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By Karen Nikos-Rose on April 16, 2020

This story by Andy Fell

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 co-wrote an editorial about the problem to be published April 3 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.

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.

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