI 41 · 80.9% good
Blair County, Pennsylvania
AQI 41 · 71.9% good
Bonner County, Idaho
AQI 41 · 71.3% good
What San Benito 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 41 means for exposure. Health guidance
- See how San Benito County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare San Benito County with its California neighbours before drawing a conclusion about the region. All of California
Based on 223 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 San Benito County, California? ▼
San Benito County has a median Air Quality Index (AQI) of 41, rated "Good." 90.6% of monitored days (202 out of 223) had good air quality in 2025.
What is the main pollutant in San Benito County? ▼
The primary pollutant in San Benito County is Ozone (O3), which was the main AQI driver on 197 days (88% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does San Benito County have? ▼
In 2025, San Benito County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 71.
Is the air quality in San Benito County getting better or worse? ▼
Air quality in San Benito County is improving based on 5-year trends (2020-2025). Best year: 2023 with 316 good days. Worst year: 2025 with 202 good days.
What does AQI 41 mean for health? ▼
San Benito County's median AQI of 41 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 San Benito County compare to other counties in California? ▼
San Benito County has 90.6% 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 San Benito County? ▼
The 90th percentile AQI for San Benito County is 50, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 71 (Moderate).
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.