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Lordly K, Kober L, Jadidi M, Antoun S, Dworkin SB, Karataş AE. Understanding lifetime and dispersion of cough-emitted droplets in air. INDOOR + BUILT ENVIRONMENT : THE JOURNAL OF THE INTERNATIONAL SOCIETY OF THE BUILT ENVIRONMENT 2023; 32:1929-1948. [PMID: 38023440 PMCID: PMC10657780 DOI: 10.1177/1420326x221098753] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 04/19/2022] [Indexed: 12/01/2023]
Abstract
To understand the exact transmission routes of SARS-CoV-2 and to explore effects of time, space and indoor environment on the dynamics of droplets and aerosols, rigorous testing and observation must be conducted. In the current work, the spatial and temporal dispersions of aerosol droplets from a simulated cough were comprehensively examined over a long duration (70 min). An artificial cough generator was constructed to generate reliably repeatable respiratory ejecta. The measurements were performed at different locations in front (along the axial direction and off-axis) and behind the source in a sealed experimental enclosure. Aerosols of 0.3-10 µm (around 20% of the maximum nuclei count) were shown to persist for a very long time in a still environment, and this has a substantial implication for airborne disease transmission. The experiments demonstrated that a ventilation system could reduce the total aerosol volume and the droplet lifetime significantly. To explain the experimental observations in more detail and to understand the droplet in-air behaviour at various ambient temperatures and relative humidity, numerical simulations were performed using the Eulerian-Lagrangian approach. The simulations show that many of the small droplets remain suspended in the air over time instead of falling to the ground.
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Affiliation(s)
- Kai Lordly
- Department of Aerospace Engineering, Toronto Metropolitan University, Toronto, ON, Canada
| | - Leya Kober
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
| | - Mehdi Jadidi
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
| | - Sylvie Antoun
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
| | - Seth B Dworkin
- Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
| | - Ahmet E Karataş
- Department of Aerospace Engineering, Toronto Metropolitan University, Toronto, ON, Canada
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Howard NS, Alrefaie A, Mejia NA, Ugbeye T, Schmidt BE. Characterizing Aerosol Generating Procedures With Background Oriented Schlieren. J Biomech Eng 2023; 145:074502. [PMID: 36961437 PMCID: PMC10158973 DOI: 10.1115/1.4062191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 03/20/2023] [Accepted: 03/20/2023] [Indexed: 03/25/2023]
Abstract
The potential for characterizing aerosol generating procedures (AGPs) using background oriented schlieren (BOS) flow visualization was investigated in two clinical situations. A human-scale BOS system was used on a manikin simulating jet ventilation and extubation. A novel approach to representation of the BOS images using line integral convolution allows direct evaluation of both magnitude and direction of the refractive index gradient field. Plumes issuing from the manikin's mouth were clearly visualized and characterized in both experiments, and it is recommended that BOS be adapted into a clinical tool for risk evaluation in clinical environments.
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Affiliation(s)
- N. Scott Howard
- School of Medicine, Case Western Reserve University Otolaryngology, Head and Neck Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH 44106
| | - Abdulaziz Alrefaie
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University Cleveland, Cleveland, OH 44106
| | - Nicholas A. Mejia
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University Cleveland, Cleveland, OH 44106
| | - Tosan Ugbeye
- S.C.O.P.E. Medical Cleveland, Cleveland, OH 44106
| | - Bryan E. Schmidt
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University Cleveland, Cleveland, OH 44106
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3
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Zhang S, Yan Z, Zhang Y, Wu X, Liu L, Yang A, Duan M. Protocol of a randomised controlled trial to assess medical staff's inhalation exposure to infectious particles exhaled by patients during oesophagogastroduodenoscopy and the efficacy of surgical masks in this context. BMJ Open 2023; 13:e068291. [PMID: 36854596 PMCID: PMC9980315 DOI: 10.1136/bmjopen-2022-068291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/02/2023] Open
Abstract
BACKGROUND Aerosol-generating procedures such as oesophagogastroduodenoscopy (OGD) result in infectious particles being exhaled by patients. This substantially increases the medical staff's risk of occupational exposure to pathogenic particles via airway inhalation and facial mucosal deposition. Infectious particles are regarded as a key route of transmission of SARS-CoV-2 and, thus, represents a major risk factor for medical staff during the ongoing COVID-19 pandemic. There is a need for quantitative evidence on medical staff's risk of multiroute exposure to infectious particles exhaled by patients during OGD to enable the development of practical, feasible and economical methods of risk-reduction for use in OGD and related procedures. This randomised controlled trial (RCT)-Personal protective EquiPment intervention TrIal for oesophagogastroDuodEnoscopy (PEPTIDE)-aims to establish a state-of-the-art protocol for quantifying the multiroute exposure of medical staff to infectious particles exhaled by patients during real OGD procedures. METHOD AND ANALYSIS PEPTIDE will be a prospective, two-arm, RCT using quantitative methods and will be conducted at a tertiary hospital in China. It will enrol 130 participants (65 per group) aged over 18. The intervention will be an anthropomorphic model with realistic respiratory-related morphology and respiratory function that simulates a medical staff member. This model will be used either without or with a surgical mask, depending on the group allocation of a participant, and will be placed beside the participants as they undergo an OGD procedure. The primary outcome will be the anthropomorphic model's airway dosage of the participants' exhaled infectious particles with or without a surgical mask, and the secondary outcome will be the anthropomorphic model's non-surgical mask-covered facial mucosa dosage of the participants' exhaled infectious particles. Analyses will be performed in accordance with the type of data collected (categorical or quantitative data) using SPSS (V.26.0) and RStudio (V.1.3.959). ETHICS AND DISSEMINATION Ethical approval for this RCT was obtained from the Ethics Committee of Peking Union Medical College Hospital (ZS-3377). All of the potential participants who agree to participate will provide their written informed consent before they are enrolled. The results will be disseminated through presentations at national and international conferences and publications in peer-reviewed journals. TRIAL REGISTRATION NUMBER NCT05321056.
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Affiliation(s)
- Shengyu Zhang
- Department of Gastroenterology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Zhiyu Yan
- Department of Gastroenterology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- 4+4 M.D. Program, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Yuheng Zhang
- Department of Gastroenterology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xi Wu
- Department of Gastroenterology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Li Liu
- Department of Building Science, Tsinghua University, Beijing, China
- Laboratory of Eco-Planning & Green Building, Ministry of Education, Tsinghua University, Beijing, China
| | - Aiming Yang
- Department of Gastroenterology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
- State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Mengjie Duan
- Department of Building Science, Tsinghua University, Beijing, China
- Laboratory of Eco-Planning & Green Building, Ministry of Education, Tsinghua University, Beijing, China
- Vanke School of Public Health, Tsinghua University, Beijing, China
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4
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Oh W, Ooka R, Kikumoto H, Han M. Numerical modeling of sneeze airflow and its validation with an experimental dataset. INDOOR AIR 2022; 32:e13171. [PMID: 36437664 DOI: 10.1111/ina.13171] [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: 10/04/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 06/16/2023]
Abstract
In this study, we aimed at providing datasets using experimental results to validate the sneeze airflow. In addition, the boundary conditions for the sneeze simulation that could reproduce the sneeze airflow in the experimental results are presented and reviewed. The validation datasets were created by performing ensemble-average analysis with the experimental results of particle image velocimetry, and these were used to explore the boundary conditions to reproduce the sneeze airflow. As a result of the sneeze airflow reproduced by computational fluid dynamics simulation, the magnitude ranges of maximum velocity at the interface were observed to be 21.1-23.9 m/s for males and 17.9-20.3 m/s for females, which were higher than those of coughing. Compared with the experimental results, the root-mean-square error range for the overall airflow distribution was 0.19-0.23 m/s, whereas the error range for the magnitude of the maximum velocity at a criterion point was 0.03-0.08 m/s. The total sneezing airflow volume was in the range of 0.36-0.48 L, which was relatively low compared with that of coughing. Thus, this study provides important fundamental boundary conditions for computational fluid dynamics analysis, validated by experimental results, to interpret the spread of infectious particles by sneezing.
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Affiliation(s)
- Wonseok Oh
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Ryozo Ooka
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Hideki Kikumoto
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Mengtao Han
- School of Architecture and Urban Planning, Huazhong University of Science and Technology, Wuhan, China
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Zhou G, Burnett GW, Shah RS, Lai CY, Katz D, Fried EA. Development of an Easily Reproducible Cough Simulator With Droplets and Aerosols for Rapidly Testing Novel Personal Protective Equipment. Simul Healthc 2022; 17:336-342. [PMID: 35238849 DOI: 10.1097/sih.0000000000000644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION The current COVID-19 pandemic has produced numerous innovations in personal protective equipment, barrier devices, and infection mitigation strategies, which have not been validated. During high-risk procedures such as airway manipulation, coughs are common and discrete events that may expose healthcare workers to large amounts of viral particles. A simulated cough under controlled circumstances can rapidly test novel devices and protocols and thus aid in their evaluation and the development of implementation guidelines. Physiologic cough simulators exist but require significant expertise and specialized equipment not available to most clinicians. METHODS Using components commonly found in healthcare settings, a cough simulator was designed for clinicians to easily assemble and use. Both droplet and aerosol particle generators were incorporated into a bimodal experimental system. High-speed flash photography was used for data collection. RESULTS Using a gas flow analyzer, video recordings, and high-speed digital photography, the cough and particle simulators were quantitatively and qualitatively compared with known physiologic cough parameters and in vivo Schlieren imaging of human coughs. CONCLUSIONS Based on our validation studies, this cough and particle simulator model approximates a physiologic, human cough in the context of testing personal protective equipment, barrier devices, and infection prevention measures.
