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Medicine Science

Why You Shouldn't Wear a COVID-19 Mask That Has a Valve 228

Posted by msmash from the closer-look dept.
In some states and major cities, it's now mandatory to wear a mask in public to prevent the spread of COVID-19. That mask could be anything from a handkerchief to a designer cotton mask to a full-blown N95 respirator, so long as you have something between your mouth and nose and the world around you. But in California's Bay Area, there's a new stipulation: You can wear any style of mask you want, so long as it doesn't have a valve in it. What? Why? Because a mask with a valve may protect you from some pathogens in the air, but it doesn't protect the people around you from your own breath.
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Why You Shouldn't Wear a COVID-19 Mask That Has a Valve More

Why You Shouldn't Wear a COVID-19 Mask That Has a Valve

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  • Same problem with cloth masks (Score:4, Insightful)

    by superdave80 ( 1226592 ) on Friday May 08, 2020 @05:16PM (#60038114)

    What? Why? Because a mask with a valve may protect you from some pathogens in the air, but it doesn't protect the people around you from your own breath.

    No different from the cloth masks they are now allowing. One reason I hate wearing my cloth mask (I only put it on to go in stores), is because it fogs up my glasses. Well, gee, I wonder why? Could it be that my breath is actually escaping out the sides (the path of least resistance), rather than magically forcing itself through the fabric? Nah.....

    • Same issue/concern for me. I comply with the mask recommendation but don't believe it's doing much for me other than looking like a bandito.

      • Re: (Score:3, Informative)

        by Anonymous Coward

        >>don't believe it's doing much for me other than looking like a bandito.

        Your mask does little for you.
        Joe's mask protects you.

        • >>don't believe it's doing much for me other than looking like a bandito.

          Your mask does little for you. Joe's mask protects you.

          Your mask protects you from touching your face and mouth with your hands, and the viruses you might have picked up from surfaces.

        • That's some of the problem. There are people who believe they are an independent state and everyone else is a foreign state. If they get a plague well it's sad but at least the United State of Me didn't catch it! As soon as someone says we're all in this together they point and start shouting "I found another socialist!"

        • My N100 rated mask probably protects me at least somewhat.

    • Re: (Score:2)

      by kbahey ( 102895 )

      One reason I hate wearing my cloth mask (I only put it on to go in stores), is because it fogs up my glasses.

      It fogs your glasses because it is not tight on the nose.

      I found that myself when my wife made cloth masks for us. Initially, she used a straightened paper clip for the edge that goes on the nose. It worked perfectly, but it was not very comfortable.

      Then she used a couple of pipe cleaners (from the Dollar store). They are padded and have a thinner wire, so they are more comfortable. Still, they occas

      • >"However, the idea is to make the exhaled air more diffuse, so it spreads around and dilutes the virus, with a lower speed than with a valve right near the nose."

        Actually, the idea is to capture droplets for than anything else. The virus, itself, in non-droplet form, can just sail through most masks as if there was nothing there at all. Most any mask will help with droplet expelling, which happens mostly from sneezing, coughing, and talking.

        But here is the real kicker- once those caught droplets DRY,

        • "But here is the real kicker- once those caught droplets DRY, the virus will be liberated and sail right through cloth and surgical masks in either direction"

          Will it ? Any source on that ? Is the virus still active ?

          • >"Will it ? Any source on that ? Is the virus still active ?"

            It is my assumption based on information about how the virus can live for days in cloth, and it doesn't take long for droplets to evaporate.

            Based on life experience and what I have read and some deductive logic, I wouldn't recommend wearing the same cloth or normal paper mask for several hours straight. It will need to rest in isolation for several days or sterilized in some fashion after some reasonable amount of use.

            • If it desiccates that'll harm the virus, it's lifetime is surface dependent.
              Still, having several masks and rotating is a good idea. It also lets you *gasp* wash 'em! And that seems like a good idea for something on your face...

      • That does not mean it is air tight at all. None of the cloth masks are, nor are they 100% protection

        Neither are the N95 masks, the virus is smaller than the holes. But it's a lower probability of infection.

