15HEALTH CHaRT: The Climate Health and Risk Tool

To reduce the risk of climate effects on health, decision makers need to understand three important factors: where risks are highest; the unique place-specific and community-level drivers of risk; and specific interventions to reduce specific risk drivers, including effectiveness and implementation considerations. We have developed CHaRT (the Climate Health and Risk Tool) to provide users with these three critical pieces of information. CHaRT risk models use a geographic, hierarchical fuzzy logic framework that exposes the causal pathway of climate-sensitive health risks at the level of a census tract. Through the CHaRT interface, users explore the node-based model along with associated maps to determine where risks are greatests and the factors driving those risks. For each risk factor, CHaRT provides specific risk-reduction guidance, including information on relevant interventions, their effectiveness in preventing adverse health impacts, their costs, implementation timelines, potential unintended consequences, and examples of implementation. We have implemented a heat-health risk CHaRT model for Washington State based on the IPCC risk framework in which risk is a combination of vulnerability, exposure, and hazard and a systematic literature review of factors linking heat with adverse health impacts. Integral to this model are socio-economic factors associated with equity, including those related to race (a proxy for environmental racism), education, limited English, and poverty. Health, demographic, and built environment factors are also incorporated. We have produced model results using thirty-year historical and future climate data, as well as for individual days during the 2021 heat dome, an unprecedented extreme heat event responsible for excess morbidity and mortality in the Pacific Northwest. In general, historical and future heat hazard is most intense east of the Cascade mountain range in less populated regions of the state. However, results also show that vulnerability is high in many locations in the more highly populated Puget Sound region and along the Interstate 5 corridor, where heat hazard is most often low. Results for the heat dome, though, show that these areas exhibit high risk during exceptional heat events. Feedback from users indicates that CHaRT is useful for supporting community conversations about the drivers of climate-sensitive risks and options for risk reduction, expediting decision making to reduce heat-related health risks.