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)
22
Good
Decatur, Illinois
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
3.99 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
17.96 μg/m³
0
55
155
255
425
605+
15.63 ppb
0
55
71
86
201
201+
0.77 ppb
0
36
76
186
605
1005+
6.39 ppb
0
54
101
361
1250
2050+
0.29 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Decatur, Illinois
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AQI 22
Good
3.54μg/m³
PM2.5
17.06μg/m³
PM10
16.84ppb
O3
0.57ppb
SO2
10.84ppb
NO2
0.28ppm
CO
AQI 23
Good
3.40μg/m³
PM2.5
16.89μg/m³
PM10
24.50ppb
O3
0.54ppb
SO2
3.78ppb
NO2
0.25ppm
CO
AQI 22
Good
3.51μg/m³
PM2.5
16.03μg/m³
PM10
16.91ppb
O3
0.53ppb
SO2
3.62ppb
NO2
0.28ppm
CO
AQI 24
Good
3.18μg/m³
PM2.5
13.63μg/m³
PM10
25.67ppb
O3
0.69ppb
SO2
6.73ppb
NO2
0.15ppm
CO
AQI 22
Good
4.25μg/m³
PM2.5
19.00μg/m³
PM10
17.00ppb
O3
0.45ppb
SO2
4.05ppb
NO2
0.19ppm
CO
AQI 38
Good
6.72μg/m³
PM2.5
22.17μg/m³
PM10
16.75ppb
O3
0.54ppb
SO2
6.61ppb
NO2
0.29ppm
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 10:00:00 on 2026-01-22.
In the last 24 hours, the best air quality in Decatur, Illinois was observed at 03:00:00 on 2026-01-23.
As of now, the AQI in Decatur, Illinois is 22, indicating Good conditions.
Decatur, Illinois air has the highest levels of PM2.5.
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 3.991 μg/m3.
The PM10 concentration in Decatur, Illinois is 17.956 μg/m3 at the moment.
The current carbon monoxide (CO) concentration in Decatur, Illinois is 0.287 ppm.
Currently, Decatur, Illinois has a sulfur dioxide (SO2) concentration of 0.767 ppb.
The current ozone (O3) level in Decatur, Illinois at the moment is 15.632 ppm.
Nitrogen dioxide (NO2) level in Decatur, Illinois at the moment is 6.39 ppb.
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