Is "double masking" (wearing two masks) recommended to prevent COVID-19 transmission?
CDC recommends using layers of material to reduce respiratory droplets leaking in and out of your mask. One layering strategy is to use a cloth mask that has multiple layers of fabric. Another strategy is to wear two masks or to
“double mask”. One way to do this is to wear a medical procedure mask underneath a cloth mask. The second mask should push the edges of the inner mask against your face, reducing the amount of air that leaks around the edges of the masks. A recent study conducted in a laboratory found that this “double mask” combination provided much better protection to the wearer and to others as compared with a cloth mask by itself or a medical procedure mask by itself.
However, the following mask combinations should not be used to "double mask"
Do not combine two medical procedure masks to create a “double mask.” Medical procedure masks are not designed to fit tightly and wearing a second medical procedure mask on top of the first medical procedure mask does not help to improve the fit.
Do not combine a KN95 mask with any other masks. You should only useone KN95 mask at a time, and you should not use any type of second mask on top of or underneath a KN95 mask. Find more information about masks on the CDC website.
How can I improve the fit of my mask to prevent air leakage?
Nose Wires: Use cloth or medical procedure masks that have a nose wire (a metal strip along the top of the mask) to help prevent air leakage at the top of the mask. Nose wires can also help to prevent fogging of eyeglasses. To get a good fit, make sure to bend the nose wire over the nose to conform to your face.
Mask fitters and braces: These devices can be used over a medical procedure mask or cloth mask to imrpve the fit by helping reduce air leakage from around the edges of the mask.
Knotting and tucking: Knot the ear loops of a 3-ply face mask where they join the edge of the mask, then fold and tuck the unneeded material under the edges. This method is called “knotting and tucking” (for instructions see this youtube video).