Environment, development, and health: the vulnerability of sub-populations in İstanbul to heat extremes

The Mediterranean region is highly vulnerable to climate risks such as prolonged and more intense heat waves with increased drought. İstanbul has the climate characteristics of the Mediterranean region and interacts with the surrounding climate regions. Also, the city is the largest among Türkiye’s major urban areas. The study aims to determine the vulnerability of İstanbul residents to heat extremes as well as their mortality risks according to region, age group, sex, and cause of death. The distributed lag non-linear model was used to analyze risk by establishing a statistical relationship between extreme temperatures and mortality rates. A separate model was defined for each sub-population group and the increase in mortality risks was estimated when daily maximum temperatures increased from minimum mortality temperature to the heat wave threshold. The highest increase in excess rate was observed in the low urbanization region (19.5%) followed by the medium urbanization region (18.0%). Mortality risk was also higher in people aged ≥ 65 years (20.9%), females (16.2%), people with cerebrovascular (53.4%) and respiratory diseases (40.7%). The vulnerability in less populated areas is likely to be due to the cumulative intensity of regional heat waves as well as inadequate access to health services, housing, and climatization conditions in these areas; in addition, as the population density of the elderly increases, regional vulnerability is considered to be higher. The findings of this multidisciplinary study can guide decision makers and be implemented in future local climate action plans, public health strategies, and people-friendly urban design in line with Sustainable Development Goals (SDGs).