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Airflow Videos Show Masks with Exhalation Valves Don't Slow Spread of Covid-19
- helsinki 6y agoNot all that useful without measuring a mask’s ability to filter the particles.
- olliej 6y agoMasks with valves are only designed to limit particle flow inwards, otherwise the valves area would have to have the same thickness and construction as the rest of the mask. The mask is not just about stopping you getting infected by something, it’s also about reducing your ability to transmit it to others. In fact a mask is more effective at limit transmission from you than to you. That’s why we have multiple layers - everyone wears a mask, limits travel, limits exposure to others, ensures as much distance as possible, maximizes the surrounding air volume when in the presence of others, etc.
- olliej 6y agoThe need for valveless masks was established months ago. Are people still arguing about this (aside from anti-maskers, etc)
- helsinki 6y agoValved masker here. If everyone used a valved mask, wouldn’t it reduce transmission rate moreso than everyone wearing valveless masks?
- inakarmacoma 6y agoNo, why would that be the case. One protects in two directions. The other projects in one direction.
- olliej 6y agoNo it would make it worse. Valves masks intentionally do not filter air you breathe out, so if you’re a carrier you’re fairly close to being mask less. Masks are better at preventing outgoing transmission than incoming so you’ve deliberately ruined the thing that a mask should be most effective as.
- postalrat 6y agoFace shields don't either yet those are used as PPE. I don't think anyone is saying vented masks are ideal. Though they are probably better than most simple cotton masks, they aren't as good as an unvented N95.
- nikolay 6y agoYou assume masks filter out 100%. Most people wear masks with less than 50% filtration and some wearing single layer polyester actually aerosolized droplets and make them worse than not wearing anything. People believe that aerosols and droplets behave the same way - a droplet may splash into a face shield, but aerosols don't behave the same way and won't hit the shield at all.
- jjeaff 6y agoI don't buy it. More like: masks with exhalation valves don't slow spread of covid -as well as masks without-. You are still personally protected just the same. And if you are personally protected, you are less likely to catch the virus and spread it along.
- dusted 6y agoI'll bite :) let's say your mask protects you from N% of the droplets you inhale. and let's say MY mask protects you from N% of the droplets I exhale. Now, are you more protected if: a. Only I wear a mask. b. Only you wear a mask. c. We both wear a mask.
- NeutronStar 6y agoI'll bite. You are more protected with 2 masks. However, your not unprotected with only 1 mask. Therefore, having a valve mask wouldn't protect others from you, but you would still be protected from others. Now if both don't wear mask, we have an issue.
- jjeaff 6y agoBoth wearing masks, obviously. But that isn't what the title says. It is saying that a mask with a valve doesn't slow the spread of covid. Obviously, one of us wearing a mask is better than neither of us wearing a mask. I think maybe the implication is that if the person wearing the mask already has covid, it isn't going to slow the spread to others. Which makes sense. But if you at least wear a valved mask, you will be less likely to catch covid in the first place.
- postalrat 6y agoHow does a video show if a virus is being spread or not? It seems like this is the year all science is done through videos and diagrams.
- lionkor 6y ago> How does a video show if a virus is being spread or not? It doesn't. The video starts with a good 3 second disclaimer about just this. Either way, I'll bite. It's been shown that SARS-Cov2 is transmitted through the air[1], amongst other ways. Visualizing the flow of one person's breath you can identify the route that the breath takes. Generally, if the breath goes past or through a lot of fabric, the larger water droplets tend to stick to the fabric. The virus is usually carried in the air on tiny airborne water droplets. This means that if water droplets stick to the inside of the mask's fabric, a lot of the viruses will as well, thus decreasing the spread. You know a mask works because it feels a bit damp inside. That's a sign of it doing the job. A mask will not fully "stop" the spread. It helps to reduce the velocity of the air exiting your body, and captures a lot of the water vapor that carries the virus. > It seems like this is the year all science is done through videos and diagrams. There is no better way to relay the information gathered through schlieren imaging than to just show the recording. That's why its called "imaging". 1: https://www.pnas.org/content/117/26/14857 https://www.pnas.org/content/117/26/14857
- muzika 6y agoMasks are needed to protect not the wearer, but those around him. Same reason why doctors wear masks when performing surgeries.
