San Joaquin, California Air Quality
San Joaquin has a median AQI of 54, earning an air quality grade of B — good air quality that ranks better than 5% of US cities. Air quality has been improving steadily over the past decade, a positive sign for residents. Ground-level ozone is the primary concern, typically peaking on warm sunny days due to vehicle and industrial emissions. In 2025, San Joaquin recorded 122 good air quality days (40% of monitored days) and 25 unhealthy days.
Population: 3,708 • County: Fresno
Current AQI
Quick Facts
| Current AQI | 18 — Good |
| Air Quality Grade | B |
| Median AQI (2025) | 54 |
| vs. U.S. Cities | Better than 5% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 25 |
| 10-Year Trend | ↑ Improving |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for San Joaquin is sourced from the Tranquillity monitoring area, located approximately 11 miles from city center. This EPA-certified station continuously tracks ground-level ozone, the primary driver of air quality alerts in this area.
Wildfire smoke is a significant factor in San Joaquin's air quality, with regional fires capable of pushing AQI from Good to Unhealthy within hours during fire season (typically July through October). On smoke-impacted days, staying indoors with windows closed and running an air purifier with a HEPA filter is the most effective protection.
AQI Trend (10 Years)
Air Quality Days by Year
San Joaquin Median AQI by Year
Annual EPA air quality data for San Joaquin — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 54 | 122 | 25 | 157 | Ozone |
| 2024 | 67 | 71 | 79 | 169 | Ozone |
| 2023 | 64 | 97 | 58 | 156 | Ozone |
| 2022 | 71 | 78 | 70 | 159 | Ozone |
| 2021 | 68 | 62 | 82 | 278 | PM2.5 |
| 2020 | 76 | 75 | 99 | 346 | PM2.5 |
| 2019 | 63 | 113 | 66 | 187 | Ozone |
| 2018 | 75 | 61 | 98 | 185 | Ozone |
| 2017 | 75 | 76 | 120 | 207 | Ozone |
| 2016 | 76 | 62 | 105 | 190 | Ozone |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About San Joaquin Air Quality
What is the air quality in San Joaquin today?
The current AQI in San Joaquin is 18, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in San Joaquin getting better or worse?
Air quality in San Joaquin has been improving. The median AQI has dropped 22 points (from 76 in 2016 to 54 in 2025), a positive trend for residents.
What is the most common air pollutant in San Joaquin?
Ozone is the primary air pollutant in San Joaquin, responsible for 214 days (70% of monitored days) in 2025. Ground-level ozone forms when sunlight reacts with emissions from vehicles and industry, typically peaking on hot summer afternoons.
How many unhealthy air days does San Joaquin have per year?
In 2025, San Joaquin recorded 40% good air quality days (122 days) out of 304 monitored days. There were 24 Unhealthy for Sensitive Groups days and 1 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 157.
What air quality grade does San Joaquin receive?
San Joaquin receives an air quality grade of B, placing it better than 5% of US cities. This is based on a median AQI of 54 in 2025, with 122 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 5% of US cities
Nearby Cities
Protect Your Health
With a median AQI of 54, indoor air purification is recommended
See Recommended Purifiers ↓Get AQI Alerts
Receive notifications when air quality changes in San Joaquin
National Rankings
See how San Joaquin compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for San Joaquin
Ozone is San Joaquin's primary pollutant. Standard HEPA filters don't capture ozone molecules — you need activated carbon or PECO technology to chemically break them down. We highlight those units here.
Blueair Blue Pure 211+
High performance for large rooms with simple operation.
- ✓Good room size match
- ✓Recommended for your air quality
- ✓High performance
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Other Great Options
Honeywell HPA300
Powerful workhorse for large rooms. Built to last.
Molekule Air Pro
Commercial-grade with patented PECO technology for destroying pollutants.
RabbitAir MinusA2
Stylish wall-mountable design with customizable artwork panels.
Not sure which air purifier is right for you?
Learn more about different types of air purifiers and how to choose the best one for your needs.
Read our complete buying guide →