Recent events have shown that buildings are vulnerable to terrorist attacks involving biological agents. The most serious effects of such an attack are on the health of the occupants of the buildings. Building occupants may suffer health effects ranging from irritation to severe sickness to death. An attack may also have long-term economic and other impacts due to contamination of the building. Several organizations, including the Army Corps of Engineers, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), and the Centers for Disease Control and Prevention (CDC), recognize this terrorist threat and have issued guidance documents on how to deal with it. These documents, while useful, suffer from the fact that the scientific, engineering, and economic information needed to determine optimum courses of action is inadequate. The tools and technologies required to implement optimum courses of action are often not available, are too expensive to use, or are inadequate.