Worst air pollution Harpenden, today and tomorrow
Today (16 July): Air quality in Harpenden is fair. AQI and O3 are fair; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 4:00 PM (O3: 31.6/100).
Tomorrow (17 July 2026): Air quality in Harpenden is fair. All pollutants stay as today. Pollution peaks around 3:00 PM (O3: 37.8/100). Airmine updates local air quality forecasts four times daily.
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Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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Harpenden's air quality reflects its position within Hertfordshire, with local traffic and the town's built-up core as the main contributors. Commuter traffic feeding onto the A38 adds a further, consistent contribution to local readings. Inland breezes from the surrounding countryside do most of the work keeping things in check, more so than any local policy or infrastructure change.
Today - 16 July | Pollution peaks at 16:00
AQI:
Fair
31.6/100
PM2.5 (fine particles):
Good
8.7/100
PM10 (coarse particles):
Good
3.1/100
NO2 (nitrogen dioxide):
Good
12.6/100
O3 (ozone):
Fair
31.6/100
SO2 (sulfur dioxide):
Good
2.1/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
2.8/100
PM1 (ultrafine particles):
Good
7.6/100
Levels show the poorest local air quality during the day
Tomorrow - 17 July | Pollution peaks at 15:00
AQI:
Fair
37.8/100
PM2.5 (fine particles):
Good
13.3/100
PM10 (coarse particles):
Good
4.6/100
NO2 (nitrogen dioxide):
Good
17.0/100
O3 (ozone):
Fair
37.8/100
SO2 (sulfur dioxide):
Good
3.5/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
4.0/100
PM1 (ultrafine particles):
Good
11.9/100
Pollen forecast in Harpenden
View pollen forecastFrequently Asked Questions
Is air quality bad in Harpenden right now?
On 16 July 2026, overall air quality in Harpenden is fair. AQI is the main air quality indicator at 31.6/100. Pollution peaks around 4:00 PM (O3: 31.6/100).
Will air quality be worse tomorrow in Harpenden?
On 17 July 2026, air quality conditions in Harpenden will be similar to today, with AQI forecast at fair at 37.8/100. Pollution peaks around 3:00 PM (O3: 37.8/100).
When is air pollution at its worst in Harpenden?
Harpenden doesn't have one fixed air quality level — it swings between two extremes each year. Summer's more of a mixed bag: ozone can spike in strong sun, but overall dispersion tends to be better than the depths of winter. Winter tends to be worst, with wood burning, home heating, and still, cold air trapping traffic fumes from the A38 closer to ground level.
Are air quality levels in Harpenden 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.
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Data provided by Airmine — Last update: 16 July 2026 at 10:33 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.
For long term forecasts and maps, see the Airmine app