This discussion will focus on current and emerging technologies for the detection and study of bacteria dispersed into outdoor air, with applications to public health, agriculture, ecological health and international security. Recent studies of bacteria in the natural atmosphere have focused on two general areas: aerosol dispersal of bacterial pathogens from land sources and aerosol pathogen surveillance; and increasingly comprehensive taxonomic surveys of bacterial diversity in the outdoor air. These studies represent significant starting points in efforts to understand the composition, transport, survival and viability of bacteria in the outdoor air. Many significant questions still remain to be answered about patterns of dispersal of bacterial pathogens in air, factors affecting their transport, survival and viability, and the overall abundance, composition and consequences of bacteria in air.