Stay updated with real-time air quality in O'Fallon, Illinois 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)
24
Good
O'Fallon, Illinois
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
4.00 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
25.96 μg/m³
0
55
155
255
425
605+
19.66 ppb
0
55
71
86
201
201+
0.60 ppb
0
36
76
186
605
1005+
4.82 ppb
0
54
101
361
1250
2050+
0.17 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Low
O'Fallon, Illinois
O'Fallon, Illinois
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AQI 24
Good
4.00μg/m³
PM2.5
25.96μg/m³
PM10
19.66ppb
O3
0.60ppb
SO2
4.82ppb
NO2
0.17ppm
CO
AQI 24
Good
4.00μg/m³
PM2.5
25.96μg/m³
PM10
19.66ppb
O3
0.60ppb
SO2
4.82ppb
NO2
0.17ppm
CO
AQI 23
Good
3.87μg/m³
PM2.5
24.64μg/m³
PM10
19.44ppb
O3
0.60ppb
SO2
4.84ppb
NO2
0.15ppm
CO
AQI 27
Good
4.53μg/m³
PM2.5
22.76μg/m³
PM10
19.99ppb
O3
0.61ppb
SO2
4.78ppb
NO2
0.16ppm
CO
AQI 22
Good
4.50μg/m³
PM2.5
21.23μg/m³
PM10
19.68ppb
O3
0.61ppb
SO2
4.71ppb
NO2
0.16ppm
CO
AQI 27
Good
5.20μg/m³
PM2.5
26.25μg/m³
PM10
22.70ppb
O3
0.59ppb
SO2
4.87ppb
NO2
0.15ppm
CO
Air quality data and pollutant measurements for Illinois, USA adhere to strict US EPA standards. The data is collected from multiple reliable sources, including satellites and ground-based monitoring stations. This data is further analyzed and enhanced using machine learning and advanced algorithms that factor in elements such as traffic and population density, ensuring accurate and reliable results.
Source: Ambee Data Sources
The air quality for O'fallon, Illinois is updated every hour.
The worst air quality in O'fallon, Illinois in the last 24 hours was observed at 04:00:00 on 2026-06-07.
In the last 24 hrs, the best air quality in O'fallon, Illinois was observed at 09:00:00 on 2026-06-08.
The current air quality in O'fallon, Illinois is 24, categorized as Good based on real-time data.
The most common pollutant in O'fallon, Illinois is PM10.
If the air quality in O'fallon, Illinois is poor, consider staying indoors and wearing a mask to protect yourself.
The current PM2.5 concentration at O'fallon, Illinois is 3.997 μg/m3.
The current PM10 concentration at O'fallon, Illinois is 25.959 μg/m3.
The current carbon monoxide (CO) concentration at O'fallon, Illinois is 0.166 ppm.
The current sulfur dioxide (SO2) concentration at O'fallon, Illinois is 0.605 ppb.
The current ozone (O3) concentration at O'fallon, Illinois is 19.661 ppm.
The current nitrogen dioxide (NO2) concentration at O'fallon, Illinois is 4.818 ppb.
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