A collaboration between the University of Hertfordshire in the United Kingdom and the Biomedical Advanced Research and Development Authority (BARDA), part of the Office of the Assistant Secretary for Preparedness and Response (ASPR) within the U.S. Department of Health and Human Services, has resulted in the development of a decontamination decision tool and updated guidance for mass casualties. PRISM introduces the “triple protocol” of dry, wet, and technical (specialist) decontamination.