Terrorists intent on causing many deaths and severe disruption to our society could, in theory, cause hundreds to tens of
thousands of deaths and significant contamination of key urban facilities by using chemical or biological (CB) agents.
The attacks that have occurred to date, such as the 1995 Aum Shinrikyo CB attacks and the 2001 anthrax letters, have
been very small on the scale of what is possible. In order to defend against and mitigate the impacts of large-scale
terrorist attacks, defensive systems for protection of urban areas and high-value facilities from biological and chemical
threats have been deployed. This paper reviews analyses of such scenarios and of the efficacy of potential response
options, discusses defensive systems that have been deployed and detectors that are being developed, and finally outlines
the detection systems that will be needed for improved CB defense in the future. Sandia's collaboration with San
Francisco International Airport on CB defense will also be briefly reviewed, including an overview of airport facility
defense guidelines produced in collaboration with Lawrence Berkeley National Laboratory. The analyses that will be
discussed were conducted by Sandia National Laboratories' Systems Studies Department in support of the U.S.
Department of Homeland Security (DHS) Science and Technology Directorate, and include quantitative analyses
utilizing simulation models developed through close collaboration with subject matter experts, such as public health
officials in urban areas and biological defense experts.