Environmental Health and Preventive Medicine

, Volume 19, Issue 1, pp 56–63

Heat-related mortality risk model for climate change impact projection


    • Faculty of Health and Sport SciencesUniversity of Tsukuba
  • Masahide Kondo
    • Faculty of MedicineUniversity of Tsukuba
  • Glenn McGregor
    • School of EnvironmentUniversity of Auckland
  • Ho Kim
    • School of Public HealthSeoul National University
  • Yue-Leon Guo
    • Environmental and Occupational MedicineNational Taiwan University (NTU) College of Medicine and NTU Hospital
    • Institute of Occupational Medicine and Industrial HygieneNational Taiwan University
  • Yasuaki Hijioka
    • Center for Social and Environmental Systems ResearchNational Institute for Environmental Studies
  • Minoru Yoshikawa
    • Environment and Energy Division 1Mizuho Information and Research Institute
  • Kazutaka Oka
    • Environment and Energy Division 1Mizuho Information and Research Institute
  • Saneyuki Takano
    • Environment and Energy Division 1Mizuho Information and Research Institute
  • Simon Hales
    • Department of Public HealthUniversity of Otago
  • R. Sari Kovats
    • Department of Social and Environmental Health ResearchLondon School of Hygiene and Tropical Medicine
Regular Article

DOI: 10.1007/s12199-013-0354-6

Cite this article as:
Honda, Y., Kondo, M., McGregor, G. et al. Environ Health Prev Med (2014) 19: 56. doi:10.1007/s12199-013-0354-6



We previously developed a model for projection of heat-related mortality attributable to climate change. The objective of this paper is to improve the fit and precision of and examine the robustness of the model.


We obtained daily data for number of deaths and maximum temperature from respective governmental organizations of Japan, Korea, Taiwan, the USA, and European countries. For future projection, we used the Bergen climate model 2 (BCM2) general circulation model, the Special Report on Emissions Scenarios (SRES) A1B socioeconomic scenario, and the mortality projection for the 65+-year-old age group developed by the World Health Organization (WHO). The heat-related excess mortality was defined as follows: The temperature–mortality relation forms a V-shaped curve, and the temperature at which mortality becomes lowest is called the optimum temperature (OT). The difference in mortality between the OT and a temperature beyond the OT is the excess mortality. To develop the model for projection, we used Japanese 47-prefecture data from 1972 to 2008. Using a distributed lag nonlinear model (two-dimensional nonparametric regression of temperature and its lag effect), we included the lag effect of temperature up to 15 days, and created a risk function curve on which the projection is based. As an example, we perform a future projection using the above-mentioned risk function. In the projection, we used 1961–1990 temperature as the baseline, and temperatures in the 2030s and 2050s were projected using the BCM2 global circulation model, SRES A1B scenario, and WHO-provided annual mortality. Here, we used the “counterfactual method” to evaluate the climate change impact; For example, baseline temperature and 2030 mortality were used to determine the baseline excess, and compared with the 2030 excess, for which we used 2030 temperature and 2030 mortality. In terms of adaptation to warmer climate, we assumed 0 % adaptation when the OT as of the current climate is used and 100 % adaptation when the OT as of the future climate is used. The midpoint of the OTs of the two types of adaptation was set to be the OT for 50 % adaptation.


We calculated heat-related excess mortality for 2030 and 2050.


Our new model is considered to be better fit, and more precise and robust compared with the previous model.


Heat-related mortalityExcess deathsClimate changeProjectionAdaptation

Copyright information

© The Japanese Society for Hygiene 2013