Description of the built environment associated with fatal heat-related injuries during the 2021 western North American extreme heat event

British Columbia (BC) experienced 619 heat-related deaths during the 2021 heat dome, according to the BC Coroners Service (BCCS). Many of those deaths were among highly susceptible people, with poverty, schizophrenia, and other chronic conditions being significant risk factors for death in epidemiologic analyses. Many of the fatal heat-related injuries were recorded in specific building types, including mobile homes and high-rise multi-unit residential buildings (MURBs). Understanding these built environment characteristics where injuries and deaths occurred could assist in planning for future extreme heat events and implementing measures to mitigate potential injuries. However, developing this understanding has previously required physical access to individual sites to document their specific attributes, which is resource-intensive and prohibitive for large-scale studies. This study demonstrates the potential to leverage publicly available imagery to reduce the effort required to gather built environment characteristics. By combining street addresses of known fatal heat-related injuries with satellite and street view data from Google Maps and Earth, the study collected data for each site where an injury occurred. Analysis of the information found disproportionate representation of specific building types, absence of greenery and mature trees, and built environment density patterns in multiple settings. The study results indicate that characteristics such as building orientation, amount of glass surface area, and the condition of structures could all factor into risk to susceptible people during extreme heat events. Furthermore, two distinct building typologies were among these injury locations: high-rise MURBs with high window-to-façade surface area ratio and older, shorter buildings with few windows. The study demonstrated the value of publicly available visual data, and methods could be applied to other disasters such as wildfires and floods.