National Weather Service, Emergency Medical Services, Scripps Institution of Oceanography/UCSD and California EPA Collaboration on Heat Health Impact and Public Notification for San Diego County

Abstract:

The National Weather Service (NWS) has issued official heat alerts in the form of either a heat advisory or excessive heat warning product to the public and core partners for many years. This information has traditionally been developed through the use of triggers for heat indices which combine humidity and temperature. The criteria typically used numeric thresholds and did not consider impact from a particular heat episode, nor did it factor seasonality or population acclimation.

In 2013, the Scripps Institution of Oceanography, University of California, San Diego in collaboration with the Office of Environmental Health Hazard Assessment, of the California Environmental Protection Agency and the NWS completed a study of heat health impact in California, while the NWS San Diego office began modifying their criteria towards departure from climatological normal with much less dependence on humidity or heat index. The NWS changes were based on initial findings from the California Department of Public Health, EpiCenter California Injury Data Online system which documents heat health impacts. Results from the UCSD study were finalized and published in 2014; they supported the need for significant modification of the traditional criteria.

In order to better understand the impacts of heat on community health, medical outcome data were provided by the County of San Diego Emergency Medical Services Branch, which is charged by the County’s Public Health Officer to monitor heat-related illness and injury daily from June through September. The data were combined with UCSD research to inform the modification of local NWS heat criteria and establish trigger points to pilot new procedures for the issuance of heat alerts. Finally, practices and procedures were customized for each of the county health departments in the NWS area of responsibility across extreme southwest California counties in collaboration with their Office of Emergency Services. The end result of the collaboration was to better define temperature thresholds relative to local climate, levels of heat related responses and activation, as well as to develop standardized terminology on public notifications. In 2014, the County of San Diego Office of Emergency Services incorporated heat alerts into the emergency push notification system for 2 significant heat waves.