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Affiliation(s)
- George Zhou
- From the Department of Anesthesiology, Perioperative and Pain Medicine (G.Z.), Stanford University Hospital, Stanford, CA; Department of Anesthesiology, Perioperative and Pain Medicine, Icahn School of Medicine at Mount Sinai, New York, NY (G.W.B., C.Y.L., D.K., E.A.F.); and Department of Anesthesiology and Critical Care Medicine (R.S.S.), Memorial Sloan Kettering Cancer Center, New York, NY
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6
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Schmitt J, Wang J. A critical review on the role of leakages in the facemask protection against SARS-CoV-2 infection with consideration of vaccination and virus variants. INDOOR AIR 2022; 32:e13127. [PMID: 36305058 PMCID: PMC9828278 DOI: 10.1111/ina.13127] [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: 06/01/2022] [Revised: 09/18/2022] [Accepted: 09/19/2022] [Indexed: 05/28/2023]
Abstract
The protection provided by facemasks has been extensively investigated since the beginning of the SARS-CoV-2 outbreak, focusing mostly on the filtration efficiency of filter media for filtering face pieces (FFP), surgical masks, and cloth masks. However, faceseal leakage is a major contributor to the number of potentially infectious airborne droplets entering the respiratory system of a susceptible individual. The identification of leaking spots and the quantification of leaking flows are crucial to estimate the protection provided by facemasks. This study presents a critical review on the measurement and calculation of facemask leakages and a quantitative analysis of their role in the risk of SARS-CoV-2 infection. It shows that the pairing between the mask dimensions and the wearer's face is essential to improve protection efficiency, especially for FFP2 masks, and summarizes the most common leaking spots at the interface between the mask and the wearer's face. Leakage is a crucial factor in the calculation of the protection provided by facemasks and outweighs the filtration performances. The fit factors measured among mask users were summarized for different types of face protection. The reviewed data were integrated into a computational model to compare the mitigation impact of facemasks with vaccination with consideration of new variants of SARS-CoV-2. Combining a high adoption rate of facemasks and a high vaccination rate is crucial to efficiently control the spread of highly infectious variants.
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Affiliation(s)
- Jean Schmitt
- Department of Civil, Environmental and Geomatic Engineering, ETH ZurichInstitute of Environmental EngineeringZurichSwitzerland
- Laboratory for Advanced Analytical Technologies, EmpaSwiss Federal Laboratories for Materials Science and TechnologyDubendorfSwitzerland
| | - Jing Wang
- Department of Civil, Environmental and Geomatic Engineering, ETH ZurichInstitute of Environmental EngineeringZurichSwitzerland
- Laboratory for Advanced Analytical Technologies, EmpaSwiss Federal Laboratories for Materials Science and TechnologyDubendorfSwitzerland
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7
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Abstract
During the early phase of the COVID-19 pandemic, many respiratory therapies were classified as aerosol-generating procedures. This categorization resulted in a broad range of clinical concerns and a shortage of essential medical resources for some patients. In the past 2 years, many studies have assessed the transmission risk posed by various respiratory care procedures. These studies are discussed in this narrative review, with recommendations for mitigating transmission risk based on the current evidence.
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Affiliation(s)
- Jie Li
- Department of Cardiopulmonary Sciences, Division of Respiratory Care, Rush University, Chicago, Illinois
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8
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Jamal A, Safar M, Tarakmeh M, Jamal M, Alsaadi K, Safar A. Impact of COVID-19 on Surgical Interventions and Medical Practices in Pediatric Otolaryngology: A Narrative Review. Cureus 2022; 14:e23835. [PMID: 35530923 PMCID: PMC9069848 DOI: 10.7759/cureus.23835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2022] [Indexed: 11/05/2022] Open
Abstract
The novel coronavirus disease 2019 (COVID-19) pandemic has become a major public health challenge. All types of elective and semi-urgent medical care and procedures have been discontinued during the pandemic to maintain the capacity to care for patients with this disease. The pandemic has had a significant impact on almost every medical field, including pediatric otolaryngology. This review highlights the impact of COVID-19 on surgical interventions and medical practices in pediatric otolaryngology owing to its direct association with ear, nose, and throat disorders, with an emphasis on immediate and potential long-term transformations in clinical practice. We reviewed several articles and scientific websites and summarized the currently available evidence and best practices for safety in the field of otolaryngology during the COVID-19 pandemic. Extensively discussed issues in pediatric otolaryngology include surgical interventions, medical practices, modes of transmission of COVID-19, personal protective equipment, and duration of exposure. Otolaryngologists should preserve their integrative medical approaches and subspecialty expertise during the COVID-19 pandemic. There has been a marked change in the approach to managing pediatric ear, nose, and throat conditions, both in the outpatient department and operating room, during the COVID-19 pandemic. The pandemic requires a great deal of flexibility and necessitates exploring new opportunities to create a safe and patient-friendly environment for children with otolaryngology problems. Many of the precautions implemented will remain necessary until a robust evidence shows the pandemic has come to an end.
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9
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Rahimi P, Islam MS, Duarte PM, Tazerji SS, Sobur MA, El Zowalaty ME, Ashour HM, Rahman MT. Impact of the COVID-19 pandemic on food production and animal health. Trends Food Sci Technol 2022; 121:105-113. [PMID: 34898853 PMCID: PMC8647343 DOI: 10.1016/j.tifs.2021.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 06/11/2021] [Accepted: 12/04/2021] [Indexed: 12/24/2022]
Abstract
BACKGROUND Severe acute respiratory coronavirus syndrome 2 (SARS-CoV-2) is the etiological agent of coronavirus disease 2019 (COVID-19). SARS-CoV-2 was first detected in Wuhan, China and spread to other countries and continents causing a variety of respiratory and non-respiratory symptoms which led to death in severe cases. SCOPE AND APPROACH In this review, we discuss and analyze the impact of the COVID-19 pandemic on animal production systems and food production of meat, dairy, eggs, and processed food, in addition to assessing the impact of the pandemic on animal healthcare systems, animal healthcare quality, animal welfare, food chain sustainability, and the global economy. We also provide effective recommendations to animal producers, veterinary healthcare professionals, workers in animal products industries, and governments to alleviate the effects of the pandemic on livestock farming and production systems. KEY FINDINGS AND CONCLUSIONS Port restrictions, border restrictions, curfews, and social distancing limitations led to reduced quality, productivity, and competitiveness of key productive sectors. The restrictions have hit the livestock sector hard by disrupting the animal feed supply chain, reducing animal farming services, limiting animal health services including delays in diagnosis and treatment of diseases, limiting access to markets and consumers, and reducing labor-force participation. The inhumane culling of animals jeopardized animal welfare. Egg smashing, milk dumping, and other animal product disruptions negatively impacted food production, consumption, and access to food originating from animals. In summary, COVID-19 triggered lockdowns and limitations on local and international trade have taken their toll on food production, animal production, and animal health and welfare. COVID-19 reverberations could exacerbate food insecurity, hunger, and global poverty. The effects could be massive on the most vulnerable populations and the poorest nations.
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Affiliation(s)
- Parastoo Rahimi
- Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Md Saiful Islam
- Department of Microbiology and Hygiene, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Phelipe Magalhães Duarte
- Postgraduate Program in Animal Bioscience, Federal Rural University of Pernambuco (UFRPE), Recife, Pernambuco, Brazil
| | - Sina Salajegheh Tazerji
- Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Md Abdus Sobur
- Department of Microbiology and Hygiene, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Mohamed E El Zowalaty
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Hossam M Ashour
- Department of Integrative Biology, College of Arts and Sciences, University of South Florida, St. Petersburg, FL 33701, USA
| | - Md Tanvir Rahman
- Department of Microbiology and Hygiene, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
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10
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Kerl J, Gena AW, Alsaad H, Voelker C, Dellweg D. Influence of wearing masks on exhaled air aerodynamics. J Med Eng Technol 2022; 46:231-242. [PMID: 35176956 DOI: 10.1080/03091902.2022.2026507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Since aerosol inhalation is the most common mechanism for COVID-19 infection, the respiratory protective devices (RPDs) have the highest importance in personal protection. The aim of this study was to assess the efficiency of 10 different RPDs in shortening the travelling distance of exhaled air by range measurement using the schlieren imaging technique. When a RPD is worn by a person resting in a seated position, the expired air does not exceed the human convective boundary layer (CBL). Instead, the CBL lifts the expired aerosols vertically up. Thus, they have a prolonged travelling time in the surrounding air and become less harmful by several mechanisms of virus content decay. Coughing as well as expiration valves can cause far reaching expiration air clouds that cross horizontally the human CBL by opening leakage airway corridors into different directions. Measured by the range of expired air an FFP2 mask provided high security under all conditions tested. A non-vented full-face mask with two viral filters performed even better because of its airtight fit and the excellent filtering capacity of the viral filters during inspiration and expiration, even during cough manoeuvres.
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Affiliation(s)
- Jens Kerl
- Fachkrankenhaus Kloster Grafschaft GmbH, Schmallenberg, Germany
| | - Amayu W Gena
- Department of Building Physics, Bauhaus-Universität Weimar, Weimar, Germany
| | - Hayder Alsaad
- Department of Building Physics, Bauhaus-Universität Weimar, Weimar, Germany
| | - Conrad Voelker
- Department of Building Physics, Bauhaus-Universität Weimar, Weimar, Germany
| | - Dominic Dellweg
- Fachkrankenhaus Kloster Grafschaft GmbH, Schmallenberg, Germany
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11
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Tang JW, Caniza MA, Dinn M, Dwyer DE, Heraud JM, Jennings LC, Kok J, Kwok KO, Li Y, Loh TP, Marr LC, Nara EM, Perera N, Saito R, Santillan-Salas C, Sullivan S, Warner M, Watanabe A, Zaidi SK. An exploration of the political, social, economic and cultural factors affecting how different global regions initially reacted to the COVID-19 pandemic. Interface Focus 2022; 12:20210079. [PMID: 35261734 PMCID: PMC8831085 DOI: 10.1098/rsfs.2021.0079] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 01/13/2022] [Indexed: 12/15/2022] Open
Abstract
Responses to the early (February–July 2020) COVID-19 pandemic varied widely, globally. Reasons for this are multiple but likely relate to the healthcare and financial resources then available, and the degree of trust in, and economic support provided by, national governments. Cultural factors also affected how different populations reacted to the various pandemic restrictions, like masking, social distancing and self-isolation or self-quarantine. The degree of compliance with these measures depended on how much individuals valued their needs and liberties over those of their society. Thus, several themes may be relevant when comparing pandemic responses across different regions. East and Southeast Asian populations tended to be more collectivist and self-sacrificing, responding quickly to early signs of the pandemic and readily complied with most restrictions to control its spread. Australasian, Eastern European, Scandinavian, some Middle Eastern, African and South American countries also responded promptly by imposing restrictions of varying severity, due to concerns for their wider society, including for some, the fragility of their healthcare systems. Western European and North American countries, with well-resourced healthcare systems, initially reacted more slowly, partly in an effort to maintain their economies but also to delay imposing pandemic restrictions that limited the personal freedoms of their citizens.
