Main content
What you need to know about masks
Media Contact
Gana Ahn

With so many different options on the market, Emory epidemiologists Jodie Guest and Marybeth Sexton discuss which masks are most protective against COVID-19.

As the highly infectious COVID-19 Omicron variant continues to spread, more than 99% of U.S. counties are currently considered areas of high community transmission. Amid this surge, wearing a well-fitted mask remains one of the best defenses individuals can take against COVID-19.

On Jan. 14, the Centers for Disease Control and Prevention (CDC) updated its consumer mask website to emphasize protection, fit and comfort. With so many different masks on the market, and some more accessible than others, it can be hard to decide which mask to choose.

Jodie Guest, PhD, professor and vice chair of the department of epidemiology at Rollins School of Public Health, and Marybeth Sexton, MD, assistant professor of medicine in the division of infectious diseases at Emory University School of Medicine, teamed up to discuss the most effective masks, tips for improving their fit and proper mask hygiene.

Their conversation is part of an online video series hosted by Guest, who also leads the Emory COVID-19 Outbreak Response Team, answering questions related to the COVID-19 pandemic.

Q: What is an N95 mask?

A: “The N95 is really considered the premier mask that we have,” says Guest. These respirators are approved by the National Institute for Occupational Safety and Health (NIOSH) to filter out 95% of particles in the air around the wearer.

“Because of the way that they seal to your face and because of what they're made out of, they really do filter out the majority of respiratory particles, viruses, whatever is in the air around you, so that you don't breathe that in,” says Sexton. 

N95 masks have two straps that fit around the back of the head and a nose bridge that molds to the wearer’s face. When wearing the mask, an individual can perform a seal check by placing their hands over the mask and breathing in. “You should feel the mask collapse a little bit as you breathe in,” Sexton says. “And then take a breath out — you should feel it push against your hands, but you should not feel air up by your eyes or around the sides. That's how you know that it's on correctly.” 

Sexton warns that N95 masks only protect against COVID-19 if worn properly. “I can't wear this for more than 30 minutes without feeling like my face is going numb or I'm going to pass out,” she says. “If you have that experience and you're going to be moving this up and down your face, pulling it out to take a breath, putting it back on, taking it off some of the time, then that extra 5% or 10% filtration that you theoretically get with this is useless because you don't have it on right. So, you want the best quality mask that fits you well and that you are going to be able to wear comfortably for a long period of time.”

Q: What is a KN95 mask?

A: KN95 masks can also filter out 95% of particles in the air. Because these masks are primarily manufactured in China and tested to meet Chinese standards, they are not approved by NIOSH. Sexton notes that some KN95 masks are manufactured and validated by both Chinese and American companies.

KN95 masks are typically “pretty sturdy, well-fitting, thick masks,” Sexton says. They have ear loops and a nose bridge that can be pinched to mold to the wearer’s face. They also have a three-dimensional tent shape, creating an air pocket around the mouth and bottom of the nose that makes it easier to breathe comfortably.

To make sure KN95 masks are fitted properly, check to make sure no air escapes above the eyes, around the sides of the face or below the chin when exhaling.

Guest prefers the fit of the KN95 to the N95. “I don’t feel like they fit as tightly, even when I get a good seal on it, so for me these are a little bit more comfortable than an N95, especially for longer periods of use.”

Sexton agrees. “I can wear one of these for a couple hours comfortably, and potentially even forget I have it on,” she says.

Q: What is a KF94 mask?

A: KF94 masks can filter up to 94% of particles in the air. They are tested to meet Korean standards of air filtration, so they are also not approved by NIOSH. 

Like KN95s, these masks have ear loops, nose bridges and a three-dimensional shape that creates an air pocket around the lips and bottom of the nose. 

“For me, this mask happens to work particularly well,” Guest says. “Just like the KN95, this does not touch my lips or the bottom of my nose, so it doesn’t change my diction and I can teach an entire class for hours in this and forget that I have it on.”

To make sure KF94 masks are fitted properly, check to make sure no air escapes above the eyes, around the sides of the face or below the chin when exhaling. 

Q: How protective are surgical masks?

A: Three-ply surgical masks, also called procedure masks, can work well for some people depending on fit. They have ear loops and an adjustable nose bridge, but they may not fit snugly on individuals with smaller faces.

To flatten any gaps at the sides of the surgical mask, Sexton suggests layering a well-fitted cloth mask on top. “There are studies that were done during the Delta wave that showed that this kind of combo, or something where you modify the mask in some way to make it fit better, was around 90-91% effective. So, you can get this to be almost as effective as some of these other masks, but it's got to fit you right.”

In addition to layering with a cloth mask, twisting or knotting the ear loops on a surgical mask can help it fit more snugly.

“If you have access to them, I think surgical masks are preferable to cloth masks,” Guest adds.

