Research Suggests Proper Fit of COVID Face Masks Is More Important Than Material

COVID Mask Fit

A team of researchers studying the effectiveness of different types of face masks has found that in order to provide the best protection against COVID-19, the fit of a mask is as important, or more important, than the material it is made of.

The researchers, from the University of Cambridge, carried out a series of different fit tests, and found that when a high-performance mask — such as an N95, KN95 or FFP2 mask — is not properly fitted, it performs no better than a cloth mask. Minor differences in facial features, such as the amount of fat under the skin, make significant differences in how well a mask fits.

The results, published in the journal PLoS ONE, also suggest that the fit-check routine used in many healthcare settings has high failure rates, as minor leaks may be difficult or impossible to detect by the wearer. While the sample size was small, the researchers hope their findings will help develop new fit tests that are quick and reliable, in the case of future public health emergencies. The current study only evaluated the impact of fit on the wearer of the mask — the team will evaluate how fit impacts the protection of others in future research.

The COVID-19 pandemic has made well-fitting face masks a vital piece of protective equipment for healthcare workers and civilians. While the importance of wearing face masks in slowing the spread of the virus has been demonstrated, there remains a lack of understanding about the role that good fit plays in ensuring their effectiveness.

“We know that unless there is a good seal between the mask and the wearer’s face, many aerosols and droplets will leak through the top and sides of the mask, as many people who wear glasses will be well aware of,” said Eugenia O’Kelly from Cambridge’s Department of Engineering, the paper’s first author. “We wanted to quantitatively evaluate the level of fit offered by various types of masks, and most importantly, assess the accuracy of implementing fit checks by comparing fit check results to quantitative fit testing results.”

For the study, seven participants first evaluated N95 and KN95 masks by performing a fit check, according to NHS guidelines. Participants then underwent quantitative fit testing — which uses a particle counter to measure the concentration of particles inside and outside the mask — while wearing N95 and KN95 masks, surgical masks, and fabric masks. The results assessed the protection to the mask wearer, which is important in clinical settings.

N95 masks — which are a similar standard to the FFP3 masks available in the UK and the rest of Europe — offered higher degrees of protection than the other categories of masks tested; however, most N95 masks failed to fit the participants adequately.

In their study, the researchers found that when fitted properly, N95 masks filtered more than 95% of airborne particles, offering superior protection. However, in some cases, poorly-fitted N95 masks were only comparable with surgical or cloth masks.

“It’s not enough to assume that any single N95 model will fit the majority of a population,” said O’Kelly. “The most widely-fitting mask we looked at, the 8511 N95, fit only three out of the seven participants in our study.”

One observation the researchers made during their study was the width of the flange of the mask — the area of the material which comes in contact with the skin — may be a critical feature to fit. Masks that fit the greatest number of participants tended to have wider, more flexible flanges around the border.

In addition, small facial differences were observed to have a significant impact on quantitative fit. “Fitting the face perfectly is a difficult technical challenge and, as our research showed, small differences such as a centimeter wider nose or slightly fuller cheeks can make or break the fit of a mask,” said O’Kelly.

Self-performed fit-checks are attractive because they save on time and resources, and are often the only method of fit testing available. However, this study, and studies of fit-check systems in other countries, indicate that such fit-check systems are not reliable.

The researchers hope that their results will be of use for those who are working on new technologies and programs to assess fit, so that healthcare and other frontline workers are adequately protected in the case of any future pandemics. Additionally, they hope these results will bring attention to the importance of fit in clinical-grade masks, especially if such masks are to be widely used by the public. This study did not evaluate the impact of fit on protecting others, which is a future area of research.

Reference: “Comparing the fit of N95, KN95, surgical, and cloth face masks and assessing the accuracy of fit checking” by Eugenia O’Kelly, Anmol Arora, Sophia Pirog, James Ward and P. John Clarkson, 22 January 2021, PLOS ONE.
DOI: 10.1371/journal.pone.0245688

15 Comments on "Research Suggests Proper Fit of COVID Face Masks Is More Important Than Material"

  1. Why do you keep the scare tatics up?
    The Great Dr St Fauci said at the beginning of this that mask won’t help. He said the virus particles are to small to be stopped by a mask.
    STOP trying to control people with fear.

  2. Tom, have you never learned from your past mistakes? Would you go to a surgeon or dentist who did not wear a mask?

  3. As a mask maker of at least 10 styles, mask wearer, and reader of scores of articles on mask research, there are other points that should be added to proper fit: people tend to take their masks on and off, potentially getting viruses on their hands from the outside of the masks, or from the inside, if they have a disease. People will be more inclined to take a mask off when they leave a building if it is uncomfortable. A well fitting mask is comfortable for a longer period of time, even hours, thereby reducing the potential spread of viruses. Secondly, some of the worst fitting masks I’ve observed are the so called surgical masks, which often flair way out on the sides, allowing lots of air to escape unheeded. Supposedly if you follow someone down a hallway, you are exposed to whatever escapes from the sides and flows back. At least these days people aren’t saying that they suffer from CO buildup in a mask. If that were true, the mask would increase in size like a balloon.

