Worst air pollution Welwyn Garden City, today and tomorrow
Today (9 August): Air quality in Welwyn Garden City is fair. PM1 is fair; AQI and O3 are medium; PM2.5, PM10, NO2, SO2, CO, and HCHO are good. Pollution peaks around 4:00 PM (O3: 57.0/100).
Tomorrow (10 August 2026): Air quality in Welwyn Garden City is fair. AQI worsens to fair; O3 increases to fair; PM1 decreases to good; all other pollutants stay as today. Pollution peaks around 5:00 PM (O3: 24.6/100). Airmine updates local air quality forecasts four times daily.
Get the full experience in the Airmine app.
Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
Follow your pollen exposure and performance with the free Airmine–Strava integration. See your pollen and air quality exposure for every Strava activity.
Welwyn Garden City's position in Hertfordshire means air quality is mostly determined by local road traffic and the compact scale of the centre. Residential heating and light industry add a modest seasonal contribution, though moist Atlantic fronts keep overall levels moderate. Rush-hour queues near the A46 are usually when readings climb the most.
Today - 9 August | Pollution peaks at 16:00
AQI:
Medium
57.0/100
PM2.5 (fine particles):
Good
16.7/100
PM10 (coarse particles):
Good
4.5/100
NO2 (nitrogen dioxide):
Good
12.1/100
O3 (ozone):
Medium
57.0/100
SO2 (sulfur dioxide):
Good
1.5/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
7.0/100
PM1 (ultrafine particles):
Fair
22.0/100
Levels show the poorest local air quality during the day
Tomorrow - 10 August | Pollution peaks at 17:00
AQI:
Fair
24.6/100
PM2.5 (fine particles):
Good
4.2/100
PM10 (coarse particles):
Good
1.6/100
NO2 (nitrogen dioxide):
Good
3.0/100
O3 (ozone):
Fair
24.6/100
SO2 (sulfur dioxide):
Good
0.6/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
3.2/100
PM1 (ultrafine particles):
Good
3.1/100
Pollen forecast in Welwyn Garden City
View pollen forecastFrequently Asked Questions
Is air quality bad in Welwyn Garden City right now?
On 9 August 2026, overall air quality in Welwyn Garden City is fair. PM1 is the main pollutant at 22.0/100. Pollution peaks around 4:00 PM (O3: 57.0/100).
Will air quality be worse tomorrow in Welwyn Garden City?
On 10 August 2026, air quality conditions in Welwyn Garden City will be similar to today, with AQI forecast at fair at 24.6/100. Pollution peaks around 5:00 PM (O3: 24.6/100).
When is air pollution at its worst in Welwyn Garden City?
Air quality in Welwyn Garden City isn't the same all year round — it really shifts with the seasons. Winter mornings can be the trickiest, with cold, still conditions trapping A46 traffic fumes and smoke from home fires close to the ground. Summer brings a different issue — stronger sunlight can push up ozone levels on hot, sunny days, even though traffic pollution itself often disperses more easily.
Are air quality levels in Welwyn Garden City based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
Why doesn’t the forecast always reflect wildfire impacts?
Airmine’s forecast uses CAMS (Copernicus Atmosphere Monitoring Service) as its background atmospheric model. While CAMS includes wildfire emissions, these are derived from satellite observations and are not available in real time. During rapidly evolving wildfire events, there may therefore be a delay before increased emissions are incorporated into the model. As a result, the forecast may temporarily underestimate PM₂.₅ and other pollutants associated with wildfire smoke.
During rapidly evolving wildfire events, CAMS may lag by approximately 1–2 days before increased wildfire emissions are fully represented, which can lead to temporary underestimation of PM₂.₅ concentrations in Airmine’s forecast.
Want to see air quality forecasts for other cities in United Kingdom?
Check air quality in other popular cities:
Data provided by Airmine — Last update: 9 August 2026 at 20:27 CEST (Data is updated four times daily.)
This forecast is produced independently using Airmine's own atmospheric data and models.
Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.
Disclaimer: Forecasts are provided for informational purposes only and should not be relied upon as medical advice. Actual pollen and air quality conditions may vary from the forecast. If you have allergies, asthma, or another medical condition, consult a healthcare professional. Please see our Terms of Service for important information about limitations of liability.
Get the full experience in the Airmine app.