BARNET’S most polluted green areas are in Mill Hill and Hendon, according to new research data.

A survey of air pollution levels in London has found more than a quarter of the city’s open spaces breach the European Union’s safety limit of 40 micrograms of Nitrogen Dioxide per cubic centimetre (μg/cm3).

ASI Data Science has published an online map of the areas surveyed, which shows Mill Hill Green has 52 μg/cm3 and Mill Hill Park West has 39 μg/cm3.

Other parks above the limit included Malcolm Park and Brent Green in Hendon and Dollis Valley Green Walk in Temple Fortune.

ASI Data Science Fellow Pablo Mosteiro, who produced the research, said: “Huge numbers of Londoners are unknowingly going for walks, playing with their children and having their lunchtime sandwich in open spaces with appalling air quality.

“Our new website will allow them to see whether there are any better and cleaner alternatives nearby.”

While no parks in Barnet reached the levels of Whittington Gardens, near Cannon Street, which hit 99 μg/cm3, the worst parks had equal if not greater levels of Nitrogen Dioxide than many parks closer to Central London.

Areas of Barnet further away from the City, such as High Barnet, East Barnet and Whetstone, were generally cleaner with levels around the 28 μg/cm3 mark.

Representatives from ASI have now called on Mayor of London Sadiq Khan to prioritise improving the air quality in the city.

CEO Marc Warner said: “The city's parks are often referred to as the ‘lungs of London’. We now know that these lungs aren't as healthy as we'd hoped.”

ASI Data Science’s map of green spaces in London, with cleaner air marked in light green and more polluted areas in dark red, is available here.