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Exposure to traffic-related air pollution and risk of development of childhood asthma: A systematic review and meta-analysis

Khreis, Haneen; Kelly, Charlotte; Tate, James; Parslow, Roger; Lucas, Karen; Nieuwenhuijsen, Mark


Haneen Khreis

James Tate

Roger Parslow

Karen Lucas

Mark Nieuwenhuijsen


Background and objective The question of whether children's exposure to traffic-related air pollution (TRAP) contributes to their development of asthma is unresolved. We conducted a systematic review and performed meta-analyses to analyze the association between TRAP and asthma development in childhood. Data sources We systematically reviewed epidemiological studies published until 8 September 2016 and available in the Embase, Ovid MEDLINE (R), and Transport databases. Study eligibility criteria, participants, and interventions We included studies that examined the association between children's exposure to TRAP metrics and their risk of ‘asthma’ incidence or lifetime prevalence, from birth to age 18 years old. Study appraisal and synthesis methods We extracted key characteristics of each included study using a predefined data items template and these were tabulated. We used the Critical Appraisal Skills Programme checklists to assess the validity of each included study. Where four or more independent risk estimates were available for a continuous pollutant exposure, we conducted overall and age-specific meta-analyses, and four sensitivity analyses for each summary meta-analytic exposure-outcome association. Results Forty-one studies met our eligibility criteria. There was notable variability in asthma definitions, TRAP exposure assessment methods and confounder adjustment. The overall random-effects risk estimates (95% CI) were 1.08 (1.03, 1.14) per 0.5 × 10− 5 m− 1black carbon (BC), 1.05 (1.02, 1.07) per 4 μg/m3nitrogen dioxide (NO2), 1.48 (0.89, 2.45) per 30 μg/m3nitrogen oxides (NOx), 1.03 (1.01, 1.05) per 1 μg/m3Particulate Matter


Khreis, H., Kelly, C., Tate, J., Parslow, R., Lucas, K., & Nieuwenhuijsen, M. (2017). Exposure to traffic-related air pollution and risk of development of childhood asthma: A systematic review and meta-analysis. Environment International, 100, 1-31.

Journal Article Type Review
Acceptance Date Nov 10, 2016
Online Publication Date Nov 21, 2016
Publication Date 2017-03
Deposit Date Jan 25, 2021
Journal Environment International
Print ISSN 0160-4120
Electronic ISSN 1873-6750
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 100
Pages 1-31
Keywords Asthma; Childhood; Traffic-related air pollution; Meta-analysis; Black carbon; Transport policy
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