Before the London Olympic Games, in order to effectively improve the air quality in London, Boris Johnson, mayor of London and member of the Olympic Committee, announced that large trucks and small buses must meet the low emission area standard by January 2012  These vehicles have been included in the low emission area since October 2010
On the one hand, pollutants come from direct emission pollution, on the other hand, from the weather. Because we can't control the weather, we can only control the amount of pollution emitted.
 If these cars do not meet the emission standards, they will have to pay fines, which shows that the biggest cause of pollution in London is the amount of traffic pollution