Scientists have assessed the filtering efficiency provided by various types of facemask modifications, and found that masks made of two layers of woven nylon are some of the most effective when fit snug against the wearer's face.
The scientists, including those from the University of North Carolina (UNC) School of Medicine in the US, noted that over the course of the COVID-19 pandemic, there have been a number of innovative ''hacks,'' devices, and mask enhancements that claim to improve the performance of conventional masks.
However, they believe there have been few evaluations of the efficiency of these face coverings or mask enhancements at filtering airborne particles. In the study, published in the journal JAMA Internal Medicine, the scientists assessed the protectiveness of various kinds of consumer-grade and modified masks, assuming the mask wearer was exposed to the virus.
According to the researchers, surgical masks offered 38.5 percent filtration efficacy, but when the ear loops were tied in a specific way to tighten the fit, the efficacy improved to 60.3 percent. When a layer of nylon was added, they said these masks offered 80 percent effectiveness.
''Limiting the amount of virus is important because the more viral particles we're exposed to, the more likely it is we will get sick and potentially severely ill,'' said Emily Sickbert-Bennett, another co-author of the study from UNC.
The study found that cotton bandanas folded and worn as ''bandit style masks'' were only 49 percent effective, whereas N95 respirators were 98 percent protective. According to the researchers, the presence of nose bridges, and the washing of cotton and nylon masks, significantly improved their protectiveness.
''While modifications to surgical masks can enhance the filtering capabilities and reduce inhalation of airborne particles by improving the fit of the mask, we demonstrated that the fitted filtration efficiencies of many consumer-grade masks were nearly equivalent to or better than surgical masks,'' said study co-first author Phillip Clapp from the UNC School of Medicine.
