San Miguel, California Air Quality
San Miguel has a median AQI of 48, earning an air quality grade of B+ — good air quality that ranks better than 18% of US cities. Air quality has remained relatively stable over the past decade. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2024, San Miguel recorded 193 good air quality days (53% of monitored days).
Population: 3,967 • County: Contra Costa
Current AQI
Quick Facts
| Current AQI | 9 — Good |
| Air Quality Grade | B+ |
| Median AQI (2024) | 48 |
| vs. U.S. Cities | Better than 18% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 0 |
| 10-Year Trend | → Stable |
| 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 Miguel is sourced from the Concord monitoring area, located approximately 4 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
Wildfire smoke is a significant factor in San Miguel'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 Miguel Median AQI by Year
Annual EPA air quality data for San Miguel — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2024 | 48 | 193 | — | 94 | PM2.5 |
| 2023 | 51 | 173 | 2 | 110 | PM2.5 |
| 2022 | 51 | 175 | 2 | 129 | PM2.5 |
| 2021 | 47 | 195 | 5 | 150 | PM2.5 |
| 2020 | 49 | 192 | 18 | 221 | PM2.5 |
| 2019 | 43 | 238 | 4 | 129 | PM2.5 |
| 2018 | 55 | 111 | 18 | 270 | PM2.5 |
| 2017 | 54 | 131 | 12 | 175 | PM2.5 |
| 2016 | 46 | 210 | 3 | 143 | PM2.5 |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2024 Air Quality Summary
Primary Pollutant Days (2024)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About San Miguel Air Quality
What is the air quality in San Miguel today?
The current AQI in San Miguel is 9, 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 Miguel getting better or worse?
Air quality in San Miguel has been stable. The median AQI has risen 2 points (from 46 in 2016 to 48 in 2024).
What is the most common air pollutant in San Miguel?
PM2.5 is the primary air pollutant in San Miguel, responsible for 348 days (96% of monitored days) in 2024. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does San Miguel have per year?
In 2024, San Miguel recorded 53% good air quality days (193 days) out of 361 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 94.
What air quality grade does San Miguel receive?
San Miguel receives an air quality grade of B+, placing it better than 18% of US cities. This is based on a median AQI of 48 in 2024, with 193 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 18% of US cities
Nearby Cities
Get AQI Alerts
Receive notifications when air quality changes in San Miguel
National Rankings
See how San Miguel compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for San Miguel
San Miguel faces elevated PM2.5 from wildfire smoke in addition to year-round traffic and industrial sources. We prioritize True HEPA units with high smoke CADR — essential for rapid air cleaning during smoke events.
Blueair Blue Pure 211+
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Other Great Options
Molekule Air Pro
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