Those who choose to wear a mask made of thin nylon -- or bandana material -- are not doing themselves or others much good when it comes to protecting from the COVID-19 virus, Western Carolina University Engineering Professor Hayri Sezer has found through a lab test.
“We find the neck scarf (bandana) was not effective at all,” said Sezer.
Using Schlieran imaging that uses a high-speed camera, a mirror and a human subject, Sezer and his engineering students were able to examine the concentration of air flow coming out from the subject’s mouth using different types of masks.
The imaging showed flow from coughing both with and without masks, with the goal of illustrating how easily particles that could contain the COVID-19 virus can flow into the air of a person choosing to wear inferior masks during the pandemic.
“The camera is a high-speed camera taking 10,000 frames per second," Sezer said.
“The jersey mask did better,” Sezer said.
He and his students tested WCU sweatshirt-type jersey material. The visual imaging of the cough flow shown was a vast improvement over thinner masks tested in terms of amount of particles the material blocked.
Sezer also found on the flow image results that air inevitably escapes from the top of a typical mask, which he feels isn’t something that can be fixed.
“I would advise against constantly trying to adjust your mask because that, too, can contaminate your mask," Sezer said. "The air flows up rather than directly out.”
He felt for that reason the concern is minimal and that the emphasis for flow concern should be for breath flow going directly towards another person or persons when masks are made of thin, flimsy material.
“I’m very interested in this topic,” said Ulises Vargas, a WCU engineering major. “We’re in a pandemic. It’s crucial to find information -- good information -- and that’s what we’re trying to do here.”
Vargas and two other engineering students in Sezer’s flow visualization class are ramping up for a different mask test that will measure the size of particles and speed at which they come out of a test subject’s mouth.
“To see how fast a cough leaves your mouth,” said Luke Meares, an engineering student participating in the study. “Or if it goes through the mask, or if the mask is effective in stopping it.”