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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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Deng Z, Chen Q. What is suitable social distancing for people wearing face masks during the COVID-19 pandemic? INDOOR AIR 2022; 32:e12935. [PMID: 34605574 PMCID: PMC8652892 DOI: 10.1111/ina.12935] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/05/2021] [Accepted: 09/18/2021] [Indexed: 05/06/2023]
Abstract
COVID-19 has caused the global pandemic and had a serious impact on people's daily lives. The respiratory droplets produced from coughing and talking of an infected patient were possible transmission routes of coronavirus between people. To avoid the infection, the US Centers for Disease Control and Prevention (CDC) advised to wear face masks while maintaining a social distancing of 2 m. Can the social distancing be reduced if people wear masks? To answer this question, we measured the mass of inhaled droplets by a susceptible manikin wearing a mask with different social distances, which was produced by coughing and talking of an index "patient" (human subject) also wearing a mask. We also used the computational fluid dynamics (CFD) technology with a porous media model and particle dispersion model to simulate the transmission of droplets from the patient to the susceptible person with surgical and N95 masks. We compared the CFD results with the measured velocity in the environmental chamber and found that the social distancing could be reduced to 0.5 m when people wearing face masks. In this case, the mass concentration of inhaled particles was less than two people without wearing masks and with a social distancing of 2 m. Hence, when the social distancing was difficult, wearing masks could protect people. We also found that the leakage between the face mask and the human face played an important role in the exhaled airflow pattern and particle dispersion. The verified numerical model can be used for more scenarios with different indoor environments and HVAC systems. The results of this study would make business profitable with reduced social distancing in transportation, education, and entertainment industries, which was beneficial for the reopening of the economy.
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Affiliation(s)
- Zhipeng Deng
- School of Mechanical EngineeringPurdue UniversityWest LafayetteINUSA
| | - Qingyan Chen
- Department of Building Environment and Energy EngineeringThe Hong Kong Polytechnic UniversityKowloonHong Kong
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Okrasa M, Leszczyńska M, Sałasińska K, Szczepkowski L, Kozikowski P, Nowak A, Szulc J, Adamus-Włodarczyk A, Gloc M, Majchrzycka K, Ryszkowska J. Viscoelastic Polyurethane Foams with Reduced Flammability and Cytotoxicity. MATERIALS (BASEL, SWITZERLAND) 2021; 15:151. [PMID: 35009298 PMCID: PMC8746040 DOI: 10.3390/ma15010151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 12/11/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
Consistent and proper use of respiratory protective devices (RPD) is one of the essential actions that can be taken to reduce the risk of exposure to airborne hazards, i.e., biological and nonbiological aerosols, vapours, and gases. Proper fit of the facepiece and comfort properties of RPDs play a crucial role in effective protection and acceptance of RPDs by workers. The objective of the present paper was to develop viscoelastic polyurethane foams for use in RPD seals characterised by proper elasticity, allowing for the enhancement of the device fit to the face and the capability of removing moisture from the skin in order to improve the comfort of RPD use. Moreover, it was pivotal to ensure the non-flammability of the foams, as well as a simultaneous reduction in their cytotoxicity. The obtained foams were characterised using scanning electron microscopy, infrared spectroscopy, thermogravimetry, and differential scanning calorimetry. Measurements also involved gel fraction, apparent density, compression set, rebound resilience, wettability, flammability, and cytotoxicity. The results are discussed in the context of the impact of modifications to the foam formulation (i.e., flame-retardant type and content) on the desired foam properties. The test results set directions for future works aimed to develop viscoelastic polyurethane foams that could be applied in the design of respiratory protective devices.
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Affiliation(s)
- Małgorzata Okrasa
- Department of Personal Protective Equipment, Central Institute for Labour Protection—National Research Institute, Wierzbowa 48, 90-133 Lodz, Poland; (A.A.-W.); (K.M.)
| | - Milena Leszczyńska
- Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warszawa, Poland; (M.L.); (K.S.); (M.G.); (J.R.)
| | - Kamila Sałasińska
- Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warszawa, Poland; (M.L.); (K.S.); (M.G.); (J.R.)
- Department of Chemical, Aerosol and Biological Hazards, Central Institute for Labour Protection—National Research Institute, Czerniakowska 16, 00-701 Warszawa, Poland;
| | | | - Paweł Kozikowski
- Department of Chemical, Aerosol and Biological Hazards, Central Institute for Labour Protection—National Research Institute, Czerniakowska 16, 00-701 Warszawa, Poland;
| | - Adriana Nowak
- Department of Environmental Biotechnology, Lodz University of Technology, 90-530 Lodz, Poland; (A.N.); (J.S.)
| | - Justyna Szulc
- Department of Environmental Biotechnology, Lodz University of Technology, 90-530 Lodz, Poland; (A.N.); (J.S.)
| | - Agnieszka Adamus-Włodarczyk
- Department of Personal Protective Equipment, Central Institute for Labour Protection—National Research Institute, Wierzbowa 48, 90-133 Lodz, Poland; (A.A.-W.); (K.M.)
| | - Michał Gloc
- Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warszawa, Poland; (M.L.); (K.S.); (M.G.); (J.R.)
| | - Katarzyna Majchrzycka
- Department of Personal Protective Equipment, Central Institute for Labour Protection—National Research Institute, Wierzbowa 48, 90-133 Lodz, Poland; (A.A.-W.); (K.M.)
| | - Joanna Ryszkowska
- Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warszawa, Poland; (M.L.); (K.S.); (M.G.); (J.R.)
