London's ultra-low emission zone (ULEZ) has been linked to an improvement in children's lung growth, according to a study.
ULEZ charges drivers £12.50 per day for entering any of the capital's boroughs in older, more polluting vehicles.
Health measurements taken in 2018, before it was introduced, showed children in London had significantly smaller lung size compared with children in Luton.
But as the scheme was phased in, the study found the youngsters' lung health improved so that the two groups became comparable over a five-year period.
A team led by scientists at Queen Mary University came up with their findings after giving more than 3,400 children, aged six to nine, yearly tests between 2018 and 2022.
They found that improved lung growth trajectories were strongly related to air quality improvements.
Joint senior author of the report Chris Griffiths, a professor at Oxford and Queen Mary, said: "Traffic pollution in cities damages children's health and development.
"We provide the strongest evidence yet on how these harms can be prevented.
"Ambitious clean air zones should be considered a priority for cities globally with traffic-related air pollution."
ULEZ was introduced in 2019 and expanded to cover the areas inside the North and South Circular roads in 2021 and the whole of London in 2023.
Critics of the scheme argued it unfairly penalised people who can't afford newer vehicles. Some of the cameras that police the ULEZ zone were vandalised.
London mayor Sir Sadiq Khan said the research "proves we were right to act and reinforces my decision to extend the benefits of cleaner air to every child in London".
"Introducing and expanding ULEZ involved incredibly difficult decisions," he added.
"It was very tough, and a vocal minority backed by vested interests made it extremely difficult, but I refused to stand by while air pollution continued to damage Londoners' health."
People whose lungs are not fully developed by early adulthood are said to have an increased risk of asthma, cardiovascular and metabolic disease and premature death as adults.
Eighty-four primary schools took part in the research. To evaluate the children's lungs, researchers measured how much air they could forcibly exhale in one second (known as FEV1).
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They found the London kids' exposure to nitrogen dioxide fell twice as fast and more than twice as much compared with the Luton children in the years after ULEZ came in.
As their exposure decreased, the London children's FEV1 score increased by 10ml per year more than those in Luton.
There was also a bigger fall in the proportion of children with clinically impaired lung function: going from 14% to 9% in London but only 9% to 7% in Luton.
The research appears in The Lancet Public Health journal.
(c) Sky News 2026: London's ULEZ linked to improved lung growth in children, says study

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