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Li Y, Li J, Hu J, Yu X, Li Z, Cao J. Quantitative evaluation of the impact of indoor relative humidity on deposition of aerosols generated during tooth grinding in a real-world clinical setting. Clin Oral Investig 2024; 28:292. [PMID: 38693418 DOI: 10.1007/s00784-024-05683-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 04/24/2024] [Indexed: 05/03/2024]
Abstract
OBJECTIVES Exposure to aerosol particles generated from tooth grinding has a negative impact on the health of dental personnel. The aim of this study was to quantitatively analyze the impact of indoor relative humidity (IRH) on the deposition of these suspended particles in a well-controlled dental environment. MATERIALS AND METHODS In this study, a humidity control system was employed to effectively regulate and maintain indoor relative humidity (IRH). A novel computer-assisted numerical control system was developed to pre-treat the molar specimens, and accurately simulate clinical tooth grinding procedures. Each procedure was performed in triplicate, with an online real-time particle counter (ORPC; TR-8301, TongrenCo.) measuring aerosol production. All testing devices were controlled remotely. The data obtained were statistically analyzed using descriptive statistics and non-parametric tests (Kruskal-Wallis/ Dunn's post hoc test with Bonferroni correction, p < 0.05). RESULTS The findings showed that with increasing IRH, the maximum peak concentration of aerosol particles decreased by 397% from 6.51 × 107 particles/m3 at 30% to 1.64 × 107 particles/m3 at 80%. The Kruskal-Wallis test results indicated a statistically significant effect of IRH on the aerosol increment (p < 0.05). CONCLUSIONS Increasing the IRH level can effectively promote the deposition of aerosol particles, with a return to baseline within 15 min after reaching 60% or above. CLINICAL RELEVANCE Our study suggested that maintaining IRH above 70% during the cleaning process, allowing natural recovery to ambient humidity levels within 15 min after cleaning, and taking basic precautions, may lead to an adequate reduction in the possible health risks of aerosol contamination.
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Affiliation(s)
- Yugang Li
- School of Mechanical Engineering, Guizhou University, Guiyang, China
- Guizhou Equipment Manufacturing Polytechnic, Guiyang, China
| | - Jiachun Li
- School of Mechanical Engineering, Guizhou University, Guiyang, China.
| | - Jie Hu
- School of Mechanical Engineering, Guizhou University, Guiyang, China.
| | - Xiaoyan Yu
- Guiyang Hospital of Stomatology, Guiyang, China
| | - Zhe Li
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Jichao Cao
- College of Mechanical and Vehicle Engineering, Hunan University, Changsha, China
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2
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Leidemann J, Dias JP, Al-Nasra M. Design of customizable personal protective equipment for 3-D printing: Performance evaluation of N95 respirators using computational fluid dynamics. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2024; 21:169-188. [PMID: 38451217 DOI: 10.1080/15459624.2023.2299811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
3-D printing the structural components of facemasks and personal protective equipment (PPE) based on 3-D facial scans creates a high degree of customizability. As a result, the facemask fits more comfortably with its user's specific facial characteristics, filters contaminants more effectively with its increased sealing effect, and minimizes waste with its cleanable and reusable plastic structure compared to other baseline models. In this work, 3-D renditions of the user's face taken with smartphone laser scanning techniques were used to generate customized computer-aided design (CAD) models for the several components of an N95 respirator, which are each designed with considerations for assembly and 3-D printing constraints. Thorough analyses with computational fluid dynamics (CFD) simulations were carried out to verify the respirator's efficiency in filtering airborne contaminants to comply with industry safety guidelines and generate data to showcase the relationships between various input and output design parameters. This involved a comparative study to identify the ideal cross-sectional geometry of exposed filter fabric, a sensitivity study to evaluate the respirator's ability to protect the user in various scenarios, and the 3-D printing of several prototypes to estimate printing time, cost of materials, and comfort level at the user's face. Results showed that the combination of different digital tools can increase efficiency in the design, performance assessment, and production of customized N95-rated respirators.
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Affiliation(s)
- Jack Leidemann
- Department of Civil and Mechanical Engineering, Shippensburg University of Pennsylvania, Shippensburg, PA, USA
| | - João Paulo Dias
- Department of Civil and Mechanical Engineering, Shippensburg University of Pennsylvania, Shippensburg, PA, USA
| | - Moayyad Al-Nasra
- Department of Civil and Mechanical Engineering, Shippensburg University of Pennsylvania, Shippensburg, PA, USA
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3
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Li YG, Li JC, Yu XY, Hu J, Li Z, Cao JC. Quantitative assessment of aerosol contamination generated during tooth grinding with a speed-increasing handpiece. J Dent 2023; 139:104631. [PMID: 37495202 DOI: 10.1016/j.jdent.2023.104631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 06/29/2023] [Accepted: 07/21/2023] [Indexed: 07/28/2023] Open
Abstract
OBJECTIVES Tooth grinding produces a significant amount of aerosol particles. The aim of this study was to quantitatively assess particle contamination produced from tooth grinding with a speed-increasing handpiece across a real-world clinical setting. METHODS All molar crowns were pretreated into cylinders with a uniform size. A novel computer-assisted numerical control system was used to parametrically study the bur speed: from 20,000 (20 K) to 200 K rpm at 20 K rpm intervals. 5-minute tooth grinding was performed in triplicate at each speed setting. Three online real-time particle counters (ORPC; TR-8301, TongrenCo.) were placed at 3 positions (0.5, 1, and 1.5 m) to evaluate particle production. All experimental instruments were controlled remotely. The data obtained were statistically analyzed using descriptive statistics and non-parametric tests (Scheirer-Ray-Hare and Kruskal-Wallis/ Dunn-Bonferroni tests, p < 0.05). RESULTS The concentration level of aerosol particles production during the grinding experiment was elevated above the control group for all conditions, and increased with bur speed at any location (the maximum peak, reaching 5.59 × 107 particles/m3, at 200 K and 1 m), with differences between conditions. The effect of speed on the increment of particles across different channels compared to the control group was statistically significant among locations (p < 0.001). CONCLUSIONS Statistically significant particle contamination was produced using a speed-increasing handpiece, but the contamination level for each experimental condition was reduced to baseline within 30 min, and most particles with a diameter greater than 1üm produced at low speeds (80 K or lower) tended to settle within 1 m. CLINICAL RELEVANCE Our study suggested that the use of a speed-increasing handpiece below 80 K and 30 min of fallow time may lead to an adequate reduction in the health effects of particle contamination.
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Affiliation(s)
- Yu-Gang Li
- School of Mechanical Engineering, Guizhou University, Guiyang, China; Guizhou Equipment Manufacturing Polytechnic, Guiyang, China
| | - Jia-Chun Li
- School of Mechanical Engineering, Guizhou University, Guiyang, China.
| | - Xiao-Yan Yu
- Guiyang Hospital of Stomatology, Guiyang, China
| | - Jie Hu
- School of Mechanical Engineering, Guizhou University, Guiyang, China
| | - Zhe Li
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Ji-Chao Cao
- College of Mechanical and Vehicle Engineering, Hunan University, Changsha, China
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4
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Geng CL, Zhu XY, Chen N. Optimizing indoor air quality: CFD simulation and novel air cleaning methods for effective aerosol particle inhibition in public spaces. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:120528-120539. [PMID: 37943437 DOI: 10.1007/s11356-023-30832-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 10/30/2023] [Indexed: 11/10/2023]
Abstract
In contemporary building ventilation, displacement and mixing ventilation demand high air volumes for rapid virus elimination, resulting in elevated energy consumption. To minimize the spread of viruses and decrease energy consumption for ventilation, this study employed CFD to explore the efficacy of a downward uniform flow field in impeding the transmission of aerosol particles in a high-traffic public facility, like a supermarket. The findings indicate that the downward uniform flow field proves insufficient when individuals remain static for extended periods. A wind speed of 0.1 m/s or higher becomes essential to overpower the stationary thermal plume, which disrupts this flow field. In areas with human presence, however, this technique is found to be particularly efficient since mobile heat sources do not generate a fixed thermal plume. A 0.05 m/s downward uniform flow field can settle 90% of particles within just 22 s. This flow pattern contributes to the swift settling of aerosol particles and effectively diminishes their dispersion. Employing this flow pattern in public places with increased foot traffic, like supermarkets, can lower the risk of contracting novel coronavirus without augmenting energy consumption. In order to implement the flow field in a part of the domain, a new air purification device is proposed in this study. The device combined with shelves can optimize the flow field uniformity through the MLA (PSO-SVR) algorithm and alteration of the air distribution structure. The uniformity of the final flow field increased to 0.925. The combination of data-driven MLA with CFD showed good performance in predicting the flow field uniformity. These findings offer valuable insights and practical applications for the prevention and control of respiratory diseases, particularly in post-epidemic scenarios.
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Affiliation(s)
- Chao-Long Geng
- China University of Mining and Technology, Xuzhou, China
| | - Xu-Yanran Zhu
- China University of Mining and Technology, Xuzhou, China
| | - Ning Chen
- China University of Mining and Technology, Xuzhou, China.
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5
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Liu H, Liu Z, He J, Hu C, Rong R, Han H, Wang L, Wang D. Reducing airborne transmission of SARS-CoV-2 by an upper-room ultraviolet germicidal irradiation system in a hospital isolation environment. ENVIRONMENTAL RESEARCH 2023; 237:116952. [PMID: 37619635 DOI: 10.1016/j.envres.2023.116952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/08/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
Upper-room ultraviolet germicidal irradiation (UVGI) technology can potentially inhibit the transmission of airborne disease pathogens. There is a lack of quantitative evaluation of the performance of the upper-room UVGI for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) airborne transmission under the combined effects of ventilation and UV irradiation. Therefore, this study aimed to explore the performance of the upper-room UVGI system for reducing SARS-CoV-2 virus transmission in a hospital isolation environment. Computational fluid dynamics and virological data on SARS-CoV-2 were integrated to obtain virus aerosol exposure in the hospital isolation environment containing buffer rooms, wards and bathrooms. The UV inactivation model was applied to investigate the effects of ventilation rate, irradiation flux and irradiation height on the upper-room UVGI performance. The results showed that increasing ventilation rate from 8 to 16 air changes per hour (ACH) without UVGI obtained 54.32% and 45.63% virus reduction in the wards and bathrooms, respectively. However, the upper-room UVGI could achieve 90.43% and 99.09% virus disinfection, respectively, with the ventilation rate of 8 ACH and the irradiation flux of 10 μW cm-2. Higher percentage of virus could be inactivated by the upper-room UVGI at a lower ventilation rate; the rate of improvement of UVGI elimination effect slowed down with the increase of irradiation flux. Increase irradiation height at lower ventilation rate was more effective in improving the UVGI performance than the increase in irradiation flux at smaller irradiation height. These results could provide theoretical support for the practical application of UVGI in hospital isolation environments.
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Affiliation(s)
- Haiyang Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Zhijian Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China.
| | - Junzhou He
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Chenxing Hu
- School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Rui Rong
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Hao Han
- State Key Laboratory of NBC Protection for Civilian, Beijing, 100191, China.
| | - Lingyun Wang
- State Key Laboratory of NBC Protection for Civilian, Beijing, 100191, China
| | - Desheng Wang
- State Key Laboratory of NBC Protection for Civilian, Beijing, 100191, China
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Voidarou C, Rozos G, Stavropoulou E, Giorgi E, Stefanis C, Vakadaris G, Vaou N, Tsigalou C, Kourkoutas Y, Bezirtzoglou E. COVID-19 on the spectrum: a scoping review of hygienic standards. Front Public Health 2023; 11:1202216. [PMID: 38026326 PMCID: PMC10646607 DOI: 10.3389/fpubh.2023.1202216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
The emergence of COVID-19 in Wuhan, China, rapidly escalated into a worldwide public health crisis. Despite numerous clinical treatment endeavors, initial defenses against the virus primarily relied on hygiene practices like mask-wearing, meticulous hand hygiene (using soap or antiseptic solutions), and maintaining social distancing. Even with the subsequent advent of vaccines and the commencement of mass vaccination campaigns, these hygiene measures persistently remain in effect, aiming to curb virus transmission until the achievement of herd immunity. In this scoping review, we delve into the effectiveness of these measures and the diverse transmission pathways, focusing on the intricate interplay within the food network. Furthermore, we explore the virus's pathophysiology, considering its survival on droplets of varying sizes, each endowed with distinct aerodynamic attributes that influence disease dispersion dynamics. While respiratory transmission remains the predominant route, the potential for oral-fecal transmission should not be disregarded, given the protracted presence of viral RNA in patients' feces after the infection period. Addressing concerns about food as a potential viral vector, uncertainties shroud the virus's survivability and potential to contaminate consumers indirectly. Hence, a meticulous and comprehensive hygienic strategy remains paramount in our collective efforts to combat this pandemic.
