Wearing two masks delivers little additional benefit in blocking the viral spread of COVID-19 compared with one properly fitted mask, according to Japanese supercomputer simulations.
Using a single, good-fitting surgical-type mask, made of non-woven material, provides 85% effectiveness in blocking particles, Reuters reported. But adding a second polyurethane mask on top of the first one increased effectiveness to just 89%. And wearing two non-woven masks doesn't work, either, because air resistance within them forces air to leak out round the edges.
"The performance of double masking simply does not add up," wrote the researchers, led by Makoto Tsubokura.
"Researchers used the Fugaku supercomputer to model the flow of virus particles from people wearing different types and combinations of masks, according to a study released on Thursday by research giant Riken and Kobe University," Reuters wrote. "The Riken research team previously used the Fugaku supercomputer to model how humidity can affect viral contagion and the infection risks in trains, work spaces, and other environments."
But the U.S. Centers of Disease Control and Prevention – along with the nation's top immunologist, Dr. Anthony Fauci – have said that two masks are better than one.
Fauci, an immunologist and director of the National Institute of Allergy and Infectious Diseases, who served on former President Trump’s White House Coronavirus Task Force and is now President Biden’s chief medical adviser on COVID-19, said in January that two masks are likely more effective than one.
"If you have a physical covering with one layer, you put another layer on it, just makes common sense that it likely would be more effective," Fauci said NBC News.
The New York Times also reported in January that two masks are better than one..
"Football coaches do it. President-elects do it. Even science-savvy senators do it. As cases of the coronavirus continue to surge on a global scale, some of the nation’s most prominent people have begun to double up on masks – a move that researchers say is increasingly being backed up by data," reads a Times story.
During the presidential campaign, Biden was seen wearing two masks as he traveled to North Carolina for a campaign stop, one cloth mask atop a surgical-type one.
"Biden, who was photographed wearing a white mask under a Navy blue one, was joined by (son) Hunter’s teen daughter, Finnegan, just days after her father’s emails made national headlines," the Daily Mail reported. "Finnegan also appeared to be wearing a white mask under a Navy blue one that read: 'Vote.' "
Also in January, CNBC reporter Contessa Brewer said three masks is even better than two, citing unnamed "experts."
"So yeah, the experts keep telling us that wearing masks is really about protecting ourselves, protecting others from ourselves in the event that we are contagious," Brewer said. "But you know if other people aren’t wearing their masks or they’re wearing them improperly, we need to protect ourselves. So experts say you can double up with a tight weave fabric mask for added protection."