Aerobiology is the study of microbiological particles that have, either naturally or purposefully, been introduced into the air. Bioaerosols are attractive as terrorist weapons because they are silent, invisible, and odorless, and can be introduced clandestinely to strike without warning. The fate and transport of bioaerosols is a complicated issue, however, involving many physical and biochemical factors. Both the physical properties of bioaerosols and the likelihood for their successful delivery depend largely on the dissemination method applied.