Obesity magnifies adverse effects of NO2 on asthma in kids

Obese children are more vulnerable to classroom nitrogen dioxide (NO₂) exposure and in turn suffer from worse asthma symptoms, reports a recent study.

“Environmental interventions targeting indoor school NO₂ levels may improve asthma health for obese children,” the researchers said. “Although our findings would not remain statistically significant after adjustment for multiple comparisons, the large effect sizes warrant future study of the interaction of obesity and pollution in paediatric asthma.”

Of the 271 students (aged 4–13 years), half were of normal weight and fell within the fifth to the 84th body mass index (BMI) percentiles. Fifteen percent were overweight and 35 percent were obese. Percent predicted forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV₁) were both lower in obese asthmatics.

Classroom NO₂ levels correlated with asthma outcomes in obese children. For instance, each 10-ppb increase in NO₂ more than doubled the likelihood of healthcare utilization for asthma-related symptoms (odds ratio [OR], 2.44, 95 percent confidence interval [CI], 1.15–5.14).

The same change in classroom NO₂ also corresponded to a significant increase in the risk of missing a school day due to asthma (OR, 3.11, 95 percent CI, 1.29–7.51) and of changing caregiver plans due to the child’s asthma (OR, 4.24, 95 percent CI, 2.33–7.70).

Increasing NO₂ levels had no significant effect on the examined asthma symptoms in participants who were overweight or of normal weight.