Selecting respirators for control of worker exposure to infectious aerosols.

A method for selecting respirators for protection in infectious aerosol environments was developed, building on a procedure used to choose respiratory protection for environments containing nonbiological contaminants. Modifications in the traditional respirator selection method are proposed for situations where information on occupational exposure limits, toxicity, and airborne concentrations is absent. Toxicity is determined from risk rankings proposed by a variety of organizations. The nature of the activity allows assessment of source generation, which is combined with room volume and airflow to obtain a ranking of airborne concentration. Finally, concentration and toxicity ranks determine a minimum assigned protection factor, which corresponds to a respirator class. Case studies are presented to illustrate the proposed decision logic. For each situation, the procedure yielded choices that were both protective and reasonable. These results suggest that the procedure will be applicable to a variety of settings for a range of infectious organisms.