Stay updated with real-time air quality in Defiance, Ohio 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)
49
Good
Defiance, Ohio
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
8.79 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
39.80 μg/m³
0
55
155
255
425
605+
24.38 ppb
0
55
71
86
201
201+
0.64 ppb
0
36
76
186
605
1005+
4.21 ppb
0
54
101
361
1250
2050+
0.17 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Low
Defiance, Ohio
Defiance, Ohio
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AQI 33
Good
6.38μg/m³
PM2.5
25.29μg/m³
PM10
17.64ppb
O3
1.29ppb
SO2
4.33ppb
NO2
0.17ppm
CO
AQI 33
Good
6.08μg/m³
PM2.5
29.22μg/m³
PM10
22.88ppb
O3
1.07ppb
SO2
4.60ppb
NO2
0.18ppm
CO
AQI 22
Good
4.10μg/m³
PM2.5
11.12μg/m³
PM10
17.22ppb
O3
1.29ppb
SO2
7.24ppb
NO2
0.20ppm
CO
AQI 22
Good
4.02μg/m³
PM2.5
17.20μg/m³
PM10
23.01ppb
O3
1.23ppb
SO2
3.55ppb
NO2
0.17ppm
CO
AQI 21
Good
1.14μg/m³
PM2.5
5.13μg/m³
PM10
22.90ppb
O3
1.01ppb
SO2
6.37ppb
NO2
0.17ppm
CO
AQI 16
Good
3.33μg/m³
PM2.5
9.88μg/m³
PM10
15.66ppb
O3
1.41ppb
SO2
6.81ppb
NO2
0.19ppm
CO
Air quality data and pollutant measurements for Ohio, 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 Defiance, Ohio is updated every hour.
The worst air quality in Defiance, Ohio in the last 24 hours was observed at 11:00:00 on 2025-12-09.
In the last 24 hrs, the best air quality in Defiance, Ohio was observed at 05:00:00 on 2025-12-10.
The current air quality in Defiance, Ohio is 49, categorized as Good based on real-time data.
The most common pollutant in Defiance, Ohio is PM2.5.
If the air quality in Defiance, Ohio is poor, consider staying indoors and wearing a mask to protect yourself.
The current PM2.5 concentration at Defiance, Ohio is 8.786 μg/m3.
The current PM10 concentration at Defiance, Ohio is 39.804 μg/m3.
The current carbon monoxide (CO) concentration at Defiance, Ohio is 0.167 ppm.
The current sulfur dioxide (SO2) concentration at Defiance, Ohio is 0.638 ppb.
The current ozone (O3) concentration at Defiance, Ohio is 24.381 ppm.
The current nitrogen dioxide (NO2) concentration at Defiance, Ohio is 4.214 ppb.
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