Currently funded studies have quantitated the effect of mass air flow in animal laboratories and developed methods for optimal use using an assay system of polyoma virus infection developed in this laboratory. Other parameters included environmental impact, animal growth, cost-effectiveness and engineering feasibility. Controlled studies proposed in this application will be performed in a mass air flow room and a conventionally ventilated room with airborne polyoma virus to determine if more economical designs of mass air flow can be developed that are as efficient as presently available systems by using less expensive filters and a lower air velocity when no personnel are in the mass air flow room. The efficiency of other preventives of airborne infections, namely, increased turbulent ventilation, elimination of bedding, ultraviolet irradiation and contact transmission will be determined relative to mass air flow. Cost analysis will be performed in all studies using technician hours and kilowatt hours utilized per week, among other factors. Separate studies are designed to further quantitate the polyoma assay system. Aerosol stability, sensitivity to disinfectants and exact mode of infection will add to information gathered in these studies on the airborne ID50 and in vivo biohazard correlates of in vitro classification. The results of these studies will increase cost effectiveness of many methods of ventilation.