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Affiliation(s)
| | - Georgios Rozos
- Veterinary Directorate, South Aegean Region, Ermoupolis, Greece
| | - Elisavet Stavropoulou
- Department of Medicine, Lausanne University Hospital (CHUV), University of Lausanne, Lausanne, Switzerland
| | - Elpida Giorgi
- Laboratory of Hygiene and Environmental Protection, Department of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
| | - Christos Stefanis
- Laboratory of Hygiene and Environmental Protection, Department of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
| | - Georgios Vakadaris
- Laboratory of Hygiene and Environmental Protection, Department of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
| | - Natalia Vaou
- Laboratory of Hygiene and Environmental Protection, Department of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
| | - Christina Tsigalou
- Laboratory of Hygiene and Environmental Protection, Medical School, Democritus University of Thrace, Alexandroupolis, Greece
| | - Yiannis Kourkoutas
- Laboratory of Applied Microbiology and Biotechnology, Department of Molecular Biology and Genetics, Democritus University of Thrace, Alexandroupolis, Greece
| | - Eugenia Bezirtzoglou
- Laboratory of Hygiene and Environmental Protection, Department of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
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7
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Martínez-Espinosa E, Carvajal-Mariscal I. Virus-laden droplet nuclei in vortical structures associated with recirculation zones in indoor environments: A possible airborne transmission of SARS-CoV-2. ENVIRONMENTAL ADVANCES 2023; 12:100376. [PMID: 37193349 PMCID: PMC10163794 DOI: 10.1016/j.envadv.2023.100376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 05/03/2023] [Indexed: 05/18/2023]
Abstract
Droplet nuclei dispersion patterns in indoor environments are reviewed from a physics view to explore the possibility of airborne transmission of SARS-CoV-2. This review analyzes works on particle dispersion patterns and their concentration in vortical structures in different indoor environments. Numerical simulations and experiments reveal the formation of the buildings' recirculation zones and vortex flow regions by flow separation, airflow interaction around objects, internal dispersion of airflow, or thermal plume. These vortical structures showed high particle concentration because particles are trapped for long periods. Then a hypothesis is proposed to explain why some medical studies detect the presence of SARS-CoV-2 and others do not detect the virus. The hypothesis proposes that airborne transmission is possible if virus-laden droplet nuclei are trapped in vortical structures associated with recirculation zones. This hypothesis is reinforced by a numerical study in a restaurant that presented possible evidence of airborne transmission by a large recirculating air zone. Furthermore, a medical study in a hospital is discussed from a physical view for identifying the formation of recirculation zones and their relation with positive tests for viruses. The observations show air sampling site located in this vortical structure is positive for the SARS-CoV-2 RNA. Therefore, the formation of vortical structures associated with recirculation zones should be avoided to minimize the possibility of airborne transmission. This work tries to understand the complex phenomenon of airborne transmission as a way in the prevention of transmission of infectious diseases.
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Affiliation(s)
- E Martínez-Espinosa
- Industrial and Environmental Processes Department, Instituto de Ingeniería, UNAM, Ciudad Universitaria, Mexico City 04510, México
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8
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Vita G, Woolf D, Avery-Hickmott T, Rowsell R. A CFD-based framework to assess airborne infection risk in buildings. BUILDING AND ENVIRONMENT 2023; 233:110099. [PMID: 36815961 PMCID: PMC9925846 DOI: 10.1016/j.buildenv.2023.110099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/31/2023] [Accepted: 02/12/2023] [Indexed: 06/18/2023]
Abstract
The COVID-19 pandemic has prompted huge efforts to further the scientific knowledge of indoor ventilation and its relationship to airborne infection risk. Exhaled infectious aerosols are spread and inhaled as a result of room airflow characteristics. Many calculation methods and assertions on risk assume 'well-mixed' flow conditions. However, ventilation in buildings is complex and often not showing well-mixed conditions. Ventilation guidance is typically based on the provision of generic minimum ventilation flow rates for a given space, irrespective of the effectiveness in the delivery of the supply air. Furthermore, the airflow might be heavily affected by the season, the HVAC ventilation, or the opening of windows, which would potentially generate draughts and non-uniform conditions. As a result, fresh air concentration would be variable depending upon a susceptible receptor's position in a room and, therefore, associated airborne infection risk. A computational fluid dynamics (CFD) and dynamic thermal modelling (DTM) framework is proposed to assess the influence of internal airflow characteristics on airborne infection risk. A simple metric is proposed, the hourly airborne infection rate (HAI) which can easily help designers to stress-test the ventilation within a building under several conditions. A case study is presented, and the results clearly demonstrate the importance of understanding detailed indoor airflow characteristics and associated concentration patterns in order to provide detailed design guidance, e.g. occupancy, supply air diffusers and furniture layouts, to reduce airborne infection risk.
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Affiliation(s)
- Giulio Vita
- Wirth Research Ltd, Charlotte Avenue, Bicester, OX27 8BL, United Kingdom
- University of Birmingham School of Engineering Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Darren Woolf
- Wirth Research Ltd, Charlotte Avenue, Bicester, OX27 8BL, United Kingdom
| | | | - Rob Rowsell
- Wirth Research Ltd, Charlotte Avenue, Bicester, OX27 8BL, United Kingdom
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9
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Norvihoho LK, Yin J, Zhou ZF, Han J, Chen B, Fan LH, Lichtfouse E. Mechanisms controlling the transport and evaporation of human exhaled respiratory droplets containing the severe acute respiratory syndrome coronavirus: a review. ENVIRONMENTAL CHEMISTRY LETTERS 2023; 21:1701-1727. [PMID: 36846189 PMCID: PMC9944801 DOI: 10.1007/s10311-023-01579-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/13/2023] [Indexed: 05/24/2023]
Abstract
Transmission of the coronavirus disease 2019 is still ongoing despite mass vaccination, lockdowns, and other drastic measures to control the pandemic. This is due partly to our lack of understanding on the multiphase flow mechanics that control droplet transport and viral transmission dynamics. Various models of droplet evaporation have been reported, yet there is still limited knowledge about the influence of physicochemical parameters on the transport of respiratory droplets carrying the severe acute respiratory syndrome coronavirus 2. Here we review the effects of initial droplet size, environmental conditions, virus mutation, and non-volatile components on droplet evaporation and dispersion, and on virus stability. We present experimental and computational methods to analyze droplet transport, and factors controlling transport and evaporation. Methods include thermal manikins, flow techniques, aerosol-generating techniques, nucleic acid-based assays, antibody-based assays, polymerase chain reaction, loop-mediated isothermal amplification, field-effect transistor-based assay, and discrete and gas-phase modeling. Controlling factors include environmental conditions, turbulence, ventilation, ambient temperature, relative humidity, droplet size distribution, non-volatile components, evaporation and mutation. Current results show that medium-sized droplets, e.g., 50 µm, are sensitive to relative humidity. Medium-sized droplets experience delayed evaporation at high relative humidity, and increase airborne lifetime and travel distance. By contrast, at low relative humidity, medium-sized droplets quickly shrink to droplet nuclei and follow the cough jet. Virus inactivation within a few hours generally occurs at temperatures above 40 °C, and the presence of viral particles in aerosols impedes droplet evaporation.
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Affiliation(s)
- Leslie Kojo Norvihoho
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Jing Yin
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Zhi-Fu Zhou
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Jie Han
- School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Bin Chen
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
| | - Li-Hong Fan
- The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, 710061 Shaanxi People’s Republic of China
| | - Eric Lichtfouse
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi People’s Republic of China
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10
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Derk RC, Coyle JP, Lindsley WG, Blachere FM, Lemons AR, Service SK, Martin SB, Mead KR, Fotta SA, Reynolds JS, McKinney WG, Sinsel EW, Beezhold DH, Noti JD. Efficacy of Do-It-Yourself air filtration units in reducing exposure to simulated respiratory aerosols. BUILDING AND ENVIRONMENT 2023; 229:109920. [PMID: 36569517 PMCID: PMC9759459 DOI: 10.1016/j.buildenv.2022.109920] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/03/2022] [Accepted: 12/12/2022] [Indexed: 05/20/2023]
Abstract
Many respiratory diseases, including COVID-19, can be spread by aerosols expelled by infected people when they cough, talk, sing, or exhale. Exposure to these aerosols indoors can be reduced by portable air filtration units (air cleaners). Homemade or Do-It-Yourself (DIY) air filtration units are a popular alternative to commercially produced devices, but performance data is limited. Our study used a speaker-audience model to examine the efficacy of two popular types of DIY air filtration units, the Corsi-Rosenthal cube and a modified Ford air filtration unit, in reducing exposure to simulated respiratory aerosols within a mock classroom. Experiments were conducted using four breathing simulators at different locations in the room, one acting as the respiratory aerosol source and three as recipients. Optical particle spectrometers monitored simulated respiratory aerosol particles (0.3-3 μm) as they dispersed throughout the room. Using two DIY cubes (in the front and back of the room) increased the air change rate as much as 12.4 over room ventilation, depending on filter thickness and fan airflow. Using multiple linear regression, each unit increase of air change reduced exposure by 10%. Increasing the number of filters, filter thickness, and fan airflow significantly enhanced the air change rate, which resulted in exposure reductions of up to 73%. Our results show DIY air filtration units can be an effective means of reducing aerosol exposure. However, they also show performance of DIY units can vary considerably depending upon their design, construction, and positioning, and users should be mindful of these limitations.
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Affiliation(s)
- Raymond C Derk
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Jayme P Coyle
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - William G Lindsley
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Francoise M Blachere
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Angela R Lemons
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Samantha K Service
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Stephen B Martin
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26505, USA
| | - Kenneth R Mead
- Division of Field Studies and Engineering, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, OH, 45226, USA
| | - Steven A Fotta
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Jeffrey S Reynolds
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Walter G McKinney
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Erik W Sinsel
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - Donald H Beezhold
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
| | - John D Noti
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1000 Fredrick Lane, Morgantown, WV, 26508, USA
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11
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Mirza S, Niwalkar A, Gupta A, Gautam S, Anshul A, Bherwani H, Biniwale R, Kumar R. Is safe distance enough to prevent COVID-19? Dispersion and tracking of aerosols in various artificial ventilation conditions using OpenFOAM. GONDWANA RESEARCH : INTERNATIONAL GEOSCIENCE JOURNAL 2023; 114:40-54. [PMID: 35431597 PMCID: PMC8990448 DOI: 10.1016/j.gr.2022.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 02/23/2022] [Accepted: 03/09/2022] [Indexed: 05/11/2023]
Abstract
The current COVID-19 pandemic has underlined the importance of learning more about aerosols and particles that migrate through the airways when a person sneezes, coughs and speaks. The coronavirus transmission is influenced by particle movement, which contributes to the emergence of regulations on social distance, use of masks and face shield, crowded assemblies, and daily social activity in domestic, public, and corporate areas. Understanding the transmission of aerosols under different micro-environmental conditions, closed, or ventilated, has become extremely important to regulate safe social distances. The present work attempts to simulate the airborne transmission of coronavirus-laden particles under different respiratory-related activities, i.e., coughing and speaking, using CFD modelling through OpenFOAM v8. The dispersion coupled with the Discrete Phase Method (DPM) has been simulated to develop a better understanding of virus carrier particles transmission processes and their path trailing under different ventilation scenarios. The preliminary results of this study with respect to flow fields were in close agreement with published literature, which was then extended under varied ventilation scenarios and respiratory-related activities. The study observed that improper wearing of mask leads to escape of SARS-CoV-2 containminated aerosols having a smaller aerodynamic diameter from the gap between face mask and face, infecting different surfaces in the vicinity. It was also observed that aerosol propagation infecting the area through coughing is a faster phenomenon compared to the propagation of coronavirus-laden particles during speaking. The study's findings will help decision-makers formulate common but differentiated guidelines for safe distancing under different micro-environmental conditions.
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Affiliation(s)
- Shahid Mirza
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India
| | - Amol Niwalkar
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India
| | - Ankit Gupta
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Sneha Gautam
- Karunya Institute of Technology and Sciences, Karunya Nagar, Coimbatore 641114, Tamil Nadu, India
| | - Avneesh Anshul
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Hemant Bherwani
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Rajesh Biniwale
- CSIR-National Environmental Engineering Research Institute, Nagpur 440020, Maharashtra, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Rakesh Kumar
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
- Council of Scientific and Industrial Research (CSIR), Anusandhan Bhawan, 2 Rafi Ahmed Kidwai Marg, New Delhi 110001, India
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12
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Argyropoulos CD, Skoulou V, Efthimiou G, Michopoulos AK. Airborne transmission of biological agents within the indoor built environment: a multidisciplinary review. AIR QUALITY, ATMOSPHERE, & HEALTH 2022; 16:477-533. [PMID: 36467894 PMCID: PMC9703444 DOI: 10.1007/s11869-022-01286-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 11/17/2022] [Indexed: 06/17/2023]
Abstract
The nature and airborne dispersion of the underestimated biological agents, monitoring, analysis and transmission among the human occupants into building environment is a major challenge of today. Those agents play a crucial role in ensuring comfortable, healthy and risk-free conditions into indoor working and leaving spaces. It is known that ventilation systems influence strongly the transmission of indoor air pollutants, with scarce information although to have been reported for biological agents until 2019. The biological agents' source release and the trajectory of airborne transmission are both important in terms of optimising the design of the heating, ventilation and air conditioning systems of the future. In addition, modelling via computational fluid dynamics (CFD) will become a more valuable tool in foreseeing risks and tackle hazards when pollutants and biological agents released into closed spaces. Promising results on the prediction of their dispersion routes and concentration levels, as well as the selection of the appropriate ventilation strategy, provide crucial information on risk minimisation of the airborne transmission among humans. Under this context, the present multidisciplinary review considers four interrelated aspects of the dispersion of biological agents in closed spaces, (a) the nature and airborne transmission route of the examined agents, (b) the biological origin and health effects of the major microbial pathogens on the human respiratory system, (c) the role of heating, ventilation and air-conditioning systems in the airborne transmission and (d) the associated computer modelling approaches. This adopted methodology allows the discussion of the existing findings, on-going research, identification of the main research gaps and future directions from a multidisciplinary point of view which will be helpful for substantial innovations in the field.
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Affiliation(s)
| | - Vasiliki Skoulou
- B3 Challenge Group, Chemical Engineering, School of Engineering, University of Hull, Cottingham Road, Hull, HU6 7RX UK
| | - Georgios Efthimiou
- Centre for Biomedicine, Hull York Medical School, University of Hull, Cottingham Road, Hull, HU6 7RX UK
| | - Apostolos K. Michopoulos
- Energy & Environmental Design of Buildings Research Laboratory, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
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13
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Liu H, Liu Z, Wang Y, Hu C, Rong R. Distribution of droplets/droplet nuclei from coughing and breathing of patients with different postures in a hospital isolation ward. BUILDING AND ENVIRONMENT 2022; 225:109690. [PMID: 36246843 PMCID: PMC9547661 DOI: 10.1016/j.buildenv.2022.109690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 09/11/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Suspected and confirmed cases of infectious diseases such as COVID-19 are diagnosed and treated in specific hospital isolation wards, posing a challenge to preventing cross-infection between patients and healthcare workers. In this study, the Euler-Lagrange method was used to simulate the evaporation and dispersion of droplets with full-size distribution produced by fluctuating coughing and breathing activities in an isolation ward. The effects of supply air temperature and relative humidity, ventilation rates and patient postures on droplet distribution were investigated. The numerical models were validated by an aerosol experiment with an artificial saliva solution containing E. coli bacteria conducted in a typical isolation ward. The results showed that the small size group of droplets (initial size ≤87.5 μm) exhibited airborne transmission in the isolation ward, while the large size group (initial size ≥112.5 μm) were rapidly deposited by gravitational effects. The ventilation rate had a greater effect on the diffusion of droplet nuclei than the supply air temperature and relative humidity. As the air changes per hour (ACH) increased from 8 to 16, the number fraction of suspended droplet nuclei reduced by 14.2% and 6.4% in the lying and sitting cases, respectively, while the number fraction of escaped droplet nuclei increased by 16.2% and 14.6%. Regardless of whether the patient was lying or sitting, the amount of droplet nuclei deposited on the ceiling was highest at lower ventilation rates. These results may provide some guidance for routine disinfection and ventilation strategies in hospital isolation wards.
