Long-term air pollution exposure under EU limits and adolescents' lung function: Modifying effect of abnormal weight in GINIplus/LISA birth cohorts

Abstract Background Abnormal weights, e.g. Obesity, has shown strong modifying effect on the association between air pollution exposure and lung function impairment in adults. Research Questions How may weight status modify the effects of long-term air pollution on adolescents’ lung function, particularly in areas with pollution levels much lower than the current EU air quality standards? Study Design and Methods In this observational study, we investigated 2224 adolescents from the German GINIplus/LISA birth cohorts. Lung function was measured at age 15 years. Under, normal and over/obese weights were defined using percentiles of body mass index. Average concentrations of air pollution were modelled at residential addresses at four exposure windows between 0–15 years. Multivariable linear regression models were fitted by weight group on lung function with exposure at each window or cumulative exposure since birth. Results The median air pollution concentrations were half to two-thirds of the EU standards. Significant associations were observed only for individuals with under and over/obese weights. For example, per interquartile range increase in nitrogen dioxide at the 15th-year exposure window, the forced expiratory volume in one second (FEV1) declined by -2.9% [95% confidence interval (CI): -5.2 to -0.5%] for underweight group and -3.4% (95%CI: -5.4 to -1.2%) for over/obese weight group. Similarly, longer exposure to moderate-level air pollution since birth was significantly associated with lung function impairment for groups with abnormal weights. Interpretation Exposure to low-to-moderate levels of air pollution was associated with lung function impairment for adolescents with abnormal weights. Longer exposure aggravated the adverse effect. Whether there may be critical exposure window since birth warrants further exploration.