        It's all about playing the odds. When the odds of infection are low enough, the disease will go away.

        • Most respirators are actually quite effective at filtering out particles smaller than their pore size. Electrostatic interactions make the particles stick to the filter media.

    • Re:Same problem with cloth masks (Score:4, Informative)

      by Fly Swatter ( 30498 ) on Friday May 08, 2020 @05:43PM (#60038256) Homepage
      I had the same problem with my home-made mask, until I made a mask with a proper nose fitment which included 2 bent pieces of copper wire in the lining to fit and form around the nose. Now I no longer breath into my eyes.

      • Personally, I want a Tusken Raider mask and robes. That should keep me safe. Mostly by making everyone stay away.

        • You'll have crowds of neckbeards chasing you, wanting to ask how you made it and trying to recite Monty Python skits with you.

        • Personally, I want a Tusken Raider mask and robes. That should keep me safe. Mostly by making everyone stay away.

          Also handy for queueing single file.

          Personally I'd prefer a Breen suit [fandom.com].

    • Does it matter though? It's possible (pure speculation here) that even a cloth mask may at least reduce the velocity and therefore range of any virus particles - thereby reducing the probability of infection.

      • Re: (Score:3)

        by dgatwood ( 11270 )

        So do some valve masks. My half mask respirator has a valve that routes outflow through a separate path, but there's still a filter there, just nowhere near the P100 level of filtration that the inflow filters achieve.

        Either way, this is dumb. We should either mandate real, effective masks that actually filter enough do some good, or don't bother mandating them at all. Doing it half-a**ed just results in bizarre rule like this that punish people who take their health seriously (and are thus unlikely to

        • We should either mandate real, effective masks that actually filter enough do some good, or don't bother mandating them at all.

          Guess what would happen if the government did that?
          1. The 'required' masks would become hideously expensive -- because you have no choice
          2. The 'required' masks would become almost impossible to get -- either from lack of supply, or false scarcity to drive up the price
          3. Enjoy getting ticketed/jailed/roughed up by cops over mask-related bullshit

          • Re:Same problem with cloth masks (Score:4, Interesting)

            by dgatwood ( 11270 ) on Friday May 08, 2020 @06:52PM (#60038562) Homepage Journal

            There's mass manufacturing of masks happening right now, and the virus has mostly burned itself out in China, so those Chinese factories are cranking out KN95 masks largely for export at this point. They cost a buck or two in quantities of 1,000 or more. Some places won't even sell them in quantities of less than 10,000, 50,000, or even 100,000. One order of 100,000 masks would allow you to hand out masks to every single person in a small city.

            There really isn't a shortage of mask manufacturing, for the most part, from what I'm seeing. There might be a shortage of medical-grade, certified mask manufacturing. But there definitely is a complete breakdown of the entire supply chain between those manufacturers (almost all of which are in China) and the general public here in the U.S. That is something that the government can and should help with.

            • But the n95 masks generally have exhaust valves.

              Bottom line is that unless you require positive pressure bag-in/bag-out respirators, people can’t really breathe. I can only wear my half-mask respirator (purchased for fire season) for a half hour before getting dizzy; cloth masks are about 5 minutes if worn properly or an hour if worn as a “beak” with an opening at the bottom (only one headband strap engaged, bottom side just held together.

              Anything you put over your mouth and nose is going

              • I have severe allergies, and mild asthma, and having to wear something restricting my breathing, regardless of what it is, aggravates them both. There's no way I could go through years of having to have a stupid mask on my face all the time.

                • Re: (Score:2)

                  by dgatwood ( 11270 )

                  You're also probably at much higher risk of bad outcomes, so you should ideally be having someone else do your shopping, if possible.

                  • Already had it, back in February, got over it, recovered completely from it, back to riding my bike 200+ miles a week.

              • Re: (Score:2)

                by dgatwood ( 11270 )

                But the n95 masks generally have exhaust valves.

