• disaster;
  • emergency medicine;
  • emergency medical services;
  • health care capacity;
  • health services;
  • health care;
  • public health services;
  • surge capacity


To describe the characteristics of the demand for medical care during sudden-impact disasters, focusing on local U.S. communities and the initial phases of sudden-impact disasters.


Established databases and published reports were used as data sources. Data were obtained to describe the baseline capacity of the U.S. medical system. Information for the initial phases of a sudden-impact disaster was sought to allow for characterization of the length of time before a U.S. community can expect arrival of outside assistance, the expected types of medical surge demands, the expected time for the peak in medical-care demand, and the expected health system access points.


The earliest that outside assistance arrived for a community subject to a sudden-impact disaster was 24 hours, with a range from 24 to 96 hours. After sudden-impact disasters, 84% to 90% of health care demand was for conditions that were managed on an ambulatory basis. Emergency departments (EDs) were the access point for care, with peak demand time occurring within 24 hours. The U.S. emergency care system was functioning at relatively full capacity on the basis of data collected for the study that showed that annually, 90% of EDs were boarding admitted inpatients, and 75% were diverting ambulances.


As part of planning for sudden-impact disasters, communities should be expected to sustain medical services for 24 hours, and up to 96, before arrival of external resources. For effective medical surge-capacity response during sudden-impact disasters, there should be a priority for emergency medical care with a focus on ambulatory injuries and illnesses.