Improved warning systems have done much to reduce natural disaster losses by giving people more time to prepare. For a tornado a community may have an advance warning of several minutes. For a hurricane it might be several days. And although earthquakes cannot be predicted, vulnerable areas expect and prepare for them. But what about those events, disasters in and of themselves, that cannot be forseen and that can affect large numbers of people within minutes or hours? An earthquake can cause the release of hazardous substances. A sudden wind change can steer toxic gasses from a volcano toward a city. The Atmospheric Release Advisory Capability (ARAC) is a national emergency response service of the Lawrence Livermore National Laboratory that is designed to improve decision-making in just such an event.

After receiving just a minimum amount of information (time, location, and type of hazardous release), an ARAC response is set in motion. In less than two hours, and sometimes in minutes, ARAC will access the relevant data sources and synthesize the information to give emergency managers the probable path of the release, the extent to which it will spread, and the affected population and areas. Emergency managers can use ARAC plots and expertise to develop an appropriate response strategy to minimize hazards to life and health as well as property. The program provides support until all airborne releases are terminated, hazardous threats are mapped, and the impacts are assessed. In addition, ARAC can be used as a training tool by using actual real-time weather information to create a realistic release scenario so that authorities are ready for the real thing. Currently in use at many U.S. Department of Energy facilities, this capability could be developed for use at the state and local levels and could serve as a powerful tool for those at the front lines.