SARS-CoV-2 concentrations and virus-laden aerosol distributions in outdoor air
sciencedirect.com
sciencedirect.com
I seem to remember having read wording in one of the many papers that we surely all skimmed in 2020 that looked suspiciously like a statement declaring side in a scientific community that still considered both possible. (something like "We are working with the Independent Probability per Virion Assumption here" or something like that.
For getting infected, it's like lottery tickets.
For severity of infection, a bunch of "winning" lottery tickets make it difficult for your immune system to catch up. Getting a large exposure is like giving the virus multiple viral generations of a head start without being noticed by the immune system.
So as a rough example, let's say social distancing recommendation is 6ft (this changes by jurisdiction). Then for a football field to be "crowded" you would need more than 57,600 / (pi * 36) = ~510 people evenly distributed on it. If the social distancing recommendation is 20ft, then you can only have 57,600 / (pi * 400) = 45 people on the football field before it starts getting crowded.
(Addendum: there’s the obvious question, why not just wear a mask 100% of the time? There are no downsides, right? — There can be. Perhaps my mask had been in use for a while, I suspect it’s gotten dirty enough to be a potential health hazard, but I don’t have another mask to replace it? I’d still use it if people are around, but would try to reduce my exposure to it otherwise. Maybe I have asthma or some type of breathing difficulty, and wearing a mask makes it worse? I think those two are probably among the most common reasons.)
This behavior seems to be part of Call Out Culture.
I think not wearing masks again will be easy to normalise. For example, Hong Kong got hit by the first SARS and everyone wore a mask for a time, and then when it was over all was back to normal and masks quickly became rare.
Larger countries (including the US) that are more sparsely populated and tend to rely on central messaging from authorities less will probably have areas that are slower at adopting new measures (or lack thereof), which may be frustrating, but I imagine large cities will be able to react promptly.
The societal norm/expectation that we wear clothing in public is no big deal. Why can’t we have a similar mask-wearing norm? I don’t see many anti-clothers protesting city hall over their right to go naked.
Hopefully that’s not how things work, or the effect has no practical significance.
Second best option, we’ll find a way to compensate for that.
Else, maybe we shouldn’t normalise masks to such a degree except for periods when it’s necessary.
Another side-effect is that masks should be replaced regularly, so everyone wearing masks at all times would mean a lot of waste (hopefully bio-degradable).
>FACT: People should NOT wear masks while exercising
>People should NOT wear masks when exercising, as masks may reduce the ability to breathe comfortably.
>Sweat can make the mask become wet more quickly which makes it difficult to breathe and promotes the growth of microorganisms. The important preventive measure during exercise is to maintain physical distance of at least one meter from others.
Personally these days, for outdoors, I use the following algorithm:
1. Over 6 feet away from people: Wear a mask below the nose (so I can have it ready for state #2 below, when needed).
2. Under 6 feet away from someone (even if just passing them by): Wear a mask properly (i.e. over the mouth AND nose).
Edit: Formatting.
As for my personal set of rules: if I can distance 12 feet I don't wear one. If I am frequently passing people (on sidewalks or trails) I keep it on. If it is fairly empty and I pass someone every once in a while, I keep the mask in my hand and breath through it when I pass someone.
Why not just take it off? I want to have easy access to move it up when needed. I am typically just walking and the weather is cool these days, so I do not experience sweating. Also since the hot air is not exhaled directly into the mask, it prevents/slows down the heating of the mask.
Why not wear it fully? I find it easier sometimes to breathe without a mask. So, when it is safe to do so, I lower it.
None at all. I’ve taken to getting my daily exercise in the early morning and late evening just to avoid talking to/arguing with my neighbors/the busybody brigade. The fact that I walk well out into the street when there aren’t any cars keeping roughly 15 to 30 feet from just about anyone and line of sight on everyone around me does not change this.
You're right that avoidance is the best bet here, for the time being.
These are people that have been manipulated and fixed with beliefs inserted into their reptile brain.
This is not the neocortex speaking - arguing on the basis of reason (pointing to a study) will not convince them that a mask is unnecessary away from people, in a field or outdoors.
They must be engaged in the same way they were manipulated - by appealing to emotion. It's a tough nut to crack.
