A new report by City Hall reveals that particle emissions from car exhausts are estimated to be 31% lower in outer London in 2024 than they would have been without the ULEZ expansion.

Mayor of London Sadiq Khan in April 2019 launched the world's first 24-hour Ultra Low Emission Zone (ULEZ) in central London.

The zone was expanded across inner London in 2021, and across the whole capital In August 2023, bringing the zone to around five million people living in outer London.

Reviewed by an independent advisory group of experts, the report shows that the ULEZ has led to substantial improvements in air quality in outer London and across the capital.

Alongside NO2 (nitrogen dioxide) and PM2.5 (particle emission) reductions, NOx (nitrogen oxides) emissions from cars and vans are also estimated to be 14 per cent lower in outer London.

According to the report, the biggest reductions in NO2 levels have been in central London (54%) but there have also been substantial reductions in inner London (29%) and outer London (24%).

The Mayor of London, Sadiq Khan, said: "When I was first elected, evidence showed it would take 193 years to bring London's air pollution within legal limits if the current efforts continued.

"However, due to our transformative policies we are now close to achieving it this year.

"Today's (7 March 2025) report shows that ULEZ works, driving down levels of pollution, taking old polluting cars off our roads and bringing cleaner air to millions more Londoners.

"The decision to expand the ULEZ was not something I took lightly, but this report shows it was the right one for the health of all Londoners.

"It has been crucial to protect the health of Londoners, support children's lung growth, and reduce the risk of people developing asthma, lung cancer and a host of other health issues related to air pollution. 

"With boroughs in outer London seeing some of the biggest reductions in harmful emissions and London's deprived communities also seeing greater benefits, this report shows why expanding ULEZ London-wide was so important.

"Thanks to ULEZ and our other policies, all Londoners are now breathing substantially cleaner air - but there is still more to do, and I promise to keep taking action as we build a greener, fairer London for everyone." 

Inner London has seen a 29% reductions in NO2 levels (credit: Cesar Medina).

As a result of all phases of the ULEZ, NOx emissions from road transport are estimated to be 36 per cent lower across London in 2024, 

Cumulatively between 2019 and 2024, the equivalent of nearly three million one-way passenger trips between Heathrow and New York has been saved in carbon due to ULEZ as a whole.

Data from the report, alongside independent analysis, also found that the ULEZ expansion has not impacted footfall or retail and leisure spending in either outer London or London as a whole.

Van compliance in outer London is over 90 per cent for the first time. In February 2017, just 12 per cent of vans met the ULEZ standards, demonstrating the schemes' impact on reducing the number of more polluting older vans driving in London.

Dr Maria Neira, Director, Department of Environment, Climate Change and Health at the World Health Organization commented: "Improving air quality through initiatives like the Ultra Low Emission Zone in London is crucial for protecting public health and reducing the burden of disease.

"Cleaner air leads to healthier communities, lower rates of respiratory and cardiovascular illnesses, and a better quality of life for all residents.

"The World Health Organization commends the efforts of cities like London in implementing measures to reduce emissions from vehicles and improve air quality, which ultimately contribute to a healthier and more sustainable urban environment."

To read the full report click here.