title: Assessing spatial associations between thermal stress and mortality in Hong Kong: a small-area ecological study.
abstract: OBJECTIVE
  Physiological equivalent temperature (PET) is a widely used index to assess thermal comfort of the human body. Evidence on how thermal stress-related health effects vary with small geographical areas is limited. The objectives of this study are (i) to explore whether there were significant patterns of geographical clustering of thermal stress as measured by PET and mortality and (ii) to assess the association between PET and mortality in small geographical areas.
  
  
  METHODS
  A small area ecological cross-sectional study was conducted at tertiary planning units (TPUs) level. Age-standardized mortality rates (ASMR) and monthly deaths at TPUs level for 2006 were calculated for cause-specific diseases. A PET map with 100 m × 100 m resolution for the same period was derived from Hong Kong Urban Climatic Analysis Map data and the annual and monthly averages of PET for each TPU were computed. Global Moran's I and local indicator of spatial association (LISA) analyses were performed. A generalized linear mixed model was used to model monthly deaths against PET adjusted for socio-economic deprivation.
  
  
  RESULTS
  We found positive spatial autocorrelation between PET and ASMR. There were spatial correlations between PET and ASMR, particularly in the north of Hong Kong Island, most parts of Kowloon, and across New Territories. A 1°C change in PET was associated with an excess risk (%) of 2.99 (95% CI: 0.50-5.48) for all natural causes, 4.75 (1.14-8.36) for cardiovascular, 7.39 (4.64-10.10) for respiratory diseases in the cool season, and 4.31 (0.12 to 8.50) for cardiovascular diseases in the warm season.
  
  
  CONCLUSIONS
  Variations between TPUs in PET had an important influence on cause-specific mortality, especially in the cool season. PET may have an impact on the health of socio-economically deprived population groups. Our results suggest that targeting policy interventions at high-risk areas may be a feasible option for reducing PET-related mortality.
authors.affiliation: School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Thuan-Quoc
authors.initials: TQ
authors.lastname: Thach
authors.affiliation: School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Qishi
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: Department of Geography, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Poh-Chin
authors.initials: PC
authors.lastname: Lai
authors.affiliation: Department of Geography, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Paulina Pui-Yun
authors.initials: PP
authors.lastname: Wong
authors.affiliation: School of Public Health, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Patsy Yuen-Kwan
authors.initials: PY
authors.lastname: Chau
authors.affiliation: Department of Public Health Medicine, School of Public Health, University of Bielefeld, Bielefeld, Germany.
authors.forename: Heiko J
authors.initials: HJ
authors.lastname: Jahn
authors.affiliation: Department of Public Health Medicine, School of Public Health, University of Bielefeld, Bielefeld, Germany.
authors.forename: Dietrich
authors.initials: D
authors.lastname: Plass
authors.affiliation: Institute for Environmental Meteorology, Planning Department, Kassel University, Kassel, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Katzschner
authors.affiliation: Department of Public Health Medicine, School of Public Health, University of Bielefeld, Bielefeld, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kraemer
authors.affiliation: School of Public Health, The University of Hong Kong, Hong Kong SAR, China. Electronic address: hrmrwcm@hku.hk.
authors.forename: Chit-Ming
authors.initials: CM
authors.lastname: Wong
mesh_terms: D002318:Cardiovascular Diseases / Q000401:mortality; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000706:statistics & numerical data; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D012120:Respiration Disorders / Q000401:mortality*; D012621:Seasons; D013312:Stress, Physiological
keywords: Hong Kong; Local Indicators of Spatial Association (LISA); Mortality; Physiological equivalent temperature (PET); Socio-economic deprivation; Thermal stress