The Abstracts of the paper carried by the Journal of JACA
Currently, Nagasaki University is constructing a BSL-4 facility, which is scheduled to be completed this summer. This paper introduces the installation location of the facility, the outline of the building, the configuration of the BSL-4 laboratory, its ancillary equipment, and how to use it. In addition, we will explain WHO and Japanese regulations related to BSL-4 facilities, and explain matters such as earthquake resistance and airtightness that Nagasaki University has made important in facility design. Then, we summarize the future measures for the actual operation of the suit-type BSL-4 facility of Nagasaki University, which is the first in Japan.
The architectonic airtightness at the biosafety facilities and clean room is very important function from contamination control and the energy saving. But the evaluation standard about the airtightness is not maintained in Japan, and technological knowledge is not accumulated sufficiently.
Others have estimated measurement of the airtightness in many facilities. This report based on the results, explains about architectonic airtightness, method for measurement, investigation method of leakage points and measuring evaluation cases at cleanrooms.
Besides, it’s expected that the proposed original evaluation standard is useful for appropriate building facilities and maintenance management.
Air is sent through ducts in the air conditioning of buildings such as offices, restaurants, and laboratories. There are various types of dampers that control the amount of air, and one of them controls the room pressure. It is mainly used in clean rooms, and it is also used to prevent cross-contamination by creating a pressure difference between adjacent rooms. This room pressure control damper directly measures the room pressure and controls the angle of the damper blades so that the room pressure will be the set pressure. This paper introduces the structure and characteristics of the damper, and explains the control of room pressure using it.
For quality assurance of pharmaceuticals, room pressures of pharmaceutical manufacturing facilities need to be precisely controlled. However, the room pressure fluctuates due to several causes, i.e. starting and stopping of local exhaust ventilators, fluctuation of the reference pressure, gusts from outside air intakes, opening and closing doors, mode switching of air conditioning systems. It is thought that these fluctuations of room pressure can be suppressed by constant return air volume control, passing reference air through a long distance, combination of ducting and motor dumpers, combination of constant room pressure control and constant air volume control, and holding the operating state of each air conditioning device as room pressures rise and fall. It is shown that these methods are effective for room pressure control by theories and experiments using the equipment that imitated a real building.
Based on aerosol mechanics, the transmission mode of SARS-CoV-2 was analyzed. It is considered that there should be a transmission mode of aerosol cloud between droplet and airborne. If we use the theory of aerosol cloud transmission to analyze all kinds of suspected airborne cases in the epidemic situation, we can get a very reasonable explanation, and put forward the corresponding concerns and prevention and mitigation measure for this mode of transmission.
COVID-19 in the world in 2020 is typical microbial airborne infectious disease, which cause immeasurable human losses, even far more than PM2.5, formaldehyde, VOCs and other hazards. An aerosol is a mixture of air with solid or liquid particles dispersed in it. Microorganisms generally have a certain volume, the air cleaner can use conventional filtration technology to remove air microorganisms. For this reason, the annual domestic sales of air cleaners in Japan increase about 3 million units in this year. On the other hand, dust collection test methods for air cleaners are specified in JEM1467 (Japan), GB/T18801 (China) and AHAM AC-1 (US) respectively. As a test method for determining the removal performance of air cleaners against airborne viruses, there is JEM1467 Annex D “Evaluation test of air purifier removal performance against airborne viruses” by the Japan Electrical Manufacturers’ Association. However, in actual tests, from the viewpoint of biohazard, bacteriophages such as MS2 and Phi-X174 are used instead of viruses. By the way, since the particle size of droplet nuclei in influenza virus and SARS-CoV-2 is said to be about 0.1μm, the authors used alternative particles with virus-equivalent diameter (for example, KCl, PAO, PSL, Tabaco smoke etc.) as the test particles. In this study, comparative experiment was conducted to determine the removal performance of an air cleaner using Escherichia coli bacteriophage and virus-equivalent diameter substitute particles as test particles.