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A basic clothing item that you likely already have tucked away in a drawer could make your homemade coronavirus face mask more protective, according to a preliminary study.
Researchers at Northeastern University in Boston determined that wearing pantyhose over a mask could help to filter out more airborne particles when compared to wearing a mask alone.
The pantyhose creates a snugger fit around the wearer’s face, sealing in the loose edges of the masks, said Loretta Fernandez, an assistant professor of civil and environmental engineering at Northeastern University and one of the study’s authors.
For the study, researchers determined the percent particle removal for 10 homemade, fabric masks “of different designs, with and without filter layers, as well as three commercially-produced surgical-type masks.” They noted that “N95 masks were used to validate the method, and a 3M model 1826 surgical mask was used as a baseline for comparison of other masks of this style.”
They used an instrument called a PortaCount to measure how well the masks filtered out air particles, ranging from 20 nanometers to 1,000 nanometers, according to NPR. (For context, SARS-CoV-2, the virus that causes COVID-19, is about 60 to 140 nanometers in diameter.)
When testing a 3M surgical mask, for instance, the researchers determined that without the pantyhose, the mask blocked out 75 percent of small particles. With the added pantyhose layer, however, some 90 percent of small particles were blocked.
"Adding a layer that keeps the mask tight to the face is going to improve the function of any of these masks," Fernandez told NPR. “How well they protect us is not only a matter of what material we're using to do the filtering but also how well [the mask] seals to the face, so that we're trying to avoid air making it around the mask into our breathing zone."
The findings come as more states mandate some sort of facial covering while running essential errands, which is in line with recently updated Centers for Disease Control and Prevention (CDC) guidelines.
As for homemade fabric masks, when worn with pantyhose, performance increased between 15 and 50 percent, the researchers found. When worn alone, these masks blocked 30 percent or less of particles.
To add the pantyhose layer, researchers cut a ring of material from one leg of the stockings, about 8 to 10 inches from top to bottom, according to NPR.