Emergency management short term response to extreme heat in the 25 most populated U.S. cities

Abstract

BackgroundExtreme heat events are a leading weather-related killer in the United States and are predicted to increase in frequency, duration, and intensity. Emergency managers lead short-term response to heat events as well as other natural and man-made hazards with discretion to develop criteria to activate heat responses, such as opening cooling centers and increasing surveillance activities. We aim to describe and summarize emergency management plans for short-term response to extreme heat events across the U.S. MethodsInformation on hazard mitigation plans (HMP) and heat response plans (HRP) in the 25 most populated cities in the US were collected from the National Science Foundation's Natural Hazards Engineering Research Infrastructure DesignSafe Data Depot; interviews with emergency managers; and Freedom of Information Act requests. Obtained responses and policy documents were analyzed to answer the following questions developed in consultation with the National Weather Service (NWS), Weather Program Office: 1. How many locations have developed an HRP? 2. What are the emergency management heat response activation thresholds and metrics for emergency response? 3. Do thresholds change with cascading hazards? 4. Are heat vulnerability indexes (HVI) and/or social vulnerability indexes (SVI) included, and 5. Are health outcomes considered in the development of thresholds? Results1. There is no statistical difference in the prevalence of HRPs across geographic regions in the U.S. 2. Initial response thresholds vary greatly across locations from an ambient temperature of 80–85F (26–29 C) to a Heat Index of 108F (42 C). Eighty-eight (22 of 25) percent of locations are using the NWS Heat Index and twelve percent (3 of 25) are using the experimental HeatRisk Product. 3. Sixty-Eight (17 of 25) percent of cities consider cascading hazards, such as a power grid outage, in their HMP or HRP. None of the cities, however, lower response thresholds, as explicitly written in the plans, during these events. 4. Forty percent (10 of 25) of municipalities have an HVI or SVI included or addressed in their plans, & 5. Three of the cities (New York, Phoenix, & Boston) have adapted response thresholds based on local epidemiological studies DiscussionThere is little consistency in the advisory, warning, and watch criteria thresholds across cities which may be a source of confusion to the public. If such criteria are to be tailored to each geographic location, local epidemiological studies and vulnerabilities should help inform the criteria.