Small speech droplets are now eyed as a likely mode of the coronavirus transmission, instead of coughing or sneezing droplets, according to a recent study.
The study published Wednesday by the Proceedings of the National Academy of Sciences in the US, showed the potential importance of the airborne lifetime of small speech droplets in COVID-19 spread.
“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 the window of view with time constants in the range of 8 to 14 min,” it said.
The observations confirmed there is a substantial probability that normal speaking causes airborne virus transmission in confined environments.
Researchers said although it has long been recognized that respiratory viruses can be transmitted via droplets generated by coughing or sneezing, it is less widely known that normal speaking also produces thousands of oral fluid droplets with a broad size distribution.
Those small droplets can harbor a variety of respiratory pathogens, including measles and influenza virus as well as Mycobacterium tuberculosis.
High viral loads of severe acute respiratory syndrome coronavirus have been detected in oral fluids of infected patients, including asymptomatic ones, according to the study.
But the possible role of small speech droplets, which potentially could remain airborne for extended periods, has not been widely appreciated, it added.
Since emerging in China last December, the coronavirus has spread to 188 countries and territories, infecting more than 4.37 million people and killed nearly 300,000. In all, an excess of 1.56 million have recovered.
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