All well and good as long as everyone buys into social distancing. Unfortunately plenty of people believe in neither masks nor social distancing, so you can't trust that people (strangers in the same vicinity) will stay 6ft apart.
Passing someone on a sidewalk means you're within 6 feet for maybe 5 seconds, which would constitude about 0.5% of such a "close contact" exposure.
They also say that several factors with insufficient data mean that it's unclear how things like ventilation, indoor vs outdoor, mask vs no mask, etc, affect the exposure assessment.
https://www.cdc.gov/coronavirus/2019-ncov/php/contact-tracin...
https://aapsonline.org/mask-facts/
Here is an article from July about mask usage in Europe.
https://www.economist.com/graphic-detail/2020/07/08/face-off...
I'm all for wearing masks and I do it.
But not when road biking where I very rarely (1 in 20 rides) come within 20 feet of a human being, other than people driving by me at 55 mph.
I also don't wear a mask when running, for the same reason.
Maybe if you're running / biking on the sidewalks of NYC, then sure, wear a mask! But on an empty country road outside of major cities?
I know the chances of transmission between me riding my bike and a pedestrian are low, but it feels easy to be cautious.
Best of luck pointing to the actual study. Are you going to print it out and carry it with you?
Please understand, I'm not criticizing you -- except to maybe point out that you place an awful lot of unfounded faith in your fellow human beings.
What won't change is the risk profile of wearing vs not wearing a mask. Wearing a mask despite necessity is an inconvenience, but unlikely to result in harm. Not wearing mask, even if current science says is safe to do so, is still exposure to potential harm that may have been unforeseen. For instance a transmission vector that is not yet a well characterized one. This is why I personally take a dim view to these sorts "following the science" arguments.
It really bothers me when the CEO of that health company was being harrassed for not wearing a mask after he has recovered from an infection, the mask would do nothing for him or anybody else, but he wasn’t using it as a political statement so he was doing wrong?
Some kinds of signaling are useless at best, problematic at worst. But wearing a mask even if you believe you technically don't require one to avoid being contagious seems like a common sense way to promote community during a stressful time to be around strangers - they don't know you, they don't know your medical history, they have no way of knowing when you wait near eachother in the grocery checkout line whether you're carrying antibodies and presumably not capable of being contagious or whether you're just flagrantly ignoring public health advice.
(Ignoring, of course, the subset of people who would inevitably falsely assume they were not capable of being contagious for whatever reasons even if they really could be... we probably all know that friend who swears they had COVID earlier in the year, but did not get tested at the time and have not had an antibody test since to verify. Do we really want those people getting the idea that their anecdotal illness is an opt-out from face coverings in public?)
The many interpretations of public health messaging around the world have shown us pretty well over the last 8 months that many people do really poorly with developing science and/or nuance. "Wear your mask in public, always" removes a lot of room for error, either malicious or just misinformed.
You're right that it's political - except that it has actual detrimental consequences to society to normalize doing unnecessary things, especially when your goal is expressly to divide people (as that's literally the main thrust of what what "political statements" in the form of virtue signalling accomplish).
Rational, well-informed people should wear masks indoors and in busy outdoor areas, and enjoy some fresh air when they can get away from that. Wearing a mask when you don't need to to "reinforce" unnecessary behaviour is irrational, and will continue to make anyone who is anti-mask think that you're not approaching the situation reasonably.
Wearing a mask outdoor: no
People walking solo in open spaces with masks on - which I see a couple times per week on my morning run - perpetuates a scientifically false narrative. I'm not going to object. If that makes them comfortable. But it's also a false sense of comfort. I'm not sure that's a good thing.
That aside, I'm not in a big city. I'm in the suburbs. I'm talking about the local park and such. My morning run is through a local small university, currently closed. I see more deer than people some mornings. In that context, I've seen people from a distance walking alone with a mask on. It's 8 am. No one else around. There's no scientific reason for a mask.
I believe masks are important. They are essential. But that's no justification for unnecessary masks. In fact, we should be conserving masks. Not wearing them when they're not necessary.
That's a big "if". When's the last time you were tested?
Because that's the actual reason to wear a mask. Preventing yourself from getting infected is less relevant than preventing yourself from infecting others.
> A passing squirrel or a bird is not going to infect anyone.
I don't know about those two animals specifically, but it is very much possible for COVID to spread via animals (that is, indeed, in all likelihood how the COVID pandemic started in the first place).
