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)
40
Good
O'Fallon, Illinois
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
5.55 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
17.94 μg/m³
0
55
155
255
425
605+
43.08 ppb
0
55
71
86
201
201+
1.06 ppb
0
36
76
186
605
1005+
3.16 ppb
0
54
101
361
1250
2050+
0.20 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Low
O'Fallon, Illinois
O'Fallon, Illinois
Scroll To Air Quality MapLoading...
AQI 40
Good
5.55μg/m³
PM2.5
17.94μg/m³
PM10
43.08ppb
O3
1.06ppb
SO2
3.16ppb
NO2
0.20ppm
CO
AQI 40
Good
5.55μg/m³
PM2.5
17.94μg/m³
PM10
43.08ppb
O3
1.06ppb
SO2
3.16ppb
NO2
0.20ppm
CO
AQI 40
Good
6.52μg/m³
PM2.5
29.93μg/m³
PM10
43.08ppb
O3
1.14ppb
SO2
3.28ppb
NO2
0.20ppm
CO
AQI 39
Good
6.41μg/m³
PM2.5
25.68μg/m³
PM10
41.84ppb
O3
1.11ppb
SO2
3.26ppb
NO2
0.20ppm
CO
AQI 39
Good
5.47μg/m³
PM2.5
18.06μg/m³
PM10
41.86ppb
O3
1.06ppb
SO2
3.19ppb
NO2
0.20ppm
CO
AQI 42
Good
6.38μg/m³
PM2.5
25.62μg/m³
PM10
45.08ppb
O3
1.16ppb
SO2
3.33ppb
NO2
0.20ppm
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 05:00:00 on 2026-07-23.
In the last 24 hrs, the best air quality in O'fallon, Illinois was observed at 03:00:00 on 2026-07-23.
The current air quality in O'fallon, Illinois is 40, categorized as Good based on real-time data.
The most common pollutant in O'fallon, Illinois is O3.
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 5.547 μg/m3.
The current PM10 concentration at O'fallon, Illinois is 17.937 μg/m3.
The current carbon monoxide (CO) concentration at O'fallon, Illinois is 0.198 ppm.
The current sulfur dioxide (SO2) concentration at O'fallon, Illinois is 1.059 ppb.
The current ozone (O3) concentration at O'fallon, Illinois is 43.082 ppm.
The current nitrogen dioxide (NO2) concentration at O'fallon, Illinois is 3.164 ppb.
All Rights Reserved © Ambee Inc. 2025