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Affiliation(s)
- Haiyang Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Zhijian Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Yongxin Wang
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Chenxing Hu
- School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Rui Rong
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
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14
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Du C, Chen Q. Virus transport and infection evaluation in a passenger elevator with a COVID-19 patient. INDOOR AIR 2022; 32:e13125. [PMID: 36305056 PMCID: PMC9874880 DOI: 10.1111/ina.13125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 05/22/2023]
Abstract
Contaminant transport and flow distribution are very important during an elevator ride, as the reduced social distancing may increase the infection rate of airborne diseases such as COVID-19. Studying the airflow and contaminant concentration in an elevator is not straightforward because the flow pattern inside an elevator changes dramatically with passenger movement and frequent door opening. Since very little experimental data were available for elevators, this investigation validated the use of computational fluid dynamics (CFD) based on the RNG k- ∈ $$ \in $$ turbulence model to predict airflow and contaminant transport in a scaled, empty airliner cabin with a moving passenger. The movement of the passenger in the cabin created a dynamic airflow and transient contaminant dispersion that were similar to those in an elevator. The computed results agreed reasonably well with the experimental data for the cabin. The validated CFD program was then used to calculate the distributions of air velocity, air temperature, and particle concentration during an elevator ride with an index patient. The CFD results showed that the airflow pattern in the elevator was very complex due to the downward air supply from the ceiling and upward thermal plumes generated by passengers. This investigation studied different respiratory activities of the index patient, that is, breathing only, breathing, and coughing with and without a mask, and talking. The results indicated that the risk of infection was generally low because of the short duration of the elevator ride. If the index patient talked in the elevator, two passengers in the closest proximity to distance would be infected.
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Affiliation(s)
- Chengbo Du
- School of Mechanical EngineeringPurdue UniversityWest LafayetteIndianaUSA
| | - Qingyan Chen
- Department of Building Environment and Energy EngineeringThe Hong Kong Polytechnic UniversityKowloonHong Kong
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15
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Zhao Y, Feng Y, Ma L. Impacts of human movement and ventilation mode on the indoor environment, droplet evaporation, and aerosol transmission risk at airport terminals. BUILDING AND ENVIRONMENT 2022; 224:109527. [PMID: 36060217 PMCID: PMC9428122 DOI: 10.1016/j.buildenv.2022.109527] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/16/2022] [Accepted: 08/20/2022] [Indexed: 05/29/2023]
Abstract
The dispersion of the coronavirus pandemic has caused immense damage worldwide, and people have begun to ruminate epidemic prevention strategies for public places. Airport terminals with a high number of occupied passengers have become potentially high-risk regions for aerosol transmission of coronavirus disease 2019 (COVID-19). In this study, the Eulerian-Lagrangian approach and realizable k-ε turbulence model were used to numerically simulate airflow organization and aerosol transmission when passengers are moving slowly in a line. During the aerosol transmission period, evaporation was considered a key factor influencing the particle size distribution at the beginning of aerosol transmission from humans. Moreover, passenger movement at the airport terminal was attained by employing dynamic mesh algorithms. Based on the relative direction of passengers and air vents when queuing in the terminal building, we studied three conditions: windward walking, leeward walking, and crosswind walking. The results of this study showed that the walking has an important influence on droplet distribution. Droplet distribution indicates that individuals standing behind patients during queuing movements have a higher risk of infection than those standing in front of them. A significant aerosol accumulation was discovered at 0.5 m behind the patient when passengers moved simultaneously. An aerosol transmission distance of 15 s aligned with the passenger's walking direction could reach up to 9.32 m. Furthermore, although the evaporation time of the large droplets was longer than that of the small droplets, both large and small droplets evaporated rapidly after exhalation. The crosswind influence caused the droplets to travel farther away in a direction perpendicular to human movement, which increased the distance by approximately 1.26 m compared to the absence of the crosswind influence.
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Affiliation(s)
- Yu Zhao
- School of Civil Engineering, Faculty of Infrastructure Engineering, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian, 116024, China
| | - Yao Feng
- School of Civil Engineering, Faculty of Infrastructure Engineering, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian, 116024, China
| | - Liangdong Ma
- School of Civil Engineering, Faculty of Infrastructure Engineering, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian, 116024, China
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16
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Coupled discrete phase model and Eulerian wall film model for numerical simulation of respiratory droplet generation during coughing. Sci Rep 2022; 12:14849. [PMID: 36050319 PMCID: PMC9434508 DOI: 10.1038/s41598-022-18788-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/19/2022] [Indexed: 11/26/2022] Open
Abstract
Computational fluid dynamics is widely used to simulate droplet-spreading behavior due to respiratory events. However, droplet generation inside the body, such as the number, mass, and particle size distribution, has not been quantitatively analyzed. The aim of this study was to identify quantitative characteristics of droplet generation during coughing. Airflow simulations were performed by coupling the discrete phase model and Eulerian wall film model to reproduce shear-induced stripping of airway mucosa. An ideal airway model with symmetric bifurcations was constructed, and the wall domain was covered by a mucous liquid film. The results of the transient airflow simulation indicated that the droplets had a wide particle size distribution of 0.1–400 µm, and smaller droplets were generated in larger numbers. In addition, the total mass and number of droplets generated increased with an increasing airflow. The total mass of the droplets also increased with an increasing mucous viscosity, and the largest number and size of droplets were obtained at a viscosity of 8 mPa s. The simulation methods used in this study can be used to quantify the particle size distribution and maximum particle diameter under various conditions.
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17
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Jia M, Mei D, Li J, Liu Z, Duan W, Hou S. Analysis of the spread of cough droplets and body deposition fraction in the smart classroom in different seasons. HYGIENE AND ENVIRONMENTAL HEALTH ADVANCES 2022; 3:100015. [PMID: 37519422 PMCID: PMC9439850 DOI: 10.1016/j.heha.2022.100015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 06/24/2022] [Accepted: 06/25/2022] [Indexed: 11/23/2022]
Abstract
Smart classrooms are a relatively confined public space for college students. SARS-COV-2 and other respiratory viruses have been shown to pose a more significant threat to human health in relatively confined spaces. Using numerical simulation method to simulate the transmission and concentration distribution of virus-carrying droplets in smart classrooms in three different seasons (summer, winter, transitional seasons: spring and autumn). The Realizable k-ε model is used to simulate the airflow pattern in the smart classroom, and the Lagrangian method is used to simulate the transmission of droplets. The transmission process of droplets produced from the teacher standing on the platform and the student sitting on the seat is studied. The influence of three kinds of outdoor temperature on droplet transmission and the body deposition fraction of people in the smart classroom is analyzed. The results show that droplet transmission speed is maximum at the temperature of 5 degrees when the outdoor temperature is 5 °C, 20 °C, and 35 °C respectively. At 10 s, the transmission distance of droplets increases by 9.55% compared with that at 20 °C and 10.31% compared with that at 35 °C. In addition, the body deposition fraction is also affected by the location of the vent, with downwind contact being 6 times more likely than upwind contact. The research results can provide suggestions and measures for epidemic prevention and control in smart classrooms.
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Affiliation(s)
- Mengfan Jia
- College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, Hubei, China
- School of Mechanical &Automotive Engineering, South China University of Technology, Guangzhou, 510641, Guangdong, China
| | - Dan Mei
- College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, Hubei, China
| | - Jiaqian Li
- College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, Hubei, China
| | - Zihan Liu
- College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, Hubei, China
- Northeastern University School of Resources and Civil Engineering, Northeastern University, Shenyang, 110819, Liaoning, China
| | - Wenzhu Duan
- College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, Hubei, China
| | - Shanshan Hou
- College of Resources and Environmental Engineering, Wuhan University of Science and Technology, Wuhan, 430081, Hubei, China
- School of Mechanical &Automotive Engineering, South China University of Technology, Guangzhou, 510641, Guangdong, China
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18
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Issakhov A, Omarova P, Borsikbayeva A. Assessment of airborne transmission from coughing processes with thermal plume adjacent to body and radiators on effectiveness of social distancing. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:66808-66840. [PMID: 35508854 DOI: 10.1007/s11356-022-18713-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
The new coronavirus disease COVID-19 has caused a worldwide pandemic to be declared in a very short period of time. The complexity of the infection lies in asymptomatic carriers that can inadvertently transmit the virus through airborne droplets. This kind of viral disease can infect the human body with tiny particles that carry various bacteria that are generated by the respiratory system of infected patients. In this study, numerical results are proposed that demonstrate the effect of human body temperature and temperature from radiators in a room on the spread of the smallest droplets and particles in an enclosed space. The numerical model proposed in this work takes into account the sedimentation of particles and droplets under the action of gravitational sedimentation and transport in a closed room during the processes of breathing, sneezing or coughing. Various cases were considered, taking into account normal human breathing, coughing or sneezing, as well as three different values of the rate of emission of particles from the human mouth. The heat plume, which affects the concentration of particles in the breathing zone, spreads the particle up to a distance of 4.29 m in the direction of the air flow. It can also be seen from the results obtained that the presence of radiators strongly affects the propagation of particles of various sizes in a closed room. From the obtained results, it should be noted that in order to recommend the optimal social distance, it is necessary to take into account many factors, especially momentum, gravity, human body temperature, as well as the process of natural convection, which greatly affect the propagation of particles in a closed room. The conclusions drawn from the results of this work show that, given the environmental conditions, the social distance of 2 m may not be enough.
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Affiliation(s)
- Alibek Issakhov
- Al-Farabi, Kazakh National University, Almaty, Republic of Kazakhstan.
- Kazakh British Technical University, Almaty, Republic of Kazakhstan.
- International Information Technology University, Almaty, Republic of Kazakhstan.
| | - Perizat Omarova
- Al-Farabi, Kazakh National University, Almaty, Republic of Kazakhstan
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19
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Huang W, Wang K, Hung CT, Chow KM, Tsang D, Lai RWM, Xu RH, Yeoh EK, Ho KF, Chen C. Evaluation of SARS-CoV-2 transmission in COVID-19 isolation wards: On-site sampling and numerical analysis. JOURNAL OF HAZARDOUS MATERIALS 2022; 436:129152. [PMID: 35739698 PMCID: PMC9106403 DOI: 10.1016/j.jhazmat.2022.129152] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/06/2022] [Accepted: 05/11/2022] [Indexed: 05/29/2023]
Abstract
Although airborne transmission has been considered as a possible route for the spread of SARS-CoV-2, the role that aerosols play in SARS-CoV-2 transmission is still controversial. This study evaluated the airborne transmission of SARS-CoV-2 in COVID-19 isolation wards at Prince of Wales Hospital in Hong Kong by both on-site sampling and numerical analysis. A total of 838 air samples and 1176 surface samples were collected, and SARS-CoV-2 RNA was detected using the RT-PCR method. Testing revealed that 2.3% of the air samples and 9.3% of the surface samples were positive, indicating that the isolation wards were contaminated with the virus. The dispersion and deposition of exhaled particles in the wards were calculated by computational fluid dynamics (CFD) simulations. The calculated accumulated number of particles collected at the air sampling points was closely correlated with the SARS-CoV-2 positive rates from the field sampling, which confirmed the possibility of airborne transmission. Furthermore, three potential intervention strategies, i.e., the use of curtains, ceiling-mounted air cleaners, and periodic ventilation, were numerically investigated to explore effective control measures in isolation wards. According to the results, the use of ceiling-mounted air cleaners is effective in reducing the airborne transmission of SARS-CoV-2 in such wards.
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Affiliation(s)
- Wenjie Huang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China
| | - Kailu Wang
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China; Centre for Health Systems and Policy Research, JCSPHPC, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China
| | - Chi-Tim Hung
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China; Centre for Health Systems and Policy Research, JCSPHPC, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China
| | - Kai-Ming Chow
- Department of Medicine and Therapeutics, Prince of Wales Hospital, Shatin, N.T. 999077, Hong Kong, China
| | - Dominic Tsang
- Public Health Laboratory Centre, Centre for Health Protection, Kowloon 999077, Hong Kong, China
| | - Raymond Wai-Man Lai
- Department of Microbiology, Prince of Wales Hospital, Shatin, N.T. 999077, Hong Kong, China
| | - Richard Huan Xu
- Department of Rehabilitation Science, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Kowloon 999077, Hong Kong, China
| | - Eng-Kiong Yeoh
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China; Centre for Health Systems and Policy Research, JCSPHPC, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China
| | - Kin-Fai Ho
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China.
| | - Chun Chen
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China; Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China.
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20
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Multi-objective performance assessment of HVAC systems and physical barriers on COVID-19 infection transmission in a high-speed train. JOURNAL OF BUILDING ENGINEERING 2022; 53:104544. [PMCID: PMC9022448 DOI: 10.1016/j.jobe.2022.104544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 04/11/2022] [Accepted: 04/17/2022] [Indexed: 06/16/2023]
Abstract
A computational fluid dynamics (CFD) simulation was performed to model and study the transmission risk associated with cough-related SARS-CoV-2 droplets in a real-world high-speed train (HST). In this study, the evaporating of the droplets was considered. Simulation data were post-processed to assess the fraction of the particles deposited on each passenger's face and body, suspended in air, and escaped from exhausts. Firstly, the effects of temperature, relative humidity, ventilation rate, injection source, exhausts' location and capacity, and adding the physical barriers on evaporation and transport of respiratory droplets are investigated in long distance HST. The results demonstrate that overall, 6–43% of the particles were suspended in the cabin after 2.7 min, depending on conditions, and 3–58% of the particles were removed from the cabin in the same duration. Use of physical barriers and high ventilation rate is therefore recommended for both personal and social protection. We found more exhaust capacity and medium relative humidity to be effective in reducing the particles' transmission potential across all studied scenarios. The results indicate that reducing ventilation rate and exhaust capacity, increased aerosols shelf time and dispersion throughout the cabin.
