Air Quality in San Mateo, California
27
Median AQI (2024)
73
Max AQI (2024)
↓ improving
10-Year Trend
PM2.5
Primary Pollutant
281
Good Days (2024)
4
Monitoring Stations
AQI Trend (Median)
Air Quality Days by Category
Annual Summary
| Year | Median AQI | Max AQI | Good Days | Moderate Days | Unhealthy Days | Ozone Days | PM2.5 Days |
|---|---|---|---|---|---|---|---|
| 2024 | 27 | 73 | 281 | 38 | 0 | 48 | 258 |
| 2023 | 31 | 71 | 355 | 8 | 0 | 295 | 16 |
| 2022 | 36 | 85 | 267 | 98 | 0 | 179 | 179 |
| 2021 | 36 | 90 | 290 | 75 | 0 | 199 | 163 |
| 2020 | 37 | 199 | 257 | 99 | 10 | 136 | 219 |
| 2019 | 39 | 122 | 276 | 87 | 2 | 135 | 216 |
| 2018 | 42 | 197 | 236 | 116 | 13 | 90 | 262 |
| 2017 | 42 | 155 | 238 | 120 | 7 | 123 | 229 |
| 2016 | 47 | 70 | 214 | 152 | 0 | 80 | 271 |
| 2015 | 35 | 101 | 297 | 67 | 1 | 198 | 144 |
Recent Daily AQI
| Date | AQI | Category | Primary Pollutant |
|---|---|---|---|
| Dec 31, 2024 | 50 | Good | PM2.5 |
| Dec 30, 2024 | 22 | Good | PM2.5 |
| Dec 29, 2024 | 2 | Good | PM2.5 |
| Dec 28, 2024 | 21 | Good | PM2.5 |
| Dec 27, 2024 | 28 | Good | PM2.5 |
| Dec 26, 2024 | 15 | Good | PM2.5 |
| Dec 25, 2024 | 38 | Good | PM2.5 |
| Dec 24, 2024 | 14 | Good | PM2.5 |
| Dec 23, 2024 | 39 | Good | PM2.5 |
| Dec 22, 2024 | 46 | Good | PM2.5 |
| Dec 21, 2024 | 29 | Good | PM2.5 |
| Dec 20, 2024 | 66 | Moderate | PM2.5 |
| Dec 19, 2024 | 54 | Moderate | PM2.5 |
| Dec 18, 2024 | 38 | Good | PM2.5 |
| Dec 13, 2024 | 10 | Good | PM2.5 |
| Dec 12, 2024 | 29 | Good | PM2.5 |
| Dec 11, 2024 | 73 | Moderate | PM2.5 |
| Dec 10, 2024 | 50 | Good | PM2.5 |
| Dec 9, 2024 | 23 | Good | PM2.5 |
| Dec 8, 2024 | 61 | Moderate | PM2.5 |
| Dec 7, 2024 | 73 | Moderate | PM2.5 |
| Dec 5, 2024 | 59 | Moderate | PM2.5 |
| Dec 4, 2024 | 61 | Moderate | PM2.5 |
| Nov 24, 2024 | 7 | Good | PM2.5 |
| Nov 23, 2024 | 12 | Good | PM2.5 |
| Nov 22, 2024 | 0 | Good | PM2.5 |
| Nov 21, 2024 | 0 | Good | PM2.5 |
| Nov 20, 2024 | 1 | Good | PM2.5 |
| Nov 19, 2024 | 23 | Good | PM2.5 |
| Nov 18, 2024 | 16 | Good | PM2.5 |
| Nov 17, 2024 | 21 | Good | PM2.5 |
| Nov 16, 2024 | 27 | Good | PM2.5 |
| Nov 15, 2024 | 23 | Good | PM2.5 |
| Nov 14, 2024 | 14 | Good | PM2.5 |
| Nov 13, 2024 | 13 | Good | PM2.5 |
| Nov 12, 2024 | 21 | Good | PM2.5 |
| Nov 11, 2024 | 11 | Good | PM2.5 |
| Nov 10, 2024 | 51 | Moderate | PM2.5 |
| Nov 9, 2024 | 53 | Moderate | PM2.5 |
| Nov 8, 2024 | 40 | Good | PM2.5 |
| Nov 7, 2024 | 26 | Good | PM2.5 |
| Nov 6, 2024 | 11 | Good | PM2.5 |
| Nov 5, 2024 | 18 | Good | PM2.5 |
| Nov 4, 2024 | 13 | Good | PM2.5 |
| Nov 3, 2024 | 12 | Good | PM2.5 |
| Nov 2, 2024 | 13 | Good | PM2.5 |
| Nov 1, 2024 | 20 | Good | PM2.5 |
