Experiments were performed in a 50 m 3 simulated OR as shown in Figure . The room was equipped with typical OR air flow obstructions including surgical lights, tables and medical equipment. The room also contained healthcare worker manikins. An Illuvia Sense (Aerobiotix, Miamisburg, OH) air-cleaning device that recirculates local air back into the room at a rate of 450 cfm after passing through HEPA filtration and a UV chamber was present in the corner of the room. An activated carbon filter (ultra-fiber cm108) (Troy Filters) measuring approximately 46 x 46 cm was placed in a slot at the air inlet. The activated carbon filter had a thickness of approximately 0.3175 cm and density of approximately .034 g/cm . The activated carbon filter was positioned just behind the inlet of the device so that when the device is on all incoming air is forced to pass through it. VOCs were measured with calibrated Aeroqual (Aukland, New Zealand) gas sensitive semiconductor VOC sensors (Series 500) that measure from 0-25 ppm with an accuracy of ± 0.1 ppm ± 10% and a resolution of 0.1 ppm. VOC levels were monitored with the air cleaning device on and off. Two VOC sensors were placed in the room. Sensor 1 was stationed near the opposite corner of the room, approximately 18 ft. away. Sensor 2 was stationed near the same wall as the air cleaning device and approximately 7 ft. from the air outlet. Readings were taken every minute. VOCs were introduced into the room by placing an open dish of toluene (Aldrich) in the center of the room on top of the sternum of a manikin resting on an operating bed. When a sufficiently high level of VOCs were detected, the toluene dish was covered and removed from the room. The room ventilation system was not in operation during the experiments in order to reduce the rate of natural gas exchange.