Early-Life Exposure to Traffic-related Air Pollution and Lung Function in Adolescence

Abstract

Rationale: Exposure to air pollution during infancy has been related to lung function decrements in 8-year-old children, but whether the negative effects remain into adolescence is unknown.

Objectives: To investigate the relationship between long-term air pollution exposure and lung function up to age 16 years.

Methods: A total of 2,278 children from the Swedish birth cohort BAMSE (Children, Allergy, Milieu, Stockholm, Epidemiological Survey) performed spirometry at age 16 years. Levels of outdoor air pollution from local road traffic were estimated (nitrogen oxides [NOx] and particulate matter with an aerodynamic diameter of <10 μm [PM10]) for residential, daycare, and school addresses during the lifetime using dispersion modeling. Associations between exposure in different time windows and spirometry indexes were analyzed by linear regression and mixed effect models.

Measurements and main results: Exposure to traffic-related air pollution during the first year of life was associated with FEV1 at age 16 years of -15.8 ml (95% confidence interval [CI], -33.6 to 2.0 for a 10 μg/m(3) difference in NOx), predominately in males (-30.4 ml; 95% CI, -59.1 to -1.7), and in subjects not exposed to maternal smoking during pregnancy or infancy. Later exposures appeared to have had an additional negative effect. High exposure during the first year of life was also associated with odds ratios for FEV1 and FVC less than the lower limit of normal (LLN) (defined as a z-score < -1.64 SD) of 3.8 (95% CI, 1.3-10.9) and of 4.3 (95% CI, 1.2-15.0), respectively. The results for PM10 were similar to those for NOx.

Conclusions: Exposure to traffic-related air pollution in infancy is negatively associated with FEV1 at age 16 years, leading to increased risk of clinically important deficits.

Keywords: life course; lung function; nitrogen oxide; particulate matter; spirometry.