The CDC released guidance on the use of 2 masks and the modification of a single procedure mask to improve performance.
The CDC study examined a 3-ply cloth cotton mask placed over a 3-ply medical procedure mask. It also examined a medical procedure mask with knots tied in the earloops near the mask, and excess material tucked in at the edge.
The primary benefit of double masking or mask modification is the improved fit of the mask on your face. Specifically, it seals the gaps on the edges of your mask (side gaps).
