Association between long-term exposure to air pollution and sleep disorder in Chinese children: the Seven Northeastern Cities study

Study Objectives: There is limited knowledge regarding the effects of air pollution on sleep disorders, particularly in children. The aim of this study is to investigate this association in Chinese children. Methods: During 2012-2013, 59 754 children aged 2-17 years were randomly selected from 27 districts in seven northeastern Chinese cities. All participants' sleep was evaluated with the Sleep Disturbance Scale for Children. Four year average concentrations of pollutants were calculated for particles with an aerodynamic diameter of <= 1 mu m (PM1), <= 2.5 mu m (PM2.5) from a spatial statistical model, and <= 10 mu m (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O-3), and carbon monoxide (CO) from monitoring stations. To examine the effects, two-level regression analysis was used, controlling for covariates. Results: We observed that sleep disorder was generally associated with all air pollutants, with the highest odds among PM1 exposure for male (odds ratio [OR] 1.55; 95% confidence interval [95% CI] 1.36-1.76) and female (OR 1.50; 95% CI 1.30-1.72) children. The overall strongest association with sleep disorder symptom was exposure to PM1 and Disorders of Excessive Somnolence (OR 1.43; 95% CI 1.30-1.58). PM1 and PM2.5 were strongly associated with all sleep disorder symptoms in females (ORs ranged for PM1 from 1.19 to 1.49; and PM2.5 1.18 to 1.44). The association between air pollutants and total sleep score was generally greater in female than in male children. Conclusions: Our findings suggest that exposure to air pollutants increases the odds of sleep disorder in children and point to the need to make reducing exposure to air pollutants a public health priority.