Testing of a downflow system for high risk infectious disease isolation rooms

Isolation room airflows for infectious diseases are designed to minimise the risk of transmission of airborne pathogens to those outside the room and to protect healthcare workers who tend to the patient. This study considers the risk in the vicinity of the patient and conducts an experimental investigation into a downflow ventilation design to evaluate whether it is capable of providing protection to a healthcare worker. Anemometry and smoke tests are conducted in a mock up room to assess influence of ventilation rate, extract design, heat loads and flow local to a healthcare worker. Results show a good downward flow can be established, but a fan speed capable of delivering 0.35m/s and central extract are required to create a uniform flow. Heat loads and a healthcare worker leaning over the bed both compromise downflow effectiveness; local flow acceleration and exhaust can mitigate to some extent

Assessing the near patient infection risk in isolation rooms

Isolation rooms designed for protection against airborne infection have been designed based on a certain number of ACH and a differential pressure with adjacent spaces. In the validation process of an isolation room, gas tracer is generally used to simulate airborne infection. The experiments carried out focused on studying the risk of infection when the recipient is very close to the source (i.e. hospital staff working very close to an infectious patient) and studying how gas tracer tests compare to bacteriological tests. The results show good comparison between the behaviour of gas tracer and bacteria in the same room and the bed in different positions, thus validating the use of a tracer gas to represent the airborne behaviour of bioaerosols