Exposure Control Indoors with Wearable Personal Exhaust Unit

A wearable personalized ventilation (PV) unit to reduce the risk from airborne disease contamination is reported. The PV unit consists of a nozzle, installed on a headset, which is used to locally exhaust the exhaled air before it mixes with the surroundings. Experiments at 22 °C were performed in a full-scale test room furnished as a double bed hospital room. A breathing thermal manikin with a realistic free convection flow around the body and breathing cycle was used to mimic a sick doctor. A second thermal manikin and a heated dummy were used to resemble two lying patients. The air exhaled by the doctor was mixed with tracer gas (R134 A) to mimic airborne pathogens. The PV nozzle was positioned frontally 0.02 m from the mouth of the doctor exhausting 0.25 L/s air. The performance of the PV in combination with mixing background air distribution at 3 ACH was compared with the case of only mixing background air distribution at 3, 6 and 12 ACH. The use of the device showed a great potential in reducing the concentration of exhaled air in the room to the level measured under mixing ventilation alone at 12 ACH. The high potential to capture exhaled air, makes the wearable PV applicable as an efficient engineering control method that can reduce the spread of pathogen laden air from sick occupants in densely occupied spaces, i.e. cinemas, public transportation, office buildings etc.