Cloth Face Coverings [Masks] provide a physical barrier that reduces the transfer of airborne droplets which cause respiratory infections. A properly fitted face covering only increase protection when it fits snuggly across the nose, along the sides of the face and under the chin. A face covering/mask does not guarantee protection against the transmission of any disease.
https://extension.okstate.edu/coronavirus/media/home/diy-masks-english-covid-19.pdf
This series was created by Dr. Lynn Boorady and Dr. Sumit Mandal with Design, Housing, and Merchandising, and Karla Knoepfli with Oklahoma 4H and is as part of the OSU Extension effort in combating COVID-19.
You can find more information at the following websites:
https://www.cdc.gov/
https://extension.okstate.edu/coronavirus.html