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How good are various types of masks?

Published on 54 Comments on How good are various types of masks?

I would like to know how good various kinds of masks are, but this turns out to be a surprisingly hard thing to find out. Partly this is because different studies come to different conclusions and partly because recommendations are often qualitative ("N95 is better than surgical," "cloth masks don't work") rather than quantitative. What I'd like is something like this:

This is rough guesswork, and I have no idea how accurate it is. Probably not very. I'm not even sure what the right measure is. Filtration efficiency? The risk ratio of passing along disease? Or something else?

But even with caveats and error bars, it seems like someone should be able to produce a chart like this backed by the best recent research. Has anyone done it? If not, will someone please give it a go?

54 thoughts on “How good are various types of masks?”

            1. iamr4man

              Yeah, I’ve been considering those for her. But I’ve been wondering if that anti-viral layer actually works, at least to some extent. She is pretty satisfied with those. The company also sells N95s with an anti-viral layer.

              1. Traveller

                Let me add another positive vote for the KF94's...they are more comfortable than the 95,s and....look less dorky than the 95's. The KF94's fit flatter on your face.

                I quite like them....if you can find any now, make sure these are LG's and from Korea....but Amazon is sold out right now.

                Good Luck, Traveller

                1. iamr4man

                  Since this all began I’ve tried dozens of different kinds of masks. I’ve always gone for the k or kn’s. The ones that work for me are the 3m Auras. They are the only ones I’ve found that don’t fog up my glasses. They were pretty easily had until the current push toward better masks. Luckily I have a good supply of them.
                  Masks with straps that go around the ears are easier to use, I think. My daughter the school teacher (who has to help the kids test) prefers around the ear.

      2. Crissa

        The study they use is bs because it assumes the n95 is fitted but none of the others are - and the cloth is a single layer of t-shirt material, which no one who's doing a mask requirement allows.

        So it's not measuring anything from real life.

  2. Rattus Norvegicus

    I just got 50 Kimberly-Clark N95's from Amazon for about $50. They are genuine, at least from all the markings and packaging. And they are pretty comfortable, although they look silly.

    I happen to like the headband rather than the ear loop style and they have a bendable nosepiece to get a better fit (is this what a fitted mask is?). Anyway I took the CDC advice and upped my masking.

    1. TheMelancholyDonkey

      "is this what a fitted mask is?"

      No. A fitted mask means that you have gone in and had someone figure out which of the many N95 masks is properly shaped for your face, and how to wear it.

      1. gyrfalcon

        "Gone in" where? Who does this?

        I've not heard about it before, and I sure could use it since the N95s I have are too tight in various uncomfortable places on my head.

        2. tomtom502

          Businesses & medical do tests for their employees. You put on a hood and they spray saccharin or bitter tasting stuff in and you shouldn't be able to taste it. You can get a 3M kit for $300 (3M FT-10 or FT-30). There are 3M instruction videos on Youtube.

          Fitting means playing with the wire around the nose and trying different masks to find something that seals well on your face.

          Here is an easy way to fit a mask:

          1. Watch the 3M video and become aware of what leakage feels like
          2. Put on chilled glasses, or go outside on a cold day, leaks will fog them up straightaway.
          3. You have to be clean shaven to fit a mask

          If you pay attention to a seal you will find out pretty quickly that surgical masks can't be sealed, but you can learn to fit N95 / KN95 / KF94 if you spend some time feeling for the seal and fussing. Once you get it down it is easy, you can feel the leaks.

          Personal note: Although KN95 seals well, their construction causes them to drift up or down while you talk. KF94 is much better this way. I never use N95 because I don't like two straps around my head.

    3. Salamander

      An actual N95 will not have ear loops. It should have 2 straps that go around your head and can be adjusted to fit. Fit testing can be done by somebody who was trained to do it, using a variety of irritant or other scents and verifying that the mask screens them out.

  4. Vog46

    I have actually spoken to a person who was wearing an N-95 mask.
    He was very proud of himself, said his brother helped him fit it to his face
    He felt totally protected and thought that he would be protecting his fellow man.

    I asked when he had his beard trimmed last and he told me over 2 years ago.

    *********sigh*************

    C'mon folks - use your heads.

    1. Salamander

      OSHA rules: you can't wear a respirator, including N95s, with a beard. His brother ought to be ashamed for giving the dude a false sense of security.

      1. Vog46

        Amen to that Salamander.
        Although a powered air purifying respirator could be worn by bearded people.
        The point here is that masks are there to protect OTHER people from YOUR aerosol particles as much as to protect you from theirs.
        Stupid is an epidemic and those guys were........

  5. jte21

    There's also the question of what mask is best for protecting *others* if you're the infected one exhaling the virus, and which one is best for protecting *you* from inhaling the virus. May be N95 in both cases, but I've seen wildly different advice on that over the past two years ranging from "If you're both wearing some kind of mask, even a cloth one, you're pretty safe" to "unless you're wearing an N95 respirator, inside a hazmat suit, living on the moon, you're going to get sick and die".

    1. golack

      The later variants are more infectious, so better masks are needed. Good cloth masks, i.e. 3-layers and seals against your face, still help, but they went from offering good protection to just ok protection. The first ones I got didn't seal well and didn't have a wire to pinch against the nose--so they're not that useful now. The next batch seal pretty good and have a pocket for a filter, so they are better. The range of quality/usefulness in "cloth masks" means authorities have to err on the side of caution.

  6. fredtopeka

    Aaron Collins has been testing masks for a while and has accumulated a bunch of data ( https://youtube.com/user/coll0412 if you go to any of his videos, there's a link to an Excel sheet with all the data). He also has some recommendation videos, but hasn't really put it all together.

