Air pollution across the capital has plummeted as a result of the expanded Ultra Low Emission Zone (ULEZ), evidence reveals.
Despite widespread controversy when the ULEZ was expanded to Greater London in August 2024, a new City Hall report shows that the scheme – described as the largest clean air zone in the world – has led to substantial improvements in air quality.
The research, extensively reviewed by an independent advisory group of experts, finds that particle emissions (PM 2.5) from vehicle exhausts are 31% lower in outer London in 2024 than they would have been without the ULEZ expansion.
Roadside nitrogen dioxide (NO2) levels, a toxic gas that exacerbates asthma, impedes lung development and raises the risk of lung cancer, have decreased by a record 27% across the entire capital. The biggest cuts in NO2 levels have been in central London (54%) but there have also been substantial reductions in inner London (29%) and outer London (24%).
Alongside NO2 and PM2.5 reductions, NOx (nitrogen oxides) emissions from cars and vans are also estimated to be 14% lower in outer London.
The boroughs that have seen the biggest reductions in NOx emissions due to the ULEZ expansion are Sutton, Merton, Croydon, Harrow and Bromley, where harmful emissions are estimated to be around 15% lower in due to the ULEZ expansion. Notably, both Bromley and Harrow took part in a failed legal challenge to stop the ULEZ expansion.
Across all phases of the ULEZ, which first launched in April 2019 in central London, NOx emissions from road transport are estimated to be 36% lower across London in 2024, a saving of around 3,400 tonnes – the equivalent of approximately one year of emissions from all passenger car trips in Los Angeles.
The report also shows that the ULEZ has led to savings in carbon emissions since the scheme first started.
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 the ULEZ as a whole.
Air quality has improved at 99% of air quality monitoring sites across London since 2019, and London’s air quality is improving at a faster rate than the rest of England.
Both the report and independent analysis show that the expansion of the ULEZ has not been to the expense of footfall or retail and leisure spending in either outer London or London as a whole – despite fears. Visitor footfall in outer London increased by almost 2% in the year after the London-wide ULEZ expansion.
Mayor of London Sadiq Khan said: “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. ”
TfL data also shows the extent of Londoners’ switch to cleaner vehicles; 96.7% of vehicles seen driving in London are now ULEZ compliant, up from 91.6% in June 2023 and 39% in February 2017, when changes associated with the ULEZ began.
Van compliance in outer London is over 90% for the first time (90.7%). In February 2017, just 12% of vans met the ULEZ standards, demonstrating the schemes’ impact on reducing the number of more polluting older vans driving in London.
In London, around 4,000 premature deaths per year were previously attributed to toxic air. Air pollution increases the risk of developing asthma, lung cancer, heart disease and stroke, and there is growing evidence that air pollution exposure increases the risk of developing dementia.
The World Health Organization welcomed the City Hall findings and said improving air quality through initiatives such as the London ULEZ is crucial for protecting public health and reducing the burden of disease.
Dr Maria Neira, director of the Department of Environment, Climate Change and Health, outlined: “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 such as London in implementing measures to reduce emissions from vehicles and improve air quality, which ultimately contribute to a healthier and more sustainable urban environment.”