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Affiliation(s)
- Julian W. Tang
- Respiratory Sciences, University of Leicester, Leicester, UK
| | | | - Mike Dinn
- British Antarctic Survey Medical Unit, Emergency Department, University Hospitals Plymouth NHS Trust, Plymouth, UK
| | - Dominic E. Dwyer
- NSW Health Pathology - Institute for Clinical Pathology and Medical Research, and University of Sydney, Westmead, New South Wales, Australia
| | | | - Lance C. Jennings
- Department of Pathology and Biomedical Science, University of Otago, and Canterbury Health Laboratories, Christchurch, New Zealand
| | - Jen Kok
- NSW Health Pathology - Institute for Clinical Pathology and Medical Research, and University of Sydney, Westmead, New South Wales, Australia
| | - Kin On Kwok
- JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
- Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
- Hong Kong Institute of Asia-Pacific Studies, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
- Shenzhen Research Institute of the Chinese University of Hong Kong, Shenzhen, People's Republic of China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Tze Ping Loh
- Laboratory Medicine, National University Hospital, Singapore, Singapore
| | - Linsey C. Marr
- Civil and Environmental Engineering, Virginia Tech, VA, USA
| | - Eva Megumi Nara
- Instituto de Investigaciones en Ciencias de la Salud, Universidad Nacional de Asunción, San Lorenzo, Paraguay
| | - Nelun Perera
- Clinical Microbiology, University Hospitals of Leicester NHS Trust, Leicester, UK
| | - Reiko Saito
- Division of International Health, Niigata University, Niigata, Japan
| | | | - Sheena Sullivan
- WHO Collaborating Centre for Reference and Research on Influenza, Royal Melbourne Hospital, Melbourne, Australia
- Department of Infectious Diseases, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Matt Warner
- British Antarctic Survey Medical Unit, Emergency Department, University Hospitals Plymouth NHS Trust, Plymouth, UK
| | - Aripuanã Watanabe
- Department of Parasitology, Microbiology and Immunology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Sabeen Khurshid Zaidi
- Karachi Institute of Medical Sciences affiliated with National University of Medical Sciences, Karachi, Pakistan
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12
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Derrick D, Kabaliuk N, Longworth L, Pishyar-Dehkordi P, Jermy M. Speech air flow with and without face masks. Sci Rep 2022; 12:837. [PMID: 35039580 PMCID: PMC8763952 DOI: 10.1038/s41598-021-04745-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 12/28/2021] [Indexed: 01/02/2023] Open
Abstract
Face masks slow exhaled air flow and sequester exhaled particles. There are many types of face masks on the market today, each having widely varying fits, filtering, and air redirection characteristics. While particle filtration and flow resistance from masks has been well studied, their effects on speech air flow has not. We built a schlieren system and recorded speech air flow with 14 different face masks, comparing it to mask-less speech. All of the face masks reduced air flow from speech, but some allowed air flow features to reach further than 40 cm from a speaker's lips and nose within a few seconds, and all the face masks allowed some air to escape above the nose. Evidence from available literature shows that distancing and ventilation in higher-risk indoor environment provide more benefit than wearing a face mask. Our own research shows all the masks we tested provide some additional benefit of restricting air flow from a speaker. However, well-fitted mask specifically designed for the purpose of preventing the spread of disease reduce air flow the most. Future research will study the effects of face masks on speech communication in order to facilitate cost/benefit analysis of mask usage in various environments.
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Affiliation(s)
- Donald Derrick
- New Zealand Institute of Language, Brain, and Behaviour, University of Canterbury, Christchurch, 8041, New Zealand.
| | - Natalia Kabaliuk
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand
| | - Luke Longworth
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand
| | | | - Mark Jermy
- Department of Mechanical Engineering, University of Canterbury, Christchurch, 8041, New Zealand
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13
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Nazaroff WW. Indoor aerosol science aspects of SARS-CoV-2 transmission. INDOOR AIR 2022; 32:e12970. [PMID: 34873752 DOI: 10.1111/ina.12970] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 11/17/2021] [Accepted: 11/26/2021] [Indexed: 05/04/2023]
Abstract
Knowledge about person-to-person transmission of SARS-CoV-2 is reviewed, emphasizing three components: emission of virus-containing particles and drops from infectious persons; transport and fate of such emissions indoors; and inhalation of viral particles by susceptible persons. Emissions are usefully clustered into three groups: small particles (diameter 0.1-5 µm), large particles (5-100 µm), and ballistic drops (>100 µm). Speaking generates particles and drops across the size spectrum. Small particles are removed from indoor air at room scale by ventilation, filtration, and deposition; large particles mainly deposit onto indoor surfaces. Proximate exposure enhancements are associated with large particles with contributions from ballistic drops. Masking and social distancing are effective in mitigating transmission from proximate exposures. At room scale, masking, ventilation, and filtration can contribute to limit exposures. Important information gaps prevent a quantitative reconciliation of the high overall global spread of COVID-19 with known transmission pathways. Available information supports several findings with moderate-to-high confidence: transmission occurs predominantly indoors; inhalation of airborne particles (up to 50 µm in diameter) contributes substantially to viral spread; transmission occurs in near proximity and at room scale; speaking is a major source of airborne SARS-CoV-2 virus; and emissions can occur without strong illness symptoms.
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Affiliation(s)
- William W Nazaroff
- Department of Civil and Environmental Engineering, University of California, Berkeley, California, USA
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14
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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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15
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Jayadev C, Mochi Basavaraj T, Pandey K, Pinto R, Pandey SP, Basu S, Roy AS, Shetty R. Risk Assessment of Aerosol Generation During Vitreoretinal Surgery Using High Speed Imaging Amidst the COVID-19 Pandemic. Transl Vis Sci Technol 2021; 10:17. [PMID: 34647963 PMCID: PMC8525865 DOI: 10.1167/tvst.10.12.17] [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] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to discuss the propensity of aerosol and droplet generation during vitreoretinal surgery using high speed imaging amidst the coronavirus disease 2019 (COVID-19) pandemic. Methods In an experimental set up, various steps of vitreoretinal surgery were performed on enucleated goat eyes. The main outcome measures were visualization, quantification of size, and calculation of aerosol spread. Results During intravitreal injection, insertion of cannulas, lensectomy, and vitrectomy with both 23 and 25-gauge instruments, with either valved or nonvalved cannulas, aerosols were not visualized which was confirmed on imaging. Although there was no aerosol generation during active fluid air exchange (FAE), there was bubbling and aerosol generation at the exit port of the handle during passive FAE. Under higher air pressure, with reused valved and fresh nonvalved cannulas, aerosol generation showed a trajectory 0.4 to 0.67 m with droplet size of 200 microns. Whereas removing cannulas or suturing under active air infusion (35 mm Hg and above) aerosols were noted. Conclusions Based on the above experiments, we can formulate guidelines for safe vitrectomy during COVID-19. Some recommendations include the use of valved cannulas, avoiding passive FAE or to direct the exit port away from the surgeon and assistant, and to maintain the air pressure less than or equal to 30 mm Hg. Translational Relevance In the setting of the COVID-19 pandemic, the risk from virus laden aerosols, as determined using an experimental setup, appears to be low for commonly performed vitreoretinal surgical procedures.
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Affiliation(s)
- Chaitra Jayadev
- Vitreoretina Department, Narayana Nethralaya Eye Institute, Bangalore, India
| | | | - Khushboo Pandey
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India
| | - Roven Pinto
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India
| | - Shashi Prabha Pandey
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India
| | - Saptarshi Basu
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India
| | - Abhijit Sinha Roy
- Imaging, Biomechanics and Mathematical Modeling solutions, Narayana Nethralaya Foundation, Bangalore, India
| | - Rohit Shetty
- Vitreoretina Department, Narayana Nethralaya Eye Institute, Bangalore, India
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Garcia GA, Hines JA, Wang EW, Davila JR, Chiang B, Choi DY. Contamination of multiuse eyedrop bottles by exhaled air from patients wearing face masks during the COVID-19 pandemic: Schlieren imaging analysis. J Cataract Refract Surg 2021; 47:1167-1174. [PMID: 34468454 PMCID: PMC10954301 DOI: 10.1097/j.jcrs.0000000000000590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 01/13/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine whether mask-induced redirected exhaled air through the superior mask gap contacts multiuse eyedrop bottles during drop administration and the efficacy of interventions to reduce such exposure. SETTING Academic ophthalmology center. DESIGN Interventional analysis. METHODS Schlieren airflow imaging was taken of an examinee wearing frequently used face masks and enacting common clinical scenarios-with and without manual occlusion of the superior mask gap and/or neck extension-and maximum visible vertical breath plume height was quantified. Bottle height during eyedrop administration was measured for 4 ophthalmologists during instillation to 8 eyes of 4 subjects. RESULTS Breath plume height (mean ± SD 275.5 ± 16.3 mm) was significantly greater than mean bottle height (13.9 ± 4.7 mm; P < .01). Plume height was reduced with manual mask occlusion vs without (P < .01) and was also lower than mean bottle height with manual mask occlusion (P < .01) but not in the absence of occlusion (P < .01). Neck extension alone did not adequately redirect liberated breath to prevent contact with a bottle. CONCLUSIONS Exhaled air liberated from commonly worn patient face masks was able to contact multiuse eyedrop bottles during eyedrop administration. These findings have important patient safety implications during the coronavirus disease 2019 pandemic and with other respiratory pathogens because these multiuse bottles could potentially serve as vectors of disease. Occlusion of the superior mask gap significantly reduces breath contamination and should be strongly considered by eyecare providers during drop administration in eye clinics.
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Affiliation(s)
- Giancarlo A. Garcia
- Department of Ophthalmology, Byers Eye Institute at Stanford University, Palo Alto, CA, USA
| | - Jacob A. Hines
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Evan W. Wang
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Jose R. Davila
- Department of Ophthalmology, Byers Eye Institute at Stanford University, Palo Alto, CA, USA
| | - Bryce Chiang
- Department of Ophthalmology, Byers Eye Institute at Stanford University, Palo Alto, CA, USA
| | - Daniel Y. Choi
- Department of Ophthalmology, Byers Eye Institute at Stanford University, Palo Alto, CA, USA
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17
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Peña-Monferrer C, Antao S, Manson-Sawko R. Numerical investigation of respiratory drops dynamics released during vocalization. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:083321. [PMID: 34471339 PMCID: PMC8404381 DOI: 10.1063/5.0059419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/01/2021] [Indexed: 05/14/2023]
Abstract
Release of drops from a human body has been the focus of many recent investigations because of the current COVID-19 pandemic. Indirect virus transmission from asymptomatic individuals has been proved to be one of the major infectious routes and difficult to quantify, detect, and mitigate. We show in this work a detailed and novel numerical investigation of drops released during vocalization from a thermal manikin using a large eddy simulation coupled with Lagrangian tracking of drops. The vocalization experiment was modeled using existing data from the literature for modeling exhaled airflow, emission rate, and size distribution. Particular focus was on the definition of the boundary conditions for the exhalation process. Turbulence was compared with experimental data for the near mouth region for 75 exhalation breathing cycles and showed the sensitivity of different modeling assumptions at the mouth inlet. The results provide insights of special interest for understanding drop dynamics in speech-like exhalation modes, modeling the mouth inlet boundary conditions, and providing data for verifying other more simplified models.
