Stay updated with real-time air quality in San Marcos, California featuring accurate data on AQI, PM2.5, PM10, O3, NO2, SO2, and CO levels. Use our interactive map and detailed forecasts to monitor pollution trends, manage health risks, and plan your daily activities with confidence.
Live AQI (Air Quality Index)
27
Good
San Marcos, California
Last updated: ... (Local time)
Good
Fine
Moderate
Poor
Very poor
Hazardous
4.96 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
20.57 μg/m³
0
55
155
255
425
605+
20.08 ppb
0
55
71
86
201
201+
0.38 ppb
0
36
76
186
605
1005+
17.71 ppb
0
54
101
361
1250
2050+
0.24 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Low
San Marcos, California
San Marcos, California
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AQI 27
Good
5.34μg/m³
PM2.5
24.03μg/m³
PM10
21.98ppb
O3
0.41ppb
SO2
9.01ppb
NO2
0.14ppm
CO
AQI 22
Good
3.87μg/m³
PM2.5
12.05μg/m³
PM10
22.50ppb
O3
0.42ppb
SO2
14.78ppb
NO2
0.18ppm
CO
AQI 27
Good
5.34μg/m³
PM2.5
24.46μg/m³
PM10
28.25ppb
O3
0.41ppb
SO2
5.37ppb
NO2
0.14ppm
CO
AQI 22
Good
4.30μg/m³
PM2.5
16.13μg/m³
PM10
22.02ppb
O3
0.41ppb
SO2
7.07ppb
NO2
0.19ppm
CO
AQI 27
Good
5.44μg/m³
PM2.5
17.95μg/m³
PM10
23.83ppb
O3
0.41ppb
SO2
6.12ppb
NO2
0.18ppm
CO
AQI 22
Good
4.00μg/m³
PM2.5
13.04μg/m³
PM10
24.17ppb
O3
0.41ppb
SO2
7.18ppb
NO2
0.19ppm
CO
Air quality measurements for California, USA meet strict US EPA standards. These measurements are collected from reliable sources, including satellites and ground-based monitoring systems. Advanced algorithms and machine learning techniques are applied to the data, factoring in variables such as traffic and population density, to ensure precision and reliability.
Source: Ambee Data Sources
Air quality data for San Marcos, California is updated on an hourly basis.
The worst air quality in San Marcos, California was recorded at 08:00:00 on 2025-07-24.
The best air quality in San Marcos, California was recorded at 05:00:00 on 2025-07-25.
The real-time air quality index in San Marcos, California is 24, currently categorized as Good.
The most common pollutant in San Marcos, California is O3.
If the air quality in San Marcos, California is poor, limit outdoor activities and use a mask to safeguard your health.
The measured PM2.5 levels in San Marcos, California at present are 3.539 μg/m3.
The current PM10 levels in San Marcos, California are 15.978 μg/m3.
The current carbon monoxide (CO) level in San Marcos, California is 0.135 ppm.
The current sulfur dioxide (SO2) levels in San Marcos, California are 0.288 ppb.
The current ozone (O3) levels at San Marcos, California is 25.521 ppm.
The current nitrogen dioxide (NO2) levels at San Marcos, California is 11.03 ppb.
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