A measurable improvement in children’s lung health has been seen in London since the introduction of traffic restrictions in an effort to cut air pollution, according to a study published in the Lancet.
Scientists compared the lung capacity of children in Luton, a town about 60 kilometres north of London, with that of children living in London.
They found that children in the UK capital had smaller lungs before London introduced its ultra-low emission zone (Ulez), but that over five years this changed so that the two groups had similar levels of lung size and health.
The study also found that the proportion of children who had clinically impaired lung function fell twice as much in London as in Luton over the period.
Ulez, which was introduced in central London in April 2019 and expanded to outer London in August 2023, charges drivers to bring older vehicles with more polluting engines into the city.
It’s designed to limit the amount of nitrogen dioxide in the air, a pollutant linked to breathing and circulation conditions like asthma and respiratory infections.
The study’s findings, which were published in The Lancet Public Health, “will provide crucial evidence on real-life interventions that deliver life-changing health benefits for children,” Professor Lucy Chappell, chief scientific adviser at the Department of Health and Social Care and chief executive officer of the National Institute for Health and Care Research, said in a statement published with the report.
“Air pollution is a global issue,” said Ian Mudway, associate professor in the School of Public Health at Imperial College London and joint senior author of the study. “If we want to improve the lives of children living in high-traffic urban environments, we need bold and ambitious measures.”
The expansion of Ulez in 2023, under Mayor Sadiq Khan, drew criticism from opponents who said it would penalise poorer Londoners and do little to solve the air quality problem in the city.
Since then, the mayor’s office has released evidence suggesting that levels of nitrogen dioxide have dropped, though they remain higher than the maximum levels recommended by the World Health Organisation.
“We already knew that the Ulez reduced air pollution,” said Helen Wood, a research fellow at Queen Mary University of London, and the study’s lead author. “But now we know that children’s lung health has improved at the same time, which is a really important finding for children and parents living in London.”
Others cautioned against inferring causality from the results. Stephen Burgess, professor of bio-statistics at the University of Cambridge, said factors such as the pandemic may have played a role. The documented change in lung function is “striking,” he said. However, it’s “more questionable” whether the improvements are due solely to the introduction of Ulez, he added.
Mr Khan said the study “proves we were right” to move ahead with the Ulez expansion, “and reinforces my decision to extend the benefits of cleaner air to every child in London.”
The study, which looked at more than 3,400 children, was led by researchers from Queen Mary University of London in collaboration with Imperial College London and the Universities of Bedfordshire, Oxford, Cambridge, Edinburgh and Southern California and funded by the NIHR.