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Affiliation(s)
- C. Peña-Monferrer
- IBM Research Europe, The Hartree Centre, Warrington WA4 4Ad, United Kingdom
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18
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Srivastava S, Vasavada V, Vasavada AR, Sudhalkar A, Kothari A, Vasavada SA. Real-time imaging of airflow patterns and impact of infection control measures in ophthalmic practice: a pandemic perspective. J Cataract Refract Surg 2021; 47:842-846. [PMID: 33315732 DOI: 10.1097/j.jcrs.0000000000000538] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/02/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE To analyze exhaled airflow patterns in a clinical scenario and the impact of infection control practices and room air circulation in context of the COVID-19 pandemic. SETTING Raghudeep Eye Hospital, India. DESIGN Experimental study. METHODS Ten patients attending ophthalmic outpatient clinic (OPD) and operating room (OR) were included. Using Schlieren imaging, exhaled airflow patterns were documented with/without an N95 mask or face shield during respiratory activities. Recordings were performed with and without room air conditioning turned on. Exhaled airflow patterns in OPD and OR when using vs not using these infection control measures and the impact of room air circulation on these were compared. RESULTS Five patients each in OPD and OR were included. There was a forward stream of exhaled air from the patient's mouth/nose during all respiratory activities. An N95 mask dampened its intensity and forward transmission. Taping the mask around the nasal bridge further reduced airflow leakage. A mechanical barrier in front of the patient's face blocked forward propagation of the exhaled airflow. Turning on a forceful and direct draft of air over the surgeon's working area dampened and diverted the exhaled airflow away from the surgeons' breathing area. This effect was particularly pronounced in the OR, with the overhead laminar airflow. CONCLUSIONS Using high force airflow with the draft facing downward can dampen and divert the exhaled airflow away from healthcare providers. Using masks/mechanical barriers and taping the mask reduces potential dissemination of aerosols and, thereby, human and surface contamination.
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Affiliation(s)
- Samaresh Srivastava
- From the Raghudeep Eye Hospital, Memnagar, Ahmedabad, Gujarat, India (Srivastava, V. Vasavada, A. R. Vasavada, Sudhalkar, S. A. Vasavada); Pink City Eye Hospital, Jaipur, Rajasthan, India (Kothari)
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19
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Trancossi M, Carli C, Cannistraro G, Pascoa J, Sharma S. Could thermodynamics and heat and mass transfer research produce a fundamental step advance toward and significant reduction of SARS-COV-2 spread? INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2021; 170:120983. [PMID: 33495658 PMCID: PMC7816940 DOI: 10.1016/j.ijheatmasstransfer.2021.120983] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/10/2021] [Indexed: 05/09/2023]
Abstract
We are living an extraordinary season of uncertainty and danger, which is caused by SARS-Cov-2 infection and consequent COVID-19 infection. This preliminary study comes from both a mix of entrepreneurial experience and scientific research. It is aimed by the exigency to reach a new and more effective analysis of the risks on the filed and to reduce them inside a necessary cooperation process which may regard both research and some of the economic activities which are damaged by passive protection measures such as indiscriminate lockdowns. This global emergency requires specific efforts by any discipline that regards specific problems which need to be solved urgently. The characteristic airborne diffusion patterns of COVID-19 shows that the airborne presence of viruses depends on multiple factors which include the dimension of microdroplets emitted by a contagious person, the atmospheric temperature and humidity, the presence of atmospheric particulate and pollution, which may act as a transport vehicle for the virus. The pandemic diffusion shows a particular correlation with the air quality and levels of atmospheric pollution. Specific problems need to solved to understand better the virus, its reliability, diffusion, replication, how it attacks the persons and the conditions, which drives to both positive and deadly evolution of the illness. Most of these problems may benefit from the contribution from both heat and mass transfer and the unsteady thermodynamics of living systems which evolves according to constructal law. After the bibliographic research on the virus, emissive and spread modes, and consequent today adopted protection, a detailed analysis of the contributions which may be assessed by research in thermodynamics, heat and mass transfer, technical and chemical physics. Some possible areas of research have been identified and discussed to start an effective mobilization which may support the effort of the research toward a significant reduction of the impacts of the pandemic infection and the economic risks of new generalized lockdowns.
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Affiliation(s)
- Michele Trancossi
- IIS Galvani, Milano, Italy
- Universidade da Beira Interior, Covilha, Portugal
| | | | | | - Jose Pascoa
- Universidade da Beira Interior, Covilha, Portugal
| | - Shivesh Sharma
- Ethical Property Management Italia srl, Parma 43125, Italy
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20
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Vanden Driessche K, Mahlobo PZ, Venter R, Caldwell J, Jennings K, Diacon AH, Cotton MF, de Groot R, Hens N, Marx FM, Warren RM, Mishra H, Theron G. Face masks in the post-COVID-19 era: a silver lining for the damaged tuberculosis public health response? THE LANCET. RESPIRATORY MEDICINE 2021; 9:340-342. [PMID: 33493446 PMCID: PMC7826055 DOI: 10.1016/s2213-2600(21)00020-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 12/29/2020] [Accepted: 01/05/2021] [Indexed: 01/15/2023]
Affiliation(s)
- Koen Vanden Driessche
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research and SA/MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7550, South Africa; Division of Paediatric Pulmonology, Department of Paediatrics, University Hospital Antwerp, Edegem, Belgium; Section Paediatric Infectious Diseases, Laboratory of Medical Immunology, Radboud Centre for Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Precious Z Mahlobo
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research and SA/MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7550, South Africa
| | - Rouxjeane Venter
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research and SA/MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7550, South Africa
| | - Judy Caldwell
- Department of Health, City of Cape Town, Cape Town, South Africa
| | - Karen Jennings
- Department of Health, City of Cape Town, Cape Town, South Africa
| | - Andreas H Diacon
- Department of Medicine, Stellenbosch University, Cape Town, South Africa; TASK Applied Science, Cape Town, South Africa
| | - Mark F Cotton
- Family Clinical Centre for Research with Ubuntu (FAMCRU), Stellenbosch University, Cape Town, South Africa
| | - Ronald de Groot
- Section Paediatric Infectious Diseases, Laboratory of Medical Immunology, Radboud Centre for Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Niel Hens
- Family Medicine and Population Health (FAMPOP), Centre for Health Economic Research and Modelling Infectious Diseases (CHERMID), and Vaccine & Infectious Disease Institute, University of Antwerp, Antwerp, Belgium; Interuniversity Institute for Biostatistics and Statistical Bioinformatics (I-BIOSTAT), Data Science Institute, Hasselt University, Hasselt, Belgium
| | - Florian M Marx
- Desmond Tutu TB Centre, Department of Paediatrics and Child Health, Stellenbosch University, Cape Town, South Africa; DSI-NRF South African Centre of Excellence in Epidemiological Modelling and Analysis (SACEMA), Stellenbosch University, Stellenbosch, South Africa
| | - Robin M Warren
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research and SA/MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7550, South Africa
| | - Hridesh Mishra
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research and SA/MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7550, South Africa
| | - Grant Theron
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research and SA/MRC Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7550, South Africa.
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21
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Zhou M, Zou J. A dynamical overview of droplets in the transmission of respiratory infectious diseases. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:031301. [PMID: 33897237 PMCID: PMC8061903 DOI: 10.1063/5.0039487] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 12/29/2020] [Indexed: 05/04/2023]
Abstract
The outbreak of the coronavirus disease has drawn public attention to the transmission of infectious pathogens, and as major carriers of those pathogens, respiratory droplets play an important role in the process of transmission. This Review describes respiratory droplets from a physical and mechanical perspective, especially their correlation with the transmission of infectious pathogens. It covers the important aspects of (i) the generation and expulsion of droplets during respiratory activities, (ii) the transport and evolution of respiratory droplets in the ambient environment, and (iii) the inhalation and deposition of droplets in the human respiratory tract. State-of-the-art experimental, computational, and theoretical models and results are presented, and the corresponding knowledge gaps are identified. This Review stresses the multidisciplinary nature of its subject and appeals for collaboration among different fields to fight the present pandemic.
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Affiliation(s)
- Maoying Zhou
- School of Mechanical Engineering, Hangzhou Dianzi
University, Hangzhou, Zhejiang 310027, China
| | - Jun Zou
- State Key Laboratory of Fluid Power and Mechatronic Systems,
Zhejiang University, Hangzhou, Zhejiang 310027,
China
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22
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Hannawi S, Hannawi H, Naeem KB, Elemam NM, Hachim MY, Hachim IY, Darwish AS, Al Salmi I. Clinical and Laboratory Profile of Hospitalized Symptomatic COVID-19 Patients: Case Series Study From the First COVID-19 Center in the UAE. Front Cell Infect Microbiol 2021; 11:632965. [PMID: 33718282 PMCID: PMC7952884 DOI: 10.3389/fcimb.2021.632965] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/25/2021] [Indexed: 02/05/2023] Open
Abstract
INTRODUCTION COVID-19 is raising with a second wave threatening many countries. Therefore, it is important to understand COVID-19 characteristics across different countries. METHODS This is a cross-sectional descriptive study of 525 hospitalized symptomatic COVID-19 patients, from the central federal hospital in Dubai-UAE during period of March to August 2020. RESULTS UAE's COVID-19 patients were relatively young; mean (SD) of the age 49(15) years, 130 (25%) were older than 60 and 4 (<1%) were younger than 18 years old. Majority were male(47; 78%). The mean (SD) BMI was 29 (6) kg/m2. While the source of contracting COVID-19 was not known in 369 (70%) of patients, 29 (6%) reported travel to overseas-country and 127 (24%) reported contact with another COVID-19 case/s. At least one comorbidity was present in 284 (54%) of patients and 241 (46%) had none. The most common comorbidities were diabetes (177; 34%) and hypertension (166; 32%). The mean (SD) of symptoms duration was 6 (3) days. The most common symptoms at hospitalization were fever (340; 65%), cough (296; 56%), and shortness of breath (SOB) (243; 46%). Most of the laboratory values were within normal range, but (184; 35%) of patients had lymphopenia, 43 (8%) had neutrophilia, and 116 (22%) had prolong international normalized ratio (INR), and 317 (60%) had high D-dimer. Chest x ray findings of consolidation was present in 334 (64%) of patients and CT scan ground glass appearance was present in 354 (68%). Acute cardiac injury occurred in 124 (24%), acute kidney injury in 111 (21%), liver injury in 101 (19%), ARDS in 155 (30%), acidosis in 118 (22%), and septic shock in 93 (18%). Consequently, 150 (29%) required ICU admission with 103 (20%) needed mechanical ventilation. CONCLUSIONS The study demonstrated the special profile of COVID-19 in UAE. Patients were young with diabetes and/or hypertension and associated with severe infection as shown by various clinical and laboratory data necessitating ICU admission.
