A nuclear power plant releases radiation, as Chernobyl did in 1986. Toxic gases spread from a terrorist's bomb, as sarin did in Tokyo, Japan in 1994. These examples represent global threats to local places. Emergency response by the United Nations, the United States, and other national and international organizations requires simulation of contaminant transport by air and water plus improved estimates of global population distribution.
Geographic information is essential for quick and effective response.
Air diffusion models available today are capable of estimating contaminant plumes at spatial resolutions far exceeding those of the official censuses available for most countries. For many years, the U.S. Census Bureau has enhanced the precision of global population estimates through a manual procedure designed to allocate rural populations to 20' X 30' cells and urban populations to circles centered on major population concentrations. Yet, analysis of most hazardous releases requires data resolutions on the order of 1 square kilometer or even finer.