說話可以傳播冠狀病毒 How important is speech in transmitting coronavirus?

News Release 3-Apr-2020

University of California – Davis

Normal speech by individuals who are asymptomatic but infected with coronavirus may produce enough aerosolized particles to transmit the infection, according to aerosol scientists at the University of California, Davis. Although it’s not yet known how important this is to the spread of COVID-19, it underscores the need for strict social distancing measures — and for virologists, epidemiologists and engineers who study aerosols and droplets to work together on this and other respiratory diseases.

Aerosols are particles small enough to travel through the air. Ordinary speech creates significant quantities of aerosols from respiratory particles, said William Ristenpart, professor of chemical engineering at UC Davis. Ristenpart is co-author on an editorial about the problem to be published in the journal Aerosol Science and Technology.

These respiratory particles are about one micron, or one micrometer, in diameter. That’s too small to see with the naked eye, but large enough to carry viruses such as influenza or SARS-CoV-2.

Some individuals superemitters

Last year, Ristenpart, graduate student Sima Asadi and colleagues published a paper showing that the louder one speaks, the more particles are emitted and that some individuals are “superemitters” who give off up to 10 times as many particles as others. The reasons for this are not yet clear. In a follow-up study published in January in PLOS One, they investigated which speech sounds are associated with the most particles.

Calculating just how easily a virus like SARS-CoV-2 spreads through droplets requires expertise from different fields. From virology, researchers need to know how many viruses are in lung fluids, how easily they form into droplets and how many viruses are needed to start an infection. Aerosol scientists can study how far droplets travel once expelled, how they are affected by air motion in a room and how fast they settle out due to gravity.

“The aerosol science community needs to step up and tackle the current challenge presented by COVID-19, and also help better prepare us for inevitable future pandemics,” Ristenpart and colleagues conclude.

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Other authors on the editorial are Asadi; Professor Anthony Wexler, UC Davis Department of Mechanical and Aerospace Engineering; and Nicole Bouvier, Icahn School of Medicine at Mount Sinai.

加州大學戴維斯分校的氣溶膠科學家稱，無症狀但被冠狀病毒感染的人的正常言語可能產生足夠的氣溶膠顆粒來傳播感染。儘管目前尚不清楚這對COVID-19的傳播有多重要，但它強調了必須採取嚴格的社會隔離措施，並且需要研究氣溶膠和飛沫的病毒學家，流行病學家和工程師共同應對這種和其他呼吸道疾病。

氣溶膠的微粒足夠小，可以在空氣中傳播。加州大學戴維斯分校化學工程教授威廉·里斯滕帕特說，普通的講話會從呼吸道顆粒中產生大量的氣溶膠。 Ristenpart是有關該問題的社論的合著者，該社論將發表在《 Aerosol Science and Technology》雜誌上。

這些呼吸顆粒的直徑約為一微米或一微米。這個體積很小，無法用肉眼看到，但足夠大，可以攜帶流感或SARS-CoV-2等病毒。

一些個人超級發射者

去年，Ristenpart，研究生Sima Asadi及其同事發表了一篇論文，該論文表明，聲音越大，發射出的顆粒越多，並且有些人是“超級發射器”，其發射的微粒最多是其他人的10倍。其原因尚不清楚。在1月份發表於PLOS One的一項後續研究中，他們調查了哪些語音與大多數微粒相關。

計算像SARS-CoV-2這樣的病毒通過飛沫傳播的難易程度，需要來自不同領域的專業知識。通過病毒學，研究人員需要知道肺液中有多少種病毒，它們如何容易地形成液滴以及需要多少種病毒才能開始感染。氣溶膠科學家可以研究液滴一旦被排出會傳播多遠，它們如何受到室內空氣運動的影響以及它們在重力作用下沉降的速度有多快。

Ristenpart及其同事總結道：“氣霧劑科學界需要加緊應對COVID-19提出的當前挑戰，並幫助我們更好地為不可避免的未來大流行做好準備。”

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社論中的其他作者是Asadi；加州大學戴維斯分校機械與航天工程系Anthony Wexler教授；和西奈山伊坎醫學院的Nicole Bouvier。