A study published in the peer-reviewed journal Matter in July found that wearing two masks could increase protection from virus particles by 50% up to 75%. It not only added an extra layer of protection but also made the mask fit snugger around the face.
Consideration for double masking has become more relevant as variants that appear to be more contagious emerge from the U.K, South Africa, Brazil and California.
A single-layer mask isn’t really effective in blocking aerosols, studies show, and even homemade two- and three-ply fabric masks are only partially protective — somewhere in the 50% to 60% range of effectiveness.
The best option is to wear a cloth mask tightly over a surgical mask, providing an additional layer of filtration and improving the fit. A second option is to wear a three-layer mask that conforms tightly to the face. The idea is to use your mask as a filter and avoid having aerosols escaping out the side or bottom of your mask unfiltered.
“The idea of double masking just simply means that you’re paying attention to wearing a better mask than you might have been before,” Emory University infectious disease expert Dr. Colleen Kraft said. “If people would just wear masks in general, we would actually be fine against the variants.”