> People walking solo in open spaces with masks on - which I see a couple times per week on my morning run - perpetuates a scientifically false narrative.
No, it perpetuates a narrative of "it's better to be safe than sorry", which is about as scientific of a narrative as it gets when it comes to infectious diseases. I wear my mask when out walking or hiking specifically because I don't trust others to keep their distance, and because I care more about the possibility that I might inadvertently spread COVID to someone who'd die from it than I do about messing up my beard with a mask.
If someone unexpectedly approaches and gets within 10 yards of me, how long will it take me to put on my mask? Can I do so before that person's within 2 yards?
Better to just leave it on and leave it be rather than spend all day fumbling with it. That is:
> We need a steady state of vigilance.
Wearing a mask when out in public is that steady state. Taking it off because you think you're alone is a deviation from that steady state.
I think the key difference with the outdoors is that aerosols don’t accumulate easily, not that you couldn’t infect someone by blasting them with your breath.
Most people gain their understandings of best public health practices from the statements of authorities they trust. Unfortunately, a lot of nuance is lost when people get their information second, third, or fourth-hand.
What does it cost you to wear a mask? It's uncomfortable and annoying - I agree! If we make mask-wearing complicated (over nose, under nose, under the chin!) people will just do the most comfortable thing and it'll wind up being completely ineffective.
The coronavirus doesn't care if you are republican or democrat.
Simple rule: wear a mask when there's other people around - your life may not depend on it, but your or someone else's grandmother's might. If a vaccine is truly around the corner, we can actually cause some people not to die by wearing masks. There's just no good reason to be this selfish, prolonging this nightmare in the process.
Also, people seem to think the virus magically stops at an invisible 6 foot distance whereas in reality you need much more if you're breathing and running where you leave a much bigger trail of aerosolized particles as you run, and there's also wind carrying your breath much further than in a still situation.
I do take mask off for hikes when nobody is in sight but I always put it on when I see people are about to pass. What's annoying is people who don't put their mask on to pass you and don't stop and wait for both sides to have mask on before passing. I've been forced multiple times to abruptly stop and backtrack my steps to maintain distance while fiddling my mask on because the other person kept pressing forward impatiently.
(b) The problem is we don't know, and I'm in a risk group, so I don't want to take chances until something is proven to be safe.
But people also think (without evidence) that momentary contact closer than 6 feet is enough to spread COVID. It's almost certainly not.
You are very very very very unlikely to get COVID passing by a person for 2 seconds without wearing a mask. The infected person would have to sneeze directly into your mouth or something.
Just wear it as a chin-strap and it takes 2s to pull up and adjust. Accept that sometimes, your mask will be your only defense, and then hiking is almost as easy as ever before.
This attitude is why the US is still fighting with COVID.
Yes, it's feasible, if people prioritize getting rid of COVID instead of prioritizing beating their speed record.
And I'll probably get downvoted for this just like my other comments because this is the US. If I made these comments in Singapore or Taiwan I'd probably be upvoted a hundred times.
Then, accept that your own mask is good enough. You don't need to wait for the other person. Like sibling comments said, studies show that being outside and briefly walking by someone is not likely to result in transmission, especially when compared to being indoors with others
How close did these people get to you when trying to express their concern?
... which is why I simply wear a mask while hiking. :)
That's extremely obnoxious behavior, even though you're likely right on the low risks of transmission in sparse outdoor settings.
Wait wait wait...why should everyone be required to cater to the most paranoid people in the world, or be considered "obnoxious"? Where does this end? If I walk down the street, and someone twenty feet away from me scowls at me because I'm not wearing a mask, that's objectively their problem, not mine.
If you're so scared that you can't stand the idea of someone else being outside without obeying your rules, then perhaps you should reconsider being outside in the first place.
For anyone that lives in the area, the worst are the Nederland residents. Territorial assholes when there isn't a pandemic, and now they feel empowered to really let you have it. Going 10 miles south to trails in Jefferson County, and as long as you stay 6 feet or more, people smile and tell you to have a nice hike.
I doubt the person upthread is doing this though, given that he seems to be going close enough to people that they can stop and scold him.
Is that obnoxious?
The only accurate way is to quantify the risk, rather than blindly assert "extremely obnoxious behavior".
