title: Short-term exposure to air pollution and morbidity of COPD and asthma in East Asian area: A systematic review and meta-analysis.
abstract: BACKGROUND
  The association between short-term exposure to air pollution and morbidity of COPD and asthma has been observed in many studies. However, there is a lack of systematic review of the overall risk ratios in East Asian area to provide scientific evidence for health risk assessment.
  
  
  METHODS
  A systematic literature retrieval was conducted in December 2014. The results from eligible studies were stratified by pollutants, diseases, types of hospital utilization, and age groups of the subject. For each pollutant-outcome pair, meta-analysis was conducted to calculate the pooled risk ratios (RR) with 95% confidence intervals for every 10μg/m(3) increase in pollutants (1mg/m(3) in CO). We also performed meta-regression to explore the source of heterogeneity and funnel plots to detect publication bias.
  
  
  RESULTS
  Based on results from 26 studies, statistically significant pooled RRs of different pollutants and age groups ranged from 1.007 (SO2 in all ages) to 1.028 (O3 in all ages) for COPD general hospital admissions, 1.011 (SO2 in all ages) to 1.028 (O3 in all ages) for COPD emergency hospital admissions, 1.013 (PM10 in all ages) to 1.141 (CO in children) for all-type asthma hospital utilization, 1.010 (PM10 in all ages) to 1.141 (CO in children) for asthma general hospital admissions, and 1.009 (SO2 in all ages) to 1.040 (NO2 in children) for asthma emergency hospital admissions. The association between air pollution and asthma morbidity was generally stronger in children, but not significant in people aged 15-64.
  
  
  CONCLUSIONS
  Evidence was found that short-term exposure to air pollution was associated with increasing risk of hospital utilization for COPD and asthma in the whole population, the elderly and children, but not in people aged 15-64. Children tended to be more susceptible to the effect of air pollution on asthma morbidity.
authors.affiliation: Department of Occupational and Environmental Health, Peking University School of Public Health, No 38, Xueyuan Road, Haidian District, Beijing 100191, China. Electronic address: zhangsiqi2009@163.com.
authors.forename: Siqi
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Occupational and Environmental Health, Peking University School of Public Health, No 38, Xueyuan Road, Haidian District, Beijing 100191, China. Electronic address: liguoxing@bjmu.edu.cn.
authors.forename: Guoxing
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Occupational and Environmental Health, Peking University School of Public Health, No 38, Xueyuan Road, Haidian District, Beijing 100191, China. Electronic address: tianlin@bjmu.edu.cn.
authors.forename: Lin
authors.initials: L
authors.lastname: Tian
authors.affiliation: Department of Occupational and Environmental Health, Peking University School of Public Health, No 38, Xueyuan Road, Haidian District, Beijing 100191, China. Electronic address: guoqun1990123@163.com.
authors.forename: Qun
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Department of Occupational and Environmental Health, Peking University School of Public Health, No 38, Xueyuan Road, Haidian District, Beijing 100191, China. Electronic address: xcpan@bjmu.edu.cn.
authors.forename: Xiaochuan
authors.initials: X
authors.lastname: Pan
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000032:analysis*; D001249:Asthma / Q000453:epidemiology*; D004781:Environmental Exposure / Q000032:analysis; D005202:Asia, Eastern / Q000453:epidemiology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*
chemical_list: D000393:Air Pollutants
keywords: Air pollution; Asthma; Chronic obstructive pulmonary disease; Meta-analysis; Morbidity