New Delhi: Wearing two strictly face masks can nearly double the filtering efficiency of SARS-CoV-2 particles, preventing them from reaching the wearer’s nose and mouth and causing COVID-19, according to a study.
The research, published in the journal JAMA Internal Medicine, shows that the reason for the improved filtration is not so much adding layers of tissue, but removing any gaps or poorly fitted areas of mask.
“Medical procedure masks are designed to have very good filtration potential in terms of their material, but the way they match our faces is not perfect,” said Emily Sickbert-Bennett, an associate professor at the University of North Carolina (UNC) in the United States. , and lead author of the study.
To test the proper filtration efficiency (FFE) of a range of masks, the team filled a 10-foot by 10-foot stainless steel display room with small salt particles.
The researchers wore a combination of masks to test how effective they kept items out of their breathing space.
Each individual mask or layered mask combination was equipped with a metal sample port attached to a tube in the exposure chamber that measured the concentration of particles entering the respiratory space under the researcher’s mask.
A second tube measured the ambient concentration of particles in the chamber.
The researchers determined the FFE by measuring particle concentration in the breathing space under the mask compared to that in the chamber.
“We also asked that the researchers in the room undergo a series of movement activities to simulate the typical movements a person can make throughout their day – bending at the waist, talking and looking left, right, up and down,” Phillip said. Clapp of UNC Medical School.
According to their findings, the basic FFE of a mask differs from person to person, due to the unique face and mask of each individual.
Generally a procedure mask without changing the fit affects about 40-60% to keep COVID-19 particles large, the researchers said.
A cloth mask affects about 40%, they said.
Their latest findings on duplication of face masks show that when a tissue mask is placed over a surgical mask, the FFE has improved by about 20%.
The filtration efficiency was improved even more by a comfortable fit sleeve type, such as a layered sleeve, according to the researchers.
If layered over procedural masks, fabric masks are enhanced by removing gaps and keeping the procedural mask closer to the face, constantly covering the nose and mouth.
When a procedural mask is worn over a fabric mask, FFE improved by 16 percent.
“We’ve found that wearing two loose masks won’t give you the filtering advantage that one comfortable procedural mask will have,” Sickbert-Bennett said.
“And with the current data supporting how effective mask wear prevents the spread of COVID-19, the best kind of double masking is when you and the person you’re interacting with correctly wear a very comfortable mask,” she added.