The heat-health nexus in the urban context: A systematic literature review exploring the socio-economic vulnerabilities and built environment characteristics

Of all-natural disasters, extreme high temperatures events are the main cause of weather-related mortality. The compact urban settings of cities, the dependency on infrastructural systems as well as the larger concentration of people and economic activities make urban areas particularly vulnerable to health risks due to heat. To investigate vulnerabilities to heat, the study illustrates how vulnerability factors together with the hazard and the urban parameters determine the nexus between the heat and the health outcome, here called heat-health nexus. Peer-reviewed articles with no language limitations were searched from the first available record subjected to the imposed selection criteria. First, the information related to the study area were analysed, taking into consideration the level of resolution to investigate the scale of analysis. Then, the specific hazard parameters, divided in simple or combined weather indices, were evaluated. For sensitivity and adaptive capacity aspects, the study considered four distinct categories of de- terminants: mental and physical health, demographics, social and economic status. Finally, when looking at enhanced exposure, groups of determinants of vulnerability, divided between those describing indoor and outdoor environment conditions were analysed. Results demonstrated a heterogeneous spatial distribution of the identified case studies about heat and health in the urban context and highlighted different characteristics related to climate hazard, exposure, vulnerability and enhanced exposure factors in relation to the health of the population. This literature review demonstrate that a detailed identification of sensitivity, adaptive capacity and enhanced exposure elements is crucial in the implementation of effective adaptation measures in the health context.