David Carslaw, principal air quality scientist at Kings College London, said "to my knowledge this [level] is the highest in the world in terms of both hourly and annual mean. NO2 concentrations [in Oxford Street] are as high as they have ever been in the long history of air pollution".
The high levels of NO2, a colourless gas produced by diesel engines, were recorded by a monitoring station on the popular shopping destination. Scientists have linked NO2 to both asthma and heart attacks.
Levels of NO2 reached an average of 135 micrograms per cubic (mcg) metre of air, over three times the EU's limit of 40mcg. The figure is an average that was reached by including night times when traffic was lower, meaning that shoppers, workers and tourists are facing levels of NO2 greater than 135mcg during the day.
In March, levels of NO2 climbed as high as 463mcg. These levels are higher than those found in the bustling metropolises of both China and India. The high amounts of NO2 at Oxford Street are primarily due to the intense congestion of buses and taxis on the high street.
City Hall has faced calls to act but points that the number of buses on the busy high street has already been cut by 20 per cent, reports the Evening Standard.
A spokesman for the Mayor of London said: “Contrary to any misleading claims, London’s levels of air pollution are lower than many world cities. We know this because we are serious about monitoring pollution levels."