You still want a cotton layer closest to your face, he says, because it's a more comfortable material. But adding a filter made out of two layers of charged polypropylene could boost that filtration efficiency by as much as another 35%, Cui says. Cui says a two-layer tight-weave cotton mask alone can filter out about 35% of small particles. Once you've got static cling, ka-ching - you're back in business. "That's what you want - the cling is what's important," Chu says.Īnd unlike other materials, polypropylene keeps its electrostatic charge in the humidity created when you breathe out, says Yi Cui, a professor of materials science and engineering at Stanford University who co-authored the Nano Letters study with Chu.Ĭui and Chu note that polypropylene will lose its electrostatic charge when you wash it, but you can recharge it by ironing it or by rubbing it with a plastic glove for around 20 seconds. That's basically what's happening with this fabric: That "cling" effect traps incoming - and outgoing - droplets. Think of the static cling that can happen when you rub two pieces of fabric together, says Chu. In other words, it uses the power of static electricity. It's also called spunbond," says Chu, who's a scientific adviser to the World Health Organization and helped craft its recent detailed guidance on cloth masks.Ĭhu says polypropylene is great as a physical filter but has another benefit: It holds an electrostatic charge. "If you go to Walmart, you look for Oly-fun, which is the brand name of that fabric. The best bet for the material to slip in as a filter is polypropylene, which is derived from plastic, says Chu. Life Kit What You Need To Know About Protective Face Masks But if you can't breathe well through it, then you're less likely to keep it on. How well a mask protects is a function of both what it's made of and how well it seals to your face. When choosing a mask, experts say focus on the fabric, fit and breathability. When you combine masks with those measures, they can make a big difference. No mask will offer full protection, and they should not be viewed as a replacement for physical distancing of at least 6 feet from others, frequent hand-washing and avoiding crowds. That's the main reason to wear a mask: to protect other people from you.įace masks can also offer the wearer some protection - though how much varies greatly, depending on the type of mask. So you want to wear a face mask? Good call.Ī growing body of evidence supports the idea that wearing face masks in public, even when you feel well, can help curb the spread of the coronavirus - since people can spread the virus even without showing symptoms. hospitals a pleated surgical mask (below the KN95) a cloth mask. Left to right: a neck gaiter (aka a buff) that slips over the head a KN95 respirator, a version of the N95 respirator used in U.S.
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