People act like “but cars kill more people!” is an argument in favor of whatever dangerous thing they’re talking about, not an argument against the way cars and roads are designed and operated.
Here's an idea, you can already keep them in business, order delivery w/ no-contact delivery.
Yes, life is certainly inconvenienced, but what's the alternative? Is going out to dinner worth directly or indirectly killing another human being over?
Spoken like a true narcisist. This is the exact behavior that produces the continued rise in cases across the country.
> I certainly haven't seen the evidence that these are risky activities.
Well, I'm glad you've appointed yourself epidemiologist-in-chief.
> You can't eliminate any risk without literally putting everyone in quarantine by themselves.
No, you can eliminate much of the risk by isolating with your household, occupation permitting.
A little compassion for people would go a long way.
Could you elaborate on what "prolong" means? Say we shut down the entire country for 4 weeks and get the virus under control. Is the pandemic now "over" (i.e. no longer prolonged) and we can reopen restaurants again at full capacity and just treat individual outbreaks? Or is it going to be cyclical where cases start rising again and the governors start cracking down again ad infinitum? For island nations that can control who goes in and out it's one thing, but it's going to be very hard for USA or EU which has open borders between states to control spread of contagious disease.
So it's "extremely obnoxious" when the OP "imposes their estimates of safety on others", and the correct response is for the OP to allow the misinformed estimates of safety of the others to require a mask be pulled up.
Why stop there? Some people think that a neck gaiter or cloth mask isn't enough. Why not wear an N95 outdoors since some people "wish to avoid having to pass people who aren't wearing [N95] masks, even outdoors".
Who gets to draw the line between obeying the science vs obeying the theatrical needs of the anxious ignoramuses? Surface transmission isn't a factor with this virus, and yet I know a few folks who still insist on disinfecting every box they come in contact with. They are welcome to do that, but it's certainly not following the science. Am I to cater to these people to?
The science should! Here's what the CDC says for high intensity activities:
"Masks should be used in public settings, but if you are unable to wear a mask because of difficulty breathing during high intensity activities, choose a location with greater ventilation and air exchange (for instance, outdoors versus indoors) and where you can keep at least 6 feet from others during the activity."
The trails and parks around here (North Carolina) have enough traffic and people who believe "I do what I want" that I don't feel comfortable visiting these places period.
This is precisely the insufferable safety-ism that characterizes the 21st century.
If you feel particularly at risk in the case of infection, and you'd wish to avoid infection - stay inside and isolate.
Isn't completely fair to say that the frail among us are imposing on everyone else outdoors keeping healthy and not depressed by exercising, etc?
If you "may wish to avoid having to pass people who aren't wearing masks": stay home!
No proof
If anything, I hope this pandemic helps to normalize mask wearing. People’s mouths and noses are disgusting, and a common source of non-lethal aerosolized diseases. Prior to COVID people used to sneeze and cough all over everything in public without even thinking about it, and I used to get colds all the time. Haven’t even got the sniffles since masks became mandated. Sure, sample size of one, and all. I’ll probably continue to wear a mask in public after this all goes away. When I see an unmasked face now, I mentally think “disease carrier” and avoid. We really could use this small norm-change society-wide.
https://www.bicycling.com/news/a32097735/coronavirus-viral-s...
Personally, I figure if I can smell someone smoking as I pass them on the street, even with a KN95 mask on, it's probably a good idea to wear a mask all the time.
The risk of them getting a serious disease caused by the smoke of my cigarette is non existent, if I am far enough the smell also is not strong enough to be of real disturbance, but I see their faces and I don't blame them, since I am the one doing something that is notoriously annoying and it costs me nothing, I don't smoke if there are non smokers around and I can't avoid them or am the only one smoking.
On the other hand I can't stand loud people and when I meet one, I ask them to lower their voices.
Wearing a mask it's the same thing: it costs nothing and wearing one prevents misunderstandings, while also adding a [nobody knows exactly how effective] additional layer of protection that does not hurt.
It's analogous to you feeling like you're a safe driver but having passengers asking you to slow down. If you're not judging the danger to others commensurately to them, it seems like the onus should be on you to adjust your behavior.
