Deaths linked to air pollution in London fell by an estimated 40% over the five years from 2019, according to a new analysis by Imperial College London. The study found that nitrogen dioxide levels dropped 41% and fine particulate pollution decreased 28% during the period.
Revised Health Impact Estimates
Imperial's researchers updated their scientific evidence, showing that the impact of air pollution on health is greater than previously understood. Earlier estimates attributed 4,000 premature deaths in 2019 to air pollution, but that figure has been revised up to 6,400–8,000. In 2024, the estimated number fell to 3,800–5,100.
Dr David Dajnak, from the Imperial Environmental Research Group, said: “Our study highlights two key findings: London’s air quality has improved markedly since 2019, but despite this progress, air pollution remains a serious public health risk.” Recent evidence links air pollution to cardiovascular conditions, dementia, diabetes, and respiratory diseases.
Ulez Expansion and Borough-Level Data
The research found that outer London boroughs—including Bexley, Havering, and Sutton—had the highest ratio of deaths attributable to air pollution in 2024. City Hall said this underlined the significance of Mayor Sadiq Khan’s decision to expand the ultra-low emission zone (Ulez) to all of London in 2023, despite widespread local opposition.
While the independent Imperial report does not single out the Ulez or any other policy, Khan said: “The evidence is now overwhelming and unarguable: the bold action we have taken in London has reduced pollution, improved public health and saved lives. This latest data shows why expanding Ulez London-wide was even more important than we previously thought and is transforming lives right across our capital.”
Ulez Implementation and Compliance
The Ulez was launched in 2019 in central London and widened across inner boroughs in 2021. Vehicles that fail to meet emission standards—typically diesel engines from before 2015 or petrol from before 2004—must pay a daily charge, starting at £12.50 for cars. About 97% of vehicles driving in the zone are now compliant.
A separate study last year for the Greater London Authority showed that roadside NO2 pollution was 27% lower than expected without the Ulez.
Additional Measures and Reactions
Khan is due to visit a primary school in east London on Wednesday, echoing a 2016 visit when he pledged to speed up policies to clean up London’s air. Other measures include providing £2.7 million for indoor air quality filters in 200 primary schools and increasing zero-emission buses in Transport for London’s fleet from 30 to over 3,000 in the last decade.
Prof Stephen Holgate, special adviser on air quality at the Royal College of Physicians, called the scale of improvement “so encouraging” and “a powerful reminder that decisive, sustained action can deliver real, measurable benefits for people’s health.”
Jemima Hartshorn, of Mums for Lungs, said the research showed that Ulez helped clean up the air, but added: “Over 100,000 children went to hospital with breathing issues in London in 2024. And other cities and regions are still more polluted. Londoners need more action, and so does the rest of the country.”
