Ever since the COVID-19 outbreak happened a global debate about whether everyone should wear surgical masks in public has been brewing for quite some time. Recommendations about masks can easily get confusing, because all masks are not made equal, further varying guidance from expects and shifting guidelines from organisations add to the confusion over the effectiveness of each type of masks against the contagious virus.
Posts with an image has been circulating online which shows four different masks: An N95 mask, a surgical mask, a sponge and a cloth mask. The post claims that N95 and surgical masks both provide 95% protection, while sponge and cloth(home-made) masks offer none.
Homemade/Cloth masks are ineffective at protecting against the spread of COVID-19.
The claim is misleading.
Types Of Masks
N95 masks provide maximum protection and can effectively prevent viral spread. When properly fitted, these masks seal closely to the face and filter out 95% of particles which are 0.3 microns in size or larger.
However, there is a shortage of N95 masks even for medical professionals, who are exposed to the highest levels of SARS-CoV-2 and therefore the most in need of the strongest protection against the virus.
Surgical masks don't seal against the face, having said that it consists of non-woven polypropylene layers which are moisture resistant.
These types of masks allow about 70% of the outside air to move through the mask and about 30% travels around the sides. This is why they don't offer as much protection as N95s.
Fabric masks also permit air in around the sides, however, these lack non-woven, moisture-repelling layers. Only about 2% of airflow is obstructed in this case. Now let's talk about home made cloth masks.
Efficacy of Cloth Masks
Considering the scarcity of N95 masks, surgical masks and sponge face masks around the world, homemade masks could be effective at preventing the spread of the coronavirus as long as they are made correctly.
Thick cloth and a tight seal around the wearer's face are the two necessary features of an effective mask.
"Given the current crisis, and lacking an alternative, many layers of densely woven fabric would be the most effective because it allows for lots of voids in the layers where particles can be trapped," PolitiFact quoted Richard Peltier, an assistant professor of environmental health sciences at the University of Massachusetts-Amherst as saying.
"The mask needs to seal as tightly as possible to the face to avoid leaks, though this may not be possible with different designs, fabrics, or face shapes. Thin or porous fabrics are the least likely to be effective," he added.
An experiment was conducted by the researchers at the National Institutes of Health, U.S. using lasers to demonstrate and measure how many droplets of saliva were released into the air when a person talks with and without a cloth facial covering. The study was published in The New England Journal of Medicine.
The video of the experiment showed a cluster of droplets appearing when the researcher speaks without a mask, however nearly all the particles are blocked when he does the same with a mask.
It is noteworthy to mention that this study didn't show micro-droplets, which leaves room for further research and the need to gauge how many viral particles these smaller droplets can contain. It did, however, demonstrate that a cloth mask is better than no mask.
The authors mention that they did not assess the relative roles of droplets generated during speech, droplet nuclei and aerosols in the transmission of viruses. Through their study, they aimed at providing visual evidence of speech-generated droplets and to qualitatively describe the effect of a damp cloth cover over the mouth to curb the emission of droplets.
Therefore, homemade fabric might help keep people with COVID-19 from unknowingly passing along the virus.
Since fabric masks are not expected to provide as much protection as surgical masks, Public health officials continue to warn people to maintain at least 6 feet distance from one another, even if they are wearing masks.
"Putting a face mask on does not mean that you stop the other practices," Livescience quoted May Chu, a clinical professor in epidemiology at the Colorado School of Public Health on the Anschutz Medical Campus as saying.
"It does not mean you get closer to people, it does not mean you don't have to wash your hands as often and you can touch your face. All of that still is in place, this is just an add-on," she added.
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