Role of differential air pressure zones in the control of aerosols in a large animal isolation facility.

The uncontrolled transmission of hog cholera in a large animal isolation facility, designed to control the movement of aerosols within and between individual wings of a multiunit building, indicated the need for a critical study of aerosol behavior under existing conditions of operation. Studies with aerosols of Escherichia coli B T3 bacteriophage (T3 coliphage) conclusively demonstrated the impossibility of obtaining the desired control by means of a "static" air balance relationship between adjacent areas within the facility. Modifications needed to provide the desired control of the air-handling system are outlined and discussed.