Size of multibed patient room and airborne infection risk

The objective of this research is to investigate the relationship between the size of a multibed patient room and the risk of airborne infection. Computational fluid dynamics simulations were used to address a number of room sizes with two types of ventilation systems. Assuming that one patient was infected and that infectious agents were contained in exhaled air, the risk of airborne infection was evaluated by the respirable concentration of each patient and the concentration distribution. The results of the simulations show that the airborne infection risk reduced with an increase in the room area, and that the risk of airborne infection tended to increase when the distance between the source of infectious agents and the exhaust outlet was larger than 2.3 m under personal ventilation conditions. In ceiling cassette type conditions, an increase in the room area may increase the risk of airborne infection because the decline in ventilation efficiency and the increase in the ventilation rate decrease the risk of airborne infection.