Barnet Council’s staff may be walking through dangerously polluted air on their way to work every day, according to an independent study.

Nitrogen dioxide (NO2) air pollution can be measured in microgrammes per cubic metre (μg/m3), with the legal annual limit in any one area being 40 μg/m3.

Green party members in Whetstone have measured the NO2 levels in nine places throughout the area using diffusion tubes, with only one tested area coming in under the legal limit.

Outside the Boots store in High Road, across from Barnet Council’s Barnet House offices, a measurement was taken of 109.48 μg/m3 of NO2, meaning council workers may be breathing illegal levels of the pollutant on their way to work each day.

Co-chair of Barnet Green party Adele Ward said: “These levels are appalling – research has shown nitrogen dioxide can be an aggravating factor in asthma and other illnesses by itself as well as in combination with other pollutants.

“Nitrogen dioxide is often a good indication that the air in a location also contains other high levels of poisonous pollutants such as particulates.

“Readings we have now taken in dozens of locations around Barnet show that there are many NO2 blackspots in the borough. Air pollution is not just something affecting inner London and it is about time Barnet Council took the problem seriously.”

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Measurements taken near Alma primary school in Friern Barnet Lane were as high as 76.47 μg/m3, leading to concerns by Green party members as studies show NO2 pollution can irreparably reduce lung growth in children by 10 per cent.

The Greens also expressed concern for commuters coming to and from Totteridge & Whetstone tube station and shoppers along the High Road.

Barnet Council was recently awarded by Sadiq Khan, the Mayor of London, for its efforts to reduce air pollution, including the planting of 114 trees on streets close to busy junctions to help reduce pollution.

The trees such as Magnolia and London Plane are “nitrogen-loving” and each tree removes 2kg of carbon dioxide from the air per year.

Chair of the environment committee Cllr Dean Cohen said: “Our work to reduce the exposure of our residents to the harmful effects of air pollution has led us to recently receiving Cleaner Air Borough status from the Mayor of London through effectively monitoring and reducing air pollution.

“Highlights of other successful projects which we are working with partners to deliver through our previous action plan include the Air Quality Champion project funded by the Mayor’s Air Quality Fund, and the North Finchley Cleaner Air project part funded by the Mayor’s Air Quality Fund.”