title: [A case-crossover study on the relationship between air pollution and acute onset of cerebral hemorrhage in Hangzhou city].
abstract: OBJECTIVE
  To explore the relationship between air pollution and acute onset of cerebral hemorrhage in Hangzhou.
  
  
  METHODS
  Time-stratified case-crossover study was used to analyze the effect of aerosol optical depth (AOD), PM(10), SO(2) and NO(2) on the acute onset of cerebral hemorrhage. Conditional logistic regression was used to estimate the odds ratios (ORs) and their 95% confidence intervals (CIs) in relation to an increase of one unit of AOD and 10 microg/m(3) of air pollutants.
  
  
  RESULTS
  After adjusted temperature and relative humidity, the ORs of acute onset of cerebral hemorrhage by a unit increase in AOD at a 2 day-lag were 1.727 (95%CI: 1.103 - 2.703) in first half year and 2.412 (95%CI: 1.230 - 4.733) at a 2 day-lag in spring. For a 10 microg/m(3) increase in SO(2), the ORs were 1.119 (95%CI: 1.019 - 1.229), 1.230 (95%CI: 1.092 - 1.386), 1.254 (95%CI: 1.076 - 1.460) in the whole year (2 day-lag), in first half year (2 day-lag) and in spring (2 day-lag), respectively. NO(2) exposure in first half year (2 day-lag) was associated with cerebral hemorrhage, with OR as 0.841 (95%CI: 0.734 - 0.964). However, there were no statistical significances for AOD, SO(2), NO(2) in the rest time-periods (P > 0.05). Additionally, no association was found between PM(10) and the acute onset of cerebral hemorrhage in any time-periods (P > 0.05).
  
  
  CONCLUSIONS
  Our data showed that there was association between air pollution and the acute onset of cerebral hemorrhage, especially in spring and in the first half of the year.
authors.affiliation: Department of Epidemiology and Health Statistics, Zhejiang University School of Medicine, Hangzhou 310058, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ye
authors.forename: Xiu-Yang
authors.initials: XY
authors.lastname: Li
authors.forename: Kun
authors.initials: K
authors.lastname: Chen
authors.forename: Qing-Min
authors.initials: QM
authors.lastname: Liu
authors.forename: Hai-Qing
authors.initials: HQ
authors.lastname: Xiang
mesh_terms: D000208:Acute Disease; D000336:Aerosols / Q000009:adverse effects; D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D002543:Cerebral Hemorrhage / Q000209:etiology*; D002681:China; D016001:Confidence Intervals; D006801:Humans; D016015:Logistic Models; D009585:Nitrogen Dioxide / Q000009:adverse effects; D016017:Odds Ratio; D052638:Particulate Matter / Q000009:adverse effects; D013458:Sulfur Dioxide / Q000009:adverse effects; D013997:Time Factors
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D009585:Nitrogen Dioxide