Cross Infection in Hospital Wards with Downward Ventilation - Different Locations of Return Openings without and with Partitions between Beds

A two-bed hospital ward with one standing healthcare assistant and a ceiling-mounted low-impulse semicircular inlet diffuser is simulated in a full-scale room. Tracer gas is used for simulating gaseous contaminants, and the concentration is measured at different air change rates and different postures of the patients. A textile partition between the beds, which is typical in a hospital ward, is used for protection of the patients in some of the experiments. Three different layouts of return openings are tested. One layout with one opening at the ceiling, another with four openings at the wall opposite to the inlet diffuser, and one with a high location of these four openings. The downward recirculating flow is on average parallel with the partition, and the partition does not decrease cross infection. A high location of the four return openings decreases the risk of cross infection.