Harris County (Houston) is going to order the use of face masks while in public - most of the masks will likely be homemade or surgical type. Does wearing a mask help prevent the spread of Covid-19? Common sense tells me it would help, I’m not sure how much, but it would definitely help. I also realize if I can breathe in and out of the mask, it’s likely coronavirus particles are going in and out, too.
I realize “mask” can mean many things and “help prevent” can mean many things and I’m leaving that open ended.
Two basic benefits of the mask are that they help block viruses from being inhaled and they impede any virus being exhaled. Improvised cloth masks might just block 50% of the virus from being inhaled compared to 95% with an N95 mask. But a simple cloth mask can make a big difference in how far someone’s breath is exhaled. Here’s a video that helps demonstrate the difference between no mask and with a mask: Covid-19 : LaVision imaging technique shows how masks restrict the spread of exhaled air - YouTube In that case they are using a medical mask, but you can see how drastically shorter his breath travels with a mask versus without. The farther the virus can travel the greater chance to infect someone or some surface, so impeding that means the chance of infecting someone else is lower.
If you only have an improvised mask, try to have a gap between the mask and your face so that the exhaled air will be more diffuse. If the cloth mask is tight against your face, the exhaled air can still leave the mask with a lot of force. With a slight gap, the exhaled air is distributed over the whole mask and will leave the mask with less force.
The aspect that nobody is paying attention to is risk compensation. When people perceive that something is protecting them, they tend to engage in more risky behavior. The classic example is bicycle helmets. Nobody disputes that if your head is going to strike concrete, it’s better that it do so inside a helmet. Yet studies have shown that laws mandating helmets don’t make cyclists safer overall. Cyclists are less cautious in traffic when wearing a helmet; it has even been shown that motorists give measurably less room when passing cyclists who are wearing helmets. In other words: a helmet protects you in an accident; but it also increases the probability that an accident will occur.
Anecdotally, I’m seeing this phenomenon every time I go out. I think people are wearing tea towel face masks and then thinking (consciously or unconsciously) that this means that it’s not so critical to maintain 6-foot separation. I’ve certainly noticed that people are more inclined to keep away from me if I’m not wearing a mask.
So the argument that “they can’t hurt” doesn’t hold up. If they are not really very effective, risk compensation may mean that masks increase the rate of transmission.
You wear the mask to protect others, in case you have the virus. Asymptomatic carriers (having the virus and not knowing you have it) is common. By wearing the mask you reduce the risks that you spread it.
If everyone in public is wearing a mask, then the spread of the virus will be significantly reduced.
Last time I went into a store I motioned to a young woman that her mask had slipped down, it was no longer covering her nose. She pulled it up slightly but the stiffener to shape it around her nose was just sticking out to the sides leaving a huge open gap on either side of her nose, which she was barely covering with the mask at all. At least everybody was maintaining a reasonable distance. But there are always people who just sort of phone it in, even when lives are at stake.
It’s not going to be worse than no masks. I think it’s very unlikely it would increase the rate of transmission overall compared to no masks, but it may increase it on an ndividual basis for foolish people.
Your point is more applicable to things like bicycle and motorcycle helmets when it comes to prompting risky behavior.
Again, if you come into contact with someone without a mask and they cough on you, it will not protect you. But if that person is wearing a mask, it will reduce the chance of spread to you.
So you want to be out in public with other people wearing masks. If you choose not to wear one, then you’re only thinking about yourself and not others.
Why would you think that? It seems like an exact parallel to me. If anything the psychological effect is much stronger in a situation where people are frustrated at being cooped up at home for weeks, unable to work or socialize. If the government is telling people that masks make them safer, do you really think that doesn’t increase the probability that will go out, and that they will be less nervous about being close to other people?
And everyone always thinks that the psychological effect of risk compensation only apply to other people, who aren’t as smart as they are.
With the type of masks that are typically available to most people, and the limited protection they provide, it is entirely possible that the net effect of advising or mandating the wearing of masks might alter behavior to result in an overall increase transmission rates. It’s be a function of the degree of protection, and the size of the psychological effect, and nobody knows if the former outweighs the latter for a typical makeshift mask. Asserting that it’s obvious that it does is without foundation.
That doesn’t address risk compensation. If I’m at home and not in contact with anyone in the first place, I can’t infect them. So show me a study that looks at how the perceived increase in safety from wearing a mask affects the probability that I will mingle with other people, and how close I will get to them with a mask vs without.
These studies don’t exist. But the conclusion that wearing makeshift masks is a net positive is not as obvious as everyone seems to think.
At the very least, government advice should be strongly focused on telling people that masks have an uncertain and possibly very limited benefit, to try to minimize risk compensation behaviours.
Thanks for the video, it was very effective at getting the point across and confirms my intuition re: masks. I have a question, what exactly am I seeing (ie, the imaging)? The link says, “the visualization of gas motion based on local refractive index variations Background Oriented Schlieren (BOS, also known as Synthetic Schlieren).”
I guess my question is how small can the imaging see…are we seeing 90% - and not see 10% of the small, but transmissible particles? Are we seeing everything. (I honestly don’t know how to ask the question correctly).
