Double masks doubly effective
The director of the Centers for Disease Control and Prevention is now urging people to double-mask to help prevent the spread of the coronavirus.
Dr. Rochelle Walensky, who was recently appointed by U.S. President Joe Biden to take over the agency, also recommended wearing masks with a mouldable nose wire; knotting the ear loops on the mask; and including a cloth mask over the disposable mask.
The Atlanta-based CDC reported the results of a lab experiment that spaced two artificial heads two metres 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 about 40 per cent 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 per cent were blocked.
When both the exhaling and inhaling heads were double-masked, more than 95 per cent 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 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 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 agency also said it was taking down a do-ityourself page, which went up last year when masks were in short supply and the CDC was encouraging people to take steps to interrupt viral transmission.
Some Americans have already started doubling up. 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
Mask-wearing has long been common in some countries during respiratory outbreaks, especially in parts of Asia, but not in the United States. Maskwearing has increased, and some places enforced mask mandates, but a recent University of California survey suggested that only about half of U.S. adults wear masks when in close contact with people outside their household.
Discussions about double-masking and higherquality 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.