Key facts
- Children's lung capacity and function improved after London's Ultra Low Emission Zone (Ulez) was introduced.
- The study compared children in London with similar children in Luton.
- London children's lung growth accelerated to catch up with the control group in Luton.
- The proportion of children in London with 'clinically impaired' lung capacity fell from 14% to 9%.
- Nitrogen dioxide exposure fell twice as fast in London as in Luton after Ulez implementation.
- Researchers believe the findings provide strong evidence that clean-air zones can prevent harm to children's health.
Scientists have reported being "stunned" by the rapid recovery and growth of young children's lungs following the implementation of London's Ultra Low Emission Zone (Ulez). A study involving over 3,400 primary school children in London and Luton found that lung function and capacity, which had been stunted by pollution, showed significant improvements after Ulez reduced emissions.
The research, which followed children aged six to nine for five years, compared those in London's Ulez zone with a control group in Luton. Initial findings indicated that London children had smaller lung capacities before Ulez was introduced. However, by the end of the study period, the London children's lung growth had accelerated to reach levels comparable to those in Luton.
Professor Chris Griffiths, a senior author, described the speed of this catch-up as "surprising and impressive," suggesting that ambitious clean air zones can effectively lower pollution and rapidly restore stunted lung growth. The study measured lung capacity using tests like how much air a child could forcibly breathe out in one second. Overall, the proportion of children in London with "clinically impaired" lung capacity decreased from 14% to 9% over the study period.
Researchers noted that nitrogen dioxide levels fell twice as fast in London as in Luton, likely linking the improved lung growth to air quality enhancements following Ulez. London's Ulez, introduced in 2019 by Mayor Sadiq Khan, targets older, more polluting vehicles with a daily charge to reduce harmful emissions, particularly nitrogen dioxide from motor vehicles. The policy was later expanded to cover the entire capital.
Independent researchers acknowledged the study's potential lifelong health benefits for children, noting its careful methodology and geographical comparison. However, they cautioned that other factors, including the impact of the COVID-19 pandemic and potential differences in walking or cycling habits between the groups, should also be considered. Air pollution levels in both London and Luton remain above WHO guideline levels, indicating further work is needed.