Traffic-related Air Pollution and Lung Function in Children at 8 Years of Age A Birth Cohort Study

Rationale: Long-term exposure to air pollution has been related to lung function decrements in children, but the role of timing of exposure remains unknown. Objectives: To assess the role of long-term exposure to air pollution on lung function in school-age,children. Methods: More than 1,900 children in the Swedish birth cohort BAMSE were followed with repeated questionnaires, dynamic spirometry, and IgE measurements until 8 years of age. Outdoor concentrations of particulate matter with an aerodynamic diameter less than 10 mu m (PM10) from road traffic were estimated for residential, day care, and school addresses from birth and onward using dispersion modeling. The relationship between time-weighted average exposure during different time windows and FEV at 8 years was analyzed by linear regression, adjusting for potential confounding factors, including short-term exposure to air pollution. Measurements and Main Results: A 5th to 95th percentile difference in time-weighted average particulate matter less than 10 pm in aerodynamic diameter exposure during the first year of life was associated with a reduced FEV1 of -59.3 ml (95% confidence interval, -113 to -5.6) at 8 years of age. The negative association was particularly pronounced in children concomitantly sensitized to common inhalant or food allergens (-136.9 ml; 95% confidence interval, -224.1 to -49.7). Exposure after the first year of life seemed to have less impact on lung function at 8 years. Conclusions: Our results indicate that exposure to traffic-related air pollution during infancy affects lung function in children up to 8 years of age and particularly in those sensitized to common inhalant or food allergens.