U.S. government researchers have found that wearing two masks is better than one in slowing coronavirus spread, but health officials are not recommending that everyone double up.
On Wednesday February 10, the Centers for Disease Control and Prevention reported the results of a lab experiment that spaced two artificial heads 6 feet from each other and checked to see how many coronavirus-sized particles spewed by one were inhaled by the other.
The researchers found that wearing one mask ‘surgical or cloth’ blocked around 40% of the particles coming toward the head that was breathing in. When a cloth mask was worn on top of a surgical mask, about 80% were blocked.
When both the exhaling and inhaling heads were double-masked, more than 95% of the particles were blocked, said the CDC’s, Dr. John Brooks.
“The first challenge is to get as many as people as possible masking. And then for those that do mask, to help them get the best benefit out of that mask,” Brooks said.
The study had many limitations: The researchers used one brand of surgical mask and one kind of cloth mask, and it’s not clear if results would be the same with every product. But it echoes some earlier research that suggests two masks are better than one.
“It works,” Brooks said.
The CDC also was updating its guidance to address wearing two masks. If done correctly, a cloth mask worn over a surgical mask can tighten the gaps around the mask’s edges that can let virus particles in, the CDC said.
The report also said that some Americans have already started doubling up and experts believe that’s at least partly out of concern about new strains of coronavirus that have been found to spread more easily than the one that has driven the U.S. epidemic for the past year.
Discussions about double-masking and higher-quality masks are important, said Dr. Isaac Bogoch, an infectious diseases scientist at the University of Toronto.
“But if a significant proportion of your populations isn’t wearing a mask in the first place, then you’re having the wrong conversation,” he added.