Abstract: A centralized vacuum waste disposal system, particularly for use in hospitals, comprises one or more shredding machines feeding a remote incinerator via a ducting system through which shredded waste is drawn by an air compressor. To prevent contaminated air escaping from the system if the compressor stops running, an auxiliary device is provided to maintain a partial vacuum at all times. In addition the shredding machines preferably have drop-out exit grilles to permit efficient scavenging of the machines, and germicidal sprays for drenching the interior of the machines.