Long-term Exposure to PM10 and NO2 in Association with Lung Volume and Airway Resistance in the MAAS Birth Cohort

BACKGROUND: Findings from previous studies on the effects of air pollution exposure on lung -function during childhood have been inconsistent. A common limitation has been the quality of exposure data used, and few studies have modeled exposure longitudinally throughout early life. OBJECTIVES:We sought to study the long-term effects of exposure to particulate matter with an aerodynamic diameter <= 10 mu m (PM10) and to nitrogen dioxide (NO2) on specific airway resistance (sR(aw)) and forced expiratory volume in 1 sec (FEV1) before and after bronchodilator treatment. Subjects were from the Manchester Asthma and Allergy Study (MAAS) birth cohort (n = 1,185). METHODS: Spirometry was performed during clinic visits at ages 3, 5, 8, and 11 years. Individual-level PM10 and NO2 exposures were estimated from birth to 11 years of age through a micro-environmental exposure model. Longitudinal and cross-sectional associations were estimated using generalized estimating equations and multivariable linear regression models. RESULTS: Lifetime exposure to PM10 and NO2 was associated with significantly less growth in FEV1 (percent predicted) over time, both before (-1.37%; 95% CI: -2.52, -0.23 for a 1-unit increase in PM10 and -0.83%; 95% CI: -1.39, -0.28 for a 1-unit increase in NO2) and after bronchodilator treatment (-3.59%; 95% CI: -5.36, -1.83 and -1.20%; 95% CI: -1.97, -0.43, respectively). We found no association between lifetime exposure and sRaw over time. Cross-sectional analyses of detailed exposure estimates for the summer and winter before 11 years of age and lung function at 11 years indicated no significant associations. CONCLUSIONS: Long-term PM10 and NO2 exposures were associated with small but statistically significant reductions in lung volume growth in children of elementary-school age.