Effects of ambient air pollution on lung function growth in Chinese schoolchildren.

Objective: To evaluate the adverse effect of exposure to air pollution on lung function growth in school-aged children.

Methods: A cohort of 1983 children from three districts in Guangzhou, China was followed-up for 6 months. The children performed pulmonary function tests twice, and their parents reported the child's respiratory symptoms by self-administered questionnaires in both surveys.

Results: The annual mean concentrations of air pollutants for the past 5 years for particulate matter less than 10 microns in diameter (PM(10)), nitrogen (NO(2)), and sulfur dioxide (SO(2)) were respectively: 96.1 microg/m(3), 76.0 microg/m(3), and 65.7 microg/m(3) in the highly-polluted district (HPD), 80.3 microg/m(3), 67.6 mug/m(3), and 54.5 microg/m(3) in the moderately-polluted district (MPD), and 80.0 microg/m(3), 48.1 microg/m(3), and 52.2 microg/m(3) in the least-polluted district (LPD). After adjustment for potential confounders, significant deficits were found in the annual growth rates of forced expiratory flows at 25% (FEF(25)), and between 25% and 75% (FEF(25-75)) in boys and FEF(25) in girls (In boys, for FEF(25), -0.136 l/s, p = 0.008 in MPD and -0.153 l/s, p = 0.004 in HPD, respectively; for FEF(25-75), -0.176 l/s, p = 0.013 in MPD and -0.167 l/s, p = 0.021 in HPD, respectively. In girls, for FEF(25), -0.123 l/s, p = 0.043 in HPD), using LPD as the reference. Deficits in the annual growth rate of forced expiratory volume in 1 s (FEV(1)) were also negatively associated with air pollution in boys (-0.063 L, p = 0.032 in HPD).

Conclusions: The study adds more evidence that exposure to air pollution has adverse effects on lung function growth in schoolchildren.