Ever since the COVID-19 pandemic started, two main rules have been recommended by the WHO; wearing of face mask and social distancing. Since the virus causes respiratory disease, it is imperative to wear mask especially in public areas. The mask filters the air we breath and thus, reduces the infection rate.
Since then many people have been making home made masks. As long as they know how to sew, they feel its enough. There are also hundreds of videos on YouTube where people show how to make face masks at home in the simplest way. But the question is, what are the best materials that should be used to make the face mask most effective.
To answer this question, a group of researchers from the University of Chicago and the Argonne National Laboratory used various fabrics such as cotton, chiffon, spandex and polyester both individually and in combination.
Since it also depends on the size of droplets a person can breath in, they used an aerosol mixing chamber which produced particles of different diameters ranging from 10 nanometers to 6 micrometers at a flow rate similar to a person’s breath while at rest. They also measured the number and size of the particles before and after passing through the fabric samples.
They noted that a mask with three layers; the combination of one tightly woven cotton with two layers of polyester-spandex chiffon was the most effective, filtering out up to 99% of particles. Other combinations with the cotton such as natural silk and cotton quilt with cotton-polyester batting were equally effective.
The reason is two fold. The two different materials provide a double barrier with the cotton providing a mechanical barrier while the other fabric provides a static barrier.
A similar study was carried out by another group at the Florida Atlantic University’s College of Engineering and Computer Science. The group leader, Dr Siddartha Verma commented that simple masks such as a bandana or a handkerchief cannot provide any protection.
“Quilting cotton, with two layers stitched together, turned out to be the best in terms of stopping capability,” he explained. “For minimizing the chances of transmission, it is important to use masks made of a good seal along the edges without being uncomfortable.”
Surgical masks can be also be used where available. However those are mainly used by healthcare professionals.On the other hand, both groups also stressed on the proper wearing of the mask. Even a 1% gap can make a big difference.
“The effect of gaps between the contour of the face and the mask, as caused by an improper fit, will affect the efficiency of any face mask,” the group from the University of Chicago added.
Both groups also pointed out that social distancing and washing the homemade masks can affect their effectiveness.