"BioWatch is the Department of Homeland Security's (DHS's) system for detecting an aerosolized biological attack using collectors that are positioned strategically across the country to continuously monitor the air for biological threats. As currently deployed, BioWatch collectors draw air through filters that field technicians collect daily and transport to laboratories, where professional technicians analyze the material collected on the filter for evidence of biological threats. As part of the BioWatch program's efforts to enhance its effectiveness and capabilities, particularly with regard to detecting biological threats in challenging indoor environments, DHS requested the National Academies of Sciences, Engineering, and Medicine hold a workshop to explore alternative and effective biodetection systems for aerosolized biological agents that would meet BioWatch's technical and operational requirements, integrate into the existing system architecture and public health infrastructure, and be deployable by 2027. This publication summarizes the presentations and discussions from the workshop"--Publisher's description.