Maintenance of axenic mice in open cages in mass air flow

The effect of vertical air velocities in mass air flow systems on axenic mice maintained in open cages six inches from cages of non-axenic mice was investigated. The experiment was designed to exclude all but the airborne route of contamination. An airspeed of 10 ffet per minute was sufficient to maintain 15 of 16 animals in the axenic state in four experiments when personnel activity was minimal. During personnel activity, which consisted of changing dirty mouse cages, 26 of 32 axenic mice remained uncontaminated in an airstream of 10 and 26 feet per minute while all mice remained axenic in velocities of 35 and 49 feet per minute.