On Thursday evening Brixton Road in Lambeth breached the legal limit of one type of air pollution just five days into the year.
EU law states that the amount of nitrogen dioxide (NO₂) in the air can’t exceed 200 micrograms per cubic metre for more than 18 hours over the whole year.
But at around 9pm on 5 January an air pollution monitoring station on Brixton Road measured an hourly reading above this level for the 19th time. In fact, for 17 consecutive hours on Thursday the nitrogen dioxide levels measured at Brixton Road were above 200 micrograms per cubic metre.
Nitrogen dioxide is formed during combustion, and in total about half of the nitrogen dioxide in the air comes from road transport, meaning levels tend to be higher in cities and close to busy roads. It is harmful to health, mostly affecting the lungs, and there's evidence its effects are particularly pronounced in people who have asthma.
The European Environment Agency has said there are 14,000 premature deaths in the UK because of nitrogen dioxide every year.
Alan Andrews, a lawyer with ClientEarth, said: “This is another shameful reminder of the severity of London’s air pollution and shows why the mayor has rightly made tackling it a top priority. It is absolutely essential that he now delivers on his promises and that the national government back him to the hilt."
Last November, after ClientEarth brought a case against the government, the High Court ruled that the government's plans to tackle air pollution were "illegally poor", ordering it to come up with a better plan by July.
Simon Birkett, founder and director of Clean Air in London, said in a statement: "When conditions are as bad as they were on Thursday, when Brixton Road suffered 20 hours of exceedances in a single 24-hour period, bus services should be suspended, drivers should be advised not to drive and pedestrians should be warned to avoid the area. We also need to ban alfresco dining and the use of outdoor tables for cafes wherever and whenever the WHO [World Health Organization] guideline for hourly exposure could be breached. Emergency measures and action are needed."
Last year Brixton Road exceeded the limit 883 times in total, falling behind Putney High Street, which exceeded it 1443 times, and Oxford Street, which clocked in at 1391.
Other monitoring sites in London are expected to soon breach the annual limit for 2017. You can track air pollution data from monitoring stations around the city at Kings College London's London Air website.