• Particle and aerosol research
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• v.6 no.2
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• pp.81-90
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• 2010

Several studies have suggested the possibility of airborne transmission of infectious diseases such as tuberculosis, pandemic influenza. because the number of patients increases explosively, if infectious disease had a high basic reproduction number, pharmaceutical interventions such as vaccination, chemoprophylaxis in the early stage of epidemic. Thus, non-pharmaceutical interventions such as mask-wearing, installing air cleaners, school closure are important to control and prevent the infectious diseases. However, the current technology on the mask, air cleaning, ventilation, and etc., seems to be not originated from the understanding of infection via airborne transmission. It is important to estimate the aerodynamic behavior of saliva droplets by coughing or speaking in order to understand the phenomena of airborne infection. In addition, the prediction of transmission of infectious diseases through the air is critical to prevent or minimize the damage of infection. In this review, we reviewed the recent studies on the airborne infection by focusing on the aerodynamic characteristics of saliva droplets and modeling of airborne transmission.

• Particle and aerosol research
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• v.16 no.4
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• pp.73-94
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• 2020

Particulate infectious sources, including infectious viruses, can float in the air, causing airborne infections. To prevent indoor airborne infection, dilution control by ventilation and indoor air cleaners are frequently used. In this study, the risk of airborne infection by the operation of these two techniques was evaluated. In case of dilution control by ventilation, a high efficiency air filter was embedded at the inlet of supply air. In this study, infectious source reduction devices such as indoor air cleaner include all kinds of mechanical-filters, UV-photo catalysts and air ionizers through which air flow is forced by fans. Two mathematical models for influenza virus were applied in an infant care room where infants and young children are active, and the risk reduction efficiency was compared. As a result, in the case of individually operating the ventilator or the infectious source reduction device, the airborne infection risk reduction efficiencies were 55.2~61.2% and 53.8~59.9%, respectively. When both facilities were operated, it was found that the risk of airborne infection was reduced about 72.2~76.8%. Therefore, simultaneous operation of ventilation equipment and infectious source reduction device is the most effective method for safe environment that minimizes the risk of airborne infection of respiratory infectious diseases. In the case of a space where sufficient ventilation operation is difficult, it was found that the operation of an infectious source reduction device is important to prevent the spread of infectious diseases. This study is meaningful in that it provides an academic basis for strategies for preventing airborne infection of respiratory infectious diseases.

• The Plant Pathology Journal
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• v.35 no.6
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• pp.585-597
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• 2019

A disease forecast model for Marssonina blotch of apple was developed based on field observations on airborne spore catches, weather conditions, and disease incidence in 2013 and 2015. The model consisted of the airborne spore model (ASM) and the daily infection rate model (IRM). It was found that more than 80% of airborne spore catches for the experiment period was made during the spore liberation period (SLP), which is the period of days of a rain event plus the following 2 days. Of 13 rain-related weather variables, number of rainy days with rainfall ≥ 0.5 mm per day (L_day), maximum hourly rainfall (P_max) and average daily maximum wind speed (W_avg) during a rain event were most appropriate in describing variations in airborne spore catches during SLP (S_i) in 2013. The ASM, Ŝ_i = 30.280+5.860×L_day×P_max-2.123×L_day×P_max×W_avg was statistically significant and capable of predicting the amount of airborne spore catches during SLP in 2015. Assuming that airborne conidia liberated during SLP cause leaf infections resulting in symptom appearance after 21 days of incubation period, there was highly significant correlation between the estimated amount of airborne spore catches (Ŝ_i) and the daily infection rate (R_i). The IRM, ${\hat{R}}_i$ = 0.039+0.041×Ŝ_i, was statistically significant but was not able to predict the daily infection rate in 2015. No weather variables showed statistical significance in explaining variations of the daily infection rate in 2013.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.109-123
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• 2020

Objectives: The aims of this study were to review the standards and key components of the standards for disposable masks in Korea, the US, EU, Japan, and China and to evaluate the appropriateness of disposable masks during a virus pandemic. Methods: We reviewed the standards in the above countries and compared their key elements for each standard. For the second purpose, systemic paper gathering using key words like 'mask', 'respirator' 'virus', and 'coronavirus' in the PubMed search engine was performed. Fifty-three papers were selected and reviewed in regard to the appropriateness of test protocols with sodium chloride(NaCl) particles for virus filtration and the effectiveness against viruses. Results: The standards for masks are largely divided into two categories: US standards and EU standards. In Korea, the Ministry of Employment and Labor adapted the EU standards for workers and the Health Masks adopted the Ministry of Employment and Labor standards by the Ministry of Food and Drug Safety. Regarding airborne viral infections, WHO emphasizes only droplet infection, while many studies have shown that small particles enter the air through coughing or sneezing, which increases the possibility of airborne infection. Compared to other particles, various factors such as airborne viability and the ability to replicate the virus in the body are further involved in the virus's airborne infection rate. Airborne infection is classified into absolute air infection, preferential air infection, and opportunistic air infection. The NaCl-certified N95 mask showed good filtration efficiency against viruses and NaCl particles were proved to be a surrogate material for viruses. From this, KF94 is also expected to be effective in blocking viruses. Conclusion: The N95 test method could be used as a surrogate test method for virus filtration. N95-class masks have been found to effectively block viral infections in the air. However, surgical or medical masks are only partially effective against airborne virus infection though they could effectively block large droplet infection. However, most studies considered in this study targeted N95 in foreign countries and studies on masks actually used in Korea are very limited, so studies on microorganisms and reuse on domestic masks should be conducted in the future.

