A study based on data from 3680 children investigated the combined associations of air pollution, traffic noise and green space with overweight throughout childhood. The children were born in 1996 or 1997 and were participants in the larger Dutch PIAMA birth cohort study.
Parents participating in PIAMA completed questionnaires during pregnancy, at the child's age of 3 months and 1 year, and then annually until the child was eight years old. When the children were 11, 14, and 17, they and their parents completed separate questionnaires focusing on growth and development, as well as socio-demographic and lifestyle characteristics. The parent questionnaires included requests for exact measurements of their child's weight and height and the dates the measurements were taken. This data was used to calculate each child's body mass index (BMI) which determined whether or not they were overweight/obese. For the 3680 children participating in this study, at least one BMI measurement was available from the age of three to 17 years. Researchers used the history of children's home addresses to estimate their exposure to air pollution and traffic noise and their access to greenspace.
Results showed that children living in an urban area had greater exposure to air pollution and traffic noise but lower exposure to green space than children not living in urban areas. Traffic-related air pollution increased the risk of being overweight from age 3 to 17. Traffic noise, on the other hand, did not increase the risk of being overweight throughout childhood. For children living in an urban area, living further away from a park decreased their odds of being overweight.
Results from this study show some consistencies and inconsistencies with previous research. A consistent finding is the positive association between exposure to air pollution and overweight. Understanding the pathways through which air pollution may be associated with children's weight is not well understood. According to the authors of this study, it's unlikely that the association between air pollution and overweight can be explained by decreased physical activity levels associated with increased traffic density near the children's homes. While the research has been sparse, previous studies assessing associations between traffic noise and children's weight is consistent with the current study – that is, no association was found. Inconsistencies exist, however, in research results relating to the associations of residential exposure to greenspace and children's weight.
This research highlights the need for future studies examining the associations of green space with childhood overweight to account for air pollution concentrations.
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