WASHINGTON [US]: A new study by the University of North Carolina Health Care shows that wearing two facials can double the efficiency of filtering SARS-CoV-2-sized particles, preventing them from reaching the wearer’s nose and mouth and causing COVID-19.
The findings published in JAMA Internal Medicine also state that the reason for the improved filtration is not to add too many layers of cloth, but to eliminate any gaps or poorly suited areas of a mask.
“Medical procedure masks are designed to have very good filtering potential based on their material, but the way they fit our faces is not perfect,” said Emily Sickbert-Bennett, PhD, Associate Professor of Infectious Diseases at UNC School of Medicine and lead author of the study.
To test the mounted filtering efficiency (FFE) of a range of masks, UNC researchers worked with James Samet, PhD, and colleagues at the USEPA School of Humanities on the UNC-Chapel Hill campus. There they filled a 10-foot by 10-foot stainless steel display chamber with small aerosols of salt particles and asked researchers to give combinations of masks to test how effective they were at keeping particles out of their breathing space.
Each individual mask or layered mask combination was fitted with a metal sample port, which was attached to the tubing in the exposure chamber which measured the concentration of particles entering the breathing space under the mask of the researcher. A second tube measured the ambient concentration of particles in the chamber. By measuring the concentration of particles in the breathing space under the mask compared to that in the room, the researchers determined FFE.
“Also, the researchers in the room underwent a series of movement activities to simulate the typical movements that a person can make during the day – bending at the waist, talking and looking left, right, in up and down, ”said Phillip Clapp, PhD, an inhalation toxicologist at UNC School of Medicine, who has been testing the FFE mask with Sickbert-Bennett since the pandemic began.
According to their findings, the basic adaptive filtration efficiency (FFE) of a mask differs from person to person, due to the unique fit of each person’s face and mask. But in general, a procedure mask without changing the adjustment is about 40-60% effective in maintaining particles the size of COVID-19. A cloth mask is about 40% effective.
Their recent findings on doubling face masks show that when a cloth mask is placed over a surgical mask, FFE has improved by about 20% and improved even more with a comfortable, sleeve-like mask. an ice. When layered over procedure masks, cloth masks improve fit by eliminating gaps and keeping the procedure mask closer to the face, constantly covering the nose and mouth. When a procedure mask is worn over a cloth mask, the FFE improved by 16%.
“We’ve found that wearing two lightly mounted masks won’t give you the benefit of filtering a single procedure mask,” said Sickbert-Bennett. “And with current data supporting how effective it is to wear a mask to prevent the spread of COVID-19, the best type of double-sided mask is when you and the person you are interacting with are wearing a very suitable mask. ”(AGENCY)