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Why don't we tape surgical masks to the face to seal them airtight?

by ChristianKl1 min read14th Apr 202022 comments

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Covid-19
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As far as I understand the prime advantage of surgical masks over N95 masks lies in the N95 masks being able to seal and filter all of the air while the surgical masks allow air to pass at their sides.

Given that there are many situations where people would ideally wear N95 masks but have only access to surgical masks, why can't we improve the surgical masks by using adhesive tape to seal their borders to the face?

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I'm not sure you're right about the advantages of N95 masks over surgical masks. (Note: at present the question says "... the prime advantage of surgical masks over N95 masks ..." but I assume that's just a slip.)

N95 masks have finer filters that keep out particles smaller than surgical masks' filters do. If you tape a surgical mask to your face in a way that seals it perfectly, then while you may be doing a better job of keeping out the particles the mask can block you're still not doing much for the smaller ones.

N95 masks are notoriously tricky to fit well, but so far as I know no one tapes those to their faces. Whatever the reasons for that, many of those reasons probably apply to surgical masks (but more so, because the benefit will be smaller, because however good the fit the surgical masks are still not keeping out all the smaller particles.) I don't know those reasons, but I guess they include the following, all of which seem like they apply to surgical masks:

  • Taping a mask to your face is harder than it may sound. There isn't that much available surface between nose and eyes to tape to.
  • Your face is flexible and moves around as you talk, blink, smile, etc. Tape can peel off. Especially if you have facial hair, wrinkles, damage from earlier mask-unpeelings, etc., rather than a perfect smooth surface to tape to.
  • Surgical masks are also flexible and often have folds extending to their edges, making it difficult to seal them effectively using tape.
  • They also have straps. It seems to me that any way of taping a mask on is going to leave a "tunnel" along the straps. You can tape the straps down but they're inevitably going to move around in ways that tend to enlarge that tunnel.
  • Peeling tape off your face is painful and may do damage, especially if you are doing it repeatedly and especially if the tape is extra-sticky so as not to peel off while you're wearing the mask.
  • The slow and awkward peeling-off process keeps the mask, whose outer surface might be covered in virus particles or whatever, close to your face for longer while you're removing it.

None of this means that taping down a surgical mask won't provide any benefit. My guess is that it does. But I suspect the benefit is small enough, and the pain and inconvenience large enough, that most people won't consider it a good tradeoff.

As to whether that's right in any given case, I don't know. It would be interesting to have some actual numbers on this, but my guess is that no one's done the studies.

I presume the comment about N95s not filtering smaller particles refers to the standard of filtering 95% of particles as small at 0.3 microns and viruses such as SARS-CoV-2 are much smaller than that. (0.1 micron) While I have no expertise as a virologist, it is widely explained that N95 masks stop smaller particles than 0.3 because of the way the particles move. That random movement makes it likely they will hit the fabric and stick. Additionally, an electrostatic charge attracts the smaller particles. In fact, the scientists say, the most difficult size particle for the masks to stop are those that are 0.3 microns. The masks actually do a better job of stopping microns smaller than that. 

I think you could overcome most of those bullet points by using spirit gum instead of tape, tho I'm not sure how often you'd want to do that: even sticking an adhesive bandage to some patch of skin and changing it every day will do considerable damage after a relatively short time.

I've also come to understand that the N95 respirator is a much better filter than the paper masks could ever be, so adhering paper masks to the face might simply be nowhere near as useful as just having the right mask in the first place. My understanding is that most masks are si

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2gilch2ySticking it to your face every day for your job might be a problem, but what if you're only using it once a week to buy groceries? Maybe the better fit with no training is worth the skin damage in this case.
2gjm2yRight. Though the paper by Davies et al that Christian found suggests that at least some paper masks may not be so wretched at keeping out tiny particles.

N95 masks just need to filter 95% to get that certification. They don't filter as much as FFP3 masks but only as much as FFP2 masks. They aren't equipment that keeps out all the smaller particles.

Davis et al 2013 suggests ~90% filtration for surgical masks. I read somewhere in the literature that in cases where studies found similar effects for protection by surgical masks and N95 masks it's likely because the N95 masks didn't fit correctly.

2gjm2yDavies et al is encouraging as regards the benefits of surgical masks. Still, letting 10% in is a lot worse than letting 5% in, and the fact that the Wikipedia page about N95 masks says "Collection efficiency of surgical mask filters can range from less than 10% to nearly 90% for different manufacturers’ masks when measured using the test parameters for NIOSH certification" suggests that maybe Davies et al got lucky in which surgical masks they tested.

After doing more research into this question, I think the answer is yes, this is actually a very good idea, only it's much more convenient to use a rubber mask brace instead of tape. I summarize my findings as well as present DIY instructions on how to do this at home in a new post: https://www.lesswrong.com/posts/CrikcGiaWK9CSSzrJ/i-made-an-n95-level-mask-at-home-and-you-can-too

I've personally found that just stapling shut the outer edge of the first fold on either side of a surgical mask results in a mask that mostly sucks to my face when I breathe in. It doesn't stick well when I breathe out, though.