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Affiliation(s)
- Suad Hannawi
- Department of Medicine, Ministry of Health and Prevention, Dubai, United Arab Emirates
| | - Haifa Hannawi
- Department of Medicine, Ministry of Health and Prevention, Dubai, United Arab Emirates
- Department of Reserach, Ministry of Health and Prevention, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Kashif Bin Naeem
- Department of Medicine, Ministry of Health and Prevention, Dubai, United Arab Emirates
| | - Noha Mousaad Elemam
- Sharjah Institute for Medical Research, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
- Clinical Sciences Department, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - Mahmood Y Hachim
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates
| | - Ibrahim Y Hachim
- Sharjah Institute for Medical Research, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
- Clinical Sciences Department, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | | | - Issa Al Salmi
- Department of Medicine, Oman Medical Specialty Board, The Royal Hospital, Muscat, Oman
- The Research Section, Oman Medical Speciality Board, The Royal Hospital, Muscat, Oman
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23
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Srivastava A. COVID-19 and air pollution and meteorology-an intricate relationship: A review. CHEMOSPHERE 2021; 263:128297. [PMID: 33297239 PMCID: PMC7487522 DOI: 10.1016/j.chemosphere.2020.128297] [Citation(s) in RCA: 119] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 09/05/2020] [Accepted: 09/07/2020] [Indexed: 05/15/2023]
Abstract
Corona virus is highly uncertain and complex in space and time. Atmospheric parameters such as type of pollutants and local weather play an important role in COVID-19 cases and mortality. Many studies were carried out to understand the impact of weather on spread and severity of COVID-19 and vice-versa. A review study is conducted to understand the impact of weather and atmospheric pollution on morbidity and mortality. Studies show that aerosols containing corona virus generated by sneezes and coughs are major route for spread of virus. Viability and virulence of SARS-CoV-2 stuck on the surface of particulate matter is not yet confirmed. Studies found that an increase in particulate matter concentration causes more COVID-19 cases and mortality. Gaseous pollutant and COVID-19 cases are positively correlated. Local meteorology plays crucial role in the spread of corona virus and thus mortality. Decline in number of cases with rising temperature observed. Few studies also find that lowest and highest temperatures were related to lesser number of cases. Similarly humidity shows negative or no relationship with COVID-19 cases. Rainfall was not related whilst wind-speed plays positive role in spread of COVID-19. Solar radiation threats survival of virus, areas with lower solar radiation showed high exposure rate. Air quality tremendously improved during lockdown. A significant reduction in PM10, PM2.5, BC, NOx, SO2, CO and VOCs concentration were observed. Lockdown had a healing effect on ozone; significant increase in its concentration was observed. Aerosols Optical Depths were found to decrease up to 50%.
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Affiliation(s)
- Arun Srivastava
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.
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24
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Tang JW. SARS-CoV-2 and aerosols-Arguing over the evidence. J Virol Methods 2020; 289:114033. [PMID: 33285192 PMCID: PMC7716743 DOI: 10.1016/j.jviromet.2020.114033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/21/2020] [Accepted: 12/02/2020] [Indexed: 11/15/2022]
Abstract
This Commentary discusses various aspects around the controversial issue of SARSCoV-2 and aerosol transmission, highlighting certain counter arguments and explaining why they are invalid.
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Affiliation(s)
- Julian W Tang
- Clinical Microbiology, University Hospitals of Leicester NHS Trust, Level 5 Sandringham Building, Leicester Royal Infirmary, Infirmary Square, Leicester LE1 5WW, UK.
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25
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Staymates M. Flow visualization of an N95 respirator with and without an exhalation valve using schlieren imaging and light scattering. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2020; 32:111703. [PMID: 33244212 PMCID: PMC7684679 DOI: 10.1063/5.0031996] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
This work demonstrates the qualitative fluid flow characteristics of a standard N95 respirator with and without an exhalation valve. Schlieren imaging was used to compare an adult male breathing through an N95 respirator with and without a valve. The schlieren imaging technique showed the flow of warm air passing through these respirators but did not provide information about droplet penetration. For this, strategic lighting of fog droplets was used with a mannequin head to visualize the penetration of droplets through both masks. The mannequin exhaled with a realistic flow rate and velocity that matched an adult male. The penetration of fog droplets was also visualized with a custom system that seals each respirator onto the end of a flow tube. Results of these qualitative experiments show that an N95 respirator without an exhalation valve is effective at blocking most droplets from penetrating through the mask material. Results also suggest that N95 respirators with exhalation valves are not appropriate as a source control strategy for reducing the proliferation of infectious diseases that spread via respiratory droplets.
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Arumuru V, Pasa J, Samantaray SS. Experimental visualization of sneezing and efficacy of face masks and shields. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2020; 32:115129. [PMID: 33244217 PMCID: PMC7684680 DOI: 10.1063/5.0030101] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/01/2020] [Indexed: 05/02/2023]
Abstract
In the present work, we propose and demonstrate a simple experimental visualization to simulate sneezing by maintaining dynamic similarity to actual sneezing. A pulsed jet with Reynolds number Re = 30 000 is created using compressed air and a solenoid valve. Tracer particles are introduced in the flow to capture the emulated turbulent jet formed due to a sneeze. The visualization is accomplished using a camera and laser illumination. It is observed that a typical sneeze can travel up to 25 ft in ∼22 s in a quiescent environment. This highlights that the present widely accepted safe distance of 6 ft is highly underestimated, especially under the act of a sneeze. Our study demonstrates that a three-layer homemade mask is just adequate to impede the penetration of fine-sized particles, which may cause the spreading of the infectious pathogen responsible for COVID-19. However, a surgical mask cannot block the sneeze, and the sneeze particle can travel up to 2.5 ft. We strongly recommend using at least a three-layer homemade mask with a social distancing of 6 ft to combat the transmission of COVID-19 virus. In offices, we recommend the use of face masks and shields to prevent the spreading of droplets carrying the infectious pathogen. Interestingly, an N-95 mask blocks the sneeze in the forward direction; however, the leakage from the sides and top spreads the sneeze in the backward direction up to 2 ft. We strongly recommend using the elbow or hands to prevent droplet leakage even after wearing a mask during sneezing and coughing.
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Affiliation(s)
- Venugopal Arumuru
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of
Technology Bhubaneswar, Bhubaneswar 752050, India
| | - Jangyadatta Pasa
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of
Technology Bhubaneswar, Bhubaneswar 752050, India
| | - Sidhartha Sankar Samantaray
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of
Technology Bhubaneswar, Bhubaneswar 752050, India
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Chan Y, Angel D, Aron M, Hartl T, Moubayed SP, Smith KA, Sommer DD, Sowerby L, Spafford P, Mertz D, Witterick IJ. CSO (Canadian Society of Otolaryngology - Head & Neck Surgery) position paper on return to Otolaryngology - Head & Neck Surgery Clinic Practice during the COVID-19 pandemic in Canada. J Otolaryngol Head Neck Surg 2020; 49:76. [PMID: 33106189 PMCID: PMC7586368 DOI: 10.1186/s40463-020-00466-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/16/2020] [Indexed: 12/14/2022] Open
Abstract
The novel Coronavirus (COVID-19) has created a worldwide deadly pandemic that has become a major public health challenge. All semi-urgent and elective medical care has come to a halt to conserve capacity to care for patients during this pandemic. As the numbers of COVID-19 cases decrease across Canada, our healthcare system also began to reopen various facilities and medical offices. The aim for this document is to compile the current evidence and provide expert consensus on the safe return to clinic practice in Otolaryngology - Head & Neck Surgery. These recommendations will also summarize general precaution principles and practical tips for office across Canada to optimize patient and provider safety. Risk assessment and patient selection are crucial to minimizing exposure to COVID-19. Controversial topics such as COVID-19 mode of transmission, duration of exposure, personal protective equipment, and aerosol-generating procedures will be analyzed and discussed. Practical solutions of pre-visit office preparation, front office and examination room set-up, and check out procedures are explored. Specific considerations for audiology, pediatric population, and high risk AGMPs are also addressed. Given that the literature surrounding COVID-19 is rapidly evolving, these guidelines will serve to start our specialty back into practice over the next weeks to months and they may change as we learn more about this disease.
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Affiliation(s)
- Y Chan
- Department of Otolaryngology - Head & Neck Surgery, University of Toronto, Toronto, ON, Canada.
