Heat vulnerability index mapping for Milwaukee and Wisconsin

Context: Extreme heat waves elevate the population's risk for heat-related morbidity and mortality, specifically for vulnerable groups such as older adults and young children. In this context, we developed 2 Heat Vulnerability Indices (HVIs), one for the state of Wisconsin and one for the Milwaukee metropolitan area. Objective: Through the creation of an HVI, state and local agencies will be able to use the indices as a planning tool for extreme heat events. Design: Data used for the HVIs were grouped into 4 categories: (1) population density; (2) health factors; (3) demographic and socioeconomic factors; and (4) natural and built environment factors. These categories were mapped at the Census block group level. Main Outcome Measures: Unweighted z-score data were used to determine index scores, which were then mapped by quantiles ranging from "high" to "low" vulnerability. Results: Statewide, Menominee County exhibited the highest vulnerability to extreme heat. Milwaukee HVI findings indicated high vulnerability in the city's inner core versus low vulnerability along the lakeshore. Conclusion: Visualization of vulnerability could help local public health agencies prepare for future extreme heat events.