Belmont, California Air Quality
Belmont has a median AQI of 27, earning an air quality grade of A+ — excellent air quality that ranks better than 91% of US cities. Air quality has been improving steadily over the past decade, a positive sign for residents. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2024, Belmont recorded 281 good air quality days (88% of monitored days).
Population: 27,337 • County: San Mateo
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Quick Facts
| Current AQI | 20 — Good |
| Air Quality Grade | A+ |
| Median AQI (2024) | 27 |
| vs. U.S. Cities | Better than 91% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 0 |
| 10-Year Trend | ↑ Improving |
| Data Source | EPA AirNow |
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 30 Days
Current Pollutant Levels
Real-time data from EPA AirNow
AQI Trend (10 Years)
Air Quality Days by Year
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 Belmont Air Quality
What is the air quality in Belmont today?
The current AQI in Belmont is 20, which is rated "Good". Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Belmont getting better or worse?
Air quality in Belmont has been improving over the past decade. The median AQI dropped from 47 in 2016 to 27 in 2024.
What is the most common air pollutant in Belmont?
PM2.5 is the primary air pollutant in Belmont, responsible for the most air quality-impacted days in 2024. Particulate matter can originate from vehicle exhaust, wildfires, and industrial emissions.
How many unhealthy air days does Belmont have per year?
In 2024, Belmont had 0 days when air quality was unhealthy or unhealthy for sensitive groups (AQI above 100). There were 281 good days and 38 moderate days out of 319 days monitored.
What air quality grade does Belmont receive?
Belmont receives an air quality grade of A+, placing it better than 91% of US cities. This grade is based on a median AQI of 27 for 2024, derived from EPA monitoring data.
Air Quality Grade
Better than 91% of US cities
Nearby Cities
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National Rankings
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Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Belmont
Based on your area's air quality (median AQI: 27), we recommend these air purifiers to help protect your health indoors.
RabbitAir MinusA2
Stylish wall-mountable design with customizable artwork panels.
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Other Great Options
Molekule Air Pro
Commercial-grade with patented PECO technology for destroying pollutants.
Blueair Blue Pure 211+
High performance for large rooms with simple operation.
Dyson Pure Cool TP04
Premium all-in-one air purifier and fan with advanced features.
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Read our complete buying guide →