Every borough in London exceeds World Health Organization (WHO) limits for toxic air pollution, new data reveals.

Published by City Hall, the air quality data shows that every London borough is breaching WHO guidelines for nitrogen dioxide.

Thirty-one of the 33 London boroughs used diffusion tubes in 2021 to monitor a large number of locations in their area. Bexley and Harrow have not installed these local air quality monitors.

City Hall has now compiled the latest data from 2021 – the first time this data has been brought together – and found that all locations monitored are exceeding global WHO recommended limits for nitrogen dioxide.

Fourteen boroughs have five or more locations monitored that also exceed the less stringent UK legal limit for nitrogen dioxide.

In Brent, Croydon and Merton, more than a quarter of the locations monitored found the air to be breaching legal limits. The data also shows a very similar average pollution concentration in inner and outer London.

Mayor of London, Sadiq Khan, said: ‘London’s toxic air is leading to children growing up with stunted lungs and causes around 4,000 premature deaths a year – with the greatest number of attributable deaths in London’s outer boroughs.

‘This data is yet more shocking proof that London’s air quality has been in serious breach of the recognised global standard – and it’s a problem in every single part of the capital.’

Mayor Khan has proposed the expansion of the Ultra-Low Emission Zone (ULEZ), which will see drivers of vehicles that do not meet emissions requirements charged a daily charge.

The London boroughs of Bexley, Bromley, Hillingdon and Harrow, along with Surrey County Council have challenged this decision.