Pathways to Heat Vulnerability in Phoenix, AZ

Heat exposure is a leading cause of weather-related mortality and morbidity globally. There is strong scientific evidence that a rising global mean temperature and increasing urbanization will lead to increased per capita heat exposure over the coming decades. Though precise changes in more nuanced measures of heat exposure, which may be better correlates with heat-health outcomes, are harder to predict. At the same time, many studies indicate that social and behavioral factors may be better predictors of heat mortality and morbidity than exposure alone, both at present and in the future. Work analyzing exactly what those factors are has mostly consisted of qualitative exploration of very specific events or aggregated relationships between demographic or spatial characteristics and exposure or health outcomes. This work has provided a convincing but incomplete assessment of how and why some people are more likely than others to suffer or die from extreme heat. At the same time, there have been calls for an increased focus on mechanisms across the social sciences, and some heat studies have theorized the importance of understanding the mechanisms that generate negative heat-health outcomes. However, at the moment we have almost no empirical evidence that demonstrates the mechanistic pathways that lead from social and behavioral indicators, like demographic traits, to negative outcomes. We have analyzed closed-ended survey data collected from 163 households in Phoenix, Arizona in summer 2016 as part of the interdisciplinary 3HEAT project in order to address this shortfall. We ran several regression models to explore possible pathways from demographic variables through individual circumstances like self–reported health status, and personal behaviors like air conditioning use, to potential changes in exposure and ultimately to changes in self-reported heat-health outcomes. Preliminary results demonstrate significant relationships between some but not all hypothesized vulnerability indictors, mechanisms, and heat-health outcomes. These results demonstrate the importance of continuing research on the mechanisms of heat vulnerability in order to test common assumptions about how vulnerability operates to manifest negative outcomes and to better inform interventions aimed at reducing negative health effects.