NEXUS researchers contribute to major study linking London’s ULEZ with improved children’s lung growth
New research involving leading members of the NEXUS network has found that cleaner air following the introduction of London’s Ultra Low Emission Zone (ULEZ) was associated with improved lung growth in primary school children.
Published in The Lancet Public Health, the Children’s Health in London and Luton (CHILL) Study followed more than 3,400 children aged 6–9 years from 84 primary schools over five years.
The research was jointly led by researchers at Queen Mary University of London and the Nuffield Department of Primary Care Health Sciences at the University of Oxford, with collaborators from Imperial College London and the Universities of Bedfordshire, Cambridge, Edinburgh and Southern California.
Professor Chris Griffiths, NEXUS Director, is joint lead investigator of the CHILL Study, while Professor Ian Mudway, NEXUS Co-Lead, is also a key author on the research. Professor Monica Fletcher OBE, a member of the NEXUS leadership team, is also among the study authors.
Cleaner air associated with improved lung growth
The study compared children living in central London with children in Luton, which does not have a clean air zone and provided a reference group.
Before the ULEZ was introduced in 2019, children living in central London had significantly smaller lung capacity than children in Luton. Over the following four years, nitrogen dioxide (NO₂) pollution – an important marker of traffic exhaust emissions – fell more than twice as fast in London as in Luton.
During the same period, children’s lung growth accelerated in London, with average lung function catching up with that of children in Luton by the end of the study.
The proportion of London children with clinically impaired lung function also fell from 14% – around one in seven – to 9%, or around one in 11.
The researchers say this is the first study to demonstrate that improvements in air quality following the introduction of a clean air zone are associated with improved lung growth in children.
Professor Chris Griffiths said:
“The findings of our study provide strong evidence that ambitious clean air policies can improve children's long-term health and development. Cities around the world facing traffic-related air pollution should consider clean air zones as an important public health intervention.”
Unequal impacts of air pollution
The research also found that the effects of air pollution were not experienced equally. Across the study population, long-term exposure to air pollution was associated with reduced lung growth, with Asian and Black children experiencing significantly larger pollution-related deficits than White children.
The findings provide further evidence of the importance of understanding not only how air pollution affects health, but who is most affected and how effective interventions can reduce exposure and improve outcomes.
Connecting the findings to NEXUS
The CHILL findings are particularly relevant to the work of NEXUS as transport-related air pollution continues to evolve.
While measures such as clean air zones can substantially reduce emissions from vehicle exhausts, particles generated through tyre wear, brake wear and road wear remain an important and growing component of transport-related air pollution.
NEXUS brings together researchers from across health, engineering, environmental science and policy to better understand these non-exhaust emissions, their effects on human health and how the evidence can support effective interventions and future policy.
The CHILL Study demonstrates what can be achieved when robust research is used to evaluate real-world environmental interventions. NEXUS is building on this wider evidence base to address the next generation of questions around transport, air pollution and health.
Read the full study and find out more below.