ABSTRACT
Terrorism and regional conflicts now have joined natural disasters and technological accidents as ubiquitous threats that can strike anywhere on earth and impact areas as large as a whole region or as small as a neighborhood, city block, or single building. For first responders and humanitarian agencies, population estimates are essential for mission planning in order to determine how many emergency personnel to send, how much temporary shelter to provide, and what types and quantities of emergency supplies are needed. Over-estimates cost time and money. Under-estimates cause unnecessary suffering and may cost lives. The first need is to estimate how many people are potentially at risk, usually before it is feasible to determine how many people actually are affected.
