Is It Just Cloth?

By Leo Kong '21

The COVID-19 pandemic hit the United States in February2020, and has been striking the U.S. in the past half a year. Under this special condition, in order to have our school teaching continue to operate safely, masks become necessary. What is inside a mask? Is it really just layers of cloth covering your mouth and nose up so that there’s no droplet transmission?

The type of masks that work ideally to filtrate bacteria while maintaining air permeability are the surgical ones made of non-woven fabric. The majority of surgical masks have three layers with the filtration layer, which has the highest packing density, between the outer layer and the inner shell. The entire layers are structured in an order so that they can filter the particles in the order of size.

The outer layer is water-repellent with good air permeability and dust repellent. It’s characteristics allow this layer to repel bodily fluids and larger airborne particles that are released by talking, coughing and sneezing. This layer can be treated as the barrier that filters out the largest bacteria-carrying particles.

The middle filtration layer also has good air permeability with dust prevention, but it has the critical function of filtrating pathogens. It is the barrier dedicated for smaller particles like germs and viruses. Both the outer layer and the filtration layer are charged with static electricity with the fibers so that the particles will cling to the fibers as they try to pass by. They virtually utilize the same concept when you rub a balloon against your clothes and have it stick to the wall, or when you open up your new TV and the styrofoam sticks to your clothes.

Meanwhile the inner layer, since it has direct contact with the wearer's skin, absorbs moisture from the wearer as they exhale and sweat. Without the moisture absorbability of the inner layer, the middle layer would quickly become humid and lose its static electricity charge. This disables its ability to capture the minute particles, and the mask is pretty much useless: this is also the reason why you should keep changing your masks if you are wearing surgical ones.

Studies show that cloth masks, compared to surgical masks, tend to be less capable of blocking microbial aerosol (suspension of fine solid particles or liquid droplets in air), though still able to reduce aerosol exposure. Still, the filtration effectiveness of cloth masks largely depend on factors like thread count, number of layers, and type of fabric. Cotton ones tend to perform better than the gauze ones, and those with polypropylene work the best because that’s what the middle layer of surgical masks are made of.

So next time you go out and buy a mask, watch out for what material they are made of. Other than that, washing your hands and keeping social distance are always the rule of gold.

Tung, Tracie. “When Covering Your Face, Consider the Science of Surgical Masks.” CSUN Today

csunshinetoday.csun.edu/community/when-covering-your-face-consider-the-science-of-surgical-masks-csun-experts.

Henneberry, Brittany. “How Surgical Masks Are Made.” Thomas Net

www.thomasnet.com/articles/other/how-surgical-masks-are-made/#_Types_of_Masks.

Chughtai, Abrar, et al. “Effectiveness of Cloth Masks for Protection Against Severe Acute Respiratory Syndrome Coronavirus 2.” Centers for Disease Control and Prevention

wwwnc.cdc.gov/eid/article/26/10/20-0948_article.