
Universal masking is one of the prevention strategies recommended by CDC to slow the spread of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19)
(1). As of February 1, 2021, 14 states and the District of Columbia had universal masking mandates.
Mask wearing has also been mandated by executive order for federal property as well as on domestic and international transportation conveyances.
Cloth masks and medical procedure masks fit more loosely than do respirators (e.g., N95 facepieces).
The effectiveness of cloth and medical procedure masks can be improved by ensuring that they are well fitted to the contours of the face to prevent leakage of air around the masks’ edges.
During January 2021, CDC conducted experimental simulations using pliable elastomeric source and receiver headforms wearing a sleeve made of sheer nylon hosiery material around the neck and pulling it up over either a cloth or medical procedure mask.
https://www.cdc.gov/mmwr/volumes/70/wr/pdfs/mm7007e1-H.pdf