Urban Heat Stress and Health: A Spatio-Temporal Investigation of Urban Temperatures and Emergency Calls in Milan

Urban heat stress is an escalating urban health concern, particularly in densely populated cities where extreme heat events exacerbate health risks. This study investigates the relationship between urban heat stress and cardiovascular and respiratory emergency calls in Milan, using spatial and temporal data. By integrating geolocated emergency medical service (EMS) and Universal Thermal Climate Index (UTCI) modelling, it analyses the impact of extreme temperatures on urban health outcomes across the city of Milan. The results reveal correlation between increased temperature and a rise in emergency calls, particularly during heatwaves. Although risks extend to everyone at varying levels, the findings show that emergency incidents peak during the hottest periods, with the greatest impact on vulnerable populations. Additionally, the study finds that nighttime heat exposure, or also referred to as the "tropical nights" significantly contributes to heat stress, leading to an accumulation of heat-related emergency cases. The spatio-temporal distribution of calls further emphasizes the socio-demographic disparities in heat vulnerability, as low-income neighbourhoods, elderly or individuals living alone showing higher incidences of heat-related health emergencies. This research underscores the critical need to integrate the interplay of biometeorological, health and socio-demographic aspects to better inform urban planning and design for tailored interventions. By integrating a holistic approach for urban heat resilience, cities can develop equitable and effective strategies to mitigate heat stress and safeguard public health in a changing climate.