How Effective is a Homemade Mask at Protecting Against Coronavirus?

After months of actively saying the general public shouldn’t wear masks, the White House and Centers for Disease Control and Prevention (CDC) shifted policy for non-medical professionals, recommending that people wear face coverings to protect themselves (and others) from the novel coronavirus.

This whiplash on mask policy now means essential businesses around the country—such as some grocery stores and many doctor’s offices—now require the public to wear masks simply to enter. But with national medical equipment shortages, people have been left to their own devices, and many have started making their own face coverings.

What changed? Previously, experts thought the only way to contract the virus was person-to-person respiratory droplet transmission—through the moisture you see and feel after a cough or sneeze. But after the outcome of a Washington state choir practice in March in which nearly two-thirds of the attendees became sick—despite nobody showing symptoms like sneezing or coughing—officials began to realize that transmission through another source might be taking place: via much smaller particles, called aerosols, that hang longer in exhaled air.

The idea that someone’s bad breath could make you fatally ill is disturbing and all the more reason to don a face mask. But how effective is your home-made version? We spoke to experts to find out just how protective that piece of cloth really is.

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What a face mask can do for you

How well your homemade version can protect you is up for debate. Shawn Nasseri, MD, otolaryngologist (that’s an ear, nose, and throat specialist) and surgeon at Cedars Sinai in Los Angeles, believes there is some value to cloth facial coverings—but with the caveats that surgical and respiratory masks are better. “DIY masks can help keep the area clean and clear but they are not as effective as surgical or respiratory masks. The materials and filtration systems used to make surgical or respiratory masks are what make them more effective than DIY cotton masks.”

Because of the lack of hard data, some experts are on the fence about whether those homemade versions truly protect the wearer. “There is not much actual evidence based on scientific studies one way or the other on this question. Just a few hints, and the truth is unknown,” says Jonathan D. Mayer, PhD, professor emeritus at the University of Washington, and an expert in infectious disease epidemiology. “However, if cloth masks are made the way in which CDC and other bodies are recommending that they be made, especially out of cotton bedsheets or finely meshed T-shirts—that sort of thing—the thinking is that these may trap some of the larger droplets that contain the virus, and hence will serve as barriers for these larger droplets.”

Other doctors are adamant that cloth face masks provide zero protection. “Cloth face masks have no place in healthcare whatsoever,” says Lisa Brosseau, a retired professor from the University of Illinois at Chicago and an expert in respiratory protection. “If it’s a droplet or spray problem, you’d be better off wearing a face shield that covers your whole face. Imagining that cloth masks will make a difference, that something is better than nothing—that’s dangerous.”

While the doubters raise valid concerns, most experts still believe in the value of wearing a mask—and it has less to do with protecting yourself from others: It’s much more about keeping you from spreading the virus.

A barrier between you and the vulnerable

“The value of wearing a mask is more about protecting other people,” says Paula Cannon, PhD, professor of Molecular Microbiology and Immunology at the Keck School of Medicine at the University of Southern California. “The virus has this sneaky trick whereby people can be infected and not know it,” she explains. “You can be both presymptomatic—where you’ve already got the virus and you’ll wake up tomorrow feeling lousy but you are shedding virus without knowing it—or the other possibility is if you can frankly be completely asymptomatic.”

The silent spread is a serious concern, stresses Dr. Nasseri: “It has been seen in countries like Singapore or Iceland that up to 10 percent of patients could be asymptomatic or minimally feel cold symptoms.” So even if you don’t feel sick, it’s best to assume you have it and proceed with caution. “If you cough or sneeze wearing a face mask it will stop the vast majority of respiratory droplets. This definitely helps with minimizing the exposure of your fellow community members.”

The mask is for the community, adds Cannon. “Wear it for your neighbors, your older parents, other people,” she says. “Even if you need to get a marker and write, ‘I’m doing this for grandma’ on the outside.”

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How to make your mask as effective as possible

You can find a handy guide to making your own face mask here. But remember that it’s still important to wear it properly. “A thick fabric of woven cotton is best to use, like a kitchen towel,” Dr. Nasseri says. “When using cotton fabrics like T-shirts, bandanas or scarves, make sure to have a double layer. They should also be more form-fitting to the face and go an inch above the nose and an inch below the chin.”

Kathleen Winston, PhD, and dean of the College of Nursing at the University of Phoenix, says that to be considered effective, masks worn by the public should meet these criteria:

• Fit snugly but comfortably against the side of the face
• Be secured with ties or ear loops
• Include multiple layers of fabric
• Allow for breathing without restriction
• Be able to be laundered and machine dried without damage or change to the shape

And mask or no mask, other hygiene practices remain critical. “The best measures we can do to protect ourselves from the virus right now are social distancing, frequent hand washing, and cleaning surfaces,” says Marie-Claude Couture, PhD, assistant professor at the University of San Francisco. “Masks don’t replace other highly effective public health measures such as social distancing and hands hygiene.”

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Protect your eyes when caring for someone sick

“The thing that’s not been mentioned in the media is eye protection,” says James Cherry, MD, distinguished research professor at the David Geffen School of Medicine at UCLA and UCLA Mattel Children’s Hospital, Division of Infectious Diseases. He explains that respiratory viruses are transmitted via two routes, the nose and the eyes. “Different viruses have different abilities to infect through the eyes, and we don’t have a clue about Covid-19.”

Cannon agrees that eye protection is critical—but only for medical staff. She doesn’t believe it’s a necessary part of the conversation for non-healthcare workers. “If you are a healthcare worker in a situation where you know you’ll be up close with somebody who has coronavirus, absolutely, you should wear eye protection,” she says. (Learn how to manage a hot zone in your home.) “There, the risk of somebody coughing in your face—and into your eyes, where it can infect you with the virus—is very real.” For the general public, however, six-foot social distancing combined with masks should offer enough protection. “As you’re walking around the grocery store and keeping your distance from people, even if somebody coughs, if they’re wearing a mask and you’re six-feet away, it’s not going to get into your face.”

Wondering what you should disinfect to protect against coronavirus? Here’s the right way to disinfect your cell phone.

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The psychological benefits of face masks

“When you leave your house wearing a face covering,” says Cannon, “it sends an important message because it destigmatizes wearing a face covering. If it wasn’t a rule, people would be looking sideways at their neighbors going, ‘Is she infected?’ It normalizes this behavior, makes it easier for everybody to do it. It’s sometimes much easier to say, ‘Everybody wear a seat belt, everybody wear a mask.'” That has value, especially in these troubled and emotionally uncertain times.

There’s another mental lift, says Cannon: “It’s a very visible way of saying, ‘I care about other people, we’re all in this together, I’m doing for my part, I’m demonstrating my care and consideration for everybody else.’ These are the silver linings for this horrible situation.”