Being overweight may make asthmatic children more vulnerable to the effects of pollution

Published Online: February 11, 2013

Minority and low income populations have high rates of both obesity and asthma morbidity. These same populations also have a greater exposure to indoor pollutants, including microscopic airborne dust particles produced by cigarette smoke, cooking, sweeping, and traffic. This type of pollution is referred to as fine particulate matter (PM) and causes asthma symptoms. Another type of pollution, nitrogen dioxide (NO2), is produced by gas appliances, found in higher concentrations in urban homes, and also associated with asthma symptoms. Because overweight children breathe in higher volumes of air than normal weight children, their lungs may have more exposure to pollutants, thereby putting them at greater risk for asthma symptoms caused by pollutants.

In a study recently published in The Journal of Allergy and Clinical Immunology (JACI), Lu et al examined relationships between weight status, indoor pollution, and asthma health in a population of urban, predominantly African American 5-17 year olds with asthma. The group included 148 children with persistent asthma who underwent repeated assessment of home pollutant exposure and asthma over 1 year. The researchers found that overweight and obese children had more asthma symptoms associated with fine PM exposure than normal weight children. They also found that overweight and obese participants had more asthma symptoms associated with NO2 exposure than normal weight participants, although this was not observed across all types of asthma symptoms. Relationships between indoor pollutant exposure and acute visits for asthma, lung function, and pulmonary inflammation did not differ by weight.  

The authors’ findings suggest that being overweight may increase an asthmatic child’s susceptibility to the pulmonary effects of indoor PM2.5 and NO2 and, further, that the combination of a high prevalence of overweight and high indoor pollutant exposure in urban children with asthma could explain some of the disproportionate asthma morbidity seen in this population. The authors suggest that weight loss may reduce susceptibility to these indoor pollutants, and that overweight asthmatic children may benefit from indoor pollutant reduction to a greater extent than normal weight children. The mechanisms underlying this interaction are not known but, in addition to overweight children potentially having greater deposition of pollutants in their lungs, it is also possible that the state of chronic oxidative stress and inflammation seen in obesity may increase susceptibility to pollutants. Obese asthmatics are also resistant to the anti-inflammatory effects of corticosteroids, the primary asthma controller medication, which may also make them more susceptible to the effects of indoor pollution. The effect of overweight on the relationships between indoor pollutant exposure and asthma health has not previously been examined and additional studies are needed to confirm these findings.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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