Search

Extreme heat events have caused excess mortality in Canadian cities. In order to map the population groups most vulnerable to extreme heat in Vancouver, we overlaid multiple layers of socio-economic, environmental, and infrastructural data. By superimposing multiple disparate data layers, we were able to detect and visualize 105 socio-economically deprived dissemination areas with high vulnerability to extreme heat events. The three dissemination areas found to be most vulnerable to heat varied from the rest of the sample in terms of environmental and infrastructural variables. These three vulnerable dissemination areas also have relatively low vegetation cover as well as relatively hot surface temperatures. As such, they are socio-economically vulnerable, far from cooling and health infrastructure, and have an environment that elevates heat exposure. Our results are a preliminary step toward the development of tools that can help health authorities, city officials, and policymakers better understand who is at risk during extreme heat events, where they reside, what factors drive the risk, and ultimately what can be done to mitigate it. L'utilisation de sources de données diverses et variées pour cartographier la vulnérabilité à la chaleur : une étude de cas à Vancouver Des épisodes de chaleur accablante sont une cause de surmortalité dans les villes canadiennes. Une carte des groupes de populations les plus vulnérables à la chaleur accablante a été dressée à Vancouver en combinant plusieurs couches de données socio-économiques, environnementales et liées aux infrastructures. La superposition de couches de données diverses et variées a permis de détecter et de visualiser les 105 aires de diffusion défavorisées sur le plan socio-économique qui présentent une grande vulnérabilité en situation de chaleur accablante. Les trois aires de diffusion les plus vulnérables se distinguent du reste de l'échantillon en matière d'environnement et d'infrastructure. En outre, ces dernières ont, toute proportion gardée, un faible couvert végétal et des températures de surface chaudes. En plus de la vulnérabilité socio-économique, elles se caractérisent par un éloignement aux infrastructures de refroidissement et de santé, et par un environnement qui accroît l'exposition à la chaleur. Les résultats obtenus constituent un premier pas vers la conception d'outils pour éclairer les autorités sanitaires, les responsables municipaux et les décideurs afin d'identifier qui est exposé au risque pendant les périodes de chaleur accablante, où ils (elles) résident, quels facteurs accentuent le risque, et, finalement, les mesures à prendre pour l'atténuer. [ABSTRACT FROM AUTHOR]

Apparent temperature is more closely related to mortality during extreme heat events than other temperature variables, yet spatial epidemiology studies typically use skin temperature (also known as land surface temperature) to quantify heat exposure because it is relatively easy to map from satellite data. An empirical approach to map apparent temperature at the neighborhood scale, which relies on publicly available weather station observations and spatial data layers combined in a random forest regression model, was demonstrated for greater Vancouver, Canada. Model errors were acceptable (cross-validated RMSE = 2.04 °C) and the resulting map of apparent temperature, calibrated for a typical hot summer day, corresponded well with past temperature research in the area. A comparison with field measurements as well as similar maps of skin temperature and air temperature revealed that skin temperature was poorly correlated with both air temperature (R 2 = 0.38) and apparent temperature (R 2 = 0.39). While the latter two were more similar (R 2 = 0.87), apparent temperature was predicted to exceed air temperature by more than 5 °C in several urban areas as well as around the confluence of the Pitt and Fraser rivers. We conclude that skin temperature is not a suitable proxy for human heat exposure, and that spatial epidemiology studies could benefit from mapping apparent temperature, using an approach similar to the one reported here, to better quantify differences in heat exposure that exist across an urban landscape. [ABSTRACT FROM AUTHOR]