Acute effect of ambient air pollution on small airway lung functions among school children in Shanghai

Objective To study the acute effects of compound ambient air pollution on small airway lung functions among school children in Shanghai. Method A longitudinal survey on lung functions was conducted among 233 school-children from three schools (A, B and C, located in innerring, mid-ring and outer-ring areas). Lung function test was performed once a week for 3 times respectively, among children in school A and B in Dec. 2013 and in school C in Dec. 2014. The fourth lung function test was tested in Jun. 2014 and May 2015 in the respective schools. Results from the lung function would include items as: forced mid-expiratory flow at 25% of forced vital capacity (MEF25%), mid-expiratory flow at 50% of forced vital capacity (MEF50%), mid-expiratory flow at 75% of forced vital capacity (MEF75%) and mid-expiratory flow between 25% and 75% of the forced vital capacity (FEF25%-75%). Data regarding the daily air quality real-time of PM2.5, PM10, SO2 and NO2 in Dec. 2013, Dec. 2014, Jun. 2014 and May. 2015 from the three environmental monitoring spots and meteorological data from the Shanghai Meteorological Service system which were physically close to the three schools, were collected simultaneously. Linear mixed effect model was used to examine the levels of correlation between lung function indicators and ambient air pollutants. Results When confounding factors on meteorology and individuals were controlled, the lag effects and accumulated lag effects were found to have existed between the internal quarter rang (IQR) concentration of PM2.5 and PM10 in lag2 day and lag02 days, IQR concentration of SO2 in lag02 day and IQR concentration of NO2 lag0 day, when small airway lung functions like MEF25%, MEF50%, MEF75% and FEF25%-75%(P<0.05) were inspected. Results from the two air pollutants model analysis showed that SO2 and NO2 presenting interactive effects with PM2.5, PM10 and lag effects more significant than the individual SO2 and NO2, respectively (P<0.05). Conclusion Contents on the ambient air pollutants as PM2.5, PM10, SO2 and NO2 were negatively associated with the lung functions in the small airways of children, in Shanghai. Key words: Air pollution; Mid-expiratory flow of forced vital capacity; Mixed effect model; Primary school student