Q: How protective are cloth masks?

A: Cloth masks vary in quality, so it is difficult to determine how effective they are at filtering COVID-19 particles. Sexton says these masks can be protective if they are well-fitted and have multiple layers. She also recommends looking for cloth masks with adjustable ear loops, nose bridges and a filter pocket.

“The degree to which Omicron is more contagious really suggests that it's not going to be as forgiving of errors with your mask,” Sexton stresses. “Before, if your mask had gaps on the sides, or it was a single layer or double layer cloth mask, or it was falling below your nose occasionally and you were pulling it back up, that was probably not going to be enough to cause a problem. Now, that may be enough to cause a problem, so you really want something that's uniformly very high quality and is going to stay put.” 

“Something that you made yourself, something that has one layer, something that you can't adjust the ear loops on and that has gaps is going to be tremendously worse” at filtering out COVID-19 particles, she adds.

Q: What are counterfeit masks and how can they be avoided?

A: A mask is considered counterfeit if the manufacturer falsely claims it has been tested to certain regulatory standards. For example, a counterfeit N95 may claim to filter 95% of air particles but has not been validated to do so. 

“Real N95 masks are evaluated by NIOSH, and so we know that they meet those regulatory standards,” Sexton says, noting that NIOSH provides a list of approved respiratory masks on its website. If a brand that claims to manufacture approved respiratory masks does not appear on the NIOSH website, “then you do worry that might be a counterfeit mask that’s been made to some unknown standard.”

Although some masks may not be manufactured to NIOSH standards, they could potentially provide protection from COVID-19 particles. “They are often still thick, well-fitting masks,” Sexton says.

“It's not ‘not a mask,’ it's just a mask that hasn't been tested or is not assured to be filtering at the level that it may be claiming to be,” Guest adds.

Q: Who should be wearing a mask?

A: “Anyone over the age of two who is out in public, particularly in indoor public areas, should have a mask on,” Sexton says. “One of the blessings — and a little bit of the curse — of Omicron is that, especially if you get infected with it after vaccination or after you've had COVID before, it can be incredibly, deceptively mild in terms of symptoms.”

A person with mild symptoms such as fatigue, headache or congestion may not realize they have COVID-19. “Even if you're not particularly sick, that doesn't mean you're not going to encounter somebody really vulnerable while you're out, so if you have the mask on you make sure that you don't spread something that you haven't noticed to other people,” Sexton says.

“Remember that wearing your mask protects you and protects those around you,” Guest stresses. “This is super important as Omicron spreads across the United States. This is not for forever, but right now with a super transmissible variant this is one of your best defenses on top of being vaccinated and being boosted.”

Q: How often should you change your mask?

A: “It's a little bit variable depending on what the mask is and how long you had it on for,” Sexton says. Cloth masks should be washed after each use.

Disposable masks should never be washed. Instead, you can rotate them by leaving a used mask undisturbed in a paper bag for two days, allowing time for any viruses or bacteria on the mask to die. 

If a disposable mask is visibly dirty, wet or no longer holds its shape, it should be discarded. Reused KN95 or KF94 masks that feel hard to breathe in should also be discarded because the filter is likely blocked with particles. 

Q: Should masks be worn outdoors?

A: “The CDC does not recommend that you need to be wearing a mask outdoors in all spaces, but certainly there are times you should consider wearing a mask when you're outdoors,” Guest says.

“If I'm not going to be able to distance from other people and I'm going to be there a long time — so if I'm going to be sitting right next to somebody and having face-to-face contact with them — being outside is certainly much safer than being inside, but it's not foolproof. So, I will wear a mask in that setting,” Sexton says. 

“I think that if you're going to be spaced out, like if you were playing soccer outside, you don't need a mask on,” she adds. “It also depends on where you are because there's outside in the complete open and then there are partially enclosed sporting arenas. There are varying degrees of air movement even when you're technically outside, so if I were sitting in a crowded stadium right now, I would wear a mask.”

Q: What are some tips for improving the fit of a mask?

A: The CDC has shared recommendations for improving the fit of different kinds of masks on its website. For example, the fit of three-ply masks can be improved by knotting the ear loops and folding excess material under the edges of the mask.

Air should not escape from a mask when a person exhales. If exhaling causes an individual’s glasses to fog, the nose bridge on the mask needs to be pinched tighter to the face.

Most importantly, a properly fitting mask should cover both the nose and mouth. “Your nose is part of your respiratory tract, and so it needs to go over your nose, fit well there and then go down underneath your chin,” Guest says.

“We all have preferences, we all have styles that fit our faces best and we all have different access to masks,” Guest continues. “Whatever mask it is that fits you best — knowing that we're all in a space right now where wearing one is really important for both you personally as well as those who are around you, and the people you're going to go home to —  it's really important that you have one with you at all times and that we wear them.”

Recent News