• Korean Institute of Interior Design Journal
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• v.18 no.3
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• pp.102-113
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• 2009

The SARS virus began to appear and spread in North America and Southeast Asia in the early 2000' s, infecting and harming many people. In the process of examining the causes for the virus, studies on the airborne SARS virus and the way it spread were carried out mainly in the medical field. In the field of architecture, studies were done on the diffusion of air pollutants in buildings using gases such as $CO_2$, $N_2O$, or $SF_6$, but research on virus diffusion was limited. There were also explanations of only the diffusion process without accurate information and discussion on virus characteristics. The aim of this study is to analyze the physical characteristics of airborne virus, consider the possibility of using coupled analysis model and tracer gas for analyzing virus diffusion in building space and, based on reports of how the infection spread in a hospital where SARS patients were discovered, analyze infection risk using tracer gas density and also diffusion patterns according to the location, shape, and volume of supply diffusers and exhaust grilles. This paper can provide standards and logical principles for evaluating various alternatives for making decisions on vertical or horizontal ward placement, air supply and exhaust installation and air volumes in medium or high story medical facilities.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.12
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• pp.509-514
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• 2016

From the point of view to prevent airborne infection-related diseases such as H1N1, SARS, and MERS, an actual application of air cleaning and purification systems including technologies like UVGI has become increasingly important. Recently, an air purification system using REME (Reflective Electro Magnetic Energy) developed in the U.S. is applied for indoor air purification and sterilization technology to counteract the outbreak of new airborne infections. In this study, an air sterilization performance experiment using REME was carried out. The results verified that air sterilization performance in the case of installing a REME system in a medical center was 31%, namely the number of floating bacteria decreased by 31% after only a five-day operation. In addition, the number of culture collections in the REME operating air conditioning systems using nonpathogenic Geobacillus stearothemophilus as a biological indicator decreased maximally to 67%. A field application of REME technology will be useful to prevent airborne infection-related diseases, especially in response to public health crises due to the advent of emerging diseases.

• Journal of Environmental Health Sciences
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• v.47 no.2
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• pp.123-130
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• 2021

Objectives: Control methods against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) aerosols have been introduced. Airborne spreading theories for SARS-CoV-2 were analyzed in this study. Methods: Control methods for airborne microorganisms were discussed. Studies on theoretical estimations for airborne spreading of SARS-CoV-2 were presented and analyzed. Analytic calculations were conducted for explaining control techniques for airborne microorganisms. Results: Control methods for SARS-CoV-2 aerosols can include physical or biological procedures. Characterization of SARS-CoV-2 aerosols and massive clustering infection cases of COVID-19 support the airborne spreading theories of SARS-CoV-2. It is necessary to consider the disadvantages of control methods for airborne microorganisms. Conclusions: A study on control methods against bioaerosols is necessary to prevent the spreading of viruses. Airborne spreading theories of SARS-CoV-2 were supported by the current evidence, but further studies are needed to confirm these theories.

• Journal of The Korea Institute of Healthcare Architecture
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• v.22 no.3
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• pp.45-56
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• 2016

Purpose: The MERS(Middle East Respiratory Syndrome) outbreaks in Korea highlighted dramatically the failings of traditional hospital environment for controlling or preventing infections among both patients and healthcare workers. MERS is transmitted by droplets that can be airborne over a limited area. The point should be emphasized that MERS in South Korea was predominantly a hospital-acquired (not a community-acquired) infection, because approximately 93% of MERS cases were resulted from exposure in hospital settings. This paper tries to suggest the design guidelines of negative pressured isolation ward for the sake of proper control of severe respiratory infectious diseases. Methods: Literature survey on the design guideline and regulations of airborne infection wards in Korea, Europe U.K. and CDC of U.S. have been carries out. 4 special infection wards in Hongkong, Germany, Japan and Korea have been surveyed in order to make the best use of the experiences related to facility design and operations. Results: Operating system influencing the facility design, space organizations of infectious ward including required space and zoning, and circulations of patients, staffs and materials are proposed. Implications: The results of this paper can be the basic data for the design of the airborne infection ward and relevant regulations. Afterwards in-depth study such as the development of space standards for the single bedroom, locker room and so on could be explored.

• The Korean Nurse
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• v.23 no.4 s.127
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• pp.22-24
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• 1984

• Journal of The Korea Institute of Healthcare Architecture
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• v.21 no.1
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• pp.7-15
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• 2015

Purpose : When natural disaster occurs, the victims are evacuated to temporary shelters such as indoor gymnasiums or large space buildings until their homes are recovered. If someone in this temporary shelter is infected with an airborne infectious disease, it becomes easier for the disease to spread to the other people in the shelter than it would be under normal conditions. Therefore, temporary shelters need to provide not only water and food but also hygienic indoor conditions. Methods : In this study, the use of mechanical systems such as ultraviolet germicidal irradiation (UVGI) systems and air cleaners were simulated using numerical analysis to find out how these systems can control airborne infection in temporary shelters. An indoor gymnasium was selected as a temporary shelter for the numerical simulation model considering Korea's post-disaster response system. Influenza A virus was assumed as an airborne infectious disease and the diffusion of the virus was made by one person in the shelter. Results : The result of this study showed that the UVGI systems disinfected the virus more effectively than the air cleaners by creating a more stable airflow after the disinfection process. The air cleaners could remove the virus but since it created an unstable airflow in the temporary shelter, the virus was condensed to a certain area to show a higher virus concentration level than the source location. Implications : In the temporary shelter, it is necessary to use UVGI systems or air cleaners for hygienic indoor conditions.