Asthma UK Centre for Applied Research

Project: CHILL

CHILL (Children’s Health in London and Luton)

Air pollution has been shown to stunt children’s lung growth and increase amount of asthma attacks. London’s Ultra Low Emission Zone (ULEZ) is designed to reduce air pollution caused by traffic in central London.

Children’s Health in London and Luton (CHILL) aims to independently evaluate whether the Ultra Low Emission zone is effective at reducing air pollution in London and therefore improving children’s Health.

Effects of Pollution on Children’s Health

A schoolgirl blowing into a machine which is measuring her lung capacity

CHILL is a research study which aims to find out whether reducing air pollution from traffic is good for children’s health. We are particularly interested in whether interventions to reduce air pollution can improve children’s lung growth and respiratory symptoms, activity levels and brain function. We are also interested in whether exposure to air pollution in childhood leaves markers on genes that reflect pollution levels over time.

Image of a schoolgirl using a spirometer

We have recruited over 3,416 primary school pupils across London, Luton and Dunstable to take part. These children will be assessed once a year for up to four years.

What we’ll do

We’ll have science workshops in schools run by Centre of the Cell from Bart’s Medical School in London teaching children about:

  • Air pollution
  • How to measure it
  • How it affects our bodies

We’ll carry out health checks to assess the children’s:

  • Weight
  • Height
  • Lung function

We’ll monitor the children for up to a week to record their:

  • Activity levels
  • Routes to and from school

We ask the children’s parents or guardians to complete an annual questionnaire that provides information about respiratory symptoms and air pollution exposure. Over the following three years, the health check will be repeated once a year to see how the children’s lungs are growing. At the end of the study the parents or guardians will be asked if they want to share the children’s GP records for information about appointments for coughs and colds. Results of the study will help towns and cities across the UK and the world cut pollution and make sure children have healthy lungs.

Watch a BBC News video on the CHILL study

Visit the CHILL study website


  • CHILL is now in its third year.
  • We have visited most of the 85 schools twice. After taking a pause due to the pandemic we will start our third year testing in January 2021.
  • So far we have presented our science workshops to more than 15,000 children. We are currently designing our new workshop that will discuss how air pollution impacts the way we think.

Key People

Chris Griffiths

Chris Griffiths

Headshot of Helen E Wood

Helen E Wood

Centre Director,

Lead: Preventing asthma attacks

Project Manager - London
Based at: Queen Mary University, London Based at: Queen Mary University, London
Chris' Profile CHILL Team page
headshot of Harpal Kalsi

Harpal Kalsi

headshot of James Scales

James Scales

Research Fellow Postdoctoral Researcher
Based at: Queen Mary University, London Based at: Queen Mary University, London
CHILL Team page CHILL Team page
Headshot of Grainne Colligan

Grainne Colligan

headshot of Iva Tsocheva

Iva Tsocheva

Research Nurse Postdoctoral Researcher
Based at: Queen Mary University, London Based at: Queen Mary University, London
CHILL Team page CHILL Team page


January 2018- December 2023

Contact us

For updates on the project and related news, follow us on Twitter @CHILLpollution

If you want to contact the study team directly email us on or

Summary of Key Papers

Grainne Colligan, Ivelina Tsocheva, James Scales, Jasmine Chavda, Rosamund Dove, Harpal Kalsi, Helen Wood et al. Investigating the impact of London’s Ultra Low Emission Zone on children’s health: Children’s Health in London and Luton (CHILL): Protocol for a prospective parallel cohort study. medRxiv (2021). DOI: 10.1101/2021.02.04.21251049

Previous work in air pollution and asthma

Before the CHILL study researchers from both the MRC Asthma UK Centre in Allergic Mechanisms of Asthma and the Asthma UK Centre for Applied Research conducted the first study in the UK to show that air pollution stunts lung growth by evaluating the impact of London’s Low Emission Zone.

BBC News article: Pollution linked to 'stunted lung capacity' in London schoolchildren

News story: Exposure to air pollution restricts children’s lung development


We are funded research funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme (Reference Number 16/139/01). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.

The North Thames CLAHRC, Barts Charity, the office of the Mayor of London and the Medical Research Council, has provided extra funding for elements the study.