An Outcomes-Based Heat Information System Prototype for Phoenix, Arizona

Owing to a new awareness of the risks of climate change and extreme heat to urban populations, the negative health impacts of heat are a subject of increasing concern among public health, emergency management, and weather forecasting professionals. A paradigm shift is underway toward systems of emergency communication and response that are informed by empirical research on heat-related health outcomes. Because the epidemiology of heat-related illness varies from city to city, an improved policy response to high temperatures may need to be customized to each location. Following five years of work by the Urban Vulnerability to Climate Change project at Arizona State University (ASU), detailed empirical relationships between meteorology and heat-related health outcomes are now available for Maricopa County and Phoenix, which comprise the hottest metropolitan area in the United States during May-October. Collaboration between ASU and the Phoenix National Weather Service (NWS) Office has produced a prototype heat information and communication system that provides two types of output based on daily counts of heat-related morbidity and mortality data. The prototype information complements the existing NWS heat warning system by identifying multiple outcomes-based meteorological thresholds where specific types of heat-related health events (death, hospitalization, emergency department visit) become more likely, and by ranking days according to the likely severity of these events. This system allows a diverse range of heat responders to weigh the costs and benefits of their respective responses, and captures the seasonal (as opposed to event-based) nature of heat-related health risks in an extremely hot urban environment. This type of framework may help inform heat information and communication efforts in a variety of cities in coming years.