- Justin_K 6y agoIt goes both ways. Cutting bone and squirting saline can spray back.
- cameldrv 6y agoThey do both. Masks that effectively filter in both directions are much better at reducing transmission. Everyone should be wearing N95s or better whenever they’re indoors with someone not in their household. As an aside, if you have a valved N95, just put some duct tape over the valve and voila, unvalved N95.
- manojlds 6y agoNot this argument again. This was perhaps the major statement that made mask wearing such a difficult thing to encourage. People were like if someone else is at risk, ask them to stay at home etc. It's been proved that masks help the wearer too. It's also being theorised that masks, due to not being perfect, is giving immunity by exposing one to lower viral loads and leading to very mild or asymptomatic disease.
- deleted 6y ago[deleted]
- My7thAccount 6y agoSo the doctor is sick and is wearing a mask so that the patient “and others around him” dont get sick even though he’s treating a sick patient? It’s really simple your health your responsibility just like when you go eat McDonald’s. Can you go work out for me to while you’re wearing a mask for my sake I’m getting a little chubby from being confined to my house Just like a criminal. Why do I have to care about other people again as long as I’m not hurting them and how can you prove someone gave you an airborne virus again? In a free Society these questions all need to be answered first
- pengaru 6y agoAirlines banned valved masks on flights months ago for being ineffective.
- throwawaysea 6y agoAnd what’s the efficacy of valveless masks at reducing spreading? Given that even places with extremely high mask compliance are experiencing the same spikes as everywhere else, I have trouble believing that the benefit from masks is anything but marginal, since very few people are wearing N95 respirators. Meanwhile, for that marginal benefit everyone is being subjected to the discomfort of constrained breathing, the psychological impacts of not seeing faces/expressions, and difficulty for the hard of hearing (who rely on seeing lips/expressions). A recent study found that masks provided little benefit (https://fee.org/articles/new-danish-study-finds-masks-don-t-protect-wearers-from-covid-infection/ https://fee.org/articles/new-danish-study-finds-masks-don-t-...) but I haven’t been able to find exact numbers on the probabilistic reduction in transmission on a per-mask-material basis.
- exged 6y agoSome other studies [1] have shown that N95 valved masks are as effective at filtering exhaled droplets as unvalved cotton masks, and considerably more effective than improvised things like bandannas and neck gaiters. It makes some sense - the valve lets a lot of droplets out, but the rest of the N95 mask is probably a far better filter than a cotton mask. It doesn't contradict the claim in this article, but it's an interesting thing to ponder about the risk of the general public having seemingly all standardized on cotton masks. [1] https://advances.sciencemag.org/content/6/36/eabd3083 https://advances.sciencemag.org/content/6/36/eabd3083
- dusted 6y agono... fucking... kidding.. The whole idea with the mask is to filter air going out of infected individuals, so if there's an exhaust valve, of course they won't work.. there's a reason there aren't exhaust valves on surgical masks. I get angry that it should even be something to point out, can't people think?
- CaptainZapp 6y agoTry entering any plane operated by Lufthansa Group with a mask containing a valve. Or phrased more accurately: Don't! They won't let you. Period. N95 masks are fine, surgical masks are fine, masks with valves (or any other creative form of face covering) are explicitly not. In the very early days of mandatory masking you could get away with a doctor note. Now you need a negative test not older than 72 hours in addition to a doctors note if you try such shenanigans. I, for one, agree. E: Clarification
- lionkor 6y agoSlowing the spread is all about doing as much as possible to contain the virus. A one-way filter does not stop the spread from both sides as well as a two-way filter. Then again - as long as you're wearing any kind of mask, you're making a difference. Wear a good one that protects you and others if you want this BS to be over sooner. Wear none if you want to be that guy in every zombie movie that doesn't take the first infected seriously and dooms the planet.