Analysis of Indoor Air Flow Measurement according to Outdoor Air Intake Rate in an Outdoor Patient Department at a General Hospital

The purpose of this study is to measure and analyze indoor air flow in order to determine the possibility of HVAC operations causing airborne infections in outpatient departments of general hospitals in South Korea. Among 10 general hospitals, the emergency department in the children’s ward in the K University General Hospital using a typical central HVAC system was selected as the measurement space for this study. The indoor air flow direction was confirmed by measuring the interzonal air flow rate, differential pressure and tracer gas concentration for the central HVAC system of the study space, and three different changes in the outdoor air intake rate were applied to determine the interzonal air flow diffusion state. The study space had a high possibility of receiving patients that could cause airborne infections and there were risks of secondary infections from the airflow diffusing into adjacent spaces such as the otorhinolaryngology department or the waiting room corridor. The measurement results showed that using an HVAC system with 100% outdoor air reduced the concentration of gas rapidly, thereby lowering the probability of infection, and that the airflow did not diffuse into adjacent spaces when the study space had negative pressure.