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Air Pollution Exposure Early in Life Contributes to the Development of Asthma in Children and Adolescents

Study and editorial published in Lancet Respiratory Medicine

Thursday, December 17th, 2015

Air Pollution Exposure Early in Life Contributes to the Development of Asthma in Children and Adolescents

Results from this study, published in The Lancet Respiratory Medicine, suggest that early life or in-utero exposure to air pollution and soot may contribute to increase asthma incidence in childhood.

Raised levels of ambient air pollution are widely recognised as a risk factor for asthma exacerbation. This research, led by Ulrike Gehring, in which  Dr. Josep M. Antó and Dr. Elaine Fuertes, researchers at CREAL, an ISGlobal allied center, also participated, used land-use regression to analyse the association between air pollution exposure and the incidence of asthma and rhinoconjunctivitis in four birth cohorts from Sweden (BAMSE), Germany (GINI/LISA North and South), and the Netherlands (PIAMA). The main finding was that increasing exposure to nitrogen dioxide (NO2) and particulate matter absorbance with a diameter of less than 2·5 µm (a maker of soot) at participants’ birth addresses increased the risk of incident asthma up to age 14–16 years, but not rhinoconjunctivitis. Associations with asthma were similar in magnitude to other studies linking air pollution with asthma incidence.

Associations between asthma incidence and other measures of particulate matter were not observed.   “The present study is important and timely, because it contributes to our understanding of the adverse health effects of air pollution exposure during a crucial period of asthma susceptibility”, explained Fuertes.

The researchers combined data from 14 126 participants from four birth cohorts, and did both meta-analyses and pooled analyses showing that air pollution exposure early in life contributes to the development of asthma in children and adolescents. The large sample size and follow-up to adolescence are strengths of the study.

Positive associations were shown for both birth address and current address exposure, suggesting that air pollution exposure very early in life is a risk factor for asthma in teenage children.

Risk factors for asthma are complex and involve numerous gene–environment interactions. “Environmental exposures can affect both the developing immune system and the developing lung (eg, affecting airway size and structure) to cause asthma. Although asthma research is focused heavily on immune and inflammatory mechanisms that lead to airway hyperreactivity, alterations in airway structure develop early on in asthma, with the potential to affect mucosal immunity”, explained Antó.


Lancet Respir Med 2015

Published Online

November 10, 2015


See Online/Articles


Exposure to air pollution and development of asthma and rhinoconjunctivitis throughout childhood and adolescence: a population-based birth cohort study. Ulrike Gehring et al. The Lancet Respiratory Medicine

Air pollution and asthma incidence: doubt no more? Steve N Georasemail, Edwin van Wijngaarden, David Q Rich. The Lancet Respiratory Medicine

Image: City of Shanghai. Source: Saperaud/Wikipedia. CC. 


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