For years, biological research facilities have been using negative air pressure containment to secure and utilize the world s most dangerous biological agents. The same principle extends to our exhaust ventilation technology, which uses negative pressure from the pet cage exhaust system (HVAC) to draw and filter room air from cages and racks in a single pass flow pattern, providing complete bio-isolation between cages and cage surroundings. This technology removes airborne particles including cage-level allergens, waste gases and thermal loads. Our cage systems improve and control air quality for animals, staff and the environment. Since the cage system rack is vented only by the exhaust, the cages are kept at a negative pressure with respect to the room, and the central plenum of the rotating carousel is negative with respect to the cages. This completely eliminates the possibility of particles travelling backwards along the airway.