Lung function and methacholine responsiveness among adolescents in an air-polluted area

Outdoor air pollution is hazardous to human pulmonary health. Airway inflammation is an important cause of bronchial hyperresponsiveness. Information is not univocal about the potential effects of prolonged exposure to environmental air pollutants on lung function.

A cross-sectional study was performed to assess bronchial responsiveness to methacholine in children living in an air-polluted area. Afterwards, the same study protocol was repeated in children of similar age living in mountain valleys with virtually no air pollution.

Every child underwent a lung function test, skin tests to common allergens, total serum levels of IgE, and a challenge to methacholine at increasing doses (PD20 FEV1). Subjects were 246 children 11-12 years old living in an air-polluted area, and 285 children 11-13 years old living in mountain valleys. Respectively, 156 and 161 were negative to skin tests and had serum total IgE<100 IU/ml, and had no asthma or other recurrent or ongoing respiratory symptoms.

Lung function data, adjusted for the effect of potential confounders showed significantly lower FVC, and even more so FEV1, in the children from the polluted area. After the exclusion of subjects with positive skin tests and serum total IgE>100 IU/ml and those with history of asthma or respiratory disorders, there were higher percentages of positive responses in the challenge to methacholine in children from the polluted area (28.9 vs. 15.5%, p<0.001).

These data may corroborate the possible importance of long exposure to air pollutants on the prevalence of bronchial aspecific hyperresponsiveness in otherwise normal children.