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21
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Pan Y, Zhang H, Niu Z, An Y, Chen C. Boundary conditions for exhaled airflow from a cough with a surgical or N95 mask. INDOOR AIR 2022; 32:e13088. [PMID: 36040272 PMCID: PMC9538929 DOI: 10.1111/ina.13088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 06/10/2022] [Accepted: 07/16/2022] [Indexed: 05/12/2023]
Abstract
Wearing surgical or N95 masks is effective in reducing the infection risks of airborne infectious diseases. However, in the literature there are no detailed boundary conditions for airflow from a cough when a surgical or N95 mask is worn. These boundary conditions are essential for accurate prediction of exhaled particle dispersion by computational fluid dynamics (CFD). This study first constructed a coughing manikin with an exhalation system to simulate a cough from a person. The smoke visualization method was used to measure the airflow profile from a cough. To validate the setup of the coughing manikin, the results were compared with measured data from subject tests reported in the literature. The validated coughing manikin was then used to measure the airflow boundary conditions for a cough when a surgical mask was worn and when an N95 mask was worn, respectively. Finally, this study applied the developed airflow boundary conditions to calculate person-to-person particle transport from a cough when masks are worn. The calculated exhaled particle patterns agreed well with the smoke pattern in the visualization experiments. Furthermore, the calculated results indicated that, when the index person wore a surgical and a N95 mask, the total exposure of the receptor was reduced by 93.0% and 98.8%, respectively.
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Affiliation(s)
- Yue Pan
- Department of Mechanical and Automation EngineeringThe Chinese University of Hong KongHong Kong SARChina
| | - Haiqiang Zhang
- Department of Mechanical and Automation EngineeringThe Chinese University of Hong KongHong Kong SARChina
| | - Zhuolun Niu
- Department of Mechanical and Automation EngineeringThe Chinese University of Hong KongHong Kong SARChina
| | - Yuting An
- Department of Mechanical and Automation EngineeringThe Chinese University of Hong KongHong Kong SARChina
| | - Chun Chen
- Department of Mechanical and Automation EngineeringThe Chinese University of Hong KongHong Kong SARChina
- Shenzhen Research InstituteThe Chinese University of Hong KongShenzhenChina
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22
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Li Y, Wu C, Cao G, Guan D, Zhan C. Transmission characteristics of respiratory droplets aerosol in indoor environment: an experimental study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2022; 32:1768-1779. [PMID: 33825604 DOI: 10.1080/09603123.2021.1910629] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 03/25/2021] [Indexed: 06/12/2023]
Abstract
Transmission of droplets has been recognized as an important form of infection for the respiratory diseases. This study investigated the distribution of human respiratory droplets and assessed the effects of air change rate and generated velocity on droplet transmission using an active agent in an enclosed chamber (46 m3). Results revealed that the higher the air change rate was, the fewer viable droplets were detected in the range of <3.3 μm with ventilation; an increased air change rate can increase the attenuation of droplet aerosol. Without ventilation, the viable droplet size was observed to mainly distribute greater than 3.3 μm, which occupied up 87.5% of the total number. When the generated velocity was increased to 20 m/s, 29.38% of the viable droplets were detected at the position of 2.0 m. The findings are excepted to be useful for developing the technology of reducing droplet propagation and providing data verification for simulation research.
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Affiliation(s)
- Yanju Li
- School of Energy and Safety Engineering, Tianjin Chengjian University, Tianjin, China
| | - Chunbin Wu
- School of Energy and Safety Engineering, Tianjin Chengjian University, Tianjin, China
| | - Guoqing Cao
- Institute of Building Environment and Energy, China Academy of Building Research, Beijing, China
| | - Dexing Guan
- School of Energy and Safety Engineering, Tianjin Chengjian University, Tianjin, China
| | - Chaoguo Zhan
- School of Environmental Science and Safety Engineering, Tianjin University of Technology, Tianjin, China
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Luo Q, Ou C, Hang J, Luo Z, Yang H, Yang X, Zhang X, Li Y, Fan X. Role of pathogen-laden expiratory droplet dispersion and natural ventilation explaining a COVID-19 outbreak in a coach bus. BUILDING AND ENVIRONMENT 2022; 220:109160. [PMID: 35615259 PMCID: PMC9122785 DOI: 10.1016/j.buildenv.2022.109160] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/28/2022] [Accepted: 04/30/2022] [Indexed: 05/30/2023]
Abstract
The influencing mechanism of droplet transmissions inside crowded and poorly ventilated buses on infection risks of respiratory diseases is still unclear. Based on experiments of one-infecting-seven COVID-19 outbreak with an index patient at bus rear, we conducted CFD simulations to investigate integrated effects of initial droplet diameters(tracer gas, 5 μm, 50 μm and 100 μm), natural air change rates per hour(ACH = 0.62, 2.27 and 5.66 h-1 related to bus speeds) and relative humidity(RH = 35% and 95%) on pathogen-laden droplet dispersion and infection risks. Outdoor pressure difference around bus surfaces introduces natural ventilation airflow entering from bus-rear skylight and leaving from the front one. When ACH = 0.62 h-1(idling state), the 30-min-exposure infection risk(TIR) of tracer gas is 15.3%(bus rear) - 11.1%(bus front), and decreases to 3.1%(bus rear)-1.3%(bus front) under ACH = 5.66 h-1(high bus speed).The TIR of large droplets(i.e., 100 μm/50 μm) is almost independent of ACH, with a peak value(∼3.1%) near the index patient, because over 99.5%/97.0% of droplets deposit locally due to gravity. Moreover, 5 μm droplets can disperse further with the increasing ventilation. However, TIR for 5 μm droplets at ACH = 5.66 h-1 stays relatively small for rear passengers(maximum 0.4%), and is even smaller in the bus middle and front(<0.1%). This study verifies that differing from general rooms, most 5 μm droplets deposit on the route through the long-and-narrow bus space with large-area surfaces(L∼11.4 m). Therefore, tracer gas can only simulate fine droplet with little deposition but cannot replace 5-100 μm droplet dispersion in coach buses.
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Affiliation(s)
- Qiqi Luo
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Cuiyun Ou
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Jian Hang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Zhiwen Luo
- School of the Built Environment, University of Reading, Reading, UK
| | - Hongyu Yang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Xia Yang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Xuelin Zhang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Xiaodan Fan
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
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Katiyar SK, Gaur SN, Solanki RN, Sarangdhar N, Suri JC, Kumar R, Khilnani GC, Chaudhary D, Singla R, Koul PA, Mahashur AA, Ghoshal AG, Behera D, Christopher DJ, Talwar D, Ganguly D, Paramesh H, Gupta KB, Kumar T M, Motiani PD, Shankar PS, Chawla R, Guleria R, Jindal SK, Luhadia SK, Arora VK, Vijayan VK, Faye A, Jindal A, Murar AK, Jaiswal A, M A, Janmeja AK, Prajapat B, Ravindran C, Bhattacharyya D, D'Souza G, Sehgal IS, Samaria JK, Sarma J, Singh L, Sen MK, Bainara MK, Gupta M, Awad NT, Mishra N, Shah NN, Jain N, Mohapatra PR, Mrigpuri P, Tiwari P, Narasimhan R, Kumar RV, Prasad R, Swarnakar R, Chawla RK, Kumar R, Chakrabarti S, Katiyar S, Mittal S, Spalgais S, Saha S, Kant S, Singh VK, Hadda V, Kumar V, Singh V, Chopra V, B V. Indian Guidelines on Nebulization Therapy. Indian J Tuberc 2022; 69 Suppl 1:S1-S191. [PMID: 36372542 DOI: 10.1016/j.ijtb.2022.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 06/03/2022] [Accepted: 06/09/2022] [Indexed: 06/16/2023]
Abstract
Inhalational therapy, today, happens to be the mainstay of treatment in obstructive airway diseases (OADs), such as asthma, chronic obstructive pulmonary disease (COPD), and is also in the present, used in a variety of other pulmonary and even non-pulmonary disorders. Hand-held inhalation devices may often be difficult to use, particularly for children, elderly, debilitated or distressed patients. Nebulization therapy emerges as a good option in these cases besides being useful in the home care, emergency room and critical care settings. With so many advancements taking place in nebulizer technology; availability of a plethora of drug formulations for its use, and the widening scope of this therapy; medical practitioners, respiratory therapists, and other health care personnel face the challenge of choosing appropriate inhalation devices and drug formulations, besides their rational application and use in different clinical situations. Adequate maintenance of nebulizer equipment including their disinfection and storage are the other relevant issues requiring guidance. Injudicious and improper use of nebulizers and their poor maintenance can sometimes lead to serious health hazards, nosocomial infections, transmission of infection, and other adverse outcomes. Thus, it is imperative to have a proper national guideline on nebulization practices to bridge the knowledge gaps amongst various health care personnel involved in this practice. It will also serve as an educational and scientific resource for healthcare professionals, as well as promote future research by identifying neglected and ignored areas in this field. Such comprehensive guidelines on this subject have not been available in the country and the only available proper international guidelines were released in 1997 which have not been updated for a noticeably long period of over two decades, though many changes and advancements have taken place in this technology in the recent past. Much of nebulization practices in the present may not be evidence-based and even some of these, the way they are currently used, may be ineffective or even harmful. Recognizing the knowledge deficit and paucity of guidelines on the usage of nebulizers in various settings such as inpatient, out-patient, emergency room, critical care, and domiciliary use in India in a wide variety of indications to standardize nebulization practices and to address many other related issues; National College of Chest Physicians (India), commissioned a National task force consisting of eminent experts in the field of Pulmonary Medicine from different backgrounds and different parts of the country to review the available evidence from the medical literature on the scientific principles and clinical practices of nebulization therapy and to formulate evidence-based guidelines on it. The guideline is based on all possible literature that could be explored with the best available evidence and incorporating expert opinions. To support the guideline with high-quality evidence, a systematic search of the electronic databases was performed to identify the relevant studies, position papers, consensus reports, and recommendations published. Rating of the level of the quality of evidence and the strength of recommendation was done using the GRADE system. Six topics were identified, each given to one group of experts comprising of advisors, chairpersons, convenor and members, and such six groups (A-F) were formed and the consensus recommendations of each group was included as a section in the guidelines (Sections I to VI). The topics included were: A. Introduction, basic principles and technical aspects of nebulization, types of equipment, their choice, use, and maintenance B. Nebulization therapy in obstructive airway diseases C. Nebulization therapy in the intensive care unit D. Use of various drugs (other than bronchodilators and inhaled corticosteroids) by nebulized route and miscellaneous uses of nebulization therapy E. Domiciliary/Home/Maintenance nebulization therapy; public & health care workers education, and F. Nebulization therapy in COVID-19 pandemic and in patients of other contagious viral respiratory infections (included later considering the crisis created due to COVID-19 pandemic). Various issues in different sections have been discussed in the form of questions, followed by point-wise evidence statements based on the existing knowledge, and recommendations have been formulated.
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Affiliation(s)
- S K Katiyar
- Department of Tuberculosis & Respiratory Diseases, G.S.V.M. Medical College & C.S.J.M. University, Kanpur, Uttar Pradesh, India.
