Abstract
Negative pressure room is indispensable for controlling airborne pathogens. However, no dynamic analysis of the distributions of droplet nuclei under various air conditions has been performed. Dynamics of droplet nuclei in the negative pressure room affected by air direction were examined using a Computational Fluid Dynamics (CFD) method. The concentrations of droplet nuclei in the room were increased immediately and reached a steady state 30 minutes after patient entry. The droplets in the breath were estimated to be diluted approximately 1,200 times after air release. Once the patient leaves the room, the concentration of droplet nuclei was decreased to one thousandth after 60 minutes. No reflux was observed into the ante-room unless the inner door was closed. After opening the door, the concentration in the anteroom increased dramatically due to the refluxed air. In addition, the impact of the positions of the inlet and outlets was assessed under the same air change rate. The distance between the orifice and the positions of the inlet and the outlets significantly affected the distributions of droplet nuclei. Dynamic analysis of the distribution of droplet nuclei using a CFD method may be useful in designing the optimal isolation room for patients with airborne pathogens.