This is much easier to implement than fancy adherents; all it takes is 2 staples and a stapler, or a needle and thread. It struck me as a plausible 80-20. (Well, less than 80%. Obviously, this is no N95.)

(It might only work for some face-shapes, though.)

This generates a new problem, which would also apply to taped/glued solutions:

The front is made of a softer fabric than N95s. After an hour of wear, it will suck to my lips if I breathe in with my mouth. And since it doesn't stick on out-breaths, air still gets out the sides and sometimes the top. I don't know how much additional risk this presents, but I would be curious to hear someone weigh in.

(It also has uncomfortably-high humidity, but that's even more true of N95s.)

As a diabetic, I have a few things (insulin infusion canula, continuous glucose monitor) that attach to skin with adhesive. In principle, you could use medical tape around the edges of a normal mask, and it would improve the seal. I think the reason people don't do this is because it's a lot of effort to put on (effort which could be spent improving the fit in other ways), and it's physically painful to take off. This limits its usefulness to the range where an imperfectly-fitted N95 isn't good enough, but a positive-pressure suite isn't necessary; I'm not sure situations in that range are at all common.

I treated a COVID patient today and did just this. It was really easy to use a skin friendly hypafix or mepore that you can cut and fit around your eyes to seal tight the mask. I certainly felt more protected.

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I saw a picture in one of the Philippine papers I read periodically during the week. The man had taken a water dispenser jug and cut the bottom off, and shaped it to fit over his shoulders.

I'm not sure what he did about the top (I'm guessing plugged or taped it but not clear in the picture. I was thinking you could do something with that like, a good find filter paper at the bottom, a back back with some type of canister type filtered intake air and a small fan/blower (say from a computer) to assist air intake and vacuum cleaner hose to the top.

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I don't know anyone else's answer, but for myself, while I don't want to get a serious case of COVID, I also don't necessarily want to reduce my exposure to ambient virus particles, including COVID, all the way to zero. I want just enough exposure to keep my immune system strong and active without actually getting sick and spreading diseases to others. 

Also, when I put on even a not-sealed mask with an N95 filter, I get a headache within about 10 minutes that lasts until I take it off.  This is true even at the times when I didn't realize my mask had a removable filter inserted. I would prefer not to modify my regular mask in a way that makes it more like an N95 mask unless I really need to.

I think you overestimate two things at least. First there is still doubt about if the amount of entering virus is that predicting of the outcome. And I think you overestimate your control on how much you are able to control the amount of Virus entering your body. And I am not sure if being exposed to low quantities of virus will have any health benefit on you.

1AnthonyC1yYes, I'm aware of and agree with all of that. I don't have very high confidence in any of my assumptions and don't believe I have anything like "control" but I'm comfortable with my current risk profile, given my behavior and the stats in my region. Under current conditions I estimate that my taking additional precautions beyond what I now do, such as taping a mask on, would not be a net positive for my or anyone else's well-being.
1Nacruno961yWhat is your expected death risk if you catch it. I tried to determine mine but I ended up with a risk expectation somewhere between 0,4 and 0,001 percent. This estimation was influenced mainly by conflicting data and insecurity about how to account for absent risk factors
1AnthonyC1yYes, pretty much my estimate as well. Given the rarity and brevity of my contact with anyone outside my household and the level of cases in my region, my risk of infection in the first place remains quite low as well. Overall, even at the high end, I don't see how covid risk increases my total risk of death my more than 50%, which given my age is still low enough that I don't feel a need to take all possible precautions. I felt differently in March to May when there was even less known about what the pandemic. At some point, though, covid precautions run up against other needs (physical, mental, and emotional), and for me taping my mask to my face would cross that threshold.

This article here suggests that N95 and surgical masks performances were similar while preventing to catch the flu.

https://smartairfilters.com/en/blog/n95-mask-surgical-prevent-transmission-coronavirus/

There are multiple studies that tested both. One explanation for the result of that study is that the N95 weren't properly fitted and didn't provided the added advantages that fitted masks provide.

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I agree that tape should improve the value of the surgical mask. I've seen a number of quality respirators that will use a rubber or silicon face mask that will seal much better than the standard N95 mask people are buying. That allows the ability to actually "seat" the mask to your face and improve the seal.

However, as others point out, that doesn't change the size of the particles that are filtered. So I wonder just how much that might really help.

The surgical mask is not designed, or really intended, to protect the wearer from the external environment but the external environment (to a certain extent) from the wearer. It seems to be something of a deflection and catch device. Taping the mask might then increase the velocity of any particles passing through the surgical mask, thus spreading them more widely, as none is now deflected to the side and a bit backwards.

I think the amount of effort would would be too high for a masks that would end up being unpractical. It would not filter aerosols reliably and breathing comfort would also be undermined. Also those masks aren’t designed to be used as much as we do know. That’s my theory. But you might be right that it would make sense to do that.