Researchers at Virginia Tech University tested 11 different types of face masks, including nine cloth masks made from materials such as coffee filters, a cotton T-shirt, and other fabrics as well as a face shield and surgical mask, Yahoo! News reports. And there was a clear winner.
“We recommend now based on this study that people use a three-layer mask,” Linsey Marr, PhD, a leading aerosol scientist at Virginia Tech and co-author of the study, said during a press conference on Nov. 23. Specifically, Marr recommends a mask in which “the outer two layers are a tightly woven but flexible material that allows the mask to conform to your face,” with a layer made of vacuum bag or filtration material in the middle. If that’s the case, your face covering could allow filtration as high as 90 percent, the researchers found.
The findings back up a study published in the journal Science Advances in September out of Duke University. For that report, researchers tested 14 different masks’ ability to block respiratory droplets, and they found that other than N95s, a three-layer surgical mask allowed the fewest number of droplets to get by its barrier. And coming in third was a three-layer mask with polypropylene acting as a filter between two layers of cotton.
The Virginia Tech scientists conducting the experiment were quick to point out that, unlike the Duke researchers, they didn’t include medical-grade N95 masks—which are named such for their ability to trap at least 95 percent of particles—because “for practical reasons, having the general public run around in N95s is a challenge because of the shortage,” Marr explained.
But the most useful discovery of the experiment is that even a homemade DIY solution can be greatly beneficial to those who choose to make their own mask. “It’s not something I would ask a health care worker to wear in high-risk situations,” Marr said. “They need the best protection we can get. But given that it’s impractical to have everyone in the general public walking around wearing an N95, I think homemade masks are definitely helpful.” And for more on what works best, check out The Materials You Need to Make the Perfect Face Mask.
With the study, Marr and her team set out to determine whether masks were beneficial beyond just stopping the spread of the virus. By testing the efficiency of different types of masks, they also discovered which could provide another level of protection.
“Filtration works both ways,” Marr said. “If it works for source control, it’s going to work pretty well for exposure reduction to protect the wearer also,” which means that any mask efficient enough to stop particles from being exhaled into the air will also be good enough to keep them from being inhaled. And for more up-to-date information on COVID, sign up for our daily newsletter.
Still, researchers were quick to add that masks aren’t the only thing that will bring about the end of the pandemic. Following other public health guidelines can also play a huge role in keeping everyone safe.
“No one study by itself is going to tell you the whole story,” Marr said. “And no one intervention—masking, social distancing, hand washing, indoor ventilation—will stop the spread of COVID-19 alone. The mask is one of the many interventions that we need to combine together.” And for more on coronavirus guidelines, check out The CDC Is Now Warning You Not to Go to This One Place.