Impact of medical staff movement, airflow rate difference, and door leakage area on particle outflow in an airborne infection isolation room

Airborne Infection Isolation (AII) room are utilized to prevent the spread of infectious diseases such as the coronavirus disease 2019 (COVID-19) in 2020. However, the challenge of mitigating contaminant leaks from the AII room due to medical staff's entry still needs to be solved. This study aims to analyze the impact of airflow rate difference on contaminant outflow by conducting particle outflow experiments in a full-scale AII room chamber. The airflow rate difference was controlled by adjusting the pressure difference and door undercut height. Nine experimental cases were conducted, repeating five times for each case. Additionally, the Air Change Rate (ACR) in the AII room and the Equivalent Air Change Rate (EACR) in the anteroom were calculated using the concentration decay method to assess particle concentration reduction rate. The results indicate that the airflow rate difference did not significantly affect the particle outflow in this study. The particle concentration was 1.7–13.0 times higher when entering the AII room ("IN") than when exiting the AII ("OUT"). During "IN", the particle concentration at the upper part (1.5 m) was 1.3–3.8 times higher than at the lower part (0.5 m). In contrast, during "OUT", the upper part concentration was 0.2–0.9 times the lower part. With increases in the airflow rate difference, the EACR of the anteroom increased. These findings underscore the importance of considering airflow rate difference, medical staff's entering and exiting, and vertical concentration difference to efficiently control contaminant outflow in the AII room.