Japanese supercomputer simulations showed that only two masks provided a limited advantage in preventing viral transmission compared to one properly equipped mask.
The findings partially contradict recent recommendations from the U.S. Centers for Disease Control and Prevention (CDC) that two masks were better at reducing the human exposure to coronavirus.
Researchers used the Fugaku supercomputer to model the flow of virus particles from humans with different types and combinations of masks, according to a study published Thursday by research giant Riken and Kobe University.
Using one surgical-type mask, made of non-woven material, had an 85% effectiveness in preventing particles when worn tightly around the nose and the face. Placing a polyurethane mask on top increased the efficiency to just 89%.
Wearing two non-woven masks is not helpful as air force builds up and causes leakage around the edges.
“Achieving double-mindedness just doesn’t add up,” wrote the researchers, led by Makoto Tsubokura.
In general, N95 professional grade masks were best in protecting against infection, followed by non-woven masks, cloth masks, and finally polyurethane types, the study showed.
The Riken research team previously used the Fugaku supercomputer to model how humidity can affect viral infections and the risks of infection in trains, workplaces and other environments.
As COVID-19 epilepsy has worn off, scientific consensus has grown that the virus is spread through the air and masks are effective in controlling infection.