Delineating the impact of heat islands on human health and implications for positive mitigation and adaptation

Many cities are facing severe extreme heat challenges. Apart from heatwaves due to climate change, heat islands associated with built environment modification is a significant driver to extreme heat challenges. However, many studies have mixed the impacts of heat islands and heatwaves when documenting heat-induced threats to citizens' comfort, health, and safety. This affects decisions of investing in more heat mitigation and adaptation infrastructure in cities. Therefore, this study aims to delineate the impact of heat islands on human health for implications on land use optimization and heat-resilient infrastructure allocation for positive mitigation and adaptation. Based on literature review, this study investigates the association of heat exposure with heat-related morbidity and mortality, with factors such as climatic zones, demographic features, and socioeconomic conditions being moderation variables. Cardiovascular diseases, respiratory diseases, skin diseases, and metabolic diseases are investigated when analyzing heat-related morbidity. Interventions of air-conditioning systems, cooling centers, and education campaigns which act as effective methods to enhance adaptation capacity are also considered. This study reveals that cities are not always locations with higher mortality and morbidity compared with rural areas. Given this, urban-rural dualism is not robust to characterize heat-related mortality and morbidity due to direct heat exposure.