London’s ULEZ, Six Years On: Measuring the Impact
In our first article, we explained what London’s Ultra Low Emission Zone (ULEZ) actually is. Here, we look at what six years of evidence, including research published just last month, tells us about its effect on health, pollution, travel habits and the wider economy.
The health evidence: children’s lungs and premature deaths
The most significant recent findings come from two independent studies published in August 2026. The first, the Children’s Health in London and Luton (CHILL) study led by Queen Mary University of London and published in The Lancet Public Health, tracked lung growth in more than 3,400 children aged six to nine across 84 primary schools in London and Luton (used as a comparison area with similar traffic pollution but no clean air scheme).1
Before the ULEZ was introduced, children in London had significantly smaller lung capacity than children in Luton. Over the following five years, NO2 exposure fell more than twice as fast among the London children, and their lung growth accelerated to close the gap almost entirely. The proportion of children in London with “clinically impaired” lung function, associated with symptoms such as coughing or breathlessness, fell from 14% to 9%, compared with a smaller fall from 9% to 7% in Luton.1 Lead author Dr Helen Wood noted that while the results are encouraging, air pollution in both areas remains above World Health Organization guideline levels, so the improvement is not a reason for complacency.1
The second study, an independent analysis by Imperial College London’s Environmental Research Group, estimated that deaths associated with air pollution across London fell by around 40% between 2019 and 2024, from roughly 6,400-8,000 to 3,800-5,100 a year, alongside a 41% fall in NO2 and a 28% fall in PM2.5 concentrations over the same period.2 The same research found a 9.3% reduction in the trend for cardiac-related emergency hospital admissions and a 5.1% reduction across all admissions.2
Air pollution more broadly
TfL and the Greater London Authority’s London-wide ULEZ One Year Report, covering the first full year after the 2023 expansion, found NO2 an estimated 27% lower London-wide than it would have been without the scheme, with the largest falls in central London (54%).3 Vehicle compliance has risen sharply too: 96.7% of vehicles seen driving in outer London now meet ULEZ standards, up from just 39% in February 2017.3
Commuter habits and tourism
Evidence on behaviour change is more mixed than the pollution and health data. TfL found some shift towards public transport, but total traffic volumes have continued to rise since 2023, suggesting the ULEZ has changed the mix of traffic more than its overall volume.3 Separately, University of Cambridge research found children living within the ULEZ were significantly more likely to switch from being driven to school to walking or cycling, compared with children in Luton.4
Concerns that the 2023 expansion would hurt outer London’s high streets and tourism have not been borne out: visitor footfall in outer London rose 1.87% in the year following expansion, against 0.08% across London as a whole.3
Revenue and where it goes
The ULEZ generated £224.6 million in 2022, around £194 million in the year following the August 2023 expansion, and a record £219 million in 2025 [5]. By TfL policy, net revenue must be reinvested into running and improving London’s public transport network. TfL expects net income to become negligible and the scheme to stop generating a surplus by around 2027 as compliance keeps rising.3
In our final article on the ULEZ, we’ll look at the fairness and enforcement debate that continues to surround the scheme, and what the future holds.
Sources
- Wood HE, et al. “Impact of the Ultra Low Emission Zone on lung function growth in children in London, UK: a prospective parallel cohort study.” The Lancet Public Health, 2026. https://www.qmul.ac.uk/news/latest-news/2026/queen-mary-news/pr/introduction-of-londons-ultra-low-emission-zone-linked-to-improved-lung-growth-in-children–.html
- Imperial College London, “Introduction of London’s ULEZ linked to improved lung growth in children” / Environmental Research Group analysis of air pollution-related deaths: https://www.imperial.ac.uk/news/articles/2026/introduction-of-londons-ulez-linked-to-improved-lung-growth-in-children-/
- Greater London Authority / Transport for London, London-wide ULEZ One Year Report (March 2025): https://www.london.gov.uk/sites/default/files/2025-03/London-wide%20ULEZ%20One%20Year%20Report_Mar2025.pdf
- University of Cambridge, “Children switch to walking and cycling to school after introduction of London’s Ultra-Low Emission Zone”: https://www.cam.ac.uk/research/news/children-switch-to-walking-and-cycling-to-school-after-introduction-of-londons-ultra-low-emission
- London Assembly, “ULEZ charges and fines” (Mayor’s Question Time answer): https://www.london.gov.uk/who-we-are/what-london-assembly-does/questions-mayor/find-an-answer/ulez-charges-and-fines
