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The health of children’s lungs in London improved to the point of catching up with children outside of London following the introduction of the Ultra Low Emission Zone (ULEZ), a new study has found.
Led by Queen Mary University of London, the research links the improvement in child lung health to air quality improvement tied to the ULEZ. The scheme requires drivers of vehicles that do not meet emissions standards to pay a daily charge to enter the zone.
ULEZ was introduced in central London in 2019 before being expanded across Greater London in 2023. The study is the first evidence that a clean air zone can benefit children’s lung development.
The five-year study tracked more than 3,400 children aged six to nine at 84 primary schools in London and Luton between 2018 and 2022. Researchers from Imperial College London and the universities of Bedfordshire, Oxford, Cambridge, Edinburgh and Southern California also took part.
Luton was used as a comparison site because its children were exposed to a similar mix of traffic pollutants but were not covered by a clean air zone. Researchers had previously found that children in London had significantly smaller lungs than those in Luton.
By the end of the study, that gap had closed. London children’s lung growth had accelerated and their lung function had reached the same level as the children in Luton.
Jemima Hartshorn, Founder and Director of the nonprofit Mums for Lungs, told Zag Daily the findings showed that “impactful clean air leadership is really worth it”.
“We know that London’s polluted air stunted children’s lungs and now we can see that cleaning up the air has reversed this impact and lung damage in the same kids has caught up,” she said.
A closer look at the findings
The researchers measured forced expiratory volume in one second (FEV1). This records how much air a person can forcefully exhale after taking a full breath. They also measured exposure to nitrogen dioxide (NO2), a pollutant closely associated with vehicle exhaust. London children’s exposure to NO2 fell twice as fast and by more than twice as much as exposure among children in Luton.
As NO2 exposure fell, London children’s FEV1 increased by an additional 10ml per year compared with children in Luton. By the end of the five-year study, FEV1 was the same across the two groups.
The proportion of children with clinically impaired lung function also fell from 14% to 9% in London. In Luton, it fell from 9% to 7%.
Professor Chris Griffiths, Professor of Primary Care at the University of Oxford and Queen Mary University of London and joint senior author, said the study provided “the strongest evidence yet” on how the harms caused by traffic pollution can be prevented.
“Ambitious clean air zones should be considered a priority for cities globally with traffic-related air pollution,” he said.
Failure to reach fully developed lungs by early adulthood is associated with a higher risk of respiratory diseases including asthma and COPD, cardiovascular and metabolic disease and premature death later in life.
“The job’s not done,” Hartshorn added, explaining that air pollution in London and across much of England remains above World Health Organization guideline levels.
She called for further action to reduce pollution from transport, domestic burning, agriculture and industry.
Dr. Helen Wood, Research Fellow at Queen Mary University of London and lead author, said the findings showed that children’s lung health had improved alongside falling pollution, though warned again that “there is still work to be done”.
The researchers said the findings support wider consideration of ambitious clean air zones as a public health intervention, particularly in cities with high levels of traffic pollution.