| | - S N Gaur
- Vallabhbhai Patel Chest Institute, University of Delhi, Respiratory Medicine, School of Medical Sciences and Research, Sharda University, Greater NOIDA, Uttar Pradesh, India
| | - R N Solanki
- Department of Tuberculosis & Chest Diseases, B. J. Medical College, Ahmedabad, Gujarat, India
| | - Nikhil Sarangdhar
- Department of Pulmonary Medicine, D. Y. Patil School of Medicine, Navi Mumbai, Maharashtra, India
| | - J C Suri
- Department of Pulmonary, Critical Care & Sleep Medicine, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, India
| | - Raj Kumar
- Vallabhbhai Patel Chest Institute, Department of Pulmonary Medicine, National Centre of Allergy, Asthma & Immunology; University of Delhi, Delhi, India
| | - G C Khilnani
- PSRI Institute of Pulmonary, Critical Care, & Sleep Medicine, PSRI Hospital, Department of Pulmonary Medicine & Sleep Disorders, All India Institute of Medical Sciences, New Delhi, India
| | - Dhruva Chaudhary
- Department of Pulmonary & Critical Care Medicine, Pt. Bhagwat Dayal Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | - Rupak Singla
- Department of Tuberculosis & Respiratory Diseases, National Institute of Tuberculosis & Respiratory Diseases (formerly L.R.S. Institute), Delhi, India
| | - Parvaiz A Koul
- Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu & Kashmir, India
| | - Ashok A Mahashur
- Department of Respiratory Medicine, P. D. Hinduja Hospital, Mumbai, Maharashtra, India
| | - A G Ghoshal
- National Allergy Asthma Bronchitis Institute, Kolkata, West Bengal, India
| | - D Behera
- Department of Pulmonary Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - D J Christopher
- Department of Pulmonary Medicine, Christian Medical College, Vellore, Tamil Nadu, India
| | - Deepak Talwar
- Metro Centre for Respiratory Diseases, Noida, Uttar Pradesh, India
| | | | - H Paramesh
- Paediatric Pulmonologist & Environmentalist, Lakeside Hospital & Education Trust, Bengaluru, Karnataka, India
| | - K B Gupta
- Department of Tuberculosis & Respiratory Medicine, Pt. Bhagwat Dayal Sharma Post Graduate Institute of Medical Sciences Rohtak, Haryana, India
| | - Mohan Kumar T
- Department of Pulmonary, Critical Care & Sleep Medicine, One Care Medical Centre, Coimbatore, Tamil Nadu, India
| | - P D Motiani
- Department of Pulmonary Diseases, Dr. S. N. Medical College, Jodhpur, Rajasthan, India
| | - P S Shankar
- SCEO, KBN Hospital, Kalaburagi, Karnataka, India
| | - Rajesh Chawla
- Respiratory and Critical Care Medicine, Indraprastha Apollo Hospitals, New Delhi, India
| | - Randeep Guleria
- All India Institute of Medical Sciences, Department of Pulmonary Medicine & Sleep Disorders, AIIMS, New Delhi, India
| | - S K Jindal
- Department of Pulmonary Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - S K Luhadia
- Department of Tuberculosis and Respiratory Medicine, Geetanjali Medical College and Hospital, Udaipur, Rajasthan, India
| | - V K Arora
- Indian Journal of Tuberculosis, Santosh University, NCR Delhi, National Institute of TB & Respiratory Diseases Delhi, India; JIPMER, Puducherry, India
| | - V K Vijayan
- Vallabhbhai Patel Chest Institute, Department of Pulmonary Medicine, University of Delhi, Delhi, India
| | - Abhishek Faye
- Centre for Lung and Sleep Disorders, Nagpur, Maharashtra, India
| | | | - Amit K Murar
- Respiratory Medicine, Cronus Multi-Specialty Hospital, New Delhi, India
| | - Anand Jaiswal
- Respiratory & Sleep Medicine, Medanta Medicity, Gurugram, Haryana, India
| | - Arunachalam M
- All India Institute of Medical Sciences, New Delhi, India
| | - A K Janmeja
- Department of Respiratory Medicine, Government Medical College, Chandigarh, India
| | - Brijesh Prajapat
- Pulmonary and Critical Care Medicine, Yashoda Hospital and Research Centre, Ghaziabad, Uttar Pradesh, India
| | - C Ravindran
- Department of TB & Chest, Government Medical College, Kozhikode, Kerala, India
| | - Debajyoti Bhattacharyya
- Department of Pulmonary Medicine, Institute of Liver and Biliary Sciences, Army Hospital (Research & Referral), New Delhi, India
| | | | - Inderpaul Singh Sehgal
- Department of Pulmonary Medicine, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - J K Samaria
- Centre for Research and Treatment of Allergy, Asthma & Bronchitis, Department of Chest Diseases, IMS, BHU, Varanasi, Uttar Pradesh, India
| | - Jogesh Sarma
- Department of Pulmonary Medicine, Gauhati Medical College and Hospital, Guwahati, Assam, India
| | - Lalit Singh
- Department of Respiratory Medicine, SRMS Institute of Medical Sciences, Bareilly, Uttar Pradesh, India
| | - M K Sen
- Department of Respiratory Medicine, ESIC Medical College, NIT Faridabad, Haryana, India; Department of Pulmonary, Critical Care & Sleep Medicine, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, India
| | - Mahendra K Bainara
- Department of Pulmonary Medicine, R.N.T. Medical College, Udaipur, Rajasthan, India
| | - Mansi Gupta
- Department of Pulmonary Medicine, Sanjay Gandhi PostGraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
| | - Nilkanth T Awad
- Department of Pulmonary Medicine, Lokmanya Tilak Municipal Medical College, Mumbai, Maharashtra, India
| | - Narayan Mishra
- Department of Pulmonary Medicine, M.K.C.G. Medical College, Berhampur, Orissa, India
| | - Naveed N Shah
- Department of Pulmonary Medicine, Chest Diseases Hospital, Government Medical College, Srinagar, Jammu & Kashmir, India
| | - Neetu Jain
- Department of Pulmonary, Critical Care & Sleep Medicine, PSRI, New Delhi, India
| | - Prasanta R Mohapatra
- Department of Pulmonary Medicine & Critical Care, All India Institute of Medical Sciences, Bhubaneswar, Orissa, India
| | - Parul Mrigpuri
- Department of Pulmonary Medicine, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Pawan Tiwari
- School of Excellence in Pulmonary Medicine, NSCB Medical College, Jabalpur, Madhya Pradesh, India
| | - R Narasimhan
- Department of EBUS and Bronchial Thermoplasty Services at Apollo Hospitals, Chennai, Tamil Nadu, India
| | - R Vijai Kumar
- Department of Pulmonary Medicine, MediCiti Medical College, Hyderabad, Telangana, India
| | - Rajendra Prasad
- Vallabhbhai Patel Chest Institute, University of Delhi and U.P. Rural Institute of Medical Sciences & Research, Safai, Uttar Pradesh, India
| | - Rajesh Swarnakar
- Department of Respiratory, Critical Care, Sleep Medicine and Interventional Pulmonology, Getwell Hospital & Research Institute, Nagpur, Maharashtra, India
| | - Rakesh K Chawla
- Department of, Respiratory Medicine, Critical Care, Sleep & Interventional Pulmonology, Saroj Super Speciality Hospital, Jaipur Golden Hospital, Rajiv Gandhi Cancer Hospital, Delhi, India
| | - Rohit Kumar
- Department of Pulmonary, Critical Care & Sleep Medicine, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, India
| | - S Chakrabarti
- Department of Pulmonary, Critical Care & Sleep Medicine, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, India
| | | | - Saurabh Mittal
- Department of Pulmonary, Critical Care & Sleep Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Sonam Spalgais
- Department of Pulmonary Medicine, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | | | - Surya Kant
- Department of Respiratory (Pulmonary) Medicine, King George's Medical University, Lucknow, Uttar Pradesh, India
| | - V K Singh
- Centre for Visceral Mechanisms, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
| | - Vijay Hadda
- Department of Pulmonary Medicine & Sleep Disorders, All India Institute of Medical Sciences, New Delhi, India
| | - Vikas Kumar
- All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
| | - Virendra Singh
- Mahavir Jaipuria Rajasthan Hospital, Jaipur, Rajasthan, India
| | - Vishal Chopra
- Department of Chest & Tuberculosis, Government Medical College, Patiala, Punjab, India
| | - Visweswaran B
- Interventional Pulmonology, Yashoda Hospitals, Hyderabad, Telangana, India
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Zhu S, Lin T, Laurent JGC, Spengler JD, Srebric J. Tradeoffs between ventilation, air mixing, and passenger density for the airborne transmission risk in airport transportation vehicles. BUILDING AND ENVIRONMENT 2022; 219:109186. [PMID: 35599668 PMCID: PMC9110315 DOI: 10.1016/j.buildenv.2022.109186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/27/2022] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
Airport transportation vehicles, such as buses, aerotrains, and shuttles, provide important passenger transfer services in airports. This study quantitatively investigated COVID-19 aerosol infection risk and identified acceptable operational conditions, such as passenger occupancy rates and duration of rides, given the performance of vehicle ventilation. The greatest risk to the largest number of passengers is from an index case whose exhaled breath would take the longest time to exit the vehicle. The study identified such a case based on ventilation patterns, and it tracked the spread of viral aerosols (5 μm) by using the Wells-Riley equation to predict aerosol infection risk distribution. These distributions allowed a definition of an imperfect mixing degree (δ) as the ratio of actual risk and the calculated risk under a perfect mixing condition, and further derived regression equations to predict δ in the far-field (FF) and near-field (NF) of each passenger. These results revealed an order of magnitude higher aerosol infection risk in NF than in FF. For example, with a ventilation rate of 58 ACH (air changes per hour) and a 45% occupancy rate, unmasked passengers should stay up to 15 min in the bus and 35 min in the shuttle to limit infection risk in NF within 10%. These also indicate that masking is an important and effective risk reduction measure in transportation vehicles, especially important in NF. Overall, the analysis of imperfect air mixing allows direct comparison of risks in different transportation vehicles and a structured approach to development of policy recommendations.
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Affiliation(s)
- Shengwei Zhu
- Dept. of Mechanical Engineering, University of Maryland, College Park, MD, USA
| | - Tong Lin
- Dept. of Mechanical Engineering, University of Maryland, College Park, MD, USA
| | | | - John D Spengler
- Dept. of Environmental Health, Harvard School of Public Health, Boston, MA, USA
| | - Jelena Srebric
- Dept. of Mechanical Engineering, University of Maryland, College Park, MD, USA
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Numerical evaluation on indoor environment quality during high numbers of occupied passengers in the departure hall of an airport terminal. JOURNAL OF BUILDING ENGINEERING 2022; 51:104276. [PMCID: PMC8894729 DOI: 10.1016/j.jobe.2022.104276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/17/2022] [Accepted: 02/22/2022] [Indexed: 06/01/2023]
Abstract
The rapid development of airports and the rapid spread of coronavirus disease 2019 (COVID-19) have brought increased attention to indoor environment quality, airflow organization, key pollutant dispersion, and ventilation modes in airport terminals. However, the characteristics of these parameters, especially carbon dioxide (CO2) and aerosol diffusion, are not fully understood. Therefore, in this study, the airflow patterns; CO2 and aerosol dispersion; and several thermal environment indices, including temperature, wind velocity, and predicted mean vote (PMV), of an airport terminal departure hall with high numbers of occupied passenger were numerically evaluated using the realizable k-ε and passive scalar models. The efficacies of three common ventilation modes, namely, up-supply and up-return, up-supply and down-return with different sides, and up-supply and down-return with the same side, were evaluated based on the CO2 removal efficiency and spreading range of aerosols. The results indicated that under high numbers of occupied passenger conditions, these ventilation modes vary slightly, with respect to create a comfortable and healthy environment. In particular, the up-supply and down-return with different sides mode was the best among the modes considered, when comparing the indices of temperature, wind speed PMV, and CO2 emission efficiency. Conversely, with respect to decreasing the risk of aerosol exposure, the up-supply and down-return with the same side mode was the best. Overall, the results from this study provide fundamental information for predicting CO2 and aerosol exposure levels and will act as a reference for the design and operation of ventilation systems in airport terminal buildings.
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Numerical Investigation on the Droplet Dispersion inside a Bus and the Infection Risk Prediction. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12125909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
COVID-19 can be easily transmitted to passengers by inhaling exhaled droplets from the infected person in a bus. Therefore, studying droplet dispersion would provide further insight into the mechanism of virus transmission and predict the risk of infection among passengers on a bus. In this research, a bus equipped with air-conditioning was employed as the research object. To determine the dispersion path, concentration distribution, and escape time of the droplets, computational fluid dynamic (CFD) was applied to simulate the flow field and the droplets’ dispersion. The effect of the air supply rate, the location of vents, and the location of infected persons on the dispersion were discussed. Based on the distribution of droplets in the cabin calculated by CFD, a superposition method was used to determine the number of virus particles inhaled by every individual passenger over a four-hour journey. Then, infection risk was assessed by the Wells-Riley equation for all the passengers in the cabin after the whole journey. The results show that the distribution of droplets in the cabin is greatly influenced by the location of the infected person, and the airflow pattern is highly associated with the air supply rate and the location of vents. The infection risk of passengers located at the droplet dispersion path and the distance from the infected persons less than 2.2 m is over 10%. The increase in the air supply rate could speed up the spread of the droplets but at the same time, it could reduce the infection risk.
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Liu J, Hao M, Chen S, Yang Y, Li J, Mei Q, Bian X, Liu K. Numerical evaluation of face masks for prevention of COVID-19 airborne transmission. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:44939-44953. [PMID: 35141824 PMCID: PMC9200689 DOI: 10.1007/s11356-022-18587-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/05/2022] [Indexed: 04/15/2023]
Abstract
The COVID-19 pandemic has forced governments around the globe to apply various preventive measures for public health. One of the most effective measures is wearing face masks, which plays a vital role in blocking the transmission of droplets and aerosols. To understand the protective mechanism of face masks, especially in indoor environments, we apply a computational fluid dynamics technique to predict the lifetime of cough droplets. Therefore, we can assess the exposure risk in a ventilated room where an infected individual wears a face mask or not. We focus on the dynamic evaporation and diffusion of droplets in a human-cough process, which is a major cause for the spread of the virus. We find that wearing a face mask can effectively reduce the total mass and Sauter mean diameter of the residual droplets after a single cough. The mass concentration of virus-carrying droplets in the ventilated room decreases by 201, 43,786, and 307,060 times, corresponding to wearing cotton face masks, surgical face masks, and N95 face masks, respectively. However, the maximum travel distance of 80% droplets is insensitive to wearing a face mask or not. Therefore, the residual droplets are widely distributed due to the influence of indoor airflow. Furthermore, we study aerosol exposure risks in different areas of the room and find that high concentrations of aerosols occur in the streamline through an infected individual, especially next to the individual within 1.5 m. This strongly suggests a social distance despite the fact that the majority of droplets are filtered by face masks. This study explains the impact of face masks and airflow on indoor exposure risks and further inspires potential measures for public health, for example, no individuals should sit near the air supply opening.
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Affiliation(s)
- Jiaxing Liu
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, Liaoning, People's Republic of China
| | - Ming Hao
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, Liaoning, People's Republic of China
| | - Shulei Chen
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, Liaoning, People's Republic of China
| | - Yang Yang
- Department of Ophthalmology, Renmin Hospital of Wuhan University, Wuhan, Hubei, People's Republic of China
| | - Jian Li
- Institute of Experimental Immunology, University Clinics of Rheinische Friedrich-Wilhelms-University, Bonn, Germany
| | - Qi Mei
- Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China.
| | - Xin Bian
- School of Aeronautics and Astronautics, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
| | - Kun Liu
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, Liaoning, People's Republic of China.
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Lavrinenko A, Fabregat A, Pallares J. Comparison between fully resolved and time-averaged simulations of particle cloud dispersion produced by a violent expiratory event. ACTA MECHANICA SINICA = LI XUE XUE BAO 2022; 38:721489. [PMID: 35756946 PMCID: PMC9207831 DOI: 10.1007/s10409-022-09032-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 01/30/2022] [Indexed: 06/15/2023]
Abstract
In this work we compare the DNS results (Fabregat et al. 2021, Fabregat et al. 2021) for a mild cough already reported in the literarure with those obtained with a compressible URANS equations with a k-ϵ turbulence model. In both cases, the dispersed phase has been modelled as spherical Lagrangian particles using the one-way coupling assumption. Overall, the URANS model is capable of reproducing the observed tendency of light particles under 64 µm in diameter to rise due to the action of the drag exerted by the buoyant puff generated by the cough. Both DNS and URANS found that particles above 64 µm will tend to describe parabolic trajectories under the action of gravitational forces. Grid independence analysis allows to qualify the impact of increasing mesh resolution on the particle cloud statistics as flow evolves. Results suggest that the k-ϵ model overpredicts the horizontal displacement of the particles smaller than 64 µm while the opposite occurs for the particles larger than 64 µm.