| | - D Angel
- Division of Otolaryngology - Head & Neck Surgery, Memorial University of Newfoundland, St. John's, NL, Canada
| | - M Aron
- Division of Otolaryngology - Head & Neck Surgery, Department of Surgery, University of British Columbia, Vancouver, BC, Canada
| | - T Hartl
- Division of Otolaryngology - Head & Neck Surgery, Department of Surgery, University of British Columbia, Vancouver, BC, Canada
| | - S P Moubayed
- Division of Otolaryngology - Head & Neck Surgery, University of Montreal, Montreal, QC, Canada
| | - K A Smith
- Department of Otolaryngology - Head & Neck Surgery, University of Manitoba, Winnipeg, MB, Canada
| | - D D Sommer
- Otolaryngology - Head & Neck Surgery Division, Department of Surgery, McMaster University, Hamilton, ON, Canada
| | - L Sowerby
- Department of Otolaryngology - Head & Neck Surgery, Western University, London, ON, Canada
| | - P Spafford
- Division of Otolaryngology - Head and Neck Surgery, Department of Surgery, University of Saskatchewan, Saskatoon, SK, Canada
| | - D Mertz
- Division of Infectious Diseases, Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - I J Witterick
- Department of Otolaryngology - Head & Neck Surgery, University of Toronto, Toronto, ON, Canada
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Chamié D, Oliveira F, Braga S, Costa JR, Siqueira DAAD, Staico R, Costa R, Maldonado G, Tanajura LFL, Centemero MP, Chaves ÁJ, Abizaid ACSL, Freitas RAP, Coelho NT, Ohe LN, Abboud C, Feres F. Adapted Catheterization Laboratory Practices during the COVID-19 Pandemic: The Instituto Dante Pazzanese de Cardiologia Protocol. Arq Bras Cardiol 2020; 115:558-568. [PMID: 33027381 PMCID: PMC9363089 DOI: 10.36660/abc.20200489] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 06/24/2020] [Indexed: 01/12/2023] Open
Affiliation(s)
- Daniel Chamié
- Instituto Dante Pazzanese de Cardiologia , São Paulo , SP - Brasil
| | | | - Sérgio Braga
- Instituto Dante Pazzanese de Cardiologia , São Paulo , SP - Brasil
| | | | | | - Rodolfo Staico
- Instituto Dante Pazzanese de Cardiologia , São Paulo , SP - Brasil
| | - Ricardo Costa
- Instituto Dante Pazzanese de Cardiologia , São Paulo , SP - Brasil
| | - Galo Maldonado
- Instituto Dante Pazzanese de Cardiologia , São Paulo , SP - Brasil
| | | | | | | | | | | | | | | | - Cely Abboud
- Instituto Dante Pazzanese de Cardiologia , São Paulo , SP - Brasil
| | - Fausto Feres
- Instituto Dante Pazzanese de Cardiologia , São Paulo , SP - Brasil
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Propensity and quantification of aerosol and droplet creation during phacoemulsification with high-speed shadowgraphy amid COVID-19 pandemic. J Cataract Refract Surg 2020; 46:1297-1301. [PMID: 32649436 DOI: 10.1097/j.jcrs.0000000000000289] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE To study propensity of aerosol and droplet generation during phacoemulsification using high-speed shadowgraphy and quantify its spread amid COVID-19 pandemic. SETTING Aerosol and droplet quantification laboratory. DESIGN Laboratory study. METHODS In an experimental set-up, phacoemulsification was performed on enucleated goat eyes and cadaveric human corneoscleral rims mounted on an artificial anterior chamber. Standard settings for sculpt and quadrant removal mode were used on Visalis 100 (Carl Zeiss Meditec AG). Microincision and standard phacoemulsification were performed using titanium straight tips (2.2 mm and 2.8 mm in diameter). The main wound incisions were titrated equal to and larger than the sleeve size. High-speed shadowgraphy technique was used to detect the possible generation of any droplets and aerosols. The visualization and quantification of size of the aerosols and droplets along with calculation of their spread were the main outcome measures. RESULTS In longitudinal phacoemulsification using a peristaltic pump device with a straight tip, no aerosol generation was seen in a closed chamber. In larger wounds, there was a slow leak at the main wound. The atomization of balanced salt solution was observed only when the phacoemulsification tip was completely exposed next to the ocular surface. Under this condition, the nominal size of the droplet was approximately 50 µm, and the maximum calculated spread was 1.3 m. CONCLUSIONS There was no visible aerosol generation during microincision or standard phacoemulsification. Phacoemulsification is safe to perform in the COVID-19 era by taking adequate precautions against other modes of transmission.
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Kim J, Lee S, Joung YS. Schlieren imaging for the visualization of particles entrapped in bubble films. J Colloid Interface Sci 2020; 570:52-60. [PMID: 32135268 DOI: 10.1016/j.jcis.2020.02.085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/19/2020] [Accepted: 02/19/2020] [Indexed: 10/25/2022]
Abstract
Bubbles are one of the primary sources of transferring substances from water to air. When bubbles burst, small droplets containing microparticles and microorganisms previously suspended in water disperse. Hence, visualizing small objects in bubble films can provide a new methodology for investigating the material transfer from water to the environment and the dynamic behavior of objects in the films. We used Schlieren imaging of bubbles to visualize small objects such as bacteria and microplastics. Remarkably, black spots (Schlieren spots) appeared when light rays passed parallel to bubbles formed on the water containing microparticles and bacteria. The simulation method of Schlieren imaging of bubbles was developed to clarify the underlying mechanism and experimentally validated with different sizes and concentrations of microparticles. We found that a specific water meniscus is formed around a particle when the bubble film thickness is smaller than the particle diameter, and the meniscus plays an important role in enlarging the Schlieren spots. The Schlieren spots are forty times larger than the bubble film thickness in this work. To understand the magnification rule, we illuminated the correlation between bubble film thickness, particle diameter, and Schlieren spot diameter.
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Affiliation(s)
- Jeeyoon Kim
- Department of Mechanical Systems Engineering, Sookmyung Women's University, 100, Cheongpa-ro 47-gil, Yongsan-gu, Seoul, Republic of Korea
| | - Seunghyeon Lee
- Department of Mechanical Systems Engineering, Sookmyung Women's University, 100, Cheongpa-ro 47-gil, Yongsan-gu, Seoul, Republic of Korea
| | - Young Soo Joung
- Department of Mechanical Systems Engineering, Sookmyung Women's University, 100, Cheongpa-ro 47-gil, Yongsan-gu, Seoul, Republic of Korea.
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Godri Pollitt KJ, Peccia J, Ko AI, Kaminski N, Dela Cruz CS, Nebert DW, Reichardt JKV, Thompson DC, Vasiliou V. COVID-19 vulnerability: the potential impact of genetic susceptibility and airborne transmission. Hum Genomics 2020; 14:17. [PMID: 32398162 PMCID: PMC7214856 DOI: 10.1186/s40246-020-00267-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 04/29/2020] [Indexed: 01/08/2023] Open
Abstract
The recent coronavirus disease (COVID-19), caused by SARS-CoV-2, is inarguably the most challenging coronavirus outbreak relative to the previous outbreaks involving SARS-CoV and MERS-CoV. With the number of COVID-19 cases now exceeding 2 million worldwide, it is apparent that (i) transmission of SARS-CoV-2 is very high and (ii) there are large variations in disease severity, one component of which may be genetic variability in the response to the virus. Controlling current rates of infection and combating future waves require a better understanding of the routes of exposure to SARS-CoV-2 and the underlying genomic susceptibility to this disease. In this mini-review, we highlight possible genetic determinants of COVID-19 and the contribution of aerosol exposure as a potentially important transmission route of SARS-CoV-2.
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Affiliation(s)
- Krystal J Godri Pollitt
- Department of Environmental Health Sciences, School of Public Health, Yale University, New Haven, CT, 06510, USA.
| | - Jordan Peccia
- Department of Chemical & Environmental Engineering, School of Engineering & Applied Science, Yale University, New Haven, CT, 06520, USA
| | - Albert I Ko
- Department of Epidemiology of Microbial Diseases, School of Public Health, Yale University, New Haven, CT, 06510, USA
| | - Naftali Kaminski
- Section of Pulmonary, Critical Care and Sleep Medicine, School of Medicine, Yale University, New Haven, CT, 06520, USA
| | - Charles S Dela Cruz
- Section of Pulmonary, Critical Care and Sleep Medicine, School of Medicine, Yale University, New Haven, CT, 06520, USA
| | - Daniel W Nebert
- Department of Environmental Health and Center for Environmental Genetics, University Cincinnati Medical Center, Cincinnati, OH, 45267, USA
| | - Juergen K V Reichardt
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD, Australia
| | - David C Thompson
- Department of Clinical Pharmacy, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of Colorado Denver, Aurora, CO, 80045, USA
| | - Vasilis Vasiliou
- Department of Environmental Health Sciences, School of Public Health, Yale University, New Haven, CT, 06510, USA.
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Lindsley WG, Blachere FM, McClelland TL, Neu DT, Mnatsakanova A, Martin SB, Mead KR, Noti JD. Efficacy of an ambulance ventilation system in reducing EMS worker exposure to airborne particles from a patient cough aerosol simulator. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2019; 16:804-816. [PMID: 31638865 DOI: 10.1080/15459624.2019.1674858] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The protection of emergency medical service (EMS) workers from airborne disease transmission is important during routine transport of patients with infectious respiratory illnesses and would be critical during a pandemic of a disease such as influenza. However, few studies have examined the effectiveness of ambulance ventilation systems at reducing EMS worker exposure to airborne particles (aerosols). In our study, a cough aerosol simulator mimicking a coughing patient with an infectious respiratory illness was placed on a patient cot in an ambulance. The concentration and dispersion of cough aerosol particles were measured for 15 min at locations corresponding to likely positions of an EMS worker treating the patient. Experiments were performed with the patient cot at an angle of 0° (horizontal), 30°, and 60°, and with the ambulance ventilation system set to 0, 5, and 12 air changes/hour (ACH). Our results showed that increasing the air change rate significantly reduced the airborne particle concentration (p < 0.001). Increasing the air change rate from 0 to 5 ACH reduced the mean aerosol concentration by 34% (SD = 19%) overall, while increasing it from 0 to 12 ACH reduced the concentration by 68% (SD = 9%). Changing the cot angle also affected the concentration (p < 0.001), but the effect was more modest, especially at 5 and 12 ACH. Contrary to our expectations, the aerosol concentrations at the different worker positions were not significantly different (p < 0.556). Flow visualization experiments showed that the ventilation system created a recirculation pattern which helped disperse the aerosol particles throughout the compartment, reducing the effectiveness of the system. Our findings indicate that the ambulance ventilation system reduced but did not eliminate worker exposure to infectious aerosol particles. Aerosol exposures were not significantly different at different locations within the compartment, including locations behind and beside the patient. Improved ventilation system designs with smoother and more unidirectional airflows could provide better worker protection.
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Affiliation(s)
- William G Lindsley
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Francoise M Blachere
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Tia L McClelland
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Dylan T Neu
- Division of Field Studies & Engineering, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
| | - Anna Mnatsakanova
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Stephen B Martin
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - Kenneth R Mead
- Division of Field Studies & Engineering, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio, USA
| | - John D Noti
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
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Xu C, Nielsen PV, Liu L, Jensen RL, Gong G. Human exhalation characterization with the aid of schlieren imaging technique. BUILDING AND ENVIRONMENT 2017; 112:190-199. [PMID: 32287969 PMCID: PMC7111220 DOI: 10.1016/j.buildenv.2016.11.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 05/08/2023]
Abstract
The purpose of this paper is to determine the dispersion and distribution characteristics of exhaled airflow for accurate prediction of disease transmission. The development of airflow dynamics of human exhalation was characterized using nonhazardous schlieren photography technique, providing a visualization and quantification of turbulent exhaled airflow from 18 healthy human subjects whilst standing and lying. The flow shape of each breathing pattern was characterized by two angles and averaged values of 18 subjects. Two exhaled air velocities, u m and u p , were measured and compared. The mean peak centerline velocity, u m was found to decay correspondingly with increasing horizontal distance x in a form of power function. The mean propagation velocity, u p was found to correlate with physiological parameters of human subjects. This was always lower than u m at the mouth/nose opening, due to a vortex like airflow in front of a single exhalation cycle. When examining the talking and breathing process between two persons, the potential infectious risk was found to depend on their breathing patterns and spatial distribution of their exhaled air. Our study when combined with information on generation and distributions of pathogens could provide a prediction method and control strategy to minimize infection risk between persons in indoor environments.
