Effect of Acute PM2.5 Exposure on Lung Function in Children: A Systematic Review and Meta-Analysis

Abstract Background: Long-term exposures to particulate matter 2.5 (PM2.5) impairing lung function in children, but the effect of acute exposure has not been clarified. The objective of this study was to conduct a systematic review and meta-analysis to identify the adverse effect of acute PM2.5 exposure on lung function in children. Methods: Studies analyzing PM2.5 level and lung function in children were eligible. Effect estimates were quantified for peak expiratory flow (PEF) by using random effects models, for forced vital capacity (FVC)and forced expiratory volume in 1 s(FEV1) by using fixed effects models. Heterogeneity was investigated with Q-test and I2 statistics. Subgroup analyses were conducted to determine the effects of acute PM2.5 exposure on children of different asthmatic status and different countries.Results: A total of 11 studies with 4314 participants from Brazil, China and Japan were included finally. A 10 μg/m3 increase of PM2.5 was associated with a 1.74L/min (95% CI: -2.68, -0.90) decrease in PEF. Children with severe asthma were more susceptible to PM2.5 exposure (-3.11 L/min per 10 μg/m3 increase, 95 % CI -4.54, -1.67) than healthy children (-1.61 L/min per 10 μg/m3 increase, 95 % CI -2.34, -0.91). The change of PEF in children of Brazil was -0.38 L/min(95 % CI -0.91, 0.15) per 10 μg/m3 increase of PM2.5, which was slighter than that in China (-1.54 L/min, 95 % CI -2.33，-0.75) and Japan (-1.72 L/min, 95 % CI -3.82 , 0.36). Elevated PM2.5 exposure was also associated slight alteration of FVC and FEV1, with no significant difference presented. Conclusions: Our results demonstrated that the acute PM2.5 exposure has an adverse impact on children’s lung function, and children with severe asthma were more susceptible when PM2.5 concentration increases. The impact of PM2.5 varies among the three countries. More measures should be taken to protect lung function of children from PM2.5 exposure.