However, when using multiple layers of fabrics, filtration efficiency significantly increased to more than 80 percent for smaller particles and more than 90 percent for larger ones.
The most effective combination for filtering out aerosol particles was found to be a layer of a tightly woven cotton sheet combined with two layers of polyester-spandex chiffon, which filtered out 80 to 99 percent of particles, depending on their size. In fact, the researchers say that this combination performed close to that of an N95 mask material.
If you don’t have any polyester-spandex chiffon to hand, then substituting this fabric with natural silk or flannel, or a cotton quilt with cotton-polyester batting, was found to produce similar results. The researchers add that cotton, which is the more common material used for cloth masks, performs better when it has a tighter weave, so try to choose a cotton with a higher thread count if possible.
However, whatever fabric you choose, the team also points out that getting the right fit is also important, with the results also showing that gaps caused by a bad fit could reduce the filtering efficiency of all masks by over 60 percent.
The US Centers for Disease Control and Prevention, along with many organizations and governments around the world, recommend that people wear masks when out in public. However, many have questioned whether home-made attempts with everyday fabrics are useful in helping to prevent the spread of the disease.
Based on the new findings, the researchers conclude that masks made using a combination of readily available fabrics still have the potential to provide significant protection from respiratory aerosol droplets.
