5 Essential Facts About Using Face Masks

How do face masks help control airborne spread of COVID-19? When should I wear one? What materials are most effective? We have the answers.

by Sarah Ludwig Rausch Health Writer

By now, we've all got the memo on face masks (even if some people buck the science and refuse to wear them). But you still may have questions on how to make them, what materials to use, what materials to avoid, what type of inserts to consider, or even when it's most important to put one on, and why.

It's understandable if there's still some confusion out there. During the early days of the pandemic, the Centers for Disease Control and Prevention (CDC) did not want you buying precious surgical masks and N95 respirator masks, which were both low in global supply at that time and critical to protect healthcare workers on the frontlines. “We [didn't] want people to go out and use those types of masks because we need them,” says Kathleen Winter, Ph.D., assistant professor of epidemiology at the University of Kentucky in Lexington.

The official CDC stance back then was that you make your own, or purchase homemade face masks sewn by someone else. However, on April 3 the agency did an abrupt about-face, issuing a recommendation that remains in effect today. The CDC now urges all civilians to strap on face masks or cloth face coverings before mingling among other people, especially when you’re going to a place where it’s difficult to maintain a 6-foot distance, like the pharmacy or grocery store, or when you find yourself gathering with other folks indoors in poorly ventilated spaces, since airborne transmission has been confirmed by the CDC as being a real transmision risk. It’s also very important to don one while running essential errands if you live in an area with a significant amount of community spread (meaning hot zones of COVID-19 infections, with no known, direct cause of how the virus was transmitted). However, when you’re out in the open air walking or jogging solo, and you’re maintaining proper social distance at all times, it’s probably OK to skip the mask, according to the CDC.

Experts now know that face masks and coverings are essential for helping control the pandemic because people can transmit COVID-19 even when they’re asymptomatic (they have the virus but don't show any symptoms) or pre-symptomatic (they're carrying the virus and will eventually have symptoms), says Dr. Winter. CDC Director Robert R. Redfield, M.D., says that up to 40% of people with COVID-19 may remain asymptomatic, potentially spreading the virus without knowing it, and those who are pre-symptomatic may be even more contagious, transmitting the virus for up to 48 hours before they have symptoms.

The evidence is clear: COVID-19 is transmitted through respiratory droplets through personal (touching) contact, close (if not touching) contact, and by inhaling aerosolized clouds of infected virus. “These [droplets] can be in the air ... or [remain] on surfaces,” says Aaron Hamilton, M.D., quality and patient safety administrator at the Cleveland Clinic in Ohio. In fact, Harvard University reports that clouds of airborne virus can travel further than 6 feet and linger in rooms with poor airflow for (typically) three hours. This makes universal mask-wearing all the more important to prevent droplets from going airborne in the first place.

Here's what you need to know about face masks, based on the information available right now:

1. You Wear a Mask to Protect Other People

The number-one thing you should know about face masks? With the exception of medical-grade N95 and K95 masks, which filter out at least 95% of small airborne COVID-19 particles in the air, “a mask is not intended to protect the wearer, it’s intended to protect other people from what the wearer might be spreading,” says Steven Q. Simpson, M.D., professor of pulmonary and critical care medicine at the University of Kansas in Kansas City.

Dr. Simpson points out that the droplets from a sneeze can potentially travel up to 26 feet—although Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has stated on more than one occasion that in well-ventilated areas the famous 6-foot rule still applies. (Still, kinda makes you want to bolt rather than stick around to say “gesundheit,” doesn’t it?) And while most of us don’t usually sneeze quite that forcefully, with the arrival of allergy season more of us are sneezing more often. “That’s the point of the mask,” Dr. Simpson says. “You never know when you’re going to sneeze, and if you happen to be an asymptomatic COVID carrier, you’re [possibly] spreading that for a good long distance.”

Still, "whether you cough, sneeze, or even just talk or breathe, you can release respiratory secretions that have virus,” Dr. Winter adds. “Wearing a mask helps contain that, so you’re not spreading it into the air. We call that ‘source control.’”

The ability to purchase surgical and even K95 or N95 masks from online retailers like Amazon has eased quite a bit since the pandemic first raged. But while effective at curbing the spread of respiratory droplets and even offering substantial protection to the wear, these masks can be quite expensive, making them cost-prohibitive for many Americans. And, single-use, wear-them-once-and-toss-'em products are not so great for the environment, either. So many people prefer washable, reusable cloth (and even homemade) facial coverings.

There is evidence that homemade masks are effective at curbing spread of the virus. A study in Disaster Medicine and Public Health Preparedness looked at how masks made from 100% cotton t-shirts compared to commercial surgical masks. While both types greatly reduced the number of respiratory droplets that came out when volunteers coughed, the commercial surgical masks were three times more effective than the homemade ones. However, researchers concluded that even though homemade masks should only be used if commercial masks aren’t available, they’re better than nothing at all to help prevent the spread of infectious respiratory droplets.