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Affiliation(s)
- Akim Lavrinenko
- Departament d’Enginyeria Mecánica, Universitat Rovira i Virgili, Spain, Av. Països Catalans, Tarragona 26, 43007 Spain
| | - Alexandre Fabregat
- Departament d’Enginyeria Mecánica, Universitat Rovira i Virgili, Spain, Av. Països Catalans, Tarragona 26, 43007 Spain
| | - Jordi Pallares
- Departament d’Enginyeria Mecánica, Universitat Rovira i Virgili, Spain, Av. Països Catalans, Tarragona 26, 43007 Spain
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Kojima T, Dogru M, Yazu H, Kudo H, Tsubota K. Noninvasive Visualization of the Tear Film Microaerosol During Noncontact Tonometry Measurements. Am J Ophthalmol 2022; 241:28-39. [PMID: 35469788 DOI: 10.1016/j.ajo.2022.03.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE To investigate the aerosol generation by a noninvasive real-time observation device and assess the conditions relating to aerosolization during intraocular pressure (IOP) measurements using a commercial noncontact tonometer (NCT). STUDY DESIGN Prospective experimental and healthy eye studies. METHODS In an initial experimental study, we devised a model mannequin eye to investigate how air puff pressure and IOP of the eye affected aerosol generation. In the human study including 20 healthy volunteer control subjects, the number of tear aerosol particles generated at 20 and 40 mm Hg air puff pressures with and without eye drop was investigated. The recorded aerosol visualization video was analyzed and the number of aerosol particles generated in 5 seconds after IOP measurement was measured. RESULTS The experimental and human studies confirmed the aerosol generation during NCT measurements. In the experimental study, when the air puff pressures were set at 20 and 40 mm Hg, a lower IOP (5 mm Hg) generated significantly more aerosols than a higher IOP (25 mm Hg) (20 mm Hg, P = .0159; 40 mm Hg, P = .0079). There was also a significant positive correlation between the air puff pressure and the number of aerosol particles in both high- and low-IOP eyes (P < .001). At an air puff pressure of 40 mm Hg, the amount of aerosol generated was significantly higher with eye drop than without eye drop (P = .047). CONCLUSIONS NCT generates significant aerosolization from the tear film, the amount of which is determined by the IOP and the air puff pressure and the presence of eye drop use before the measurements.
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Dai H, Zhao B. Reducing airborne infection risk of COVID-19 by locating air cleaners at proper positions indoor: Analysis with a simple model. BUILDING AND ENVIRONMENT 2022; 213:108864. [PMID: 35136279 PMCID: PMC8813770 DOI: 10.1016/j.buildenv.2022.108864] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 01/12/2022] [Accepted: 01/31/2022] [Indexed: 05/26/2023]
Abstract
Portable air cleaners (PACs) can remove airborne SARS-CoV-2 exhaled by COVID-19 infectors indoor. However, effectively locating PAC to reduce the infection risk is still poorly understood. Here, we propose a simple model by regressing an equation of seven similarity criteria based on CFD-modeled results of a scenario matrix of 128 cases for office rooms. The model can calculate the mean droplet nucleus concentration with very low computing costs. Combining this model with the Wells-Riley equation, we estimate the airborne infection risk when a PAC is located in different positions. The two similarity criteria, B p + and G p + , are critical for characterizing the effect of the position and airflow rate of PAC on the infection risk. An infection probability of less than 10% requires B p + to be larger than 144 and G p + to be larger than 0.001. These criteria imply that locating PAC in the center of the room is optimal under the premise that the airflow rate of PAC is greater than a certain level. The model provides an easy-to-use approach for real-time risk control strategy decisions. Furthermore, the placement strategies offer timely guidelines for precautions against the prolonged COVID-19 pandemic and common infectious respiratory diseases.
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Affiliation(s)
- Hui Dai
- Department of Building Science, School of Architecture, Tsinghua University, Beijing, 100084, China
| | - Bin Zhao
- Department of Building Science, School of Architecture, Tsinghua University, Beijing, 100084, China
- Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Tsinghua University, Beijing, 100084, China
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Impact of natural ventilation on exposure to SARS-CoV 2 in indoor/semi-indoor terraces using CO 2 concentrations as a proxy. JOURNAL OF BUILDING ENGINEERING 2022; 46:103725. [PMCID: PMC8632854 DOI: 10.1016/j.jobe.2021.103725] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/20/2021] [Accepted: 11/19/2021] [Indexed: 06/16/2023]
Abstract
Nowadays, it is necessary a better airborne transmission understanding of respiratory diseases in shared indoor and semi-indoor environments with natural ventilation in order to adopt effective people's health protection measures. The aim of this work is to evaluate the relative exposure to SARS-CoV 2 in a set of virtual scenarios representing enclosed and semi-enclosed terraces under different outdoor meteorological conditions. For this purpose, indoor CO2 concentration is used as a proxy for the risk assessment. Airflow and people exhaled CO2 in different scenarios are simulated through Computational Fluid Dynamics (CFD) modelling with Unsteady Reynolds-Averaged Navier-Stokes (URANS) approach. Both spatial average concentrations and local concentrations are analyzed. In general, spatial average concentrations decrease as ventilation increases, however, depending on the people arrangement inside the terrace, spatial average concentrations and local concentrations can be very different. Therefore, for assessing the relative exposure to SARS-CoV 2 it is necessary to consider the indoor flow patterns between infectors and susceptibles. This research provides detailed information about CO2 dispersion in enclosed/semi-enclosed scenarios, which can be very useful for reducing the transmission risk through better natural ventilation designs and improving the classic risk models since it allows to check their hypotheses in real-world scenarios. Although CFD ventilation studies in indoor/semi-indoor environments have been already addressed in the literature, this research is focused on restaurant terraces, scenarios scarcely investigated. Likewise, one of the novelties of this study is to take into account the outdoor meteorological conditions to appropriately simulate natural ventilation.
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Modeling Transport of SARS-CoV-2 Inside a Charlotte Area Transit System (CATS) Bus. FLUIDS 2022. [DOI: 10.3390/fluids7020080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present in this paper a model of the transport of human respiratory particles on a Charlotte Area Transit System (CATS) bus to examine the efficacy of interventions to limit exposure to SARS-CoV-2, the virus that causes COVID-19. The methods discussed here utilize a commercial Navier–Stokes flow solver, RavenCFD, using a massively parallel supercomputer to model the flow of air through the bus under varying conditions, such as windows being open or the HVAC flow settings. Lagrangian particles are injected into the RavenCFD predicted flow fields to simulate the respiratory droplets from speaking, coughing, or sneezing. These particles are then traced over time and space until they interact with a surface or are removed via the HVAC system. Finally, a volumetric Viral Mean Exposure Time (VMET) is computed to quantify the risk of exposure to the SARS-CoV-2 under various environmental and occupancy scenarios. Comparing the VMET under varying conditions should help identify viable methods to reduce the risk of viral exposure of CATS bus passengers during the COVID-19 pandemic.
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Investigation on the evaporation and dispersion of human respiratory droplets with COVID-19 virus. INTERNATIONAL JOURNAL OF MULTIPHASE FLOW 2022; 147. [PMCID: PMC8603237 DOI: 10.1016/j.ijmultiphaseflow.2021.103904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
On March 11, 2020, COVID-19 was declared as a pandemic by World Health Organization (WHO). Effective prevention is indispensable for defeating the ongoing COVID-19 pandemic. The evaporation and diffusion characteristics of the droplet in the air are the critical factors for the virus transmission by droplets. To better understand transmission routes of COVID-19 through respiratory droplets, a new evaporation and dispersion model for respiratory droplets is proposed to estimate droplet lifetime and the size of spreading zone in air. The importance of respiratory activities and environmental factors on the transmission of respiratory viruses are further discussed. The predictive results demonstrate initial particle size, ambient temperature and relative humidity all have significant effect on the survival time and infection distance of respiratory droplets. Decreasing droplet initial size always shortens the lifetime and the transmission distance of respiratory droplets. The 100 μm droplets expelled by talking or coughing can be carried more than 2 m away. Increasing ambient temperature and decreasing ambient humidity can effectively reduce the lifetime and propagation distance of respiratory droplets, thus reducing the risk of viral infection. These findings could contribute to developing effective prevention measures for controlling infectious disease transmission via droplets.
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35
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Coldrick S, Kelsey A, Ivings MJ, Foat TG, Parker ST, Noakes CJ, Bennett A, Rickard H, Moore G. Modeling and experimental study of dispersion and deposition of respiratory emissions with implications for disease transmission. INDOOR AIR 2022; 32:e13000. [PMID: 35225395 PMCID: PMC9111502 DOI: 10.1111/ina.13000] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/05/2022] [Accepted: 01/29/2022] [Indexed: 05/16/2023]
Abstract
The ability to model the dispersion of pathogens in exhaled breath is important for characterizing transmission of the SARS-CoV-2 virus and other respiratory pathogens. A Computational Fluid Dynamics (CFD) model of droplet and aerosol emission during exhalations has been developed and for the first time compared directly with experimental data for the dispersion of respiratory and oral bacteria from ten subjects coughing, speaking, and singing in a small unventilated room. The modeled exhalations consist of a warm, humid, gaseous carrier flow and droplets represented by a discrete Lagrangian particle phase which incorporates saliva composition. The simulations and experiments both showed greater deposition of bacteria within 1 m of the subject, and the potential for a substantial number of bacteria to remain airborne, with no clear difference in airborne concentration of small bioaerosols (<10 μm diameter) between 1 and 2 m. The agreement between the model and the experimental data for bacterial deposition directly in front of the subjects was encouraging given the uncertainties in model input parameters and the inherent variability within and between subjects. The ability to predict airborne microbial dispersion and deposition gives confidence in the ability to model the consequences of an exhalation and hence the airborne transmission of respiratory pathogens such as SARS-CoV-2.
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Affiliation(s)
| | | | | | | | | | - Catherine J. Noakes
- Leeds Institute for Fluid DynamicsSchool of Civil EngineeringUniversity of LeedsLeedsUK
| | | | | | - Ginny Moore
- National Infection Service, UKHSASalisburyUK
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Mohamadi F, Fazeli A. A Review on Applications of CFD Modeling in COVID-19 Pandemic. ARCHIVES OF COMPUTATIONAL METHODS IN ENGINEERING : STATE OF THE ART REVIEWS 2022; 29:3567-3586. [PMID: 35079217 PMCID: PMC8773396 DOI: 10.1007/s11831-021-09706-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 12/28/2021] [Indexed: 05/25/2023]
Abstract
COVID-19 pandemic has started a big challenge to the world health and economy during recent years. Many efforts were made to use the computation fluid dynamic (CFD) approach in this pandemic. CFD was used to understanding the airborne dispersion and transmission of this virus in different situations and buildings. The effect of the different conditions of the ventilation was studied by the CFD modeling to discuss preventing the COVID-19 transmission. Social distancing and using the facial masks were also modeled by the CFD approach to study the effect on reducing dispersion of the microdroplets containing the virus. Most of these recent applications of the CFD were reviewed for COVID-19 in this article. Special applications of the CFD modeling such as COVID-19 microfluidic biosensors, and COVID-19 inactivation using UV radiation were also reviewed in this research. The main findings of each research were also summarized in a table to answer critical questions about the effectiveness levels of applying the COVID-19 health protocols. CFD applications for modeling of COVID-19 dispersion in an airplane cabin, an elevator, a small classroom, a supermarket, an operating room of a hospital, a restaurant, a hospital waiting room, and a children's recovery room in a hospital were discussed briefly in different scenarios. CFD modeling for studying the effect of social distancing with different spaces, using and not using facial masks, difference of sneezing and coughing, different inlet/outlet ventilation layouts, combining air-conditioning and sanitizing machine, and using general or local air-conditioning systems were reviewed.
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Affiliation(s)
- Fateme Mohamadi
- Department of Chemical Engineering, Caspian Faculty of Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Ali Fazeli
- Department of Chemical Engineering, Caspian Faculty of Engineering, College of Engineering, University of Tehran, Tehran, Iran
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37
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Yang Y, Wang Y, Tian L, Su C, Chen Z, Huang Y. Effects of purifiers on the airborne transmission of droplets inside a bus. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2022; 34:017108. [PMID: 35340683 PMCID: PMC8939553 DOI: 10.1063/5.0081230] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 12/28/2021] [Indexed: 05/25/2023]
Abstract
During an airborne infectious disease outbreak, bus passengers can be easily infected by the dispersion of exhaled droplets from an infected passenger. Therefore, measures to control the transport of droplets are necessary, such as a mask or purifier. The current research examined aerosol transport in a bus with air-conditioning. To determine the dispersion path, deposition distribution, and droplet escape time, the computational fluid dynamics were used to predict the flow field and the dispersion of droplets considering the effects of droplet size, location of the infected person, and purifier type. In addition, based on the viability and the number of virus particles in a droplet, the total number of virus particles inhaled by passengers over a 4-h journey was obtained by the superposition method. The Wells-Riley equation was then used to assess the infection risk of the passengers in the bus cabin. The results showed that droplets with a size of 1-20 μm have essentially the same deposition characteristics, and the location of the infected passenger affects the distribution of droplets' transport and the effectiveness of a purifier in removing droplets. A purifier can effectively remove droplets from passengers' coughs and reduce the infection risk of passengers. The performance of the smaller purifiers is not as stable as that of the larger purifiers, and the performance is influenced by the airflow structure where the infected passenger is located.
