title: The effects of ambient temperature on cerebrovascular mortality: an epidemiologic study in four climatic zones in China.
abstract: BACKGROUND
  Little evidence is available about the association between temperature and cerebrovascular mortality in China. This study aims to examine the effects of ambient temperature on cerebrovascular mortality in different climatic zones in China.
  
  
  METHODS
  We obtained daily data on weather conditions, air pollution and cerebrovascular deaths from five cities (Beijing, Tianjin, Shanghai, Wuhan, and Guangzhou) in China during 2004-2008. We examined city-specific associations between ambient temperature and the cerebrovascular mortality, while adjusting for season, long-term trends, day of the week, relative humidity and air pollution. We examined cold effects using a 1°C decrease in temperature below a city-specific threshold, and hot effects using a 1°C increase in temperature above a city-specific threshold. We used a meta-analysis to summarize the cold and hot effects across the five cities.
  
  
  RESULTS
  Beijing and Tianjin (with low mean temperature) had lower thresholds than Shanghai, Wuhan and Guangzhou (with high mean temperature). In Beijing, Tianjin, Wuhan and Guangzhou cold effects were delayed, while in Shanghai there was no or short induction. Hot effects were acute in all five cities. The cold effects lasted longer than hot effects. The hot effects were followed by mortality displacement. The pooled relative risk associated with a 1°C decrease in temperature below thresholds (cold effect) was 1.037 (95% confidence interval (CI): 1.020, 1.053). The pooled relative risk associated with a 1°C increase in temperature above thresholds (hot effect) was 1.014 (95% CI: 0.979, 1.050).
  
  
  CONCLUSIONS
  Cold temperatures are significantly associated with cerebrovascular mortality in China, while hot effect is not significant. People in colder climate cities were sensitive to hot temperatures, while people in warmer climate cities were vulnerable to cold temperature.
authors.forename: Yanshen
authors.initials: Y
authors.lastname: Zhang
authors.forename: Shanshan
authors.initials: S
authors.lastname: Li
authors.forename: Xiaochuan
authors.initials: X
authors.lastname: Pan
authors.forename: Shilu
authors.initials: S
authors.lastname: Tong
authors.forename: Jouni Jk
authors.initials: JJ
authors.lastname: Jaakkola
authors.forename: Antonio
authors.initials: A
authors.lastname: Gasparrini
authors.affiliation: Department of Occupational and Environmental Health, School of Public Health, Peking University, Beijing 100191, China. y.guo1@uq.edu.au.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Guo
authors.forename: Sheng
authors.initials: S
authors.lastname: Wang
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D002561:Cerebrovascular Disorders / Q000401:mortality*; D002681:China; D002980:Climate; D006801:Humans; D006813:Humidity; D009585:Nitrogen Dioxide / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis; D012306:Risk; D013696:Temperature
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D009585:Nitrogen Dioxide