Emission of airborne bacteria from a hospital incinerator

Only five studies have been found in the literature which provide any indication of the effectiveness of incineration for rendering infectious hospital waste innocuous. Although there is an indication from these studies for release of bacteria in stack gas, none of the studies identified the bacteria or determined the source of bacteria. The purpose of the present study was to investigate the potential for a hospital incinerator to release human pathogenic bacteria into the ambient environment. In this study, waste spiked with Bacillus subtillis was burned in a hospital incinerator. Although bacteria were found in the incinerator stack gas, (concentrations ranged from not detectable to 1157 colonies/m3 of air) no Bacillus subtilis was recovered from the stack gas. The results suggest that the source of the stack gas bacteria was not from unburned waste or from outdoor air. Analysis of samples of air from the incinerator room (not simultaneous with the stack gas samples) indicates that the source of the stack gas bacteria was most likely the combustion air.