  4. I am so sick and tired of masks being pushed as though they are preventing the spread of a virus. As a scientific informational publication, if you have scientists who are advising you, your story would NOT be telling such stories with a clear consciences.

  5. Wearing a mask to prevent catching and/or spreading Covid 19 is exactly like putting a chain link fence around your backyard to keep mosquitoes out!!
    Wearing 2 mask is like adding another fence around your backyard made of hog wire!!
    Wearing 2 mask also shows just how stupid you really are!!
    I wonder how many deplorable democrates are sitting on the sidelines saying “I told you that these people are so stupid – they will do anything we say!! No matter how rediculous and stupid it is!!”. Lol

  6. Fraud, mask bs, love the trolls you have commenting. No science, just control. The media is the new target, they have no morals. Only greed.

  7. Kathy Erenberg | February 28, 2021 at 9:48 pm | Reply

    Wearing a mask to prevent catching and/or spreading Covid 19 is exactly like putting a chain link fence around your backyard to keep mosquitoes out!!
    Wearing 2 mask is like adding another fence around your backyard made of hog wire!!
    Wearing 2 mask also shows just how stupid you really are!!
    I wonder how many deplorable democrates are sitting on the sidelines saying “I told you that these people are so stupid – they will do anything we say!! No matter how rediculous and stupid it is!!

  8. Katherine Rubie | March 1, 2021 at 2:24 am | Reply

    I am sick to death of you anti-maskers crying like babies about wearing a mask and then beating up or verbally abusing people who do choose to wear masks. You claim it’s a violation of your rights and Government control taking away your freedom, but then you don’t want people who choose to wear masks to have their own freedom of choice. You cannot claim freedom, while denying others of their own freedom.

    Having a temporary health directive to help REDUCE the spread of this virus is exactly that…a temporary health directive designed to reduce the transmission of disease. This is not government trying to control you. It is about government giving the best possible advantage to you and the people around you.

    No one ever claimed masks were 100% effective, or that they had no risks attached to them. We’ve known this from the very beginning of this pandemic. Some masks and materials are better than others, but none of them are guaranteed to block the virus at 100% effectiveness. The size of the virus alone is so small that it can make it’s way through nearly every possible fabric. The looser the weave of the fabric, the less effective it is for stopping the virus. The tighter the weave of the fabric makes it more difficult for the virus to penetrate the fabric.

    The primary purpose of a mask is to reduce your own respiratory aerosols from entering the air around you and potentially being breathed in by another person. The mask only secondarily protects you, but if EVERYONE wore a mask, then our own chances of catching it are eliminated too. And this article talks about what we knew last year: an N95 mask is more effective because it is properly fitted by medical personnel. Since those masks are difficult to acquire and we don’t do a fit test, then we are left with other choices.

    When you make this about yourself and refuse to wear a mask, then you take the risk into your own hands for getting the virus, but more importantly you are stripping the rights of other people to be safe in their environment, which intrudes on other people’s rights and risks THEIR health. And this just amounts to being so self-centered that you cannot stand to be inconvenienced for a little while in order to protect your friends, family, coworkers etc.

    Bottom line: no one likes wearing masks. We do it as a courtesy to protect others. And we hope that others will do the same for us. When it becomes an enforceable mandate, it is because of people who would rather think of themselves than other people. So much for patriotism… instead of defending our fellow Americans we are thinking only of our selfish interests…and IMO that is NOT an American value.

    • Karin Aldridge | March 1, 2021 at 3:44 am | Reply

      Bravo!!! You said this so well. Hopefully it will sink in to those that choose not to listen.

      • Pure, unadulterated crap from both of you. You want a mask, be wear one, but LEAVE ME OUT OF IT. I will no longer kowtow to fear mongers like yourselves. And you are wrong- it absolutely IS about control and I will not be controlled by you or any government hack that thinks like you. Put that in your nanny-state pipe and smoke it.

  9. Sheila Cunningham | March 1, 2021 at 4:27 am | Reply

    I am so tired of people talking about who wear a mask who doesn’t. I will UNTIL wear mines and if you choose not to do so, but allow people to be free to live or die just shut up about it. And for thoses of us THAT’S wearing the masks bravo may God protect and keep us safe from the crazy.

  10. Margaret Megan Hutchison | March 1, 2021 at 7:58 am | Reply

    Hi am margaret I have breathing problems I can’t wear a mask and I feel like I can’t breathe when it’s on so I have been extended from wearing one but I have sent away for one you can see through and I’m still waiting for it to be delivered to see if I can inhaler with it or not. But I see people are judgemental .they don’t understand why some people can’t .as I got breathin problems on my.life so if you see someone with out one think before you judge them

  11. My husband died of covid complications in January. For 5 days before I knew he was covid positive, I always kept my hands clean. When he was diagnosed I was tested and was negative. I was with him in the hospital 5 days before he passed. I wore a mask and washed my hands any time I touched him. I am still negative and convinced that my mask and hand washing kept me from getting the virus.

  12. Who gives a rip? This plandemic us a royal load of crap in the first place. I don’t wear a mask and haven’t since last March when I realized that the numbers didn’t and wouldn’t add up. Not am I going to take that toxic Covid vaccine. PERIOD.

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