On 30 January, Brixton Road in south London reached its annual legal limit for toxic nitrogen dioxide (NO2) – less than a month into the year. It breached the limit two days later.

The rapid breaking of the limit is a dramatic illustration of the illegal air pollution affecting most urban areas in the UK, for which the government is being sued in the high court for a third time early in 2018. High NO2 levels are estimated to cause about 23,500 early deaths a year across the nation.



The date of the 2018 breach was in fact an improvement over previous years, when the first breach usually occurred in less than a week. The improvement follows London mayor, Sadiq Khan, taking dirty buses off polluted routes and implementing a charge for more polluting vehicles in central London. But more action is needed, particularly from the government.

You can follow all the monitored sites across London in the map below, which is updated as each hour’s data is received from the London Air Quality Network, run by King’s College London.

The law requires that hourly levels of toxic NO2 must not exceed 200 micrograms per cubic metre (µg/m3) more than 18 times in a whole year. The most polluted places have vastly exceeded this in recent years: in 2016 Putney high street broke the hourly limit more than 1,200 times.

There is also an legal limit for the average NO2 level across the whole year: in 2016 this was broken at 59 of the 97 sites.

The most effective way of cutting NO2 is deterring dirty diesel vehicles from city centres with charges, but ministers have told councils this should be the measure of last resort.

How selected pollution sites fared in January