To minimize the exposure of health care workers to aerosolized ribavirin, we designed a double tent containment system with circulating mist and suction applied between the tents and we evaluated the ability of this system to contain and evacuate aerosolized ribavirin. While the drug was administered with this system at three institutions, three air sampling pumps at different locations in the room and one worn by the investigator (personal breathing zone) collected air samples onto filters for assay of ambient ribavirin. Ribavirin determinations were made by high performance liquid chromatography. A 5- to greater than 20-fold decrease in ambient ribavirin concentrations was observed with the containment system compared with those detected with a single oxyhood in use. The personal breathing zone concentration was 566.0 micrograms/m3 with the oxyhood alone and fell to a mean concentration of 43.81 +/- 33.40 micrograms/m3 with the containment system. Though the risk to exposed health care workers is unknown, this system offers a simple way to decrease significantly occupational exposure to ribavirin.