                I was talking about KN95 availability, not N95. Those are the Chinese rough-equivalent of N95, but not precisely, and not certified for healthcare use. And most of them do not have exhaust valves. Of course, if they were broadly available enough that everyone had good masks, the exhaust values wouldn't be a problem, which was my point earlier in the thread..

              • But the n95 masks generally have exhaust valves.

                Sigh. FTFA:

                The N95 respirator is a relatively new invention, introduced in the 1970s, and it was brought to market largely in response to a need in industrial America rather than medicine. [...] Early respirators were designed to be used in factories and coal mines. They filtered particulate matter, aka dust, from the air that would be harmful to breathe in. But wearing a respirator can be a miserable experience. It traps heat and vapor from your mouth. That’s why these industrial respirators had valves, so that it kept the wearer cooler and more comfortable while working a long shift, Nikki McCullough, an occupational health and safety leader at 3M, explained to me last month. If people were to breathe out flu germs in a coal mine, the coal would be just fine! [...] in the 1990s, with the rise of AIDS and a related outbreak of tuberculosis, doctors were looking for a new level of airborne protection, since tuberculosis is highly contagious through the air. That’s when the medical community bought into N95s and created its own standards for these respirators. The big difference? The medical community mandated no valves, so healthcare workers didn’t get the people around them sick.

                So the N95 masks used in industry have valves because they are trying to protect the person wearing them from breathing in dust. They don't care about what the person is breathing out.

          • Exactly correct. The answer is that "back in February", the US should have started producing masks in "mammoth quantities". If the US goes thru 100 million masks in a "normal year" and the mask have a shelf life of 5 years, it should have ordered 500 million masks "immediately". At any point in time, the "national stockpile" should have 500 million masks sitting on the shelves. Send 100 million a year to hospitals, and buy 100 million new ones to replace them so that they never go stale.

            Adjust these numbers for average use rates and product shelf life. This is where "JIT" inventory will "KUA" (Kill Us All).

            This is called managing emergency supplies.

        • The fact of the matter is that there are plenty of KN95 masks available by mail order, at least as of a couple of days ago, in part, because they don't meet U.S. medical standards. But they're still a lot better than random cloth masks and bandanas and crap.

          It doesn't matter, the cloth masks are enough to reduce the probability of infection.

    • Actually the valve mask is worse than a cloth mask for that. The cloth will snag a lot of smaller moisture droplets you exhale, but the valve will expel ALL of them.

    • Re:Same problem with cloth masks (Score:5, Informative)

      by AmiMoJo ( 196126 ) on Friday May 08, 2020 @06:04PM (#60038342) Homepage Journal

      Unless your glasses are also getting covered in little droplets of spit then the mask is working.

      The virus isn't on the CO2 and other gasses you breathe out. It's in the droplets and the mask catches most of those.

      • Re: (Score:2)

        by Hadlock ( 143607 )

        Until those droplets dry out. Coronavirus is notoriously small, at least half the size, closer to 5% the size of most viruses. As soon as the droplets dry out, they get pushed out and into the environment. Also there's varying sizes of droplets, just because you can't see them doesn't mean they're there.

        • Re: (Score:2)

          by Vihai ( 668734 )

          Are you sure those proteins can stay intact in air without a wet environment?

        • You go ahead and worry about a dry virus, I'm going to keep worrying about the ones the doctors warned me about; the ones riding on a wet micro-environment like a drop of spittle or a flake of skin.

          Stop waving hands around and trying to solve it yourself from base principles, and just listen to the doctors. It is too hard to solve it yourself.

      • Re:Same problem with cloth masks (Score:4, Informative)

        by chiefcrash ( 1315009 ) on Friday May 08, 2020 @08:30PM (#60038924)
        CO2 doesn't fog up your glasses. Moisture does....

        What exactly did you think the fog was made?

        • Re: (Score:3)

          by AmiMoJo ( 196126 )

          Moisture content of the air is not the same as droplets. Orders of magnitude difference in size.

    • Re: (Score:2)

      by ljw1004 ( 764174 )

      One reason I hate wearing my cloth mask (I only put it on to go in stores), is because it fogs up my glasses. Well, gee, I wonder why? Could it be that my breath is actually escaping out the sides (the path of least resistance), rather than magically forcing itself through the fabric? Nah....