| Oct 31, 2024 | 14 | Good | PM2.5 |
| Oct 30, 2024 | 14 | Good | PM2.5 |
| Oct 29, 2024 | 19 | Good | PM2.5 |
| Oct 28, 2024 | 16 | Good | PM2.5 |
| Oct 27, 2024 | 18 | Good | PM2.5 |
| Oct 26, 2024 | 48 | Good | PM2.5 |
| Oct 25, 2024 | 51 | Moderate | PM2.5 |
| Oct 24, 2024 | 19 | Good | PM2.5 |
| Oct 21, 2024 | 21 | Good | PM2.5 |
| Oct 20, 2024 | 30 | Good | PM2.5 |
| Oct 19, 2024 | 26 | Good | PM2.5 |
| Oct 18, 2024 | 9 | Good | PM2.5 |
| Oct 17, 2024 | 22 | Good | PM2.5 |
| Oct 16, 2024 | 9 | Good | PM2.5 |
| Oct 15, 2024 | 15 | Good | PM2.5 |
| Oct 14, 2024 | 8 | Good | PM2.5 |
| Oct 13, 2024 | 15 | Good | PM2.5 |
| Oct 12, 2024 | 14 | Good | PM2.5 |
| Oct 11, 2024 | 31 | Good | PM2.5 |
| Oct 10, 2024 | 38 | Good | PM2.5 |
| Oct 9, 2024 | 25 | Good | PM2.5 |
| Oct 8, 2024 | 47 | Good | PM2.5 |
| Oct 7, 2024 | 40 | Good | PM2.5 |
| Oct 6, 2024 | 28 | Good | PM2.5 |
| Oct 5, 2024 | 37 | Good | PM2.5 |
| Oct 4, 2024 | 58 | Moderate | PM2.5 |
| Oct 3, 2024 | 59 | Moderate | PM2.5 |
| Oct 2, 2024 | 57 | Moderate | PM2.5 |
| Oct 1, 2024 | 48 | Good | PM2.5 |
| Sep 30, 2024 | 52 | Moderate | PM2.5 |
| Sep 29, 2024 | 43 | Good | PM2.5 |
| Sep 28, 2024 | 26 | Good | PM2.5 |
| Sep 27, 2024 | 34 | Good | PM2.5 |
| Sep 26, 2024 | 25 | Good | PM2.5 |
| Sep 25, 2024 | 27 | Good | PM2.5 |
| Sep 24, 2024 | 47 | Good | PM2.5 |
| Sep 23, 2024 | 41 | Good | PM2.5 |
| Sep 22, 2024 | 40 | Good | PM2.5 |
| Sep 21, 2024 | 36 | Good | PM2.5 |
| Sep 20, 2024 | 17 | Good | PM2.5 |
| Sep 19, 2024 | 9 | Good | PM2.5 |
| Sep 18, 2024 | 3 | Good | PM2.5 |
| Sep 17, 2024 | 19 | Good | PM2.5 |
Monitoring Stations
Redwood City
San Carlos
San Carlos Airport
Twin Dolphin
Frequently Asked Questions
What is the air quality in San Mateo, California?
Based on EPA data from 2024, San Mateo has a median Air Quality Index (AQI) of 27, which is classified as "Good." The primary pollutant is PM2.5. Over the past 10 years, air quality has been improving.
Is San Mateo a good place to live for air quality?
San Mateo has a 10-year average median AQI of 37. In 2024, there were 281 days with "Good" air quality and 0 days with unhealthy conditions. No special precautions are needed for most people.
What pollutants affect San Mateo the most?
The primary pollutant driving the AQI in San Mateo is PM2.5. This is monitored by 4 active EPA stations in the county. Other pollutants tracked include ozone, PM10, nitrogen dioxide, sulfur dioxide, and carbon monoxide.
How many air quality monitoring stations are in San Mateo?
There are 4 active EPA monitoring stations in San Mateo, California. These stations continuously measure pollutant levels and contribute to the daily AQI calculations.