Scientists at Fukuoka University in Japan have found that frequently used face shields do not protect against airborne transmission of the coronavirus. To do this, they studied the dynamics of the air flow that occurs when an infected person sneezes and coughs, next to a person’s face. The research results are reported in an article published in the journal Physics of Fluids.
It is known that when sneezing in the air, vortices in the form of a ring appear, which are formed when the aerosol is suddenly ejected from round holes. The vortex captures airborne droplets and particles, including viruses. Simulations have shown that viruses can travel one meter in 0.5-1 seconds, falling over the top and bottom edges of the flap (only about 4.4 percent of the total number of drops). Moreover, if the wearer of the shield inhales, then the drops with the virus will inevitably enter the respiratory system.
Scientists have come to the conclusion that face shields can be improved to reduce the amount of air entering it. Researchers are currently developing and testing several options for improved personal protective equipment.