      I don't think people are concerned about your breath. We don't believe in miasma any longer. We're worried about your spittle.

      • Re: (Score:2)

        by MrL0G1C ( 867445 )

        They should be concerned about breath, it's what carries smaller particles that stay in the air longer. The jury is still out on whether the virus is airborne. It is suggested that many of the isolating people infected on cruise ships may have caught the virus via ventilation systems = airborne spread.

        https://www.theguardian.com/wo... [theguardian.com]

        The simple fact is the majority of people (66%) in New York who caught covid-19 recently when surveyed said they were sheltered at home. This says that either current measures

        • They're isolating at home, not under strict quarantine; they're still going out to buy groceries.

          This doesn't tell us anything. Stop over-thinking it and wait for the numbers.

    • The point is that it slows down the breath, acting as a baffle. When talking, the water droplets will be caught or else only go a short distance. Without the mask you can see on a heat camera that breath will reach out as turbulence for about a meter; with a mask the turbulence goes up and down and is diffused quicker.

      Yes, it is NOT perfect! And having no mask is not perfect either of course. So don't let perfection get in the way of doing something that can have a small effect.

      It does fog up my glasses,

    • From what I've read, homemade masks have a filtration effectiveness that ranges from 10% (just a bandanna across your mouth and nose) to 50% (several layers of fabric). Even 50% effectiveness can be very helpful in situations that force moderate exposure for a relatively short time, such as being in the grocery store to buy food. The situations when homemade masks aren't useful are when you have minimal exposure (such as walking outside and only occasionally passing someone on the sidewalk), where the odds

    • I use a bandana snugly tied on the bridge of my nose, then draping loose at the bottom. Because of the differential pressure, the vast majority of my breath is sent downward and deposited on my chest. No fogging problems.

    • This isn't hard to understand, it doesn't have to be airtight, nor stop your exhalation and force it through the netting. The virus is not very airborne. It needs to stop your phlegm, spit and/or snot from flying 10 feet and spreading everywhere, just a few drops are enough. Those drops are leaving you when you talk, cough, sneeze, spit, whatever. The mask certainly is catching the majority of that. It's not a bio suit, it's not going to stop everything.

      The goal is to reduce the infection spread rate as muc

    • Re: (Score:2)

      by HiThere ( 15173 )

      But the air that escapes out the sides is at a lower velocity when you cough or sneeze, and the larger particles have more momentum, and can't change direction as easily when you cough or sneeze.

      It does help people around you, and has a slight protective value for you. I don't know the design of the "masks with a valve", so I can't comment on them. What I really think people should wear is an air helmet with two short tubes that hang over the shoulder. And there's a flap valve in each tube so that one le

    • Well medical masks for operating room are made just for this - to prevent the patient with it's open cavity from any pathogens the personnel around may spread. So why do the work there?

    • Re: (Score:2)

      by Rei ( 128717 )

      Indeed. I'm not sure it's actually worse than a mask with a valve. It's not true that a mask with a valve does nothing. Ever sneezed inside one? I have. The sneeze droplets don't (at least by and large) decide to suddenly do a 90-degree turn and then another 90 degree turn out the valve. They just slam into the mask and make it disgusting all over the inside. Finer aerosols may pull off that maneuver, but they'll do the same thing in your average homemade cloth mask.

    • The point of the mask isn't to completely prevent your breath from escaping, it's to prevent any droplets in your breath from traveling the 10+ feet that they'd normally go when you breathe.

    • Right. And if the valve goes to the bottom or side of your mask instead of the effin' FRONT, you can wear that mask with a valve, too.

  • Maybe a dumb question? But .... (Score:4, Insightful)

    by King_TJ ( 85913 ) on Friday May 08, 2020 @05:17PM (#60038120) Journal

    If people are wearing regular old cloth bandanas or t-shirts or whatnot as their masks, and they've worn them long enough without washing them? Are they still really doing any good as far as preventing the spread of germs to other people? I would think that as a piece of cloth gets saturated with the virus particles, it stops being a useful barrier.

