Severe infectious disease such as Severe Acute Respiratory Syndrome(SARS), Influenza A virus Subtype(H1N1), Middle East Respiratory Syndrome Coronavirus(MERS) are constantly occurring. Theses high-risk respiratory diseases are mainly spread by air inflow through human respiration due to the spread of droplets such as sneezing and coughing. Therefore, prevention of secondary infections due to high-risk respiratory diseases is very important, and it is the negative pressure isolation room that is used to block the path of the secondary infection. The negative isolation room is a special ward that serves to initially isolate the infected patient and prevent the spread of secondary infections in the early stage. Unlike the general ward, it maintains the patient’s room at negative pressure and has a blocking effect to prevent the air in the room from diffusing through room airflow generated by the outside and pressure difference. In particular, Korea has experienced 186 infectious diseases and 38 deaths due to MERS in 2015, so the importance of nationally designated negative pressure isolation room has been emphasized and facilities have been expanded to cope with the public health crisis.
However, unlike the expectation that the complete containment effect was expected, it was confirmed through various previous studies that the contaminated air in the isolation room can be spread out due to various factors such as room temperature gradient, opening/closing of door, human motion. Therefore, in order to prevent contaminated air outflows in the isolation room, it is very important to establish standard operating procedures to control the factors that polluted air diffusion.
The purpose of this study is to investigate the variation of the pressure fluctuation according to the type of door(Sliding/Hinged door) through CFD simulation and to investigate the leakage of the contaminated air according to the door opening/closing. The results are as follows. First, the pressure fluctuation according to the hinged door was rapidly increased instantaneously than the preset pressure difference of 2.5Pa as the pressure of the isolation room was suddenly lowered when the door was opened. After that, the pressure in the isolation room and anteroom were made equal. However, in the process of closing the hinged door, the pressure in the isolation room is higher than the pressure in the anteroom, and the pressure is reversed. In the case of the sliding door, the pressure of the isolation room was lowered at the moment of opening the door, and the pressure difference was increased to 2.5Pa. However, unlike the hinged door, the pressure was not reversed during the closing of the door. These result show that the pressure fluctuation is large as the opening and closing speed of the door increases.
Second, the Infected air leakage according to the opening/closing of hinged door larger than the Infected air leakage according to the opening/closing of sliding door in the same door opening/closing cycle. The amount of contaminated air flow according to the opening and closing speed of the hinged door increase as the opening and closing speed of the door increases. On the other hand, in the case of the sliding door, the pollution air flow increases as the opening and closing of the sliding door speed is slower.
Third, in order to figure out the main factors of Infected air leakage according to the opening and closing of the door and the movement of the medical staff, the result of comparing of the Infected airflow amount when the door was only opened and closed and the movement of the medical staff was accompanied by the opening and closing of the door, it was found that Infected air leakage due to the opening and closing of the hinged door was larger than the Infected air leakage due to the movement of the medical staff. However, in case of sliding door, it was confirmed that the Infected air leakage according to the movement of the medical staff was larger than the Infected air leakage due to sliding door opening/closing.
Fourth, the Infected air leakage according to the opening and closing speed of the door and the movement speed of the medical staff showed that the Infected air leakage tended to increase as the opening and closing speed of the hinged door and the moving speed of the medical staff were faster. When the sliding doors were installed, the Infected air leakage tended to increase as the sliding door opening/closing speed was slower and the moving speed of the medical staff was faster.
Fifth, the Infected air leakage according to the moving direction of the medical staff showed no significant difference when the hinged door was installed. But, in the case of the sliding door, the Infected air leakage was larger when the medical staff moved from isolation room to the anteroom than from anteroom to the isolation room.