London ULEZ: Children's Stunted Lungs Recovered in Four Years
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- Researchers tracked 3,400+ children aged 6-9 in London and Luton from the year before London's Ultra Low Emission Zone launched in 2019 through four years afterward, finding London children's lungs started smaller but reached near-identical capacity to Luton's by study's end.
- Prof Chris Griffiths of Queen Mary University of London said he was "absolutely stunned" by the speed of catch-up in lung capacity, calling it "surprising and impressive," while his team measured how much air children could forcibly exhale in one second.
- Clinically impaired lung capacity among London children fell from 14% to 9% over the study period, compared with a drop from 9% to 7% in Luton, where smaller-scale anti-pollution measures were in place.
- Nitrogen dioxide exposure declined faster in London than Luton during the study, which researchers point to as the likely driver of the improved lung growth, according to the paper published in the Lancet Public Health.
- Mayor Sadiq Khan launched the central London Ulez in 2019 with a daily charge on older, more polluting vehicles, later expanding it across the capital — a policy that drew political opposition and protests despite the new evidence of health benefits.
- Independent reviewers Prof Anna Hansell and Kevin McConway praised the study's design — including its geographical comparison, which helps separate the findings from Covid-era pollution changes — but flagged that unmeasured differences between the cities and shifts in how children travelled to school could also have played a role.
- Dr Helen Wood, the study's lead author, cautioned that air pollution in both London and Luton "remains above WHO guideline levels," framing the results as evidence for clean air zones with "global relevance" for the more than a billion children living in polluted cities.
Why it matters: The London Ulez expansion has been politically contentious, with critics questioning whether the daily charge on polluting vehicles is worth the economic pain. This peer-reviewed study, using a Luton control group to isolate the policy's effect, provides the strongest evidence yet that cutting traffic emissions measurably restores children's lung growth within four years — directly strengthening Khan's case while remaining short of claiming the gains are solely due to the zone.
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