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Affiliation(s)
- Chunwen Xu
- College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, China
- Department of Civil Engineering, Aalborg University, Aalborg 9000, Denmark
| | - Peter V. Nielsen
- Department of Civil Engineering, Aalborg University, Aalborg 9000, Denmark
| | - Li Liu
- Department of Civil Engineering, Aalborg University, Aalborg 9000, Denmark
| | - Rasmus L. Jensen
- Department of Civil Engineering, Aalborg University, Aalborg 9000, Denmark
| | - Guangcai Gong
- College of Civil Engineering, Hunan University, Changsha 410082, China
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Wei J, Tang JW, Borojeni AAT, Yin S, Martin A, Finlay WH, Li Y. Low re-inhalation of the exhaled flow during normal nasal breathing in a pediatric airway replica. BUILDING AND ENVIRONMENT 2016; 97:40-47. [PMID: 32288038 PMCID: PMC7116934 DOI: 10.1016/j.buildenv.2015.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 12/04/2015] [Accepted: 12/12/2015] [Indexed: 05/16/2023]
Abstract
To estimate the fraction of the exhaled airflow that is re-inhaled during normal nasal breathing, experiments were carried out in a water tank with an anatomically accurate respiratory tract model of a 4-year-old child. The velocity of respiratory flow was scaled using similarity laws between air and water. Breath simulation was performed via a computer-controlled piston-cylinder system. Food-dye visualization allows a qualitative analysis of the re-inhaled fraction of this exhaled flow. For the quantitative analysis, neutrally buoyant particles were added to the water medium, and illuminated by the laser which illuminates the whole breathing region of the respiratory model, such that the trajectory and quantity of the re-inhaled particles can be recorded and counted. The experimental results in the pediatric airway replica show that a negligible fraction (<0.06%) of the exhaled airflow is re-inhaled during normal nasal breathing in the absence of the rising thermal plume. The artificial plume generated by a heated aluminium brick at the tank bottom increases the re-inhalation ratio by 4 times under the investigated case (albeit still at a very low value of 0.15%). Our results thus reveal that during normal nasal breathing in the present pediatric subject, the vast majority of human exhaled airflow escapes from the inhalation zone and is not re-inhaled.
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Affiliation(s)
- Jianjian Wei
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Julian W Tang
- Department of Medical Microbiology & Immunology, University of Alberta, Edmonton, Canada
- Leicester Royal Infirmary, University Hospitals Leicester, Leicester, UK
| | - Azadeh A T Borojeni
- Department of Mechanical Engineering, University of Alberta, Edmonton, Canada
| | - Shi Yin
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Andrew Martin
- Department of Mechanical Engineering, University of Alberta, Edmonton, Canada
| | - Warren H Finlay
- Department of Mechanical Engineering, University of Alberta, Edmonton, Canada
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
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Tang JW, Wilson P, Shetty N, Noakes CJ. Aerosol-Transmitted Infections-a New Consideration for Public Health and Infection Control Teams. CURRENT TREATMENT OPTIONS IN INFECTIOUS DISEASES 2015; 7:176-201. [PMID: 32226323 PMCID: PMC7100085 DOI: 10.1007/s40506-015-0057-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Since the emergence of the 2003 severe acute respiratory syndrome (SARS), the 2003 reemergence of avian A/H5N1, the emergence of the 2009 pandemic influenza A/H1N1, the 2012 emergence of Middle East respiratory syndrome (MERS), the 2013 emergence of avian A/H7N9 and the 2014 Ebola virus outbreaks, the potential for the aerosol transmission of infectious agents is now routinely considered in the investigation of any outbreak. Although many organisms have traditionally been considered to be transmitted by only one route (e.g. direct/indirect contact and/or faecal-orally), it is now apparent that the aerosol transmission route is also possible and opportunistic, depending on any potentially aerosol-generating procedures, the severity of illness and the degree and duration of pathogen-shedding in the infected patient, as well as the environment in which these activities are conducted.This article reviews the evidence and characteristics of some of the accepted (tuberculosis, measles, chickenpox, whooping cough) and some of the more opportunistic (influenza, Clostridium difficile, norovirus) aerosol-transmitted infectious agents and outlines methods of detecting and quantifying transmission.
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Affiliation(s)
- Julian W. Tang
- Clinical Microbiology, Leicester Royal Infirmary, University Hospitals Leicester, Leicester NHS Trust, Leicester, LE1 5WW UK
| | - Peter Wilson
- Clinical Microbiology, University College London Hospitals NHS Trust, London, UK
| | - Nandini Shetty
- Clinical Microbiology, University College London Hospitals NHS Trust, London, UK
| | - Catherine J. Noakes
- Institute for Public Health and Environmental Engineering, School of Civil Engineering, University of Leeds, Leeds, UK
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Chen C, Lin CH, Jiang Z, Chen Q. Simplified models for exhaled airflow from a cough with the mouth covered. INDOOR AIR 2014; 24:580-91. [PMID: 24628862 DOI: 10.1111/ina.12109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/08/2014] [Indexed: 05/02/2023]
Abstract
UNLABELLED Covering a cough can be useful in reducing the transmission of airborne infectious diseases. However, no simple method is available in the literature for predicting the exhaled airflow from a cough with the mouth covered. This investigation used smoke to visualize the airflow exhaled by 16 human subjects. Their mouths were covered by a tissue, a cupped hand, a fist, and an elbow with and without a sleeve. This study then developed simplified models for predicting the airflow on the basis of the smoke visualization data. In addition, this investigation performed numerical simulations to assess the influence of mouth coverings on the receptor's exposure to exhaled particles. It was found that covering a cough with a tissue, a cupped hand, or an elbow can significantly reduce the horizontal velocity and cause the particles to move upward with the thermal plumes generated by a human body. In contrast with an uncovered cough, a covered cough or a cough with the head turned away may prevent direct exposure. PRACTICAL IMPLICATIONS This study developed simplified models for predicting the exhaled airflow from a cough with the mouth covered. The proposed models can easily be used to investigate the risk of transmission of airborne infectious diseases in enclosed environments.
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Affiliation(s)
- C Chen
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
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Voelker C, Maempel S, Kornadt O. Measuring the human body's microclimate using a thermal manikin. INDOOR AIR 2014; 24:567-79. [PMID: 24666331 DOI: 10.1111/ina.12112] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 03/18/2014] [Indexed: 05/23/2023]
Abstract
UNLABELLED The human body is surrounded by a microclimate, which results from its convective release of heat. In this study, the air temperature and flow velocity of this microclimate were measured in a climate chamber at various room temperatures, using a thermal manikin simulating the heat release of the human being. Different techniques (Particle Streak Tracking, thermography, anemometry, and thermistors) were used for measurement and visualization. The manikin surface temperature was adjusted to the particular indoor climate based on simulations with a thermoregulation model (UCBerkeley Thermal Comfort Model). We found that generally, the microclimate is thinner at the lower part of the torso, but expands going up. At the head, there is a relatively thick thermal layer, which results in an ascending plume above the head. However, the microclimate shape strongly depends not only on the body segment, but also on boundary conditions: The higher the temperature difference between the surface temperature of the manikin and the air temperature, the faster the airflow in the microclimate. Finally, convective heat transfer coefficients strongly increase with falling room temperature, while radiative heat transfer coefficients decrease. The type of body segment strongly influences the convective heat transfer coefficient, while only minimally influencing the radiative heat transfer coefficient. PRACTICAL IMPLICATIONS The findings of this study generate a better understanding of the human body’s microclimate, which is important in fields such as thermal comfort, HVAC, or indoor air quality. Additionally, the measurements can be used by CFD users for the validation of their simulations.
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Affiliation(s)
- C Voelker
- Department of Modeling in Building Physics, University of Kaiserslautern, Kaiserslautern, Germany
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Abstract
BACKGROUND Potentially infected individuals ('source') are sometimes encouraged to use face masks to reduce exposure of their infectious aerosols to others ('receiver'). To improve compliance with Respiratory Source Control via face mask and therefore reduce receiver exposure, a mask should be comfortable and effective. We tested a novel face mask designed to improve breathability and filtration using nanofiber filtration. METHODS Using radiolabeled test aerosols and a calibrated exposure chamber simulating source to receiver interaction, facepiece function was measured with a life-like ventilated manikin model. Measurements included mask airflow resistance (pressure difference during breathing), filtration, (mask capture of exhaled radiolabeled test aerosols), and exposure (the transfer of 'infectious' aerosols from the 'source' to a 'receiver'). Polydisperse aerosols were measured at the source with a mass median aerodynamic diameter of 0.95 µm. Approximately 90% of the particles were <2.0 µm. Tested facepieces included nanofiber prototype surgical masks, conventional surgical masks, and for comparison, an N95-class filtering facepiece respirator (commonly known as an 'N95 respirator'). Airflow through and around conventional surgical face mask and nanofiber prototype face mask was visualized using Schlieren optical imaging. RESULTS Airflow resistance [ΔP, cmH2O] across sealed surgical masks (means: 0.1865 and 0.1791 cmH2O) approached that of the N95 (mean: 0.2664 cmH2O). The airflow resistance across the nanofiber face mask whether sealed or not sealed (0.0504 and 0.0311 cmH2O) was significantly reduced in comparison. In addition, 'infected' source airflow filtration and receiver exposure levels for nanofiber face masks placed on the source were comparable to that achieved with N95 placed on the source; 98.98% versus 82.68% and 0.0194 versus 0.0557, respectively. Compared to deflection within and around the conventional face masks, Schlieren optical imaging demonstrated enhanced airflow through the nanofiber mask. CONCLUSIONS Substituting nanofiber for conventional filter media significantly reduced face mask airflow resistance directing more airflow through the face mask resulting in enhanced filtration. Respiratory source control efficacy similar to that achieved through the use of an N95 respirator worn by the source and decreased airflow resistance using nanofiber masks may improve compliance and reduce receiver exposure.