    • It wasn't a very useful barrier to begin with.

    • Re:Maybe a dumb question? But .... (Score:5, Informative)

      by kbahey ( 102895 ) on Friday May 08, 2020 @05:48PM (#60038276) Homepage

      If people are wearing regular old cloth bandanas or t-shirts or whatnot as their masks, and they've worn them long enough without washing them? Are they still really doing any good as far as preventing the spread of germs to other people? I would think that as a piece of cloth gets saturated with the virus particles, it stops being a useful barrier.

      Depends on the usage.

      If you are a worker that wears a cloth mask for an entire shift, surrounded by lots of people in close proximity, then a cloth mask is not such a good idea, and you need something better. If you do, then it needs to be washed after every shift in hot water and soap.

      On the other hand, if you wear one when you go out for grocery, say every 4 or 5 days, and wear the mask for 2 hours each time, then it is not a concern. Whatever residual virus is on the mask deactivates in 72 hours or less. Wash it every other week if you want to, but it is not necessary.

    • Well if people want to have a dirty mask, I suspect that if they are dirty enough that it becomes inoculated it with something like Bacillus subtilis (a known enemy of enveloped viruses everywhere) it might even inhibit the thing.

    • Re: (Score:2)

      by Falos ( 2905315 )

      Pee-soaked pants still help keep pee in.

    • Re: (Score:2)

      by Kohath ( 38547 )

      Obviously the solution is for government to mandate washing. And require everyone to use detergent that creates a residue that shows up under a black light and fades in a few days.

      It's the only way. Complex, detailed policing of everything everyone does is the only answer they know.

      Cops will be out shooting tasers at anyone whose face mask doesn't glow under a black light. But only because the autonomous drones that do that automatically are back ordered.

  • It should be obvious. (Score:5, Funny)

    by penandpaper ( 2463226 ) on Friday May 08, 2020 @05:25PM (#60038156) Journal

    >Why You Shouldn't Wear a COVID-19 Mask That Has a Valve

    Because it doesn't make Darth Vadar breathing noises.

  • You can put tape over the valve, or a layer of cloth, or glue some N95 filter media on the inside of the mask over the valve. That way you can take advantage of the superior particle filtration and block the unfiltered exhaust path.

  • We aren't maintaining a sterile field (Score:5, Interesting)

    by magzteel ( 5013587 ) on Friday May 08, 2020 @05:38PM (#60038230)

    From the CDC: "However, respirators with exhalation valves should not be used in situations where a sterile field must be maintained (e.g., during an invasive procedure in an operating or procedure room) because the exhalation valve allows unfiltered exhaled air to escape into the sterile field."

    We are in no way maintaining a sterile field. Do you see people scrubbing down and wearing hospital gowns and sterile gloves and hair coverings? Absolutely not.

    These valves typically have a baffle that directs exhalation downward, not forward. They are easier to breath in so they are more likely to be used properly. I see people wearing whatever they can find, any old way. Some people have nose and mouth covered. Some have mouth covered. Some people wear it like a chin strap. I've seen people just pull their shirt up and hold it like a hankie. But I've yet to see someone wear a valved N95 improperly.

    I really hope this face covering thing disappears soon. Next we will be mandating burkas.

    • I have one that you can twist the valves and lock them shut, as you see fit.

    • Masks aren't for you. (I mean, sure, they also can help you, but that's not the primary reason.) They're to protect other people from you if you're a carrier. To that end, paying attention to regulations for maintaining a sterile field seems like good sense.

    • From the CDC: "However, respirators with exhalation valves should not be used in situations where a sterile field must be maintained (e.g., during an invasive procedure in an operating or procedure room) because the exhalation valve allows unfiltered exhaled air to escape into the sterile field."

      We are in no way maintaining a sterile field.

      The goal is for you to not infect other people with what you exhale, vs. blocking someone else's bodily fluids from your face while you breath in relative comfort.
      A fifth grader could figure out what a one way valve is for, I confirmed by asking one. None of us understand the "some people don't cover their nose and mouth properly so why not wear something that doesn't really do what we want" logic. How about neither.

