Study links London’s Ulez to improved lung growth in children
A study tracking schoolchildren in London and Luton found that London children’s lung size and function improved after the ultra-low emission zone (Ulez) began in 2019. Researchers followed 1,664 London children and 1,750 children in Luton from 2018 to 2022, using Luton as a comparison town without a clean-air zone. An independent expert said other factors, including pandemic-related pollution changes, mean the results cannot be attributed to Ulez with certainty.
The story
Researchers examined whether London’s ultra-low emission zone, introduced in 2019, was associated with changes in children’s lung development. They recruited 1,664 children aged six to nine in London before the scheme began and 1,750 children in Luton, a town described as having a similar mix of traffic pollutants but no clean-air zone. The children received annual school visits between 2018 and 2022, when the team measured their size and health. Before Ulez, the London group had significantly smaller lungs than the Luton group, according to the report. After the zone came into force, the London children’s lung size and function improved until they were comparable with those of children in Luton. The researchers said these improvements correlated strongly with better air quality. They reported that, within five years of Ulez’s introduction, London children’s exposure to nitrogen dioxide declined twice as fast and by twice as much as exposure among the Luton comparison group. Chris Griffiths of the University of Oxford and Queen Mary University of London, a joint senior author, said the research provided evidence that harms from traffic pollution can be prevented. However, Stephen Burgess of the University of Cambridge, who was not involved in the work, said it was unclear whether Ulez itself, rather than factors including the Covid pandemic’s effect on pollution, caused the observed changes.
Why it matters
The practical consequence is that a transport policy designed to restrict the most polluting vehicles may have health benefits measurable in children, rather than only changes in emissions or vehicle compliance. Lung capacity reduced in childhood has been associated in earlier London research with greater risks of respiratory, cardiovascular and metabolic disease later in life. If the association is confirmed in further work, city authorities weighing the costs of clean-air zones would have evidence that can be considered alongside traffic, affordability and air-quality outcomes. The comparison with Luton also gives the findings more context than a before-and-after result from London alone.
Evidence and context
London introduced Ulez in 2019 with public health among the stated reasons for the policy. The scheme restricted entry by the most polluting vehicles, though it also drew criticism from motorists over its costs and requirements. The new analysis addresses a question that was unresolved when the zone began: whether changes in urban air quality would be reflected in children’s physical development. The report places the findings against earlier research showing that, by ages eight or nine, children in London’s most polluted areas had 5% to 10% less lung capacity than peers elsewhere. Researchers attributed that impairment to nitrogen dioxide exposure. The reported London-Luton comparison therefore focuses on a health measure with potential relevance beyond short-term symptoms, while remaining an observational assessment of changes in two places over time.
Limits and unknowns
The study does not settle causation. Burgess said the observed differences could reflect factors other than Ulez, specifically including the effect of the Covid pandemic on pollution levels. The source does not provide enough detail to assess every possible difference between London and Luton, or whether children’s individual exposure, residential moves, household conditions and changes in travel were fully accounted for. Luton was selected as a comparison because it had a similar mix of traffic pollutants and no clean-air zone, but no comparison town can perfectly reproduce London’s circumstances. The results should therefore be read as encouraging comparative evidence rather than a definitive estimate of Ulez’s independent effect.
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Story timeline
Study monitoring begins
Researchers began annual school visits to measure the health and size of children in the London and Luton cohorts.
Ulez introduced
London introduced its ultra-low emission zone, restricting the most polluting vehicles from entering the zone.
Follow-up period ends
The reported annual monitoring of the children concluded.
Study links London’s Ulez to improved lung growth in children
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Highlights
- Ulez boosts children’s lung growth
- Study compares London and Luton children
- Lung function improvements post-Ulez
- Air pollution levels decline faster in London
Transcript
London’s ultra-low emission zone led to better lung size and function in children by 2022.
Researchers tracked 1,664 London children and 1,750 in Luton from 2018 to 2022 for lung health.
After Ulez started in 2019, London children’s lungs grew to match those of children in Luton.
Nitrogen dioxide exposure in London dropped twice as fast as in Luton, improving air quality.
The policy shows restricting polluting vehicles can measurably benefit children’s health long term.