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Affiliation(s)
- Shaji D Skaria
- Division of Pulmonary, Critical Care & Sleep Medicine, Stony Brook University Medical Center, 100 Nicolls Road, HSC T-17-040, Stony Brook, NY 11794-8172, USA
| | - Gerald C Smaldone
- Division of Pulmonary, Critical Care & Sleep Medicine, Stony Brook University Medical Center, 100 Nicolls Road, HSC T-17-040, Stony Brook, NY 11794-8172, USA
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Ferner RE, Aronson JK. Laughter and MIRTH (Methodical Investigation of Risibility, Therapeutic and Harmful): narrative synthesis. BMJ 2013; 347:f7274. [PMID: 24336308 PMCID: PMC3898427 DOI: 10.1136/bmj.f7274] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
OBJECTIVE To review the beneficial and harmful effects of laughter. DESIGN Narrative synthesis. DATA SOURCES AND REVIEW METHODS We searched Medline (1946 to June 2013) and Embase (1974 to June 2013) for reports of benefits or harms from laughter in humans, and counted the number of papers in each category. RESULTS Benefits of laughter include reduced anger, anxiety, depression, and stress; reduced tension (psychological and cardiovascular); increased pain threshold; reduced risk of myocardial infarction (presumably requiring hearty laughter); improved lung function; increased energy expenditure; and reduced blood glucose concentration. However, laughter is no joke-dangers include syncope, cardiac and oesophageal rupture, and protrusion of abdominal hernias (from side splitting laughter or laughing fit to burst), asthma attacks, interlobular emphysema, cataplexy, headaches, jaw dislocation, and stress incontinence (from laughing like a drain). Infectious laughter can disseminate real infection, which is potentially preventable by laughing up your sleeve. As a side effect of our search for side effects, we also list pathological causes of laughter, among them epilepsy (gelastic seizures), cerebral tumours, Angelman's syndrome, strokes, multiple sclerosis, and amyotrophic lateral sclerosis or motor neuron disease. CONCLUSIONS Laughter is not purely beneficial. The harms it can cause are immediate and dose related, the risks being highest for Homeric (uncontrollable) laughter. The benefit-harm balance is probably favourable. It remains to be seen whether sick jokes make you ill or jokes in bad taste cause dysgeusia, and whether our views on comedians stand up to further scrutiny.
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Affiliation(s)
- R E Ferner
- West Midlands Centre for Adverse Drug Reactions, City Hospital, Birmingham B18 7QH, UK
- School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK
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40
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Lindsley WG, Reynolds JS, Szalajda JV, Noti JD, Beezhold DH. A Cough Aerosol Simulator for the Study of Disease Transmission by Human Cough-Generated Aerosols. AEROSOL SCIENCE AND TECHNOLOGY : THE JOURNAL OF THE AMERICAN ASSOCIATION FOR AEROSOL RESEARCH 2013; 47:937-944. [PMID: 26500387 PMCID: PMC4615563 DOI: 10.1080/02786826.2013.803019] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Aerosol particles expelled during human coughs are a potential pathway for infectious disease transmission. However, the importance of airborne transmission is unclear for many diseases. To better understand the role of cough aerosol particles in the spread of disease and the efficacy of different types of protective measures, we constructed a cough aerosol simulator that produces a humanlike cough in a controlled environment. The simulated cough has a 4.2 l volume and is based on coughs recorded from influenza patients. In one configuration, the simulator produces a cough aerosol containing particles from 0.1 to 100 µm in diameter with a volume median diameter (VMD) of 8.5 µm and a geometric standard deviation (GSD) of 2.9. In a second configuration, the cough aerosol has a size range of 0.1-30 µm, a VMD of 3.4 µm, and a GSD of 2.3. The total aerosol volume expelled during each cough is 68 µl. By generating a controlled and reproducible artificial cough, the simulator allows us to test different ventilation, disinfection, and personal protection scenarios. The system can be used with live pathogens, including influenza virus, which allows isolation precautions used in the healthcare field to be tested without risk of exposure for workers or patients. The information gained from tests with the simulator will help to better understand the transmission of infectious diseases, develop improved techniques for infection control, and improve safety for healthcare workers and patients.
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Affiliation(s)
- William G. Lindsley
- National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Morgantown, West Virginia, USA
| | - Jeffrey S. Reynolds
- National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Morgantown, West Virginia, USA
| | - Jonathan V. Szalajda
- National Institute for Occupational Safety and Health, National Personal Protective Technology Laboratory, Pittsburgh, Pennsylvania, USA
| | - John D. Noti
- National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Morgantown, West Virginia, USA
| | - Donald H. Beezhold
- National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Morgantown, West Virginia, USA
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41
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Tang JW, Nicolle AD, Klettner CA, Pantelic J, Wang L, Suhaimi AB, Tan AYL, Ong GWX, Su R, Sekhar C, Cheong DDW, Tham KW. Airflow dynamics of human jets: sneezing and breathing - potential sources of infectious aerosols. PLoS One 2013; 8:e59970. [PMID: 23560060 PMCID: PMC3613375 DOI: 10.1371/journal.pone.0059970] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Accepted: 02/19/2013] [Indexed: 11/18/2022] Open
Abstract
Natural human exhalation flows such as coughing, sneezing and breathing can be considered as 'jet-like' airflows in the sense that they are produced from a single source in a single exhalation effort, with a relatively symmetrical, conical geometry. Although coughing and sneezing have garnered much attention as potential, explosive sources of infectious aerosols, these are relatively rare events during daily life, whereas breathing is necessary for life and is performed continuously. Real-time shadowgraph imaging was used to visualise and capture high-speed images of healthy volunteers sneezing and breathing (through the nose - nasally, and through the mouth - orally). Six volunteers, who were able to respond to the pepper sneeze stimulus, were recruited for the sneezing experiments (2 women: 27.5±6.36 years; 4 men: 29.25±10.53 years). The maximum visible distance over which the sneeze plumes (or puffs) travelled was 0.6 m, the maximum sneeze velocity derived from these measured distances was 4.5 m/s. The maximum 2-dimensional (2-D) area of dissemination of these sneezes was 0.2 m(2). The corresponding derived parameter, the maximum 2-D area expansion rate of these sneezes was 2 m(2)/s. For nasal breathing, the maximum propagation distance and derived velocity were 0.6 m and 1.4 m/s, respectively. The maximum 2-D area of dissemination and derived expansion rate were 0.11 m(2) and 0.16 m(2)/s, respectively. Similarly, for mouth breathing, the maximum propagation distance and derived velocity were 0.8 m and 1.3 m/s, respectively. The maximum 2-D area of dissemination and derived expansion rate were 0.18 m(2) and 0.17 m(2)/s, respectively. Surprisingly, a comparison of the maximum exit velocities of sneezing reported here with those obtained from coughing (published previously) demonstrated that they are relatively similar, and not extremely high. This is in contrast with some earlier estimates of sneeze velocities, and some reasons for this difference are discussed.
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Affiliation(s)
- Julian W Tang
- Alberta Provincial Laboratory for Public Health, University of Alberta Hospital, Edmonton, Canada.
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42
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Tang JW, Nicolle A, Pantelic J, Koh GC, Wang LD, Amin M, Klettner CA, Cheong DKW, Sekhar C, Tham KW. Airflow dynamics of coughing in healthy human volunteers by shadowgraph imaging: an aid to aerosol infection control. PLoS One 2012; 7:e34818. [PMID: 22536332 PMCID: PMC3335026 DOI: 10.1371/journal.pone.0034818] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 03/05/2012] [Indexed: 11/19/2022] Open
Abstract
Cough airflow dynamics have been previously studied using a variety of experimental methods. In this study, real-time, non-invasive shadowgraph imaging was applied to obtain additional analyses of cough airflows produced by healthy volunteers. Twenty healthy volunteers (10 women, mean age 32.2±12.9 years; 10 men, mean age 25.3±2.5 years) were asked to cough freely, then into their sleeves (as per current US CDC recommendations) in this study to analyze cough airflow dynamics. For the 10 females (cases 1-10), their maximum detectable cough propagation distances ranged from 0.16-0.55 m, with maximum derived velocities of 2.2-5.0 m/s, and their maximum detectable 2-D projected areas ranged from 0.010-0.11 m(2), with maximum derived expansion rates of 0.15-0.55 m(2)/s. For the 10 males (cases 11-20), their maximum detectable cough propagation distances ranged from 0.31-0.64 m, with maximum derived velocities of 3.2-14 m/s, and their maximum detectable 2-D projected areas ranged from 0.04-0.14 m(2), with maximum derived expansion rates of 0.25-1.4 m(2)/s. These peak velocities were measured when the visibility of the exhaled airflows was optimal and compare favorably with those reported previously using other methods, and may be seen as a validation of these previous approaches in a more natural setting. However, the propagation distances can only represent a lower limit due to the inability of the shadowgraph method to visualize these cough airflows once their temperature cools to that of the ambient air, which is an important limitation of this methodology. The qualitative high-speed video footage of these volunteers coughing into their sleeves demonstrates that although this method rarely completely blocks the cough airflow, it decelerates, splits and redirects the airflow, eventually reducing its propagation. The effectiveness of this intervention depends on optimum positioning of the arm over the nose and mouth during coughing, though unsightly stains on sleeves may make it unacceptable to some.
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Affiliation(s)
- Julian W Tang
- Department of Laboratory Medicine, National University Hospital, Queenstown, Singapore.
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Lindsley WG, King WP, Thewlis RE, Reynolds JS, Panday K, Cao G, Szalajda JV. Dispersion and exposure to a cough-generated aerosol in a simulated medical examination room. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2012; 9:681-90. [PMID: 23033849 PMCID: PMC4688889 DOI: 10.1080/15459624.2012.725986] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Few studies have quantified the dispersion of potentially infectious bioaerosols produced by patients in the health care environment and the exposure of health care workers to these particles. Controlled studies are needed to assess the spread of bioaerosols and the efficacy of different types of respiratory personal protective equipment (PPE) in preventing airborne disease transmission. An environmental chamber was equipped to simulate a patient coughing aerosol particles into a medical examination room, and a health care worker breathing while exposed to these particles. The system has three main parts: (1) a coughing simulator that expels an aerosol-laden cough through a head form; (2) a breathing simulator with a second head form that can be fitted with respiratory PPE; and (3) aerosol particle counters to measure concentrations inside and outside the PPE and at locations throughout the room. Dispersion of aerosol particles with optical diameters from 0.3 to 7.5 μm was evaluated along with the influence of breathing rate, room ventilation, and the locations of the coughing and breathing simulators. Penetration of cough aerosol particles through nine models of surgical masks and respirators placed on the breathing simulator was measured at 32 and 85 L/min flow rates and compared with the results from a standard filter tester. Results show that cough-generated aerosol particles spread rapidly throughout the room, and that within 5 min, a worker anywhere in the room would be exposed to potentially hazardous aerosols. Aerosol exposure is highest with no personal protective equipment, followed by surgical masks, and the least exposure is seen with N95 FFRs. These differences are seen regardless of breathing rate and relative position of the coughing and breathing simulators. These results provide a better understanding of the exposure of workers to cough aerosols from patients and of the relative efficacy of different types of respiratory PPE, and they will assist investigators in providing research-based recommendations for effective respiratory protection strategies in health care settings.
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Affiliation(s)
- William G Lindsley
- National Institute for Occupational Safety and Health, Health Effects Laboratory Division, 1095 Willowdale Road, Morgantown, WV 26505-2845, USA.
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