      Next we will be mandating burkas.

      Now you're just being stupid.

    • Next we will be mandating burkas.

      The burka is not to protect you, it is to protect my eyes from having to see you.

      Stop being so selfish.

  • ...that here in the Bay Area we'll soon have to walk backwards.

  • so long as you have something between your mouth and nose

    Does a moustache count? Part of a goatee?

  • I see so many people out-and-about wearing those valved masks. They probably have them as a leftover from wildfire season, or simply because it was the easiest thing to find. Unfortunately, I don't want to be the confrontational asshole to tell them to stop wearing those and get a mask without a valve. So I just keep my distance from those people, if I can, and mentally consider them to be a bit more risky to approach than people who wear the right sort of mask.

    However, I'm wondering when/if someone will ac

    • Unfortunately, I don't want to be the confrontational asshole to tell them to stop wearing those and get a mask without a valve.

      That's good since you're completely wrong about the issue.

  • All of these people requiring "cloth masks" for "health reasons" will eventually (maybe?) learn that cloth doesn't do anything at all to filter pathogens out of the exhaled (or inhaled) air. Similarly, the people requiring you wear a mask (of any sort) in the outside environment. Bikers, joggers -- wear masks! Because if you don't, and you exhale, air will escape your body!

    So, then what? Will they start requiring people wear completely sealed masks? If they leave their homes, they have to leave with a bag o

    • All of these people requiring "cloth masks" for "health reasons" will eventually (maybe?) learn that cloth doesn't do anything at all to filter pathogens out of the exhaled (or inhaled) air.

      Empirical experience shows wearing the masks is enough to reduce the probability of the spread of COVID. So they do something.

      They don't have to be perfect, they just need to reduce the probability.

  • none of these mask stop covid anyways so why are we concerned. its a dam illusion of safety and everyone just eats it up.

  • Cover your valve, with a bandanna. What are they going to do make you take of the respirator and wear the bandanna without it?

  • And this [preview.redd.it] is it.

  • You can wear any style of mask you want, so long as it doesn't have a valve in it. What? Why? Because a mask with a valve may protect you from some pathogens in the air, but it doesn't protect the people around you from your own breath.

    We know this already. The purpose of sub-N95 masks, down to cheapies and scarves, is to:

    1. Stop you from blowouts of larger fomites via sneeze or cough. Breath virus gets right through.

    2. Stop you from touching your nose or mouth, which is how it gets into you.

    • Re: (Score:2)

      by henni16 ( 586412 )

      From personal experience and observation, the masks are probably doing point 1, but they're doing the exact opposite of point 2 because people are constantly fiddling around with them.
      The first time I put one on for a shopping trip, it took quite some time to make my cloth mask seal so that my glasses wouldn't fog up and not fall off. When I finally managed it, I was basically deeply inhaling (had to get enough air through the now better sealing mask) whatever I had transferred from the shopping cart handle

  • Tech-ignorance re; masks is inexcusable.

    Exhalations can be filtered with A RAG OVER THE VALVE.

    The purpose of the valve is to keep from soaking the filter with MOISTURE by exhaling through it instead of the media.

    Gas masks are also designed this way, and as they're full face respirators, to prevent fogging too.

  • Cultural differences (Score:4, Interesting)

    by CptJeanLuc ( 1889586 ) on Saturday May 09, 2020 @04:12AM (#60039898)

    This will either ring a bell or not. In countries where social responsibility is a common value, people will think "oh, I better not use them, then". In countries more focused on the type of "yeah, well, noone is gonna tell _me_ what to do, if people have a problem with my breath they can wear their own mask" attitude, response would be different.

    I guess we can all have an idea where our own country is placed on that spectrum, and who is the big elephant in the room. Now consider which type of approach is more effective in fighting pandemics ...

    Human beings are social herd beings. We thrive because we learned to get together and do stuff that benefits the group, even though it is not always optimal for ourselves at a particular point in time in a short-sighted narrow perspective.

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