Traffic-related air pollution and obesity formation in children: a longitudinal, multilevel analysis.

Michael Jerrett,Fred Lurmann,Kiros Berhane,Frank Gilliland,Claudia Lam,Rob Mcconnell,Roger Chang,Talat Islam,Jennifer Wolch,Genevieve Dunton

doi:10.1186/1476-069x-13-49

Abstract

BackgroundBiologically plausible mechanisms link traffic-related air pollution to metabolic disorders and potentially to obesity. Here we sought to determine whether traffic density and traffic-related air pollution were positively associated with growth in body mass index (BMI = kg/m2) in children aged 5–11 years.MethodsParticipants were drawn from a prospective cohort of children who lived in 13 communities across Southern California (N = 4550). Children were enrolled while attending kindergarten and first grade and followed for 4 years, with height and weight measured annually. Dispersion models were used to estimate exposure to traffic-related air pollution. Multilevel models were used to estimate and test traffic density and traffic pollution related to BMI growth. Data were collected between 2002–2010 and analyzed in 2011–12.ResultsTraffic pollution was positively associated with growth in BMI and was robust to adjustment for many confounders. The effect size in the adjusted model indicated about a 13.6% increase in annual BMI growth when comparing the lowest to the highest tenth percentile of air pollution exposure, which resulted in an increase of nearly 0.4 BMI units on attained BMI at age 10. Traffic density also had a positive association with BMI growth, but this effect was less robust in multivariate models.ConclusionsTraffic pollution was positively associated with growth in BMI in children aged 5–11 years. Traffic pollution may be controlled via emission restrictions; changes in land use that promote jobs-housing balance and use of public transit and hence reduce vehicle miles traveled; promotion of zero emissions vehicles; transit and car-sharing programs; or by limiting high pollution traffic, such as diesel trucks, from residential areas or places where children play outdoors, such as schools and parks. These measures may have beneficial effects in terms of reduced obesity formation in children.

Highlights

Childhood obesity has emerged as a major public health problem in the United States and elsewhere
We hypothesized that traffic density and traffic-related air pollution would positively associate with longitudinal growth in BMI
In this cohort of children from 13 communities across Southern California, traffic-related air pollution exerted a significant effect on BMI growth and BMI level attained at age 10

Summary

Introduction

Childhood obesity has emerged as a major public health problem in the United States and elsewhere. The trend toward increasing obesity in the U.S appears to have abated over the past ten years [3], the existing high prevalence remains a concern. Growing evidence links the built environment to physical activity, dietary intake, and obesity [9]. Much of the existing evidence comes from cross-sectional studies [14], raising questions of reverse causality whereby individuals and families who would have otherwise stayed at a healthy weight locate in neighborhoods that support their already active lifestyles and nutritional food intake. Plausible mechanisms link traffic-related air pollution to metabolic disorders and potentially to obesity. We sought to determine whether traffic density and traffic-related air pollution were positively associated with growth in body mass index (BMI = kg/m2) in children aged 5–11 years

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