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Monjezi M, Jamaati H. The effects of face mask specifications on work of breathing and particle filtration efficiency. Med Eng Phys 2021; 98:36-43. [PMID: 34848036 PMCID: PMC8493656 DOI: 10.1016/j.medengphy.2021.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/01/2021] [Accepted: 10/04/2021] [Indexed: 11/29/2022]
Abstract
The outbreak of the ongoing coronavirus disease 2019 (COVID-19) pandemic has led to the recommended routine use of face masks to reduce exposure risk. In this study, the increase in work of breathing (WOB) imposed by face masks is theoretically studied for both normals and patients with obstructive and restrictive lung diseases at different levels of activity. The results show a significant increase in WOB due to face masks, which is more severe in higher activity levels. The added WOB is considerable during physical activity and may be intolerable for patients with preexisting lung disease and may contribute to inspiratory muscle fatigue and dyspnea. Moreover, in this study, the effects of the physical properties of a fibrous medium, including thickness, porosity, and fiber diameter, are analyzed on the particle filtration efficiency (PFE) and the added WOB. The relations between the physical properties of the fibrous medium and the added WOB and the PFE are shown on some contour plots as a quick and simple tool to select the desired physical properties for a single layer filter to ensure that the added WOB is comfortable while the PFE is sufficiently high.
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Affiliation(s)
- Mojdeh Monjezi
- Chronic Respiratory Diseases Research Center (CRDRC), Critical Care Department Shaheed Bahonar Ave., National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Darabad, Tehran 1955841452, Iran
| | - Hamidreza Jamaati
- Chronic Respiratory Diseases Research Center (CRDRC), Critical Care Department Shaheed Bahonar Ave., National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Masih Daneshvari Hospital, Shahid Beheshti University of Medical Sciences, Darabad, Tehran 1955841452, Iran.
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Kolesnik K, Bryan D, Harley W, Segeritz P, Guest M, Rajagopal V, Collins DJ. Respiration mask waveguide optimisation for maximised speech intelligibility. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 150:2030. [PMID: 34598640 DOI: 10.1121/10.0006235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
Both the scarcity and environmental impact of disposable face masks, as in the COVID-19 pandemic, have instigated the recent development of reusable masks. Such face masks reduce transmission of infectious agents and particulates, but often impact a user's ability to be understood when materials, such as silicone or hard polymers, are used. In this work, we present a numerical optimisation approach to optimise waveguide topology, where a waveguide is used to transmit and direct sound from the interior of the mask volume to the outside air. This approach allows acoustic energy to be maximised according to specific frequency bands, including those most relevant to human speech. We employ this method to convert a resuscitator mask, made of silicone, into respiration personal protective equipment (PPE) that maximises the speech intelligibility index (SII). We validate this approach experimentally as well, showing improved SII when using the fabricated device. Together, this design represents a unique and effective approach to utilize and adapt available apparatus to filter air while improving the ability to communicate effectively, including in healthcare settings.
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Affiliation(s)
- Kirill Kolesnik
- Biomedical Engineering Department, The University of Melbourne, Melbourne 3010, Australia
| | - David Bryan
- Biomedical Engineering Department, The University of Melbourne, Melbourne 3010, Australia
| | - William Harley
- Biomedical Engineering Department, The University of Melbourne, Melbourne 3010, Australia
| | - Philipp Segeritz
- Biomedical Engineering Department, The University of Melbourne, Melbourne 3010, Australia
| | - Matthew Guest
- Perioperative and Critical Care Services, Western Health, St. Albans 3021, Australia
| | - Vijay Rajagopal
- Biomedical Engineering Department, The University of Melbourne, Melbourne 3010, Australia
| | - David J Collins
- Biomedical Engineering Department, The University of Melbourne, Melbourne 3010, Australia
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Abstract
Many governments have imposed the public use of face masks and they are now moving towards enforcing disposable masks to abate COVID-19 transmission. While disposable masks consistently provide higher protection, they also carry multiple environmental burdens, from greenhouse gases released during production to the landfilling and littering. Conversely, reusable masks’ protection can vary from >90% certified industrial masks, similar to disposable masks, to dubious homemade or artisanal masks. This work discusses the protection provided by different masks, their impact on the environment, and new proposals combining concerns about public health and sustainability.
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