Modeling and future projections of heat-related excess mortality in İstanbul during the summer months

Aim: The goal is to develop a model that reveals the exposure-response relationship using daily temperature and death observation data for Istanbul from 2013 to 2019, and to estimate possible excess mortality for the period from 2020 to 2100 under different climate scenarios with the developed model. Materials and Method: Using daily meteorological and death data from 2013 to 2019, an ecological study was conducted with a distributed lag non-linear model (DLNM) to establish the temperature-mortality relationship. Climate model outputs were calibrated with observation data for temperature projections from 2013 to 2100. Excess mortality projections were made for different climate, population, and adaptation scenarios. Results: The cumulative relative risk for 0-7 days at the 99th percentile temperature was 1.16 (95% CI 1.1-1.22). The risk was higher in women and those over 65. The attributable mortality rate due to high temperatures during the observation period was 1.75% (95% CI 0.97-2.51), with 2,175 deaths (95% CI 1,211-3,123). In the elderly, the attributable rate was 2.04% (95% CI 1.15-2.9), with 71.4% of attributable deaths being elderly. For 2090-2099, excess mortality was predicted at 6.4% (95% CI 4.53-8.24) for the RCP4.5 scenario and 17.98% for RCP8.5. With adaptation, rates dropped to 4.85% (95% CI 2.87-6.69) and 8.77% (95% CI 2.87-13.66). Estimated excess deaths for 2090-2099 ranged from 7,735 to 163,926. Conclusion: The study projects the impact of high temperatures on mortality in Istanbul under various climate scenarios. Public health strategies and emission reduction policies are needed to mitigate climate change risks.