This illustration shows a woman wearing two face masks, a cloth mask over a surgical mask, on February 8, 2021 in Arlington, Virginia.
Olivier Douliery | AFP | Getty Images
Wearing a cloth mask over a surgical mask can significantly reduce the risk of exposure to Covid-19 and improve the fit of a mask, according to a new study from the Centers for Disease Control and Prevention.
The CDC researchers said they studied the effectiveness of different masking approaches through laboratory experiments in which they placed two artificial heads 6 feet apart and measured how many coronavirus-sized particles exhaled by one were inhaled by the other.
The researchers found that wearing just one mask, either surgically or with a cloth, prevented just over 40% of the particles from simulating breathing through an unmasked head. However, a cloth mask on a surgical mask blocked about 80% of the particles from an unmasked head. When both heads of the experiment wore two masks, more than 95% of the particles were blocked, the researchers found.
The study also found that a tighter fit can improve the effectiveness of masks. One way to improve the fit of medical masks is to “knot and stow” them. This is accomplished, said the CDC, “by bringing the corners and ear loops together on each side, tying the ear loops together where they attach to the mask, and then tucking in and flattening the resulting additional mask material to fill the side gaps minimize.”
The agency found that about 96% of the particles were blocked when both heads were wearing a knotted and hidden mask. If one of the heads wore a knotted and hidden mask and the other did not, just over 60% of the particles were blocked.
CDC director Dr. Rochelle Walensky said the results of the study “underscore the importance of wearing a mask properly and making sure it fits snugly and firmly over your nose and mouth.”
Walensky said the agency isn’t changing its original recommendation that everyone two years and older wear a mask when they’re around people who don’t live in their household.
However, the agency will update its guidelines on its website “to provide new options to improve mask customization,” Walensky said.
Those options include wearing a mask with a malleable nasal wire or wearing a cloth mask over a disposable surgical mask, she said. She added that there are new devices called mask assemblers that can help tighten a drape or medical mask for a tighter fit.
“The bottom line is, masks work and they work best when they fit well and are worn properly,” Walensky said.
The updated guidance is the latest attempt by President Joe Biden’s administration to provide clear guidance to Americans. Walensky has hired CDC scientists to review all of the agency’s guidelines issued under the previous administration to ensure they are clear and consistent.
The issue of masking became controversial last year when health officials urged Americans to wear masks in public despite President Donald Trump’s refusal to wear a mask in public for months.
The updated guidance comes at an important time in the US outbreak. Cases, hospitalizations and deaths are all decreasing, but health officials are warning that new, more contagious variants could reverse the country’s progress and cause further spikes. Reducing the spread of the virus and its new variants remains important as the country moves to vaccinate the public but is hampered by limited supplies, according to health officials.
Biden has urged all Americans to commit to wearing masks in public for his 100 days in office to help slow the spread of the virus. As of February 1, 14 states and the District of Columbia had universal masking mandates, the CDC said. Biden has also mandated the wearing of masks on all federal properties, as well as on domestic and international transportation, including public buses, trains, and planes.