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Affiliation(s)
| | | | - Linli Tian
- Author to whom correspondence should be addressed:. Tel.: 0086-13317136217
| | | | - Zhixin Chen
- Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan University of Technology, Wuhan, Hubei 430070, China
| | - Yuanyi Huang
- SAIC GM Wuling Automobile Co., Ltd, Liuzhou, Guangxi 545000, China
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38
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Liu Z, Zhu H, Song Y, Cao G. Quantitative distribution of human exhaled particles in a ventilation room. BUILDING SIMULATION 2022; 15:859-870. [PMID: 34567435 PMCID: PMC8450698 DOI: 10.1007/s12273-021-0836-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/13/2021] [Accepted: 08/19/2021] [Indexed: 05/05/2023]
Abstract
Respiratory viruses can be attached to human exhaled particles and spread from person to person through respiratory activities. The purpose of this study is to obtain the quantitative description formula of human exhaled particles in the ventilated room through amount number of numerical simulation calculations and regression statistical analysis of the simulated data. In this study, a combination of numerical simulation and laboratory experiments was used, and the results were tallied preferably. Bacillus subtilis was released as a release source to investigate the migration and distribution of bioaerosol. The results show that under the condition of high air supply velocity, due to the disturbance of human respiration and airflow, the diffusion velocity of exhaled particles was faster and the diffusion range is larger than that of low air supply velocity within the same time frame. No matter where the location of the manikin was in the room, the exhaled particles would spread to the whole room in at least 900 s. The method used in this study could be used to predict the distribution of human exhaled particles concentration in different indoor spaces, such as public transport and hospitals. These findings could provide valuable reference for the location of indoor air purifiers, which plays a guiding role in the construction of a healthy indoor environment.
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Affiliation(s)
- Zhijian Liu
- Department of Power Engineering, North China Electric Power University, Baoding, 071003 China
| | - Hangyao Zhu
- Department of Power Engineering, North China Electric Power University, Baoding, 071003 China
| | - Yangfan Song
- Department of Power Engineering, North China Electric Power University, Baoding, 071003 China
| | - Guoqing Cao
- Institute of Building Environment and Energy, China Academy of Building Research, Beijing, 100013 China
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39
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Wang W, Wang F, Lai D, Chen Q. Evaluation of SARS-COV-2 transmission and infection in airliner cabins. INDOOR AIR 2022; 32:e12979. [PMID: 35048429 DOI: 10.1111/ina.12979] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/30/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
Commercial airliners have played an important role in spreading the SARS-CoV-2 virus worldwide. This study used computational fluid dynamics (CFD) to simulate the transmission of SARS-CoV-2 on a flight from London to Hanoi and another from Singapore to Hangzhou. The dispersion of droplets of different sizes generated by coughing, talking, and breathing activities in a cabin by an infected person was simulated by means of the Lagrangian method. The SARS-CoV-2 virus contained in expiratory droplets traveled with the cabin air distribution and was inhaled by other passengers. Infection was determined by counting the number of viral copies inhaled by each passenger. According to the results, our method correctly predicted 84% of the infected/uninfected cases on the first flight. The results also show that wearing masks and reducing conversation frequency between passengers could help to reduce the risk of exposure on the second flight.
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Affiliation(s)
- Wensi Wang
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Feng Wang
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Dayi Lai
- Department of Architecture, Shanghai Jiao Tong University, Shanghai, China
| | - Qingyan Chen
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong
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40
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Liu S, Zhao X, Nichols SR, Bonilha MW, Derwinski T, Auxier JT, Chen Q. Evaluation of airborne particle exposure for riding elevators. BUILDING AND ENVIRONMENT 2022; 207:108543. [PMID: 34776597 PMCID: PMC8574099 DOI: 10.1016/j.buildenv.2021.108543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/20/2021] [Accepted: 11/02/2021] [Indexed: 05/05/2023]
Abstract
Social distancing is a key factor for health during the COVID-19 pandemic. In many indoor spaces, such as elevators, it is difficult to maintain social distancing. This investigation used computational-fluid-dynamics (CFD) to study airborne particle exposure in riding an elevator in a typical building with 35 floors. The elevator traveled from the ground floor to the 35th floor with two stops on floor 10 and floor 20, comprising 114 s. The CFD simulated the dispersion of the aerosolized particles exhaled by an index person while breathing in both lobby and elevator areas. The study calculated the accumulated dose of susceptible riders riding in elevators with the index person under different conditions including different ventilation rates, air supply methods, and elevator cab geometries. This investigation also studied a case with a single cough from the index person as the person entered the elevator. The results show that, due to the short duration of the average elevator ride, the number of particles inhaled by a susceptible rider was low. For the reference case with a 72 ACH (air changes per hour) ventilation rate, the highest accumulated particle dose by a susceptible passenger close to the index person was only 1.59. The cough would cause other riders to inhale approximately 8 orders of magnitude higher particle mass than from continuous breathing by the index person for the whole duration of the ride.
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Affiliation(s)
- Sumei Liu
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Xingwang Zhao
- School of Energy and Environment, Southeast University, Nanjing, 210096, China
| | - Stephen R Nichols
- Otis Elevator Company, Global Engineering, Five Farm Springs Road, Farmington, CT, 06032, USA
| | - Murilo W Bonilha
- Otis Elevator Company, Global Engineering, Five Farm Springs Road, Farmington, CT, 06032, USA
| | - Tricia Derwinski
- Otis Elevator Company, Global Engineering, Five Farm Springs Road, Farmington, CT, 06032, USA
| | - James T Auxier
- Otis Elevator Company, Global Engineering, Five Farm Springs Road, Farmington, CT, 06032, USA
| | - Qingyan Chen
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Kowloon, 999077, Hong Kong SAR, China
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41
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Singer BC, Zhao H, Preble CV, Delp WW, Pantelic J, Sohn MD, Kirchstetter TW. Measured influence of overhead HVAC on exposure to airborne contaminants from simulated speaking in a meeting and a classroom. INDOOR AIR 2022; 32:e12917. [PMID: 34477251 DOI: 10.1111/ina.12917] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/08/2021] [Accepted: 07/11/2021] [Indexed: 06/13/2023]
Abstract
Tracer gas experiments were conducted in a 158 m3 room with overhead supply diffusers to study dispersion of contaminants from simulated speaking in physically distanced meeting and classroom configurations. The room was contained within a 237 m3 cell with open plenum return to the HVAC system. Heated manikins at desks and a researcher operating the tracer release apparatus presented 8-9 thermal plumes. Experiments were conducted under conditions of no forced air and neutral, cooled, or heated air supplied at 980-1100 cmh, and with/out 20% outdoor air. CO2 was released at the head of one manikin in each experiment to simulate small (<5 µm diameter) respiratory aerosols. The metric of exposure relative to perfectly mixed (ERM) is introduced to quantify impacts, based on measurements at manikin heads and at three heights in the center and corners of the room. Chilled or neutral supply air provided good mixing with ERMs close to one. Thermal stratification during heating produced higher ERMs at most manikins: 25% were ≥2.5 and the highest were >5× perfectly mixed conditions. Operation of two within-zone air cleaners together moving ≥400 cmh vertically in the room provided enough mixing to mitigate elevated exposure variations.
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Affiliation(s)
- Brett C Singer
- Indoor Environment Group, Energy Analysis and Environmental Impacts Division, Building Technologies and Urban Systems Division, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Haoran Zhao
- Indoor Environment Group, Energy Analysis and Environmental Impacts Division, Building Technologies and Urban Systems Division, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Chelsea V Preble
- Indoor Environment Group, Energy Analysis and Environmental Impacts Division, Building Technologies and Urban Systems Division, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Department of Civil & Environmental Engineering, University of California, Berkeley, California, USA
| | - William W Delp
- Indoor Environment Group, Energy Analysis and Environmental Impacts Division, Building Technologies and Urban Systems Division, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Jovan Pantelic
- Indoor Environment Group, Energy Analysis and Environmental Impacts Division, Building Technologies and Urban Systems Division, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Center for the Built Environment, University of California, Berkeley, California, USA
| | - Michael D Sohn
- Indoor Environment Group, Energy Analysis and Environmental Impacts Division, Building Technologies and Urban Systems Division, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Thomas W Kirchstetter
- Indoor Environment Group, Energy Analysis and Environmental Impacts Division, Building Technologies and Urban Systems Division, Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, California, USA
- Department of Civil & Environmental Engineering, University of California, Berkeley, California, USA
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42
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El Hassan M, Assoum H, Bukharin N, Al Otaibi H, Mofijur M, Sakout A. A review on the transmission of COVID-19 based on cough/sneeze/breath flows. EUROPEAN PHYSICAL JOURNAL PLUS 2022; 137:1. [PMID: 34909366 PMCID: PMC8660964 DOI: 10.1140/epjp/s13360-021-02162-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 11/08/2021] [Indexed: 05/17/2023]
Abstract
COVID-19 pandemic has recently had a dramatic impact on society. The understanding of the disease transmission is of high importance to limit its spread between humans. The spread of the virus in air strongly depends on the flow dynamics of the human airflows. It is, however, known that predicting the flow dynamics of the human airflows can be challenging due to different particles sizes and the turbulent aspect of the flow regime. It is thus recommended to present a deep analysis of different human airflows based on the existing experimental investigations. A validation of the existing numerical predictions of such flows would be of high interest to further develop the existing numerical model for different flow configurations. This paper presents a literature review of the experimental and numerical studies on human airflows, including sneezing, coughing and breathing. The dynamics of these airflows for different droplet sizes is discussed. The influence of other parameters, such as the viscosity and relative humidity, on the germs transmission is also presented. Finally, the efficacy of using a facemask in limiting the transmission of COVID-19 is investigated.
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Affiliation(s)
- Mouhammad El Hassan
- Mechanical Engineering Department, Prince Mohammad Bin Fahd University, Al Khobar, Kingdom of Saudi Arabia
| | - Hassan Assoum
- Mechanical Engineering Department, Beirut Arab University, Tripoli, Lebanon
| | - Nikolay Bukharin
- School of Manufacturing and Automation, Southern Alberta Institute of Technology, Calgary, Canada
| | - Huda Al Otaibi
- Mechanical Engineering Department, Prince Mohammad Bin Fahd University, Al Khobar, Kingdom of Saudi Arabia
| | - Md Mofijur
- Mechanical Engineering Department, Prince Mohammad Bin Fahd University, Al Khobar, Kingdom of Saudi Arabia
- Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW 2007 Australia
| | - Anas Sakout
- LASIE, University of La Rochelle, La Rochelle, France
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Coyle JP, Derk RC, Lindsley WG, Blachere FM, Boots T, Lemons AR, Martin SB, Mead KR, Fotta SA, Reynolds JS, McKinney WG, Sinsel EW, Beezhold DH, Noti JD. Efficacy of Ventilation, HEPA Air Cleaners, Universal Masking, and Physical Distancing for Reducing Exposure to Simulated Exhaled Aerosols in a Meeting Room. Viruses 2021; 13:2536. [PMID: 34960804 PMCID: PMC8707272 DOI: 10.3390/v13122536] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/07/2021] [Accepted: 12/14/2021] [Indexed: 12/12/2022] Open
Abstract
There is strong evidence associating the indoor environment with transmission of SARS-CoV-2, the virus that causes COVID-19. SARS-CoV-2 can spread by exposure to droplets and very fine aerosol particles from respiratory fluids that are released by infected persons. Layered mitigation strategies, including but not limited to maintaining physical distancing, adequate ventilation, universal masking, avoiding overcrowding, and vaccination, have shown to be effective in reducing the spread of SARS-CoV-2 within the indoor environment. Here, we examine the effect of mitigation strategies on reducing the risk of exposure to simulated respiratory aerosol particles within a classroom-style meeting room. To quantify exposure of uninfected individuals (Recipients), surrogate respiratory aerosol particles were generated by a breathing simulator with a headform (Source) that mimicked breath exhalations. Recipients, represented by three breathing simulators with manikin headforms, were placed in a meeting room and affixed with optical particle counters to measure 0.3-3 µm aerosol particles. Universal masking of all breathing simulators with a 3-ply cotton mask reduced aerosol exposure by 50% or more compared to scenarios with simulators unmasked. While evaluating the effect of Source placement, Recipients had the highest exposure at 0.9 m in a face-to-face orientation. Ventilation reduced exposure by approximately 5% per unit increase in air change per hour (ACH), irrespective of whether increases in ACH were by the HVAC system or portable HEPA air cleaners. The results demonstrate that mitigation strategies, such as universal masking and increasing ventilation, reduce personal exposure to respiratory aerosols within a meeting room. While universal masking remains a key component of a layered mitigation strategy of exposure reduction, increasing ventilation via system HVAC or portable HEPA air cleaners further reduces exposure.
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Affiliation(s)
- Jayme P. Coyle
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - Raymond C. Derk
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - William G. Lindsley
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - Francoise M. Blachere
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - Theresa Boots
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - Angela R. Lemons
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - Stephen B. Martin
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA;
| | - Kenneth R. Mead
- Division of Field Studies and Engineering, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, OH 45226, USA;
| | - Steven A. Fotta
- Facilities Management Office, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA;
| | - Jeffrey S. Reynolds
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - Walter G. McKinney
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - Erik W. Sinsel
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - Donald H. Beezhold
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
| | - John D. Noti
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA; (J.P.C.); (R.C.D.); (F.M.B.); (T.B.); (A.R.L.); (J.S.R.); (W.G.M.); (E.W.S.); (D.H.B.); (J.D.N.)
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Stockman T, Zhu S, Kumar A, Wang L, Patel S, Weaver J, Spede M, Milton DK, Hertzberg J, Toohey D, Vance M, Srebric J, Miller SL. Measurements and Simulations of Aerosol Released while Singing and Playing Wind Instruments. ACS ENVIRONMENTAL AU 2021; 1:71-84. [PMID: 37155479 PMCID: PMC8525345 DOI: 10.1021/acsenvironau.1c00007] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Outbreaks from choir performances, such as the Skagit Valley Choir, showed that singing brings potential risk of COVID-19 infection. There is less known about the risks of airborne infection from other musical performances, such as playing wind instruments or performing theater. In addition, it is important to understand methods that can be used to reduce infection risk. In this study, we used a variety of methods, including flow visualization, aerosol and CO2 measurements, and computational fluid dynamics (CFD) modeling to understand the different components that can lead to transmission risk from musical performance and risk mitigation. This study was possible because of a partnership across academic departments and institutions and collaboration with the National Federation of State High School Associations and the College Band Directors National Association. The interdisciplinary team enabled us to understand the various aspects of aerosol transmission risk from musical performance and to quickly implement strategies in music classrooms during the COVID-19 pandemic. We found that plumes from musical performance were highly directional, unsteady and varied considerably in time and space. Aerosol number concentration measured at the bell of the clarinet was comparable to that of singing. Face and bell masks attenuated plume velocities and lengths and decreased aerosol concentrations measured in front of the masks. CFD modeling showed differences between indoor and outdoor environments and that the lowest risk of airborne COVID-19 infection occurred at less than 30 min of exposure indoors and less than 60 min outdoors.
