Six years after we measured nitrogen dioxide (NO2) pollution in Hampstead, we are returning to see what has changed.

The years since 2015 have put this public-health emergency in the news. Each year, the poisoned air brings 10,000 London lives to an early end. Throughout the city, children’s lungs fail to grow fully, leaving them for the rest of their lives vulnerable to chest and respiratory infections.

Not equally, of course. Air pollution made London’s geography. Complaints started in the 14th century. Property has always been more valuable upwind in the west. Researchers from King’s College London have shown there is no respite now for Canning Town residents. Hampstead, perched on the Thames valley rim, ventilated from the west, has long been cherished for its “sweet air”.

Ham & High: Stephen Taylor last measured the NO2 levels in Hampstead in 2015Stephen Taylor last measured the NO2 levels in Hampstead in 2015 (Image: Stephen Taylor)

So it was a wake-up call when we measured the NO2 in 2015. The World Health Organisation warns there is no level at which NO2 is harmless, but says it should be limited to 10µg/m³.

In the middle of the Heath we found twice that: 20µg/m³. In Hampstead side streets, nearly four times as much. At the junction of Arkwright Rd and Fitzjohn’s Avenue, with three schools nearby, 69µg/m³.

Where does the NO2 come from and what can we do? As the Heath reading shows, a great deal of it blows in from elsewhere. But beside Spaniards Road, which runs through the Heath, we found 72µg/m³. Little there to account for the difference but traffic.

We can’t control what blows in to the area, but we can tackle local emissions. We have particular reason to. Most London households do not own a car; 60% of Hampstead households own one or more. In the last two decades Hampstead has become “a business park for education” with an estimated 12,000 school places in an area with under 2,000 school-age children. The school-run traffic is infamous.

The forum’s 2021 survey will show we are getting the poison out of the air – or that more needs to be done. Big thanks to the participating schools, to Camden for technical advice, and to our volunteers. Visit hampsteadforum.org/airquality2021 to offer money or help to finish the job.

Stephen Taylor is chair of Hampstead Neighbourhood Forum.