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

OBJECTIVE: The objective of this study was to conduct a systematic review and meta-analysis to identify the adverse effects of acute PM2.5 exposure on lung function in children. DESIGN: Systematic review and meta-analysis. Setting, participants and measures: Eligible studies analyzing PM2.5 level and lung function in children were screened out. Effect estimates of PM2.5 measurements were quantified using random effect models. Heterogeneity was investigated with Q-test and I(2) statistics. We also conducted meta-regression and sensitivity analysis to explore the sources of heterogeneity, such as different countries and asthmatic status. Subgroup analyses were conducted to determine the effects of acute PM2.5 exposure on children of different asthmatic status and in different countries. RESULTS: A total of 11 studies with 4314 participants from Brazil, China and Japan were included finally. A 10 μg/m(3) increase of PM2.5 was associated with a 1.74L/min (95% CI: −2.68, −0.90) decrease in peak expiratory flow (PEF). Since the asthmatic status and country could partly explain the heterogeneity, we conducted the subgroup analysis. Children with severe asthma were more susceptible to PM2.5 exposure (−3.11 L/min per 10 μg/m(3) increase, 95% CI −4.54, −1.67) than healthy children (−1.61 L/min per 10 μg/m(3) increase, 95% CI −2.34, −0.91). In the children of China, PEF decreased by 1.54 L/min (95% CI −2.33, −0.75) with a 10 μg/m(3) increase in PM2.5 exposure. In the children of Japan, PEF decreased by 2.65 L/min (95% CI −3.82, −1.48) with a 10 μg/m(3) increase of PM2.5 exposure. In contrast, no statistic association was found between every 10 μg/m(3) increase of PM2.5 and lung function in children of Brazil (−0.38 L/min, 95% CI −0.91, 0.15). CONCLUSION: Our results demonstrated that the acute PM2.5 exposure exerted adverse impacts on children’s lung function, and children with severe asthma were more susceptible to the increase of PM2.5 exposure. The impacts of acute PM2.5 exposure varied across different countries.