Also, as others pointed out, this study's idea of "crowded spaces" might not align with your idea of it. If someone with COVID-19 passed me on an average-sized trail path or sidewalk breathing heavily while running, I wouldn't feel safe and I doubt many other reasonable people would either. It's not an issue of outside air vs. inside air as it is whether you end up breathing the same air as others, and you might not be a great judge of when that is or how it applies to this study.
Also, if you're interested in backing up your actions with studies, you should note that "social distancing" meaning 6ft distance which I'm assuming you're referring to has been debunked by MIT and Oxford studies.
Figuring out exactly what's safe and not is not clear cut, which is why simple rules like "wear a mask outside" is so important, because we clearly can't all be trusted to make good judgment calls.
Basically, the researchers sampled 2 outdoor locations, and found low viral loads. Why is it reasonable to conclude that all outdoor non-crowded areas are safe?
I assume that not all outdoor environments are created equal. Variables like weather, wind, humidity, and population density probably all play a large factor in transmissibility. Certainly, more than 2 samples are required before making such a generalized conclusion?
> Considering a typical inhalation rate of about 1 m3/h, as average between rest and light exercise (Adams, 1993), the concentrations would be low to spread the contagion via airborne transmission even assuming the mentioned increase of a factor 2.
(1) HEPA filters have good filtration efficiency even at particle sizes smaller than MPPS https://www.sciencedirect.com/topics/engineering/high-effici... and an adequately powered one can recirculate room air in 10-15 minuters
https://la.eater.com/platform/amp/2020/11/22/21590433/corona...
Small businesses can't afford a lot of the overhead of shuttering their doors and still paying mortgages etc. The employees there can't afford it either. I'm not saying it's a bad/good call by leaders. I'm just saying if you are mandated to shut your business, you should be able to "turn off" the economic issues associated with that. Mortgage gets extended, taxes get deferred, etc.
This is definitely a weakness of pure capitalism in a regulation environment like today. We cant shut down a businesses income and expect their expenses to remain the same.
The idea that we are a pure free market is as absurd as saying that china is pure communism. There is no pure government out there that meets the academic definition of the market they espouse. It's just not possible, never has been, never will be (I usually don't speak in absolutes but feel pretty 99.999% comfortable with this statement). There will always be gray outside the academic setting.
Err not really, if you go full swing on someone and you "intended" to stop but they block your arm and punch you in the face, arguably it's your fault. If they kill you with that punch then they would be at fault. The law around freedom is really complex. Freedom in the US isn't limited, it's complicated.
When American's use the word freedom most of them are being dumb. You do have freedoms that are protected, but that doesn't mean what you think is a freedom actually is a freedom.
I'm also going to pick on your example of the restaurant. The staff at a restaurant does get to choose to be there or not, that's a free economy. If the government shuts down restaurants, like they have in some states, then the staff can no longer choose to take on that risk. Everyone gets to choose, but there is also an obligation/responsibility with freedom that people in the USA don't seem to "get".
You are FREE to get a gun, you are then responsible for using it wisely. Lock it up, get trained with it, be safe, and learn when to pull it out. The jerks on CNN who had the rifle and were pointing it at the crowd are a great example of irresponsibility with freedom. They should have never, EVER pointed a gun at someone who did not pose an imminent threat to their person. Back to the punching example, everyone who sees a fake punch can judge HOW fake it was. Did they stop at the nose, did they just jerk their arm, did they go Suuuppppeeerrrrr slow. Those judgements matter in court to show that the person who fought back was being reasonable. The burden of reasonable action is even higher with a knife/gun.
Take free speech for example, you can actually sign away your right to free speech in a contract. There is a commedian who talks about things that are illegal to say. Free speech applies to the press, not to individuals being ass hats.
Anyway, all of that is me saying, freedom in the USA is a slogan, which is dumb. Meme's do not present great arguments, but the freedoms we do have are as well defined under the law as most place. People just don't know them.
Some state governments such as Florida allow restaurants to remain open. We can debate whether that is a good policy from a pandemic control standpoint, but why should Floridians pay Federal taxes to support restaurants that were forcibly shut down by a California county?
You could also ask why Californians should pay the Medicare taxes associated with Florida's much higher rate of COVID infection due to their opening of restaurants and the state's higher elderly population.. We're all in this together, the economy won't be back to normal until Covid is gone and all of these ridiculous states flaunting obvious public health rules are costing everyone much more than it would take to just pay restaurant employees and everyone else to stay home for a few more months.
