Study: Coronavirus May Spread Through Speech, Lingering in Air for Minutes

Published in the PNAS (Proceedings of the National Academy of Sciences of the United States of America) journal, this study shows that saliva droplets "are increasingly considered a likely mode of coronavirus transmission".

The researchers used a laser light scattering method that allowed them to discover that a person who speaks loudly in a closed space can potentially emit thousands of droplets per second. These droplets could remain suspended in the air for 8 to 14 minutes.

"It has long been recognized that respiratory viruses can be transmitted through droplets generated by coughing or sneezing. It is less widely known that speech also produces thousands of oral fluid droplets [...] Droplets can contain a variety of respiratory pathogens, including measles and influenza virus as well as Mycobacterium tuberculosis (the bacterium responsible for tuberculosis, editor’s note)," the researchers explain.

According to them, the laser light scattering method also provides "not only real-time visual evidence of the emission of saliva droplets, but also evaluates their lifespan in the air." "This direct visualization shows how speech generates airborne droplets that can remain suspended for tens of minutes or more and are capable of transmitting disease in confined spaces," they indicate.

The research teams also specify that "the viral load of saliva varies greatly from one patient to another".