Children's Health in London and Luton (CHILL)

NCT ID: NCT04695093

Last Updated: 2025-03-10

Basic Information

• Recruitment Status: ACTIVE_NOT_RECRUITING
• Total Enrollment: 3312 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2023-03-29
• Study Completion Date: 2026-07-01

Brief Summary

Investigating the impact of London's Ultra Low Emission Zone on children's respiratory health

Detailed Description

Strong evidence links urban air pollution to restrictions in children's lung growth and development and other adverse effects, including increases in respiratory and allergy symptoms, respiratory infections, asthma, and health care use. Effective interventions are urgently needed that reduce air pollution and improve child health. Low Emission Zones (LEZ) are becoming widespread but are expensive to implement and of unproven health benefit. London has some of the worst air pollution in Europe. London's Ultra Low Emission Zone (ULEZ) is the central component of London's air quality strategy. Its implementation provides a unique opportunity to test the impact of a city-wide LEZ on children's health.

The intervention:

The ULEZ is an area within which all vehicles must meet exhaust emission standards or pay a daily charge to travel. It will be implemented and paid for by Transport for London. Starting in 2019, the ULEZ will initially cover London's central Congestion Charging Zone, an area bounded by the London Inner Ring Road, that includes the City of London plus adjacent areas of eight radially adjoining Boroughs. It is projected to deliver for central London by 2020 emission reductions of -49% for NOx; - 47% for NO2; and -11% for PM10. Subject to consultation, the ULEZ will subsequently extend to include an inner London area (within London's North and South Circular roads), and a London-wide area, for heavy vehicles only.

Questions:

1. What is the impact of the ULEZ on children's lung growth (the primary outcome)?

2. What is the impact of the ULEZ on secondary outcomes, including self-reported symptoms, respiratory infection, health care use and costs?

3. Does the ULEZ reduce health inequalities? 4) Is the ULEZ good value for money?

Study design:

Quasi-experimental study using a parallel cohort design. Population: 1520 children aged 6-9 yrs old, recruited in 26 London primary schools (school years 2, 3 and 4) in London's Central Ultra Low Emission Zone. Intervention: Ultra Low Emission Zone Comparison: 1520 children aged 6-9 yrs old, recruited in 26 primary schools (school years 2, 3 and 4) in Luton, matched for ethnicity, deprivation and baseline air quality.

Outcome: PRIMARY: Lung function growth (post-bronchodilator forced expiratory volume in one second (FEV1) measured by high quality spirometry at sequential annual school visits over four years. SECONDARY: Forced vital capacity (FVC), exhaled nitric oxide (FeNO), quality of life, respiratory infections, health care use, health costs.

Sample size:

To detect a 15ml/year FEV1 difference between central and outer London cohorts at 90% power and 0.05 significance requires children in each cohort, inflated to allow for clustering effect of schools, spirometry success, child and school attrition, and pre-specified sub group analyses, giving a total of 3120 children (60 children from 26 schools in each cohort).

Duration: 6 years Air quality data: Modeled exposures by London Air Quality Network Data management: NIHR accredited Pragmatic Clinical Trials Unit Analysis: Interaction analysis controlling for effect modifiers (eg passive smoke; ethnicity); health economic cost consequence analysis.

Conditions

Pollution; Exposure; Respiratory Disease; Child Development

Study Design

• Observational Model Type: COHORT
• Study Time Perspective: PROSPECTIVE

Study Groups

London (intervention)

1606 children aged 6-9 yrs old, recruited in 44 London primary schools (years 2-4) within the Central London ULEZ area

Ultra Low Emission Zone (ULEZ)

Intervention Type: OTHER

The ULEZ comprises a Central London zone, implemented on 8th April 2019, within which polluting vehicles are subject to a charge. Using number plate recognition technology, a daily penalty charge notice is issued for vehicles entering this central zone not meeting the standard of Euro 4 for petrol, Euro 6/VI for diesel, and Euro for motorcycles.

The ULEZ will subsequently be extended to include:

1. In 2020, a London-wide ULEZ for heavy duty vehicles (HDV) within the LEZ boundary (green zone). HDVs not meeting Euro 6 standard will be charged daily.

2. In 2021, an Inner London ULEZ area for all light duty vehicles (LDV) within the boundary of the North and South Circular Roads (yellow zone). Vehicles not meeting the above criteria will be charged daily as for the Central London area.

Luton (comparison)

1706 children aged 6-9 yrs old, recruited in 41 Luton and Dunstable primary schools (years 2-4)

No interventions assigned to this group

Interventions

Ultra Low Emission Zone (ULEZ)

The ULEZ comprises a Central London zone, implemented on 8th April 2019, within which polluting vehicles are subject to a charge. Using number plate recognition technology, a daily penalty charge notice is issued for vehicles entering this central zone not meeting the standard of Euro 4 for petrol, Euro 6/VI for diesel, and Euro for motorcycles.

The ULEZ will subsequently be extended to include:

1. In 2020, a London-wide ULEZ for heavy duty vehicles (HDV) within the LEZ boundary (green zone). HDVs not meeting Euro 6 standard will be charged daily.

2. In 2021, an Inner London ULEZ area for all light duty vehicles (LDV) within the boundary of the North and South Circular Roads (yellow zone). Vehicles not meeting the above criteria will be charged daily as for the Central London area.

Intervention Type: OTHER

Other Intervention Names

Clean Air Zone

Eligibility Criteria

Inclusion Criteria

• Primary schools within, or with catchment areas that include, the Central London ULEZ.
• Primary schools within the Borough of Luton and town of Dunstable.
• State or independent sectors.

• Children attending a study school, in years 2, 3, or 4, at study inception.

Exclusion Criteria

• Schools that are not primary schools within the above boundaries.

• Children with learning or physical disabilities sufficient for them to be unable to give informed assent to the study, or to carry out study procedures.
• Children with major lung disease (not including asthma).

• Minimum Eligible Age: 9 Years
• Maximum Eligible Age: 9 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

King's College London

OTHER

Sponsor Role: collaborator

University of Edinburgh

OTHER

Sponsor Role: collaborator

University of Bedfordshire

OTHER

Sponsor Role: collaborator

University of Cambridge

OTHER

Sponsor Role: collaborator

University of Southern California

OTHER

Sponsor Role: collaborator

Queen Mary University of London

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Mays Jawad, PhD

Role: STUDY_DIRECTOR

Queen Mary University of London

Locations

Queen Mary University of London

London, , United Kingdom

Countries

United Kingdom

References

Tsocheva I, Scales J, Dove R, Chavda J, Kalsi H, Wood HE, Colligan G, Cross L, Newby C, Hall A, Keating M, Sartori L, Moon J, Thomson A, Tomini F, Murray A, Hamad W, Tijm S, Hirst A, Vincent BP, Kotala P, Balkwill F, Mihaylova B, Grigg J, Quint JK, Fletcher M, Mon-Williams M, Wright J, van Sluijs E, Beevers S, Randhawa G, Eldridge S, Sheikh A, Gauderman W, Kelly F, Mudway IS, Griffiths CJ. 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. BMC Pediatr. 2023 Nov 4;23(1):556. doi: 10.1186/s12887-023-04384-5.

Reference Type: DERIVED

PMID: 37925402 (View on PubMed)

Other Identifiers

239719

Identifier Type: -

Identifier Source: org_study_id