The health significance of airborne microorganisms emitted from wastewater was discussed. Studies were cited which determined bacteria aerosol concentrations and the factors affecting those concentrations. The aerated wastewater sources often investigated included activated sludge aeration tanks, trickling filters, land application by sprays or sprinklers, and primary sedimentation tanks. A variety of viable microorganisms, of which some were pathogenic, were detected in the air samples obtained downwind from the wastewater sources. The field studies reviewed employed numerous sampling methods, such as agar settling plates, solid media impactors, and liquid impingers. The Andersen six stage impactor was considered the sampler of choice. In most studies, the downwind viable particle concentration decreased with increasing distance from the wastewater source. Upwind samples were often used as controls. Many studies determined viable aerosol particle sizes to be of respirable size, with diameters of less than 10 microns. Factors affecting the generation of viable aerosols included aeration, aeration bubble size, the microorganism content in the wastewater, total solid level, bacterial species, wind speed, wastewater source size, and wastewater flow rate. The survival and dispersion of viable aerosols were mainly influenced by wind speed, die off, deposition, and diffusion. Some researchers concluded that the bacterial aerosols emitted from wastewater posed a respiratory or intestinal tract hazard for workers and nearby residents. However, evidence of elevated disease incidence in exposed groups was considered lacking. The authors conclude that workers and nearby residents may be exposed to viable, pathogenic aerosols. This exposure may or may not pose serious health risks.