title: Short-term Effect of Fine Particulate Matter on Children's Hospital Admissions and Emergency Department Visits for Asthma: A Systematic Review and Meta-analysis.
abstract: OBJECTIVE
  No children-specified review and meta-analysis paper about the short-term effect of fine particulate matter (PM2.5) on hospital admissions and emergency department visits for asthma has been published. We calculated more precise pooled effect estimates on this topic and evaluated the variation in effect size according to the differences in study characteristics not considered in previous studies.
  
  
  METHODS
  Two authors each independently searched PubMed and EMBASE for relevant studies in March, 2016. We conducted random effect meta-analyses and mixed-effect meta-regression analyses using retrieved summary effect estimates and 95% confidence intervals (CIs) and some characteristics of selected studies. The Egger's test and funnel plot were used to check publication bias. All analyses were done using R version 3.1.3.
  
  
  RESULTS
  We ultimately retrieved 26 time-series and case-crossover design studies about the short-term effect of PM2.5 on children's hospital admissions and emergency department visits for asthma. In the primary meta-analysis, children's hospital admissions and emergency department visits for asthma were positively associated with a short-term 10 μg/m3 increase in PM2.5 (relative risk, 1.048; 95% CI, 1.028 to 1.067; I2=95.7%). We also found different effect coefficients by region; the value in Asia was estimated to be lower than in North America or Europe.
  
  
  CONCLUSIONS
  We strengthened the evidence on the short-term effect of PM2.5 on children's hospital admissions and emergency department visits for asthma. Further studies from other regions outside North America and Europe regions are needed for more generalizable evidence.
authors: Department of Preventive Medicine, Dankook University College of Medicine, Cheonan, Korea.
authors: Hyungryul
authors: H
authors: Lim
authors: Department of Preventive Medicine, Dankook University College of Medicine, Cheonan, Korea.
authors: Ho-Jang
authors: HJ
authors: Kwon
authors: Department of Preventive Medicine, Dankook University College of Medicine, Cheonan, Korea.
authors: Ji-Ae
authors: JA
authors: Lim
authors: Department of Preventive Medicine, Dankook University College of Medicine, Cheonan, Korea.
authors: Jong Hyuk
authors: JH
authors: Choi
authors: Department of Preventive Medicine, Dankook University College of Medicine, Cheonan, Korea.
authors: Mina
authors: M
authors: Ha
authors: Department of Preventive Medicine, Dankook University College of Medicine, Cheonan, Korea.
authors: Seung-Sik
authors: SS
authors: Hwang
authors: Department of Preventive Medicine, Dankook University College of Medicine, Cheonan, Korea.
authors: Won-Jun
authors: WJ
authors: Choi
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000633:toxicity; D001249:Asthma / Q000209:etiology*; D002648:Child; D016208:Databases, Factual; D004636:Emergency Service, Hospital; D006760:Hospitalization; D006801:Humans; D052638:Particulate Matter / Q000032:analysis* / Q000633:toxicity; D012044:Regression Analysis; D012306:Risk; D012621:Seasons
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: Asthma; Child; Hospitalization; Meta-analysis; Particulate matter; Review