Ignazio Maria Viola1, Brian Peterson1, Gabriele Pisetta1, Geethanjali Pavar1, Hibbah Akhtar1,2, Filippo Menoloascina1, Enzo Mangano1, Katherine E Dunn1, Roman Gabl1, Alex Nila3, Emanuela Molinari4, Cathal Cummins5, Gerard Thompson6, Tsz-Yan Milly Lo7,8, Fiona C Denison9, Paul Digard10, Omair Malik11, Mark J G Dunn12, Catherine M McDougall7, Felicity V Mehendale8. 1. 1 School of EngineeringUniversity of Edinburgh Edinburgh EH9 3BF U.K. 2. 2 Department of Mechanical EngineeringUniversity of Engineering and Technology Lahore Lahore 54890 Pakistan. 3. 3 Lavision U.K. Ltd. Bicester EH8 9AB U.K. 4. 4 School of InformaticsUniversity of Edinburgh Edinburgh EH14 4AS U.K. 5. 5 Maxwell Institute for Mathematical Sciences, Department of Mathematics and Institute for Infrastructure and EnvironmentHeriot-Watt University Edinburgh EH16 4SB U.K. 6. 6 Centre for Clinical Brain Sciences, University of Edinburgh Edinburgh EH16 4SB U.K. 7. 7 Paediatric Critical Care Unit, Royal Hospital for Sick Children Edinburgh EH16 4UX U.K. 8. 8 Usher InstituteUniversity of Edinburgh Edinburgh EH16 4UX U.K. 9. 9 The Queen's Medical Research InstituteUnivesity of Edinburgh Edinburgh EH16 4TJ U.K. 10. 10 The Roslin InstituteUniversity of Edinburgh Midlothian EH25 9RG U.K. 11. 11 Department of AnaesthesiaRoyal Hospital for Sick Children Edinburgh EH9 1LF U.K. 12. 12 Department of Critical CareNHS Lothian Edinburgh EH1 3EG U.K.
Abstract
The SARS-CoV-2 virus is primarily transmitted through virus-laden fluid particles ejected from the mouth of infected people. Face covers can mitigate the risk of virus transmission but their outward effectiveness is not fully ascertained. Objective: by using a background oriented schlieren technique, we aim to investigate the air flow ejected by a person while quietly and heavily breathing, while coughing, and with different face covers. Results: we found that all face covers without an outlet valve reduce the front flow through by at least 63% and perhaps as high as 86% if the unfiltered cough jet distance was resolved to the anticipated maximum distance of 2-3 m. However, surgical and handmade masks, and face shields, generate significant leakage jets that may present major hazards. Conclusions: the effectiveness of the masks should mostly be considered based on the generation of secondary jets rather than on the ability to mitigate the front throughflow. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/.
The SARS-CoV-2 virus is primarily transmitted through virus-laden fluid particles ejected from the mouth of infected people. Face covers can mitigate the risk of virus transmission but their outward effectiveness is not fully ascertained. Objective: by using a background oriented schlieren technique, we aim to investigate the air flow ejected by a person while quietly and heavily breathing, while coughing, and with different face covers. Results: we found that all face covers without an outlet valve reduce the front flow through by at least 63% and perhaps as high as 86% if the unfiltered cough jet distance was resolved to the anticipated maximum distance of 2-3 m. However, surgical and handmade masks, and face shields, generate significant leakage jets that may present major hazards. Conclusions: the effectiveness of the masks should mostly be considered based on the generation of secondary jets rather than on the ability to mitigate the front throughflow. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/.
Entities:
Keywords:
COVID-19 pandemic; aerosol dispersal; aerosol generating procedures; face coverings; face masks
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