Obese children exposed to high levels of air pollutants were nearly three times as likely to have asthma, compared with non-obese children and lower levels of pollution exposure, report researchers at the Columbia University Mailman School of Public Health’s Columbia Center for Children’s Environmental Health.
The researchers followed 311 children in predominantly Dominican and African-American neighborhoods of New York City. They monitored indoor air in each child’s home for two weeks at age 5 or 6, to measure exposure to a family of air pollutants, polycyclic aromatic hydrocarbons (PAH). The child’s height and weight were measured and respiratory questionnaires were administered. In all, 20 percent were found to have asthma and 20 percent were categorized as obese based on body mass index.
The researchers found that high PAH exposure was associated with asthma only among obese children. In particular, the association was with the alkylated forms of PAH, which are emitted by vehicles and by cigarette smoke, cooking, incense, burning candles, and various other indoor sources. A two- to three-fold increase in asthma risk was seen among obese children exposed to high levels of the PAH chemicals 1-methylphenanthrene and 9-methylphenanthrene. Exposure to PAH or obesity alone did not predict asthma.
The mechanism behind the association is not well understood. One possible explanation is that sedentary lifestyle in obese children could result in more time spent indoors, thereby increasing exposure to indoor PAH. Another may have to do with more rapid breathing in those who are obese.
Better understanding of the risk factors opens the door to more targeted interventions. “These findings suggest that we may be able to bring down childhood asthma rates by curbing indoor, as well as outdoor, air pollution and by implementing age-appropriate diet and exercise programs,” says senior author Dr. Rachel Miller, professor of medicine (in pediatrics) and environmental health sciences, and co-deputy director of the Columbia Center for Children’s Environmental Health at the Mailman School of Public Health. Full results are published in Environmental Research.
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[Photo: Dr. Rachel Miller]