Both Dr. Simpson and Dr. Winter concede that homemade face masks may provide some protection for the wearer, too—though, that’s really not their purpose. “They may help a little to protect your nose or mouth from getting the virus directly into your openings if somebody coughs or sneezes right by your face,” Dr. Winter explains. The mask will probably also keep you from touching your mouth and nose, the primary way the virus appears to be spread, adds Dr. Simpson.

And, if you’re taking care of someone in your household with COVID-19, having the sick person wear a mask while you wear one, too, will likely help protect you from getting the virus, Dr. Simpson says.

2. The Material You Choose for Your Mask Matters

The same researchers also wanted to see how well a variety of household materials could block aerosolized organisms compared to material from a surgical mask. They tested material from:

  • a dish towel

  • a 100% cotton t-shirt

  • a cotton blend t-shirt

  • a pillowcase

  • a HEPA vacuum cleaner bag

  • a scarf

  • some silk

  • some linen

First, they shot high concentrations of aerosolized bacteria in 1-micron particles through each material. The surgical mask material blocked 96% of the droplets, but the vacuum cleaner bag was right behind it (95%), followed by the dish towel (83%), cotton blend t-shirt (75%), 100% cotton t-shirt (69%), and antimicrobial pillowcase (65%).

Next, they used a highly concentrated aerosolized virus in 0.02-micron particles—smaller than COVID-19—with the same materials. Again, the surgical mask material blocked the most particles (89%), followed by the vacuum cleaner bag (86%), dish towel (72%), cotton blend t-shirt (70%), antimicrobial pillowcase (69%), and linen (62%).

The researchers also tested the materials for breathability, an important factor when you’re going to be covering your mouth and nose with it. Even though the vacuum bag and the dish towel were the most effective at blocking particles, not surprisingly, they were the hardest to breathe through. The researchers decided the best items for homemade face masks were the pillowcase and the 100% cotton t-shirt, preferring the t-shirt because its stretchiness gives the wearer a better fit.

However, researchers at the University of Cinncinati came up with a different conclusion after examining everyday household materials for mask usage. Their study found that silk offered more protection than either cotton or synthetics. Why? Because silk contains natural antimicrobial, antibacterial, and antiviral properties that could help ward off the virus, according to Patrick Guerra, assistant professor of biology in UC's College of Arts and Sciences. In addition, silk repels moisture, is easy to breathe through, and is comfortable to wear.

Whichever material you choose, there are many ways to cobble together a cloth face mask at home using materials you probably have on hand. The CDC has instructions for face coverings you can sew, as well as no-sew mask tutorials for those of us who aren’t crafty. (If you happen to have a 3D printer, Rowan University has downloadable 3D patterns for face masks to make reusable masks in three different adult sizes, as well as a pattern to print a filter, if you’re so inclined.

3. Using a HEPA or AC Filter Isn’t Necessary

There are face mask tutorials out there that advise people to insert a HEPA or an AC filter into their cloth masks—but since some of these are made with fiberglass, could this be dangerous? Like so many other issues surrounding COVID-19, it’s not very clear, and people have different opinions.

Dr. Simpson says that it’s really the various chemicals involved in fiberglass production that are harmful. “Fiberglass fibers aren’t of a size that tends to get down in the lungs, and certainly not when it’s built into a filter the way that these would be,” he says. “It probably isn’t dangerous, but it isn’t necessary,” he says. In the goal to protect others, “a cloth mask is perfectly adequate,” agrees Dr. Hamilton.

4. Masks Are an Additional Tool—Not a Force Field

Wearing a face mask is never a replacement for social distancing—it’s another tool to help prevent the spread of COVID-19 in our communities. Frequent hand-washing is as critical as ever, especially since recent studies show that the virus can live on some surfaces (like plastic and metal) for days.

5. Carefully Follow Wear and Care Instructions

So, you have your homemade mask. Do you need to worry about fit and cleanliness? In a word: yes.

  • Make sure your mouth, nose, and chin are covered and that your mask goes to the backs of your cheeks. “Try to cover your mouth and nose completely, but any way that you can wear it without constantly having to adjust it and touch it is beneficial,” Dr. Winter says.

  • Your mask should fit snugly, but comfortably, and you should be able to breathe easily.

  • Though layering material does provide more protection, don’t overdo it. Check that you can still breathe comfortably.

  • Avoid touching the outside of the mask. “You don’t want to get anything that’s on the mask onto your hands,” says Dr. Winter. If you do touch it at any point, wash your hands well. When you get home, try to take your mask off without touching the outside as much as possible, and then wash your hands.

  • Launder your mask each time you’re done wearing it. “If you wash it with hot water or even just dry it on a hot cycle, that should be sufficient,” Dr. Winter says.

  • Make or purchase several homemade face masks so you always have a clean one available.

  • Don’t use face masks on children under two years old, or on anyone who is unable to take the mask off if they should have trouble breathing.

Sarah Ludwig Rausch
Meet Our Writer
Sarah Ludwig Rausch

Sarah Ludwig Rausch is a health writer and editor whose specialties include mental health, diseases, research, medications, and chronic conditions. She’s written for The Christian Science Monitor, American Cancer Society, Cleveland Clinic, PsychologyToday.com, MedShadow Foundation, the ACT Test, and more.