Excess Mortality in Istanbul during Extreme Heat Waves between 2013 and 2017

Introduction

Heat waves are one of the most common direct impacts of anthropogenic climate change. Frequency, intensity, and duration of warm spells and heat waves have increased due to global temperature rise . The number and intensity of heat waves in the Mediterranean region, including western Turkey and the Black Sea coastline, have significantly increased as well . Excess mortality due to heat wave episodes has been documented after several long and widespread heat wave episodes over the last 30 years, for example: the 1995 heat wave in the upper midwestern US, with more than 700 excess deaths in Chicago only; the 2003 European heat wave episode with more than 70,000 total excess deaths in 16 European countries; and the 2010 heat wave in India with 1344 excess deaths in the city of Ahmadabad alone.

Conclusions

This study showed that three heat wave episodes in Istanbul in 2015, 2016, and 2017 caused an increased risk of all-cause mortality: 11%, 6%, and 21%, respectively, without any harvesting effect. The total number of excess deaths during the heat wave episodes for three years was 419. These results are in line with similar studies worldwide in comparable situations for amplitude of effect, age groups most affected, and the importance of cardiovascular deaths in the episodes. Some limitations due to data availability and quality highlight potential future improvements. Since there are very limited studies about heat waves and mortality in Istanbul related to the past heat waves such as the ones in 2000, 2003, 2007, and 2010, it could not be assessed whether there were any improvement over time in terms of adaptation or behavioral change, as no historic reliable data is available. Since there are no public health intervention plans for heat waves at the local or national levels, further studies about increased death risks due to heat waves in Istanbul and other cities, as well as intervention studies, are necessary in the light of the impacts presented in this study. Other studies on heat-related ambulatory and hospital morbidity could be of great interest too for Istanbul and other regions of Turkey.