Stay updated with real-time air quality in Decatur, 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)
43
Good
Decatur, Illinois
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
2.39 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
9.94 μg/m³
0
55
155
255
425
605+
46.32 ppb
0
55
71
86
201
201+
0.13 ppb
0
36
76
186
605
1005+
0.77 ppb
0
54
101
361
1250
2050+
0.12 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Decatur, Illinois
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AQI 43
Good
4.39μg/m³
PM2.5
20.39μg/m³
PM10
45.62ppb
O3
0.47ppb
SO2
3.08ppb
NO2
0.21ppm
CO
AQI 40
Good
4.30μg/m³
PM2.5
18.80μg/m³
PM10
43.40ppb
O3
0.53ppb
SO2
2.91ppb
NO2
0.20ppm
CO
AQI 37
Good
4.11μg/m³
PM2.5
18.02μg/m³
PM10
40.01ppb
O3
0.56ppb
SO2
3.06ppb
NO2
0.20ppm
CO
AQI 41
Good
4.16μg/m³
PM2.5
19.22μg/m³
PM10
44.47ppb
O3
0.79ppb
SO2
4.45ppb
NO2
0.20ppm
CO
AQI 43
Good
4.07μg/m³
PM2.5
19.27μg/m³
PM10
45.85ppb
O3
0.98ppb
SO2
4.33ppb
NO2
0.23ppm
CO
AQI 40
Good
5.05μg/m³
PM2.5
23.04μg/m³
PM10
42.69ppb
O3
0.67ppb
SO2
3.06ppb
NO2
0.20ppm
CO
Air quality and pollutant data for Illinois, USA are sourced from ground-based monitors and satellites, adhering to US EPA standards. Machine learning and advanced algorithms enhance the data by incorporating local variables like traffic and population density, ensuring high accuracy and dependability.
Source: Ambee Data Sources
The air quality information for Decatur, Illinois is updated every hour for accuracy.
In the past 24 hours, the air quality in Decatur, Illinois was at its worst at 09:00:00 on 2026-07-23.
In the last 24 hours, the best air quality in Decatur, Illinois was observed at 11:00:00 on 2026-07-23.
As of now, the AQI in Decatur, Illinois is 43, indicating Good conditions.
Decatur, Illinois air has the highest levels of O3.
Poor air quality in Decatur, Illinois means it's advisable to stay indoors and wear a mask for your protection.
PM2.5 levels in Decatur, Illinois are currently 2.389 μg/m3.
The PM10 concentration in Decatur, Illinois is 9.939 μg/m3 at the moment.
The current carbon monoxide (CO) concentration in Decatur, Illinois is 0.118 ppm.
Currently, Decatur, Illinois has a sulfur dioxide (SO2) concentration of 0.131 ppb.
The current ozone (O3) level in Decatur, Illinois at the moment is 46.319 ppm.
Nitrogen dioxide (NO2) level in Decatur, Illinois at the moment is 0.769 ppb.
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