The Role of Maps in Neighborhood-Level Heat Vulnerability Assessment for the City of Toronto

Extreme hot weather is a threat to public health, and it is anticipated that the number of hot days and the duration of extreme heat events will increase with climate change. Already, heat-related illness and mortality is the dominant natural hazard in many countries. While everybody is at risk to varying degrees, there are known factors relating to heat exposure and sensitivity that make some population groups more vulnerable than others. The objective of this paper is to assess carto-graphic design decisions in creating heat vulnerability maps, and how they may affect the usefulness of different map types. Spatial patterns of heat vulnerability were visualized using maps representing individual exposure and sensitivity indicators, composite vulnerability indices, and geographical hot spots of vulnerability. The composite indices were calculated using the ordered weighted averaging (OWA) multi-criteria analysis method. Hot spots were determined using local indicators of spatial association (LISA). This study is part of an ongoing project which aims to identify vulnerable populations within the City of Toronto, Canada, in order to support targeted response and mitigation. The maps were found to be a valuable addition to the hot weather planning toolkit supporting neighbor-hood-level interventions.