We also know it’s airborne, worse if you’re old, obese or diabetic (which effects the immune system so no surprise there).
There seems to be a huge amount of effort and attention being put into covid research to reprove things we already knew. Is science always like this?
From the abstract: "Transmission by contact or at close range due to large respiratory droplets is widely accepted, however, the role of airborne transmission due to small respiratory droplets emitted by infected individuals (also asymptomatic) is controversial"
Wearing a mask is in many ways a lot like using a keep-cup: effective, but highly visible and a distraction from other useful measures.
You MUST stop going to large events, visiting friends and family indoors, going to restaurants, and work from home if you are able. This cannot be stated enough. Masks are necessary but not sufficient. They are neither 100% effective, nor effective enough to rapidly control SARS-CoV-2, unless used in conjunction with other measures.
[0] https://www.nature.com/articles/d41586-020-02801-8 [1] https://www.sciencedirect.com/science/article/pii/S259005362...
I am in favour of masks and agree with most things you've said about them.
I am also in favour of holding all your social and business activities outside, because masks are not enough by themselves.
In your original comment, you said that it would be simpler to wear masks than to take into account airflow differences between the open air vs indoors. I disagree with that: masks are not a simpler alternative to socialising outdoors, they are a necessary prerequisite. You must do both, not pick one or the other. Additionally, you should consider socialising less often, with a smaller group of people, and any other steps you can take without putting your mental health in jeopardy.
Also, it's surprised how people don't understand the fluid/air dynamics and actually want happens during basic activities. There are so many ways to breathe in concentrated contaminated air without even realizing it.
For example, getting a concentrated exposure when you open doors, when the the person at the drive-thru opens there small window and all the inside air flows right into your car, etc.
Well, of course, these are not highly contaminated spaces, but, still, we oversimplify things all the time.
Another vector is dog walking. In Spain, a study showed that dog owners have 78% change of getting COVID. How? Well, we know dogs and cats can carry the virus, so, you play with your dog with a mask, you give them the virus, they give it to the dogs they encounter during the walk, and that dog gives it to their owner.
There can be. Perhaps my mask had been in use for a while, I suspect it’s gotten dirty enough to be a potential health hazard, but I don’t have another mask to replace it? I’d still use it if people are around, but would try to reduce my exposure to it otherwise. Maybe I have asthma or some type of breathing difficulty, and wearing a mask makes it worse? I think those two are probably among the most common reasons.
I am still going to be wearing mine everywhere until I can get vaccinated.
Here in Finland, there is no mandatory mask usage, largely because the government hasn't been able to find a constitutionally acceptable way of mandating it. Instead, we have increasingly stern "recommendations". OTOH, the situation is relatively well in hand here still, so I suppose the political pressure to act is not as heavy as it is elsewhere.
I don't get why the Dutch government and the 'average' dutch person isn't wearing it all the time. People still consider it 'weird' to wear it and even in the capital city (Amsterdam) people look at me weirdly when I wear it outside. About 10% isn't wearing it in stores or even the airport is a place where people still skip out on the face mask. They should just enforce this rule instead of closing other places where it is actually possible to maintain the distance.
Sometimes when people get shocked by what they read here, the shock experience has more to do with encountering voices that (often loudly and/or at length, and sometimes even eloquently) express opinions we don't run into in our circles. We're all pretty good at siloing ourselves among the like-minded. Even when we're aware that a topic is divisive, we don't relate much with people on the other side of the divide. Mostly we label them as idiots or worse, and don't encounter them in their complexity.
HN is a non-siloed site [1], meaning we're all in one big room here, so it doesn't work that way. The reality is that on any divisive topic, there are millions if not billions of people on the other side of the divide, a bunch of them are here, and they tend to be otherwise normal people whose different beliefs derive from their different backgrounds rather than them being idiots or worse. One might think that makes for an easier experience, but in fact it makes things much harder.
I wrote a longer description of this a while ago if anyone is interested: https://news.ycombinator.com/item?id=23308098. Also https://news.ycombinator.com/item?id=23716395.
[1] https://hn.algolia.com/?query=silo%20by%3Adang&dateRange=all...
Thank you dang. I hope you are going to give yourself a holiday.