A City Hall study has found that the ULEZ zone has reduced harmful air pollution by 46% in central and inner London. 

The study found that in inner London there is a 21% reduction in the nitrogen dioxide concentration and a 46% decrease in central London than would have been the case without ULEZ. 

It also found it to be especially effective at reducing nitrogen dioxide at roadside locations, a 56% reduction in central London, 47% in inner London, and 37% in outer London since 2017. 

The Mayor of London, Sadiq Khan said: "The evidence from this landmark report is clear – the ULEZ works. This is beyond dispute. 

"It has already reduced toxic air pollution by almost half in central London and by over a fifth in inner London, transforming the quality of air for four million Londoners.  

"But there's still more to do. Toxic air is a matter of life and death, with around 4,000 deaths in London attributed to air pollution in 2019.  

"It's also stunting the growth of children's lungs and causing people to develop life-changing illnesses, such as cancer, lung disease, dementia and asthma. 

"With the majority of deaths attributable to air pollution in outer London, it's vital that we expand the ULEZ London-wide. 

"As Mayor, I simply won't accept that the five million people in outer London shouldn't be able to benefit from the same life-saving health impacts that ULEZ has already brought to the rest of our city. Everyone has the right to breathe clean air." 

The study also found that ULEZ had greatly reduced the number of non-compliant vehicles in central and inner London, with 94.4% of vehicles meeting ULEZ standards, compared to 39% when the expansion was announced. 

At present the ULEZ zone only applies to drivers entering the North and South-Circular roads, but from 29th August that area will expand to cover the entirety of Hounslow, meaning that all drivers in the borough without a compliant car will have to pay £12.50. 

At present Hounslow Council are in a minority of boroughs apart of the expansion to not have opposed the decision, with 11 councils having raised concerns: Harrow, Bromley, Bexley, Hillingdon, Croydon, Kingston, Richmond, Sutton, Redbridge, Barking and Dagenham, and Havering.