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Affiliation(s)
- Tehya Stockman
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Shengwei Zhu
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Abhishek Kumar
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Lingzhe Wang
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Sameer Patel
- Department of Civil Engineering, Indian Institute of Technology, Gandhinagar, Gujrat 382355, India
| | - James Weaver
- National Federation of State High School Associations, Indianapolis, Indiana 46402, United States
| | - Mark Spede
- Department of Performing Arts, Clemson University, Clemson, South Carolina 29634, United States
| | - Donald K. Milton
- Maryland Institute for Applied Environmental Health, School of Public Health, University of Maryland, College Park, Maryland 20740, United States
| | - Jean Hertzberg
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Darin Toohey
- Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Marina Vance
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Jelena Srebric
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Shelly L. Miller
- Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
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45
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Abstract
The lavatory is a fertile area for the transmission of infectious disease through bioaerosols between its users. In this study, we built a generic compact lavatory model with a vacuum toilet, and computational fluid dynamics (CFD) is used to evaluate the effects of ventilation and user behaviors on the airflow patterns, and the resulting fates of bioaerosols. Fecal aerosols are readily released into the lavatory during toilet flush. Their concentration rapidly decays in the first 20 s after flushing by deposition or dilution. It takes about 315 s to 348 s for fine bioaerosols (<10 µm in diameter) to decrease to 5% of the initial concentration, while it takes 50 and 100 µm bioaerosols approximately 11 and <1 s, respectively, to completely deposit. The most contaminated surfaces by aerosol deposition include the toilet seat, the bowl, and the nearby walls. The 10 µm aerosols tend to deposit on horizontal surfaces, while the 50 and 100 µm bioaerosols almost always deposit on the bowl. In the presence of a standing thermal manikin, the rising thermal plume alters the flow field and more bioaerosols are carried out from the toilet; a large fraction of aerosols deposit on the manikin’s legs. The respiratory droplets generated by a seated coughing manikin tend to deposit on the floor, legs, and feet of the manikin. In summary, this study reveals the bioaerosol dilution time and the easily contaminated surfaces in a compact lavatory, which will aid the development of control measures against infectious diseases.
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Lommel M, Froese V, Sieber M, Jentzsch M, Bierewirtz T, Hasirci Ü, Rese T, Seefeldt J, Schimek S, Kertzscher U, Paschereit CO. Novel measurement system for respiratory aerosols and droplets in indoor environments. INDOOR AIR 2021; 31:1860-1873. [PMID: 34096643 PMCID: PMC8242391 DOI: 10.1111/ina.12860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 04/14/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
The SARS-CoV-2 pandemic has created a great demand for a better understanding of the spread of viruses in indoor environments. A novel measurement system consisting of one portable aerosol-emitting mannequin (emitter) and a number of portable aerosol-absorbing mannequins (recipients) was developed that can measure the spread of aerosols and droplets that potentially contain infectious viruses. The emission of the virus from a human is simulated by using tracer particles solved in water. The recipients inhale the aerosols and droplets and quantify the level of solved tracer particles in their artificial lungs simultaneously over time. The mobile system can be arranged in a large variety of spreading scenarios in indoor environments and allows for quantification of the infection probability due to airborne virus spreading. This study shows the accuracy of the new measurement system and its ability to compare aerosol reduction measures such as regular ventilation or the use of a room air purifier.
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Affiliation(s)
- Michael Lommel
- Biofluid Mechanics LaboratoryInstitute for Imaging Science and Computational Modelling in Cardiovascular MedicineCharité – Universitätsmedizin BerlinAugustenburger Platz 1BerlinBerlin13353Germany
| | - Vera Froese
- Biofluid Mechanics LaboratoryInstitute for Imaging Science and Computational Modelling in Cardiovascular MedicineCharité – Universitätsmedizin BerlinAugustenburger Platz 1BerlinBerlin13353Germany
| | - Moritz Sieber
- Institute of Fluid Dynamics and Technical AcousticsHermann‐Föttinger‐InstituteChair of Fluid DynamicsTU BerlinStraße des 17. Juni, 135BerlinBerlin10623Germany
| | - Marvin Jentzsch
- Institute of Fluid Dynamics and Technical AcousticsHermann‐Föttinger‐InstituteChair of Fluid DynamicsTU BerlinStraße des 17. Juni, 135BerlinBerlin10623Germany
| | - Tim Bierewirtz
- Biofluid Mechanics LaboratoryInstitute for Imaging Science and Computational Modelling in Cardiovascular MedicineCharité – Universitätsmedizin BerlinAugustenburger Platz 1BerlinBerlin13353Germany
| | - Ümit Hasirci
- Biofluid Mechanics LaboratoryInstitute for Imaging Science and Computational Modelling in Cardiovascular MedicineCharité – Universitätsmedizin BerlinAugustenburger Platz 1BerlinBerlin13353Germany
| | - Tim Rese
- Biofluid Mechanics LaboratoryInstitute for Imaging Science and Computational Modelling in Cardiovascular MedicineCharité – Universitätsmedizin BerlinAugustenburger Platz 1BerlinBerlin13353Germany
| | - Josef Seefeldt
- Institute of Fluid Dynamics and Technical AcousticsHermann‐Föttinger‐InstituteChair of Fluid DynamicsTU BerlinStraße des 17. Juni, 135BerlinBerlin10623Germany
| | - Sebastian Schimek
- Institute of Fluid Dynamics and Technical AcousticsHermann‐Föttinger‐InstituteChair of Fluid DynamicsTU BerlinStraße des 17. Juni, 135BerlinBerlin10623Germany
| | - Ulrich Kertzscher
- Biofluid Mechanics LaboratoryInstitute for Imaging Science and Computational Modelling in Cardiovascular MedicineCharité – Universitätsmedizin BerlinAugustenburger Platz 1BerlinBerlin13353Germany
| | - Christian Oliver Paschereit
- Institute of Fluid Dynamics and Technical AcousticsHermann‐Föttinger‐InstituteChair of Fluid DynamicsTU BerlinStraße des 17. Juni, 135BerlinBerlin10623Germany
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Ren C, Xi C, Wang J, Feng Z, Nasiri F, Cao SJ, Haghighat F. Mitigating COVID-19 infection disease transmission in indoor environment using physical barriers. SUSTAINABLE CITIES AND SOCIETY 2021; 74:103175. [PMID: 34306996 PMCID: PMC8278843 DOI: 10.1016/j.scs.2021.103175] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/29/2021] [Accepted: 07/08/2021] [Indexed: 05/05/2023]
Abstract
During the normalized phase of COVID-19, droplets or aerosol particles produced by infected personnel are considered as the potential source of infection with uncertain exposure risk. As such, in densely populated open spaces, it is necessary to adopt strategies to mitigate the risk of infection disease transmission while providing sufficient ventilation air. An example of such strategies is use of physical barriers. In this study, the impact of barrier heights on the spread of aerosol particles is investigated in an open office environment with the well-designed ventilation mode and supply air rate. The risk of infection disease transmission is evaluated using simulation of particle concentration in different locations and subject to a number of source scenarios. It was found that a barrier height of at least 60 cm above the desk surface is needed to effectively prevent the transmission of viruses. For workstations within 4 m from the outlet, a 70 cm height is considered, and with a proper ventilation mode, it is shown that the barriers can reduce the risk of infection by 72%. However, for the workstations further away from the outlet (beyond 4 m), the effect of physical barrier cannot be that significant. In summary, this study provides a theoretical analysis for implementing physical barriers, as a low-cost mitigation strategy, subject to various height scenarios and investigation of their effectiveness in reducing the infection transmission probability.
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Affiliation(s)
- Chen Ren
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
| | - Chang Xi
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
| | - Junqi Wang
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
| | - Zhuangbo Feng
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
| | - Fuzhan Nasiri
- Energy and Environment Group, Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, H3G 1M8, Canada
| | - Shi-Jie Cao
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
- Global Centre for Clean Air Research, Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, United Kingdom
| | - Fariborz Haghighat
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
- Energy and Environment Group, Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, H3G 1M8, Canada
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48
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Srinivasan A, Krishan J, Bathula S, Mayya YS. Modeling the viral load dependence of residence times of virus-laden droplets from COVID-19-infected subjects in indoor environments. INDOOR AIR 2021; 31:1786-1797. [PMID: 34118165 PMCID: PMC8447420 DOI: 10.1111/ina.12868] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 05/17/2021] [Accepted: 05/23/2021] [Indexed: 05/19/2023]
Abstract
In the ongoing COVID-19 pandemic situation, exposure assessment and control strategies for aerosol transmission path are feebly understood. A recent study pointed out that Poissonian fluctuations in viral loading of airborne droplets significantly modifies the size spectrum of the virus-laden droplets (termed as "virusol") (Anand and Mayya, 2020). Herein we develop the theory of residence time of the virusols, as contrasted with complete droplet system in indoor air using a comprehensive "Falling-to-Mixing-Plate-out" model that considers all the important processes namely, indoor dispersion of the emitted puff, droplet evaporation, gravitational settling, and plate out mechanisms at indoor surfaces. This model fills the existing gap between Wells falling drop model (Wells, 1934) and the stirred chamber models (Lai and Nazarofff, 2000). The analytical solutions are obtained for both 1-D and 3-D problems for non-evaporating falling droplets, used mainly for benchmarking the numerical formulation. The effect of various parameters is examined in detail. Significantly, the mean residence time of virusols is found to increase nonlinearly with the viral load in the ejecta, ranging from about 100 to 150 s at low viral loads (<104 /ml) to about 1100-1250 s at high viral loads (>1011 /ml). The implications are discussed.
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Affiliation(s)
- Anand Srinivasan
- Health Physics DivisionBhabha Atomic Research CentreMumbaiIndia
- Homi Bhabha National InstituteBhabha Atomic Research CentreMumbaiIndia
| | - Jayant Krishan
- Health Physics DivisionBhabha Atomic Research CentreMumbaiIndia
| | - Sreekanth Bathula
- Homi Bhabha National InstituteBhabha Atomic Research CentreMumbaiIndia
- Radiation Safety and Systems DivisionBhabha Atomic Research CentreMumbaiIndia
| | - Yelia S. Mayya
- Department of Chemical EngineeringIndian Institute of Technology BombayMumbaiIndia
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49
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Silveira CP, Schneid ADC, Ribeiro IRS, Galdino FE, Cardoso MB. A nano perspective behind the COVID-19 pandemic. NANOSCALE HORIZONS 2021; 6:842-855. [PMID: 34382995 DOI: 10.1039/d1nh00135c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The global pandemic scenario has definitely pushed the scientific community to develop COVID-19 vaccines at unprecedented speed. Nevertheless, a worldwide vaccination campaign is still far from being achieved, making the usual precautionary measures as necessary as at the beginning of the outbreak. Many aspects of the SARS-CoV-2 infectious potential and disease severity do not solely rely on interactions at the molecular level but also on physical-chemical parameters that often involve nanoscale effects. Here the SARS-CoV-2 journey to infect a susceptible host is reviewed, focusing on the nanoscale aspects that play a role in the viral infectivity and disease progression. These nanoscale-driven interactions are essential to establish mitigation-related strategies.
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Affiliation(s)
- Camila Pedroso Silveira
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Postal Code 13083-970, Campinas, Brazil.
| | - Andressa da Cruz Schneid
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Postal Code 13083-970, Campinas, Brazil.
| | - Iris Renata Sousa Ribeiro
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Postal Code 13083-970, Campinas, Brazil.
- Institute of Chemistry (IQ), University of Campinas (UNICAMP), Post Office Box 6154, Postal Code 13083-970, Campinas, SP, Brazil
| | - Flávia Elisa Galdino
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Postal Code 13083-970, Campinas, Brazil.
- Institute of Chemistry (IQ), University of Campinas (UNICAMP), Post Office Box 6154, Postal Code 13083-970, Campinas, SP, Brazil
| | - Mateus Borba Cardoso
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Postal Code 13083-970, Campinas, Brazil.
- Institute of Chemistry (IQ), University of Campinas (UNICAMP), Post Office Box 6154, Postal Code 13083-970, Campinas, SP, Brazil
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50
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Pourfattah F, Wang LP, Deng W, Ma YF, Hu L, Yang B. Challenges in simulating and modeling the airborne virus transmission: A state-of-the-art review. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:101302. [PMID: 34803360 PMCID: PMC8597718 DOI: 10.1063/5.0061469] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 10/04/2021] [Indexed: 06/09/2023]
Abstract
Recently, the COVID-19 virus pandemic has led to many studies on the airborne transmission of expiratory droplets. While limited experiments and on-site measurements offer qualitative indication of potential virus spread rates and the level of transmission risk, the quantitative understanding and mechanistic insights also indispensably come from careful theoretical modeling and numerical simulation efforts around which a surge of research papers has emerged. However, due to the highly interdisciplinary nature of the topic, numerical simulations of the airborne spread of expiratory droplets face serious challenges. It is essential to examine the assumptions and simplifications made in the existing modeling and simulations, which will be reviewed carefully here to better advance the fidelity of numerical results when compared to the reality. So far, existing review papers have focused on discussing the simulation results without questioning or comparing the model assumptions. This review paper focuses instead on the details of the model simplifications used in the numerical methods and how to properly incorporate important processes associated with respiratory droplet transmission. Specifically, the critical issues reviewed here include modeling of the respiratory droplet evaporation, droplet size distribution, and time-dependent velocity profile of air exhaled from coughing and sneezing. According to the literature review, another problem in numerical simulations is that the virus decay rate and suspended viable viral dose are often not incorporated; therefore here, empirical relationships for the bioactivity of coronavirus are presented. It is hoped that this paper can assist researchers to significantly improve their model fidelity when simulating respiratory droplet transmission.
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Affiliation(s)
- Farzad Pourfattah
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | | | - Weiwei Deng
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Yong-Feng Ma
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Liangquan Hu
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Bo Yang
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
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