Rio Oso, California Air Quality
Rio Oso has a median AQI of 48, earning an air quality grade of B+ — good air quality that ranks better than 17% 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, Rio Oso recorded 130 good air quality days (61% of monitored days).
Population: 437 • County: Sutter
Current AQI
Quick Facts
| Current AQI | 32 — Good |
| Air Quality Grade | B+ |
| Median AQI (2025) | 48 |
| vs. U.S. Cities | Better than 17% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 0 |
| 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 Rio Oso is sourced from the Lincoln monitoring area, located approximately 12 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 Rio Oso'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
Rio Oso Median AQI by Year
Annual EPA air quality data for Rio Oso — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 48 | 130 | — | 100 | Ozone |
| 2024 | 49 | 195 | 5 | 115 | Ozone |
| 2023 | 49 | 192 | 3 | 105 | Ozone |
| 2022 | 52 | 154 | 5 | 119 | PM2.5 |
| 2021 | 59 | 102 | 22 | 175 | PM2.5 |
| 2020 | 53 | 162 | 31 | 356 | PM2.5 |
| 2019 | 48 | 200 | 2 | 110 | Ozone |
| 2018 | 58 | 94 | 35 | 420 | PM2.5 |
| 2017 | 56 | 128 | 9 | 130 | PM2.5 |
| 2016 | 58 | 115 | 32 | 147 | PM2.5 |
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 Rio Oso Air Quality
What is the air quality in Rio Oso today?
The current AQI in Rio Oso is 32, 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 Rio Oso getting better or worse?
Air quality in Rio Oso has been improving. The median AQI has dropped 10 points (from 58 in 2016 to 48 in 2025), a positive trend for residents.
What is the most common air pollutant in Rio Oso?
Ozone is the primary air pollutant in Rio Oso, responsible for 126 days (59% 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 Rio Oso have per year?
In 2025, Rio Oso recorded 61% good air quality days (130 days) out of 212 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 100.
What air quality grade does Rio Oso receive?
Rio Oso receives an air quality grade of B+, placing it better than 17% of US cities. This is based on a median AQI of 48 in 2025, with 130 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 17% of US cities
Nearby Cities
Get AQI Alerts
Receive notifications when air quality changes in Rio Oso
National Rankings
See how Rio Oso compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Rio Oso
Ozone is Rio Oso'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
We may earn a commission from purchases
Other Great Options
Molekule Air Pro
Commercial-grade with patented PECO technology for destroying pollutants.
Honeywell HPA300
Powerful workhorse for large rooms. Built to last.
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 →