Stay updated with real-time air quality in Welwyn Garden City, Hertfordshire 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)
26
Good
Welwyn Garden City, Hertfordshire
Last updated: ... (Local time)

Good
Fine
Moderate
Poor
Very poor
Hazardous
4.35 μg/m³
0
12.1
35.5
55.5
250.5
500.5+
6.26 μg/m³
0
55
155
255
425
605+
27.82 ppb
0
55
71
86
201
201+
0.90 ppb
0
36
76
186
605
1005+
6.19 ppb
0
54
101
361
1250
2050+
0.11 ppm
0
4.5
9.5
12.5
230.5
50.5+
Pollen Level
Moderate
Welwyn Garden City, Hertfordshire
Welwyn Garden City, Hertfordshire
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AQI 24
Good
4.13μg/m³
PM2.5
5.63μg/m³
PM10
26.44ppb
O3
0.94ppb
SO2
7.23ppb
NO2
0.12ppm
CO
AQI 24
Good
4.16μg/m³
PM2.5
7.06μg/m³
PM10
26.10ppb
O3
0.96ppb
SO2
5.15ppb
NO2
0.12ppm
CO
AQI 25
Good
4.25μg/m³
PM2.5
9.92μg/m³
PM10
27.18ppb
O3
0.95ppb
SO2
7.38ppb
NO2
0.12ppm
CO
AQI 26
Good
3.78μg/m³
PM2.5
9.86μg/m³
PM10
27.52ppb
O3
0.89ppb
SO2
4.86ppb
NO2
0.12ppm
CO
AQI 24
Good
4.34μg/m³
PM2.5
5.41μg/m³
PM10
26.43ppb
O3
0.97ppb
SO2
5.57ppb
NO2
0.12ppm
CO
AQI 26
Good
4.10μg/m³
PM2.5
8.96μg/m³
PM10
28.43ppb
O3
0.95ppb
SO2
6.10ppb
NO2
0.12ppm
CO
Air quality data and pollutant measurements for Hertfordshire, UK 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 Welwyn Garden City, Hertfordshire is updated every hour.
The worst air quality in Welwyn Garden City, Hertfordshire in the last 24 hours was observed at 02:00:00 on 2026-05-13.
In the last 24 hrs, the best air quality in Welwyn Garden City, Hertfordshire was observed at 08:00:00 on 2026-05-14.
The current air quality in Welwyn Garden City, Hertfordshire is 26, categorized as Good based on real-time data.
The most common pollutant in Welwyn Garden City, Hertfordshire is O3.
If the air quality in Welwyn Garden City, Hertfordshire is poor, consider staying indoors and wearing a mask to protect yourself.
The current PM2.5 concentration at Welwyn Garden City, Hertfordshire is 4.346 μg/m3.
The current PM10 concentration at Welwyn Garden City, Hertfordshire is 6.26 μg/m3.
The current carbon monoxide (CO) concentration at Welwyn Garden City, Hertfordshire is 0.108 ppm.
The current sulfur dioxide (SO2) concentration at Welwyn Garden City, Hertfordshire is 0.902 ppb.
The current ozone (O3) concentration at Welwyn Garden City, Hertfordshire is 27.818 ppm.
The current nitrogen dioxide (NO2) concentration at Welwyn Garden City, Hertfordshire is 6.194 ppb.
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