Bed-integrated local exhaust ventilation system combined with local air cleaning for improved IAQ in hospital patient rooms

The performance of a ventilated mattress (VM) used as a bed-integrated local exhaust ventilation system combined with air cleaning fabric (acid-treated activated carbon fibre (ACF) fabric) was developed and studied. The separate and combined effect of the VM and the local air cleaning for reducing the exposure to body generated bio-effluents in a hospital room was determined.

Full-scale experiments were conducted in a climate chamber furnished as a single-bed patient room. Two heated dummies were used to simulate a patient and a doctor in the room. The patient was lying on a bed equipped with the VM. The patient's body was covered with either a cotton sheet or with the ACF material used as a blanket.

Ammonia gas released from the patient's groins simulated the body generated bio-effluents. At the location of the groins the surface area of the VM was perforated through which the contaminated air of the bed micro-environment was exhausted. Two modes of operation were studied: 1) the exhausted polluted air was discharged out of the room and 2) the polluted air was cleaned by the ACF material installed inside the mattress and recirculated back into the room.

Both modes of operation efficiently reduced the generated bio-effluents in the room with about 70%. Reduction in the exposure to body-emitted ammonia was up to 96% when the VM was operated at only 1.5 L/s and the ACF was used as a blanket.