    Perhaps you, that would be Kevin, could.

    By the way, he really likes KF94 masks.

    1. weirdnoise

      The KF94's introduced the "boat-style" mask that has become popular. 3M has noticed, and introduced boat-style N95's, their 9205+ "Aura" masks.

      I've never been able to get a KF94 that seals properly around my nose, and the 3M Aura's are hard to find. So I wear a 3M 8210, the older cone-style mask. Looks kinda industrial (which isn't a coincidence -- that's where it's been used for decades). Aaron uses them as a benchmark in his tests, where they typically score a bit above 99.0% filtration.

  7. Dana Decker

    This is all completely backwards.

    We wouldn't have to worry about what kind of mask *we* wear if, instead, we put tiny masks on the coronavirus itself. Simple cloth masks would interfere with protein spike binding. Same with surgical masks. N95s would do just as well, but they are expensive.

    And it's doable! The COVID virus has a diameter of 100 nm. A mask that covers it would take about 250,000 atoms.

    UPSIDE: Since the COVID virus isn't a valued constituency for the GOP, there won't be objections should Biden mandate masks for all COVID viruses.

    1. Joel

      In effect, that's what the vaccines are. The spike antibodies elicited by vaccination mask the spike protein, inhibiting viral binding to the ACE2 receptor.

  8. golack

    A couple of last points:
    1. If you get new masks/respirators, esp if individually wrapped, you may want to air them out a little before wearing them.
    2. It really is better if everyone is wearing a mask or respirator properly.

    1. George Salt

      You are correct about the need to air out certain masks.

      I bought a box of 3M Aura N95 masks. They come individually wrapped. They fit well, but I noticed a strong chemical smell, a little bit like latex paint. After 30 minutes or so, my throat began to burn.

  9. Solarpup

    A big part of the problem in understanding the studies is that many of them are a combination of lab tests and models, and not "in the field" studies of how people actually wear them. At the medical school here, even prior to the pandemic, getting a fitted N95 meant taking a certification course in their proper use.

    If my experiences in the grocery store are any indication, there's a huge fraction of people who don't wear any of the masks properly, and that seems to be borne out in field studies where the differences in mask types make far less practical differences than expected. (This is the major reason the university here, while having a mask mandate, isn't specifying the kind of masks.)

    I've been using KN95s, and I actually find them pretty comfortable. The nose piece helps keep them pretty tightly fit, and I usually don't get much fogging or have too much issue breathing through them. Their not as good as a fitted N95, but the best mask is going to be the most restrictive one you'll actually wear properly and consistently. The KN95s we have hit that sweet spot for us.

    1. KenSchulz

      Would it be possible to ‘instrument’ actual masks (perhaps with tiny collection traps on interior and exterior surfaces) to allow researchers to measure the actual reduction in particulates as people go through their daily routines?

  10. middleoftheroaddem

    My wife is an ER Doctor. She comments that the biggest fallacy on masking is reuse: instead of readily changing/disposing of masks, most people put then in their pocket, car, purse etc. Thus, you are potently bringing the virus into your home or office.

    2. weirdnoise

      I've seen recommendations that if you are only using the mask for brief excursions (groceries, etc), setting it aside for a couple days (the suggestion was to put it in a labeled paper bag) and using three masks in rotation will allow you to re-use them safely a few times. Avoid handling the mask material itself (use the straps) and do proper hand hygiene and the claim was that one should be good for about eight hours of wear.

      Whatever you do, don't wash the mask. N95's use electrostatically charged meltblown material that is seriously compromised by this.

  11. Art Eclectic

    Until someone starts making KF94 or any other types of effective mask with ADJUSTABLE EAR LOOPS, I'm sticking with my less effective cloth mask.

    We have looked and looked and looked.

    1. fredtopeka

      There are KF94s with ear loops. I have a couple, but don't remember the brands (I have with me but the packaging is in Korean).

      I think Aaron Collins mentions this in some of his videos.

  12. qx49

    So many opinions about masks, and so little information! — and so many people happily sharing their opinions and misinformation.

    Anyway, Aaron Collins, and aerosol engineer, has been diligently testing masks from the start of the pandemic. All his data is up here on his publicly-shared Google drive. He also has separate data sheet for kids masks.

    (Please note: many brands of surgical masks are some of the worst performing masks he's tested.)

    https://drive.google.com/drive/folders/1eE2BERAvRzs28kG87ft3a27FS9-gHvdC

  13. Special Newb

    As I said above I usually wear N95. Spousal prefers KN95. We buy from Blue Bear.

    However the one issue is the masks are not long enough. They barely can reach my chin and cover my nose well enough not to have a gap at the top. If I could find an N95 and inch longer that would be perfect.

    1. rational thought

      Absolutely.

      Seems the n95 I find fit OK until you yawn or need to stretch your jaw. Then they are not big enough and just get out of place so you have to touch them to adjust, which partially defeats the purpose.

      And trying to keep your mouth shut enough to avoid that can tire your jaw and cause headaches

      I find the kn 94 to be better that way . Not much bigger but stay in place after you yawn.

    1. fredtopeka

      FFP2s are supposed to be very similar to KF94s, so you can substitute them when looking at the articled Steve Greene links to.

  17. Jimm

    As for the prospective graph, just one poses a problem, as you'd have to come up with a composite score, since masks can be measured for efficacy on inhale and exhale.

  19. azumbrunn

    One of the reasons for the absence of quantitative data is the fact that a mask is only fully effective when worn perfectly correctly. I'd estimate--looking at my fellow humans wearing them--that in practice the masks are on average at about 50% of their potential effectiveness.

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