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Trajectories of large respiratory droplets in indoor environment: A simplified approach

The recent pandemic of COVID-19 has brought about tremendous impact on every aspect of human activities all over the world. The main route of transmission is believed to be through coronavirus-bearing respiratory droplets. The respiratory droplets have a wide spectrum in droplet size, ranging from v...

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Detalles Bibliográficos
Autores principales: Cheng, C.H., Chow, C.L., Chow, W.K.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier Ltd. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7431329/
https://www.ncbi.nlm.nih.gov/pubmed/32836704
http://dx.doi.org/10.1016/j.buildenv.2020.107196
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author Cheng, C.H.
Chow, C.L.
Chow, W.K.
author_facet Cheng, C.H.
Chow, C.L.
Chow, W.K.
author_sort Cheng, C.H.
collection PubMed
description The recent pandemic of COVID-19 has brought about tremendous impact on every aspect of human activities all over the world. The main route of transmission is believed to be through coronavirus-bearing respiratory droplets. The respiratory droplets have a wide spectrum in droplet size, ranging from very small droplets (aerosol droplets) to large droplets of tens and even hundreds of μm in size. The large droplets are expected to move like projectiles under the action of gravity force, buoyancy force and air resistance. Droplet motion is complicated by droplet evaporation, which reduces droplet size in its trajectory and affects the force acting on it. The present work attempts to determine the trajectories of the large droplets by using a simplified single-droplet approach. It aims at providing a clear physical picture to elucidate the mechanics involved in single droplet motion and the various factors affecting the range. Assuming an indoor environment with an air temperature of 18 °C and relative humidity of 50%, the horizontal range [Formula: see text] of large respiratory droplets (diameter 120 μm–200 μm) in common respiratory activities are as follows: Speaking, [Formula: see text] ≈ 0.16 m–0.68 m, coughing, [Formula: see text] ≈ 0.58 m–1.09 m, and sneezing, [Formula: see text] ≈ 1.34 m–2.76 m. For the smaller droplets (diameter < 100 μm), the droplets are reduced to aerosol droplets (≤5 μm) due to evaporation, and will remain suspended in the air instead of falling onto the ground like a projectile.
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spelling pubmed-74313292020-08-18 Trajectories of large respiratory droplets in indoor environment: A simplified approach Cheng, C.H. Chow, C.L. Chow, W.K. Build Environ Article The recent pandemic of COVID-19 has brought about tremendous impact on every aspect of human activities all over the world. The main route of transmission is believed to be through coronavirus-bearing respiratory droplets. The respiratory droplets have a wide spectrum in droplet size, ranging from very small droplets (aerosol droplets) to large droplets of tens and even hundreds of μm in size. The large droplets are expected to move like projectiles under the action of gravity force, buoyancy force and air resistance. Droplet motion is complicated by droplet evaporation, which reduces droplet size in its trajectory and affects the force acting on it. The present work attempts to determine the trajectories of the large droplets by using a simplified single-droplet approach. It aims at providing a clear physical picture to elucidate the mechanics involved in single droplet motion and the various factors affecting the range. Assuming an indoor environment with an air temperature of 18 °C and relative humidity of 50%, the horizontal range [Formula: see text] of large respiratory droplets (diameter 120 μm–200 μm) in common respiratory activities are as follows: Speaking, [Formula: see text] ≈ 0.16 m–0.68 m, coughing, [Formula: see text] ≈ 0.58 m–1.09 m, and sneezing, [Formula: see text] ≈ 1.34 m–2.76 m. For the smaller droplets (diameter < 100 μm), the droplets are reduced to aerosol droplets (≤5 μm) due to evaporation, and will remain suspended in the air instead of falling onto the ground like a projectile. Elsevier Ltd. 2020-10 2020-08-18 /pmc/articles/PMC7431329/ /pubmed/32836704 http://dx.doi.org/10.1016/j.buildenv.2020.107196 Text en © 2020 Elsevier Ltd. All rights reserved. Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.
spellingShingle Article
Cheng, C.H.
Chow, C.L.
Chow, W.K.
Trajectories of large respiratory droplets in indoor environment: A simplified approach
title Trajectories of large respiratory droplets in indoor environment: A simplified approach
title_full Trajectories of large respiratory droplets in indoor environment: A simplified approach
title_fullStr Trajectories of large respiratory droplets in indoor environment: A simplified approach
title_full_unstemmed Trajectories of large respiratory droplets in indoor environment: A simplified approach
title_short Trajectories of large respiratory droplets in indoor environment: A simplified approach
title_sort trajectories of large respiratory droplets in indoor environment: a simplified approach
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7431329/
https://www.ncbi.nlm.nih.gov/pubmed/32836704
http://dx.doi.org/10.1016/j.buildenv.2020.107196
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