The study, which was done by researchers from the University of Chicago and the Argonne National Laboratory, looked into which fabrics are best for filtering the tiny respiratory droplets released when a person sneezes, coughs, speaks or breathes, which are believed to be the primary ways that COVID-19 is transmitted.
The researchers investigated the fabrics’ effectiveness at filtering droplets, particularly the smallest ones that are known as aerosols, by using an aerosol mixing chamber that produces particles ranging from 10 nanometers to 6 micrometers in diameter. A fan blew the aerosols across different fabric samples at a speed similar to the breathing of a person at rest. Then, the researchers measured the number and size of the particles in the air before and after they passed through the fabric samples.
The researchers found that when a single layer of fabric was used, the fabrics’ filtering efficiency ranged between 5 to 80% and 5 to 90%, depending on the size of the particles. When multiple layers of fabric were used, however, the filtering efficiency climbed up to over 80% for smaller particles and over 90% for larger particles.
The researchers also found that the combination of fabrics that is most effective in filtering out aerosols was a layer of tightly woven cotton and two layers of polyester-spandex chiffon. This combination filters out between 80% and 99% of particles, depending on their size, prompting the researchers to say that it even works similar to N95 masks.
ADVERTISEMENT - CONTINUE READING BELOW
Cotton is a relatively common material, but make sure to use cotton with a higher thread count for your mask. Polyester-spandex chiffon, on the other hand, might be less common, so you can substitute it with natural silk, flannel, or a cotton quilt with cotton-polyester, which were found to be just as effective.
Aside from the fabric you use, the fit of the mask is also important, the researchers say. The study says that a bad fit can reduce a mask’s filtering efficiency by over 60%.
For a step-by-step guide on how to create a no-sew mask, click here.