New peer-reviewed research says coronavirus droplets caused by talking remain in the air for 8-14 minutes.
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‘Speaking causes airborne virus transmission’: Coronavirus study says droplets caused by talking can last 8-14 minutes
Published: May 14, 2020 at 4:35 p.m. ET
By
Quentin Fottrell
New peer-reviewed research gives more insight into COVID-19’s rapid contagion
Talking spreads coronavirus — and likely plays a part in its contagiousness.
That’s the conclusion of a new study released Thursday published in the peer-reviewed Proceedings of the National Academy of Sciences, the official journal of the National Academy of Sciences. “These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments,” the study concludes.
‘Speech droplets generated by asymptomatic carriers of SARS-CoV-2 are increasingly considered to be a likely mode of disease transmission.’
— study published in the Proceedings of the National Academy of Sciences
The study adds to a growing body of research on why it’s important that people maintain social distancing and wear face masks. The response to COVID-19 has become a political issue. President Donald Trump and New York Gov. Andrew Cuomo have locked horns over when to reopen the economy.
“Speech droplets generated by asymptomatic carriers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are increasingly considered to be a likely mode of disease transmission,” the study found. “Highly sensitive laser light scattering observations have revealed that loud speech can emit thousands of oral fluid droplets per second.”
In a closed, stagnant-air environment, they disappear from view after 8 minutes to 14 minutes, “which corresponds to droplet nuclei of ca. 4um diameter, or 12um to 21um droplets prior to dehydration,”
the researchers wrote. One micrometer, um, is equivalent to one millionth of a meter. The coronavirus is 0.125 um. Medical-grade N95 masks are worn by medics because they can block particles of that size.
The scientists said that, while it’s long been recognized that respiratory viruses such as coronavirus can be transmitted via droplets generated by coughing or sneezing, it’s less widely known that normal speaking also produces thousands of oral fluid droplets. High viral loads of SARS-CoV-2 have been detected in oral fluids of COVID-19−positive patients, including asymptomatic ones.
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Some public spaces appear to be more hostile environments to coronavirus than others, according to
a separate study published in the journal Nature Research by a team of investigators, led by Ke Lan, professor and director of the State Key Laboratory of Virology at Wuhan University in the Chinese region where COVID-19, the disease caused by SARS-CoV-2, was first reported.
Room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can help reduce droplet spread.
High-traffic areas are best to be avoided, especially where there’s moisture. After setting up traps for small aerosols (airborne particles) in two hospitals in Wuhan, the researchers found more coronavirus aerosols in patients’ bathrooms and in changing rooms for doctors. “The potential for aerosol transmission is poorly understood,” the researchers wrote.
The study had some good news for hospitals: There were fewer aerosols in isolation wards and patient rooms with good ventilation and thorough sanitization, that study found. “Our results indicate that room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can effectively limit the concentration of SARS-CoV-2 RNA in aerosols,” they wrote.
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