Associations of ambient air pollutants with airway and allergic symptoms in 13,335 preschoolers in Shanghai, China

Abstract Findings are inconsistent in studies for impacts of outdoor air pollutants on airway health in childhood. In this paper, we collected data regarding airway and allergic symptoms in the past year before a survey in 13,335 preschoolers from a cross-sectional study. Daily averaged concentrations of ambient sulphur dioxide (SO2), nitrogen dioxide (NO2), and particulate matter with an aerodynamic diameter ≤10 μm (PM10) in the past year before the survey were collected in the kindergarten-located district. We investigated associations of 12-month average concentrations of these pollutants with childhood airway and allergic symptoms. In the two-level (district-child) logistic regression analyses, exposure to higher level of NO2 and of PM10 increased odds of wheeze symptoms (adjusted OR, 95%CI: 1.03, 1.01–1.05 for per 3.0 μg/m3 increase in NO2; 1.22, 1.09–1.39 for per 7.6 μg/m3 increase in PM10), wheeze with a cold (1.03, 1.01–1.06; 1.22, 1.08–1.39), dry cough during night (1.05, 1.03–1.08; 1.23, 1.09–1.40), rhinitis symptoms (1.11, 1.08–1.13; 1.32, 1.07–1.63), rhinitis on pet (1.11, 1.05–1.18; 1.37, 0.95–1.98) and pollen (1.12, 1.03–1.21; 1.23, 0.84–1.82) exposure, eczema symptoms (1.09, 1.05–1.12; 1.22, 0.98–1.52), and lack of sleep due to eczema (1.12, 1.07–1.18; 1.58, 1.25–1.98). Exposures to NO2 and PM10 were also significantly and positively associated with the accumulative score of airway symptoms. Similar positive associations were found of NO2 and of PM10 with the individual symptoms and symptom scores among preschoolers from different kindergarten-located district. These results indicate that ambient NO2 and PM10 likely are risk factors for airway and allergic symptoms in childhood in Shanghai, China.