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
5.25 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
16.66 μg/m³
0
55
155
255
425
605+
29.23 ppb
0
55
71
86
201
201+
0.18 ppb
0
36
76
186
605
1005+
5.45 ppb
0
54
101
361
1250
2050+
0.22 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Moderate
San Marcos, California
San Marcos, California
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AQI 33
Good
6.28μg/m³
PM2.5
12.65μg/m³
PM10
29.70ppb
O3
0.19ppb
SO2
4.17ppb
NO2
0.18ppm
CO
AQI 33
Good
6.38μg/m³
PM2.5
22.98μg/m³
PM10
31.74ppb
O3
0.19ppb
SO2
3.10ppb
NO2
0.18ppm
CO
AQI 33
Good
6.01μg/m³
PM2.5
20.13μg/m³
PM10
29.78ppb
O3
0.19ppb
SO2
4.17ppb
NO2
0.18ppm
CO
AQI 33
Good
5.66μg/m³
PM2.5
23.66μg/m³
PM10
29.64ppb
O3
0.19ppb
SO2
4.02ppb
NO2
0.17ppm
CO
AQI 44
Good
8.03μg/m³
PM2.5
22.39μg/m³
PM10
34.11ppb
O3
0.19ppb
SO2
2.84ppb
NO2
0.17ppm
CO
AQI 33
Good
5.77μg/m³
PM2.5
23.75μg/m³
PM10
29.29ppb
O3
0.19ppb
SO2
4.04ppb
NO2
0.16ppm
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 05:00:00 on 2025-06-06.
The best air quality in San Marcos, California was recorded at 11:00:00 on 2025-06-07.
The real-time air quality index in San Marcos, California is 27, 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 5.251 μg/m3.
The current PM10 levels in San Marcos, California are 16.663 μg/m3.
The current carbon monoxide (CO) level in San Marcos, California is 0.216 ppm.
The current sulfur dioxide (SO2) levels in San Marcos, California are 0.18 ppb.
The current ozone (O3) levels at San Marcos, California is 29.229 ppm.
The current nitrogen dioxide (NO2) levels at San Marcos, California is 5.454 ppb.
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