London clean-air zone linked to restored child lung growth

Children in London gained an additional 10 millilitres of lung capacity each year compared with peers in Luton after the Ultra Low Emission Zone was introduced.

Traffic pollution can stunt lung development, increasing the risk of respiratory and cardiovascular illness later in life. Researchers wanted to test whether a clean-air policy could reverse that harm.

The five-year CHILL study followed more than 3,400 children aged six to nine across 84 schools. Luton, which had similar traffic pollution but no clean-air zone, provided a comparison. After ULEZ began in 2019, nitrogen-dioxide exposure among London children fell more than twice as much and twice as quickly. Their lung capacity eventually became comparable with the Luton group, while clinically impaired lung function in London fell from 14% to 9%.

The findings provide unusually direct evidence that reducing traffic pollution can restore children’s lung growth. They do not mean the problem is solved: pollution in both cities remains above World Health Organization guidance.

Researchers say cities can adapt clean-air zones, while continued monitoring and further pollution cuts will test whether the health gains last.