Like Canada, environmental contamination gets blamed for a lot of things wrong in America. But a recent study in a respected NIH journal, Environmental Health Perspectives, offers a novel expansion of what in our lives that is wrong that we can now blame on the environment. In an article with the catchy title, “A Longitudinal Cohort Study of Body Mass Index and Childhood Exposure to Secondhand Tobacco Smoke and Air Pollution: The Southern California Children’s Health Study,” the authors report that it is not the calories that you eat that make you overweight; it’s the polluted air that you breathe.
According to the article, there is a significant increase in body mass index in children exposed over a period of years to second hand smoke and to air pollution associated with dense traffic (i.e. polyaromatic hydrocarbons described as “ambient near-roadway pollution”). The article discusses potential biological mechanisms, pointing to mice studies evaluating how the inflamation associated with exposure to air pollution might cause weight gain. Although the authors claim to eliminate confounding factors, such as parental income, through the magic of regression statistics, it’s hard not to have a sense that the increase in body mass index is causally related not to air pollution but to low socio-economic status. Smoking and and living in low value neighborhoods that are disproportionately located close to major highways are both highly correlated with low socio-economic status. Nonetheless, we should prepare ourselves for environmental studies that measure not the risk of increased mortalities but the risk of increased pounds and remedial measures that include dietary controls as well as institutional controls.
I’d like to see this study repeated in Beijing.