Control of exposure to exhaled air from sick occupant with wearable personal exhaust unit

Exposure reduction to exhaled air from a sick doctor wearing personal exhaust unit incorporated in headset-microphone was studied. Experiments were performed in a full-scale test room furnished as a double-bed hospital room with overhead ventilation at 3, 6 and 12 ACH. Room air temperature was 22 °C.

Breathing thermal manikin with realistic body and breathing cycle was used to mimic doctor. Second thermal manikin and heated dummy were used to resemble lying patients. Exhaled air by the doctor was mixed with tracer gas to mimic pathogens. The unit was positioned frontally by the mouth of the doctor at three different distances.

It was operated at 0.25 or 0.50 L/s under mixing background ventilation at 3 ACH. The use of wearable personal exhaust resulted in cleaner air in the room compared to mixing alone at 12 ACH. The high potential to capture exhaled air makes the device efficient against airborne pathogens.