A study shows that several layers of cotton cloth masks block droplets and aerosol contamination of the environment so they may help reduce the transmission of COVID-19.
Cloth masks protect against COVID-19
Associate professor of medicine at McMaster University and nephrologist at St. Joseph's Healthcare Hamilton, first author Catherine Clase said that the point of wearing masks is not that some particles could penetrate them. It is so but that they could stop some particles from entering body canals, outwardly from the wearer in particular.
Admittedly, she said that we want a mask to work in both directions, protecting the wearer and reducing contamination of the environment, including surfaces and air, from the wearer.
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The international research team that Clase is part of studied "a century of evidence, including recent data." They found that there is strong evidence that shows that cloth and cloth masks could help reduce surface and air contamination.
Clase noted that they did not find direct evidence that wearing any mask outside of a healthcare setting could help reduce the actual transmission of COVID-19. This lack of evidence has made public-health decisions regarding wearing of masks complicated. Subsequently, opinions about wearing masks in public vary across the globe.
She then said that their review suggests that cloth could block particles that include aerosol-sized particles, which supports Canadian public health policy regarding the issue.
Cloth masks protect others from the wearer
During the 1960s and 1970s, researchers found that cloth masks could protect others from the wearer. They discovered that cloth masks made of three layers, muslin-flannel-muslin, could help reduce surface contamination by 99 percent and total airborne microorganisms by 99 percent.
They also found that bacteria recovered from the smaller particles and aerosols were reduced by 88 to 99 percent.
A four-layer cotton muslin commercial mask could reduce all particles by 99 percent compared to contemporary disposable medical masks, which could only reduce from 96 to 99 percent.
Researchers also said that cloth masks had a better reduction of contamination from aerosols than medical masks.
Cloth's filtration effect varies. A single layer of scarf, t-shirt, and sweatshirt could have protection from 10 to 40 percent, and by multiplying the layers, you also increase its efficiency. Modern studies show that some combinations of cloth, such as cotton-flannel, could block more than 90 percent of particles.
Clase said that their work is just one part of a complicated puzzle. She added that one should note that when making masks, they should remember that more layers will provide protection both inward and outward. However, it will be harder to breathe, so this is not recommended for children under two years of age and people with difficulty breathing.
She also said that more research is still needed to find the best material and design to use for cloth masks so that people who are sewing masks are aware and be able to protect the people in their community.
Finally, Clase said that due to the severity of the pandemic and difficulty of controlling it, they suggest that the benefits of wearing cloth masks outweigh the possibility of them harming.
