London restricted highly polluting cars. Children’s lungs are getting healthier, study suggests

By Jack Guy, CNN

London (CNN) — Restrictions on older, more polluting vehicles from most of the British capital is “strongly” associated with improved lung health in children, according to a new study.

Researchers found that improvements in air quality following the 2019 introduction of London’s Ultra Low Emission Zone (ULEZ) helped to boost lung growth, which was previously stunted due to the effects of air pollution, said a team led by scientists from Queen Mary University of London (QMUL).

“We already knew that the ULEZ reduced air pollution 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,” said study lead author Helen Wood, a research fellow at QMUL, in a statement Wednesday.

In practice, ULEZ introduced a 24-hour, seven days a week charge of £12.50 ($17) for vehicles that don’t meet tough emissions standards. Initially covering the inner city, it was expanded in August 2023 to cover the capital’s outer boroughs and suburbs.

The study tracked more than 3,400 children aged 6 to 9 from 84 different schools in London and Luton, a town about 30 miles north of the British capital between 2018 and 2022. Luton acted as a comparison, or control, site, as it has a similar mix of traffic pollutants but no ULEZ.

Initially, children in London were found to have “significantly” smaller lung capacity than those living in Luton.

Scientists then measured the children’s lung size and health over five years during annual school visits, with data revealing that the size and health of London children’s lungs improved following the introduction of ULEZ, recovering to a similar level as those in Luton.

“Over the course of the study, the team noted that the proportion of children with clinically impaired lung function fell from 14% to 9% in London, compared with a fall from 9% to 7% in Luton,” reads the statement.

While Luton didn’t introduce a clean air zone, the local council did take action to improve air quality during the study period, including reducing speed limits and developing cycling and walking networks, according to the study.

Children whose lungs fail to develop fully by early adulthood face an increased risk of developing respiratory conditions such as asthma and COPD (chronic obstructive pulmonary disease), which includes conditions such as emphysema and chronic bronchitis, cardiovascular and metabolic disease, as well as premature death, according to researchers.

The results of the study, which show that deficits in lung health can be restored, have “major implications for improving the long-term health of children,” they said in the statement.

This is the first evidence that clean air zones, which have been introduced in a number of cities around the world, may benefit child development, researchers said.

“Air pollution is a global issue. If we want to improve the lives of children living in high-traffic urban environments, we need bold and ambitious measures,” said joint senior author Ian Mudway, associate professor in the School of Public Health at Imperial College London, in the statement.

“Our data demonstrates that clean air zones can be an effective public health intervention to prevent damage to developing lungs.”

Mayor of London Sadiq Khan, who introduced the ULEZ in April 2019, faced considerable criticism over the measure.

He wrote an op-ed in British newspaper The Guardian on Tuesday, calling the decision to implement it “my hardest decision as mayor of London,” with all of the UK’s mainstream political parties opposed to it.

“For years, politicians and pundits opposed to the Ulez have cynically sought to turn questions of public health into a crude culture war,” wrote Khan. “Today, though, it’s clear that we’re winning the battle against toxic air in the capital – and it’s London’s children who are reaping the rewards.”

‘Striking’ findings

Stephen Burgess, a professor of biostatistics at the University of Cambridge, England, who was not involved in the study, said that he had approached the research “with a high level of scepticism.”

“My expectation was that the ULEZ regulations would have little measurable impact on child health,” he said in a statement to the Science Media Centre.

“However, the findings are striking,” said Burgess, who nonetheless pointed out that there may be alternative explanations for the improvement in lung function, such as a fall in pollution levels during the Covid-19 pandemic.

“Whether this improvement can be attributed to the introduction of ULEZ regulations is more questionable,” he added. “Nevertheless, the finding is important because lung function in childhood is an important measure of health, and the study provides encouraging evidence that changes in the urban environment may benefit children’s lung development.”

However, Kevin McConway, emeritus professor of applied statistics at the UK’s Open University, who was not involved in the research, said that, while the study suggests that the introduction of ULEZ likely improved children’s lung function, it doesn’t prove a link.

“This paper does not establish that this is the only explanation, and the researchers indicate this by talking about the ULEZ introduction being ‘associated with’, that is, correlated with, faster growth in lung function, rather than definitely being a cause of that difference,” he said in comments to the Science Media Centre.

McConway added that the study was limited to just two geographical areas – London and Luton.

“I think that the results might have had a clearer interpretation if the researchers could have included data from a few more places where clean air zones were introduced, and a few more places where they weren’t,” he added.

The study was published in the journal “The Lancet Public Health.”

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