Many Americans are now advised to wear masks while outside to prevent the spread of COVID-19, according to the CDC — and this may be the case for quite some time. But highly protective yet scarce N95 and surgical masks need to be reserved for healthcare workers, so those who aren't on the frontlines should instead resort to buying or making masks with other fabrics.
Researchers now suggest that a combination of cotton with natural silk or chiffon (yes, the material many nighties are made out of) could effectively filter out airborne particles. Since the coronavirus can be spread through respiratory droplets — say when an infected person coughs or sneezes — University of Chicago professor Supratik Guha and his fellow researchers set out to determine which readily available materials best filter out the droplets.
In an article published by the American Chemical Society, the researchers explained how they came to their conclusion. After producing particles in an aerosol mixing chamber, they used fans to blow the particles at different fabrics at the same rate a human would at rest. They then measured the size of the particles before and after passing through the fabrics.
As it turns out, one layer of tightly-woven cotton combined with two layers of polyester-spandex chiffon filtered out around 80 to 99 percent of particles, making it the most effective. The researchers also got similar results substituting the chiffon with natural silk or flannel, as well as using a cotton quilt with cotton-polyester batting.
These results are comparable to the effectiveness of N95 mask material, but Guha and his team also emphasized the need for masks to fit correctly. Just a one-percent gap can reduce the mask's efficiency by half, or more.