title: Impact of extreme high temperature on mortality and regional level definition of heat wave: a multi-city study in China.
abstract: BACKGROUND
  Few multi-city studies have been conducted to explore the regional level definition of heat wave and examine the association between extreme high temperature and mortality in developing countries.
  
  
  OBJECTIVE
  The purpose of the present study was to investigate the impact of extreme high temperature on mortality and to explore the local definition of heat wave in five Chinese cities.
  
  
  METHODS
  We first used a distributed lag non-linear model to characterize the effects of daily mean temperature on non-accidental mortality. We then employed a generalized additive model to explore the city-specific definition of heat wave. Finally, we performed a comparative analysis to evaluate the effectiveness of the definition.
  
  
  RESULTS
  For each city, we found a positive non-linear association between extreme high temperature and mortality, with the highest effects appearing within 3 days of extreme heat event onset. Specifically, we defined individual heat waves of Beijing and Tianjin as being two or more consecutive days with daily mean temperatures exceeding 30.2 °C and 29.5 °C, respectively, and Nanjing, Shanghai and Changsha heat waves as ≥3 consecutive days with daily mean temperatures higher than 32.9 °C, 32.3 °C and 34.5 °C, respectively. Comparative analysis generally supported the definition.
  
  
  CONCLUSIONS
  We found extreme high temperatures were associated with increased mortality, after a short lag period, when temperatures exceeded obvious threshold levels. The city-specific definition of heat wave developed in our study may provide guidance for the establishment and implementation of early heat-health response systems for local government to deal with the projected negative health outcomes due to heat waves.
authors.affiliation: Injury Prevention Research Center, Shantou University Medical College, Guangdong, China. Electronic address: gaojinghong2007@126.com.
authors.forename: Jinghong
authors.initials: J
authors.lastname: Gao
authors.affiliation: Injury Prevention Research Center, Shantou University Medical College, Guangdong, China; Quanzhou First Hospital, Fujian, China.
authors.forename: Yunzong
authors.initials: Y
authors.lastname: Sun
authors.affiliation: State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Qiyong
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Maigeng
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Injury Prevention Research Center, Shantou University Medical College, Guangdong, China.
authors.forename: Yaogui
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Injury Prevention Research Center, Shantou University Medical College, Guangdong, China. Electronic address: lpli@stu.edu.cn.
authors.forename: Liping
authors.initials: L
authors.lastname: Li
mesh_terms: D002681:China / Q000453:epidemiology; D002947:Cities / Q000706:statistics & numerical data*; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D018882:Heat Stress Disorders / Q000401:mortality*; D006358:Hot Temperature; D006801:Humans
keywords: Definition; Extreme high temperature; Heat wave; Lag effects; Temperature–mortality relationships; Time-series models