Can cloth masks be a substitute for N95 masks?
Due to worldwide pandemic of novel corona virus disease (Covid-19), the use of face mask has increased many folds to the extent that the demand have exceeded supply. On one side the common man is being seen using industrial grade N95 mask while a health care provider is facing the short supply of the suitable mask. To clarify the matter based on evidence, and to educate the professionals as well as common man, this article will discuss the filtration ability of the masks made of cloths and compare it to N95 masks.
The Americal Chemical Society have reported about an experiment that showed that the masks made by a combination of cloths are as effective as an N95 masks.
The researchers at the University of Chicago performed a study to check the filtration ability of the cloth masks. They made masks by joining one layer of tightly woven cotton sheet1 and two layers of polyester-spandex chiffon2, which is a fabric commonly used in evening gowns. These masks filtered out 80% to 90% aerosol particles ranging from 10 nanometres to 6 micrometres in diameter at normal human respiratory flow rate and volume. This performance was close to N95 mask materials. Similar results were obtained when natural silk or flannel or cotton quilt with cotton polyester batting were substituted for the chiffon.
By this experiment, the researchers indicated that tightly woven fabric such as cotton can act as a mechanical barrier to aerosol particles, where the fabrics that hold a static charge like certain types of chiffon and natural silk serve as an electrostatic barrier. The researchers cautioned, however, that even 1% gap reduces the filtering efficiency of all masks by half or more. This fact emphasizes the proper fitting of a mask to the face.
So, what did we learn after reading this article?
The author concludes that for a common man, a cloth mask that has been made judiciously is sufficient to protect anyone from common diseases caused by viruses and bacteria, that are transmitted by aerosols or droplets. A mask fabricated by cloths will protect a man or a woman if they wear it with a proper fit to the face. A common man or woman should always use cloth mask while going out of home. A mask made up of cloth will be economical to the pocket and preserve the national resources for more specific needs.
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