Heat index spatial surveillance integral to a public health services seasonal heat response plan, county of San Diego, California

A high heat index increases risk for heat exhaustion, heat stroke and heat-related death, particularly in vulnerable populations such as young children and the elderly. In 2006, a prolonged heat wave with high relative humidity created a high heat index which threatened San Diego County residents. This prompted establishment of a heat emergency plan to anticipate and respond appropriately to heat emergencies. To identify areas threatened by heat emergencies, GIS is used to map temperature, relative humidity, and seasonal heat index collected from local weather stations.. Additionally, pre-hospital provider impressions and 911 calls are monitored daily to assess increased heat-related illness. Daily surveillance provides lead time for response personnel to set up facilities, plan for heavier use of medical services, and alert the public. Heat emergencies are coordinated by Public Health Services/Emergency Medical Services in partnership with Aging and Independent Services, which identify vulnerable populations, with local law enforcement, who contact those specifically at risk, and the Office of Media and Public Affairs, which alerts the general public.