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Recruiting into a major study of air quality and children’s respiratory health

Over the past 15 years we have been conducting research into the adverse effects of carbonaceous particulate matter on child lung development and disease.

This research led to the 2016 Royal College of Physicians’ Air Pollution Working Party report “Every Breath We Take: the lifelong effects of air pollution”, which generated the evidence base for the health effects of air pollution, informing policy makers and improving public understanding of the health effects of air pollution.

In 2018, the Children’s Health in London and Luton (CHILL) study was launched to test the impact of London’s new Ultra Low Emission Zone on children’s respiratory health. The study is measuring the respiratory function and lung capacity of 3,200 primary school children in London and in Luton annually over four years to determine the effectiveness of the latest air pollution policy emerging from the Mayor of London’s office, whilst providing an indicator of whether such initiatives should be rolled out nationally and globally.

The NIHR Clinical Research Network (CRN) North Thames, part of UCLPartners, is helping to recruit primary school children to take part in the study.


Long term exposure to air pollutants stunts lung growth in children and increases the risk of respiratory conditions such as asthma.

Recent studies have shown that attempts to reduce pollution caused by traffic in central London, such as the introduction of London’s first Low Emission Zone in 2008, led to only small improvements in air quality and did not produce substantial health benefits for children.

London’s Ultra Low Emission Zone came into force in April 2019, following the launch of the CHILL study. This provided an opportunity to find out whether this new measure would positively impact child health – research that would require recruitment of a large number of children into an innovative new study.

What we did

The £3.3m CHILL study is funded by the National Institute for Health research (NIHR), and led by the Institute of Population Health Sciences, Queen Mary University of London, one of our AHSC partners.

The CRN North Thames helped recruit 3,417 primary school children to the study to time and target.

Nurses working on the project conduct spirometry ‘blow-tests’ to measure the size and function of the participants’ lungs. Height and weight measurements are taken, and seven-day activity monitors fitted, with questionnaires sent to parents for background information. The study has been designed to be both entertaining and educational for young recruits to the study, with children enjoying a science session on pollution and health in the classroom and receiving certificates for their participation.

The CRN have recruited a unique cohort of multi-ethnic children, many from disadvantaged backgrounds, to take part in this study. Of the children recruited, one third are from south Asian backgrounds, one third from white, with significant proportions from black African, Caribbean, and mixed ethnic backgrounds.

This recruitment has been made possible through collaborative working between CRN-funded staff from NHS trusts such as Barts Health NHS Trust, Camden and Islington NHS Foundation Trust, East London NHS Foundation Trust and Hertfordshire Community NHS Trust.


CHILL provides a chance to protect our children, ensuring that they enter adulthood with the best chance of long-term physical and intellectual health. The results of the study will have major implications for cities planning air quality improvement interventions in the UK, Europe and globally.

The CRN’s support enabled us to fully staff our health assessment visits to schools, so that we could assess more than 50 children daily. We wouldn’t have been able to complete our data collection without the CRN because our core team is too small. The CRN staff are great to work with – very professional and helpful, quick to learn the protocols and really good with the children.

Dr Helen E Wood, CHILL study project manager

Next steps

The cohort of children will be followed up with annual health assessments over four years, as we look at how their lungs develop. We are now measuring cognitive development and have collected DNA to examine the impact on brain function and genetic susceptibility, respectively.

CHILL is a collaboration led by Queen Mary University of London, with King’s College London, Edinburgh University, University of Bedfordshire, University of Cambridge and University of Southern California.