That’s a fair point. In Houston/Harris County, and this is me just reading the tea leaves, but it appears the Governor is going to start opening up the “economy” in a way that’s going to put people in closer contact with each other. Harris County appears to be anticipating that and if it’s going to happen, at least require people to wear masks in public to help prevent the spread. That makes sense.
I guess the question then is, just because we’re allowed to go out, doesn’t mean we have to…but would I be more inclined to stay inside or 6 feet apart outside without a mask versus wearing a mask. I do think people would get a false sense of security and go out/get closer than 6 feet to people because they are wearing a mask. But I also think they would be outside/close to people without a mask, so better to have one on. Are there any studies/consensus on this?
What made me start this post was people I know saying masks weren’t 100% effective, didn’t work, etc. I just don’t understand why everything has to be so absolute. Some effectiveness is better. There was a poster who said a lady only had her mouth covered, not her nose. To me, that’s better. You’re still covering one of two ways to spread the disease. And the mouth is blowing forward versus down. Better is good.
But the whole point about the risk compensation issue is that (very approximately) if the perceived increase in safety from a given type of mask is greater than the actual increase in safety then the psychological tendency to engage in more risky behavior may outweigh the physical benefit of the mask. So the “something is better than nothing” argument is wrong.
Again, people should wear a mask to not protect themselves, but to protect others from you spreading the virus. We should assume that we are all asymptomatic and that we could spread the virus to others. Yes, staying at home will reduce that risk to near nil, but many of us have to work, have to buy food, etc. So when going in public, we should take steps to reduce the exposure to other people.
It’s like the real reason that many people get the seasonal flu vaccine. It’s not to keep yourself from getting sick, it’s so you don’t get it and spread it to someone else that is more vulnerable.
As long as the actual benefit is less. Sure. I don’t know that to be true one way or the other. Common sense tells me masks would help prevent spreading (actual outweighing perceived benefit), but I’m definitely open to be proven wrong.
In Texas, the Governor is going to let people go outside and return to normal sooner than he probably should. That is going to happen, people want it to happen. If that’s going to happen, then I think it’s better (safer) to do it with a mask on.
And again - I don’t dispute that if the psychological effect of risk compensation didn’t exist, wearing masks would be sure to make us all at least somewhat safer. But it does exist, it can be very strong, and it doesn’t make everyone safer to just ignore it.
Yes, I think in this situation people are still nervous about being around other people, very few people are so foolish to consider any old mask to be a panacea. Motorcycles prompt unsafe behavior in a lot of people, it’s the reason a lot of people get motorcycles, they want a thrill and they’re often only wearing the helmet because it’s the law or they’re making someone else happy by wearing it. They don’t really belief the helmet is making them much safer. It’s just adding a little bit of false sense of safety to something inherently dangerous. Nobody thinks helmets decrease the chance of a motorcycle accident.
But the main difference is that a motorcycle helmet isn’t meant to protect other people, it’s just for the rider. Enough people realize masks are more important than that so I don’t see the wide spread behavior occurring that would make masks increase the rate of transmission compared to no masks at all, not simply fail to reduce it. I think you have to back up that claim.
I don’t think you’re disputing the psychological effect exists, since you yourself in the other thread said you’d be more inclined to approach someone if they are wearing a mask. You’ve explicitly said that if I don’t wear a mask, that’s a very effective way of keeping me totally safe from you, because you won’t come anywhere near me! And obviously I’m not meaning to pick on you in particular - the psychological effect is obvious for everyone, including me.
So it’s simply a question of the magnitude of the effect, and I’m not sure why you think the burden of proof lies on one side only.
The question is: how much physical protection does a mask really grant, relative to the perceived protection, since the psychological effect will be proportional to the latter.
As I’ve said, I certainly wouldn’t dispute that if N95 masks were available in unlimited supply, we can assume that the physical protection outweighs any psychological risk compensation effect. But I’m much more skeptical about the makeshift masks that most people are wearing.
At the very least, I think there should be a much stronger focus in government guidance on trying to limit risk compensatory behaviors by telling people the truth - that we don’t have good evidence that makeshift masks are very effective at all, and that wearing them should absolutely not make anyone think that approaching other people is significantly safer.
I don’t disagree with the basic principle, but again, you are saying that so many people will wear inadequate masks and ignore all other social distancing that the transmission rate will be higher than if no one wore masks.
And I’m sure you realize that my caution in staying away from people without masks is not going to apply across the population, and probably doesn’t mean anything if no one is wearing a mask.
Hi. I’m curious about the evidence for this claim. The best cite I found in 10 minutes of googling was this 2016 article from The Guardian, which discusses a new survey of studies. The conclusion is that wearing a helmet while bicycling greatly reduces serious head injuries. Nearly a 70% reduction.
It touches on an earlier study that emphasized the Risk Compensation theory. That study seems to have been based on a very abstract experimental set-up, rather than real life results. But presumably there are other, better, studies.
I don’t follow your reasoning here. You seem to be suggesting a model where you are somehow obliged to closely approach a certain number of people every day, and it’s just a question of how you choose them.