SARS-CoV-2 concentrations and virus-laden aerosol distributions in outdoor air

It's not a threshold.

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.

I believe the other salient factor is the coefficient of my-immune-system-tends-to-implode per unit of viral load, which may or may not vary a lot between different people. Although at this point maybe it's hard to tell if the different outcomes are more to do with differences in processing the virus or differences in magnitude of viral load at time of acquisition.

Is there really much of a difference between one and the other?

I get the sense that it's reasonable, and perhaps understood, that the magnitude of exposure is correlated with severity.

My reading is that the authors were unable to find any air with appreciable COVID levels, but they’ve just added the caveat that maybe they didn’t find a sufficiently crowded area to take a sample.

I would assume "crowded areas" are areas where there are more than 1 person per [pi * <social distance recommendation>^2]

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.

These people most likely did not arrive to their conclusions by reading studies themselves, and likely aren't going to be persuaded differently by one.

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.

Judging by the replies a lot of people agree with those concerned citizens. I hope that the majority are terrified by this. It is one thing to recommend masks for legit health concerns, but it's a very slippery slope that we've already gone far down towards them becoming a religious/ political talisman that signified whether you are willing to shut up and agree with your leaders, or be an "anti-masker". We need to be more outspoken about all these baby steps toward complete submission to superstition.

> masks are only really necessary where social distancing isn't possible

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.

I saw a video where a person, walking alone on an apparently empty sidewalk, is not scolded but harassed for not wearing a mask (there is a mask, just not worn). The harasser was the one proudly filming their heroic act.

(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.)

>I tried to explain how outdoors masks are only really necessary where social distancing isn't possible

How close did these people get to you when trying to express their concern?

Actually, maybe they've read studies like this one: https://medium.com/@jurgenthoelen/belgian-dutch-study-why-in...

Typically, the best practice is to wait for results from multiple studies, and have them confirm the same conclusion. Otherwise, there is a risk it being a fluke or having some other bias in the data (e.g. environmental humidity, etc.)

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.

It doesn't matter what your understanding of the science is. By passing other people without having a mask you pull up, you're imposing your estimates of safety on others, who may wish to avoid having to pass people who aren't wearing masks, even outdoors.

That's extremely obnoxious behavior, even though you're likely right on the low risks of transmission in sparse outdoor settings.

In my city many small streets have been closed to traffic. Haven't seen anyone complain about runners/bikers not using masks in the street. But we have more than a few runners on those same blocks not masking on the sidewalk.

> for whatever good it will do...

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.

Where on earth do you live that any one at all is wearing a mask hiking?

I cycle (hard!), I wear a mask. People I pass wear a mask. Jeez, people -wear a mask. It can't be that difficult...to breathe heavily, or contain such, far from others?

The problem is when you pass other people on the trail and it's not possible to maintain a proper physical distance in passing.

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.

I tend to consider not wearing a mask like smoking near some non smoker (I'm a smoker BTW).

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.

The other day I was driving down one of the major streets in Poughkeepsie, NY. There was an old woman sitting by herself on her front stoop, wearing a mask. The sidewalk was maybe 12 or 15 feet away, and there was no one out walking.

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.

Pulling the mask up and down is unsafe for several reasons. First of all, you touch your face. Chinese scientists insist on fomite transmission being real. Second, more importantly, you need your mask tightly fit, to protect others. If you keep fiddling with it, moving up and down, it wont be tight after second or third time you do this. And from the social point of view it is just a bad signal. Period.

While I believe this study will be proven over time, it is just one study. Since it's getting colder I am keep most of my exercising inside, but when over the summer I masked up when doing outdoor activities just to be safe for myself, and to make others feel better.

> I tried to explain

... which is why I simply wear a mask while hiking. :)

I'm very pro-mask as a reasonable measure for controlling transmission however masks have been politicized and turned into a symbol of in/out group dynamics on both the left and the right. Masks are now triggers to the extremists on both sides and it's impossible to act reasonably and please either group as I'm either seen as a fascist anti-masker or a recruit in the red army. It seems the loud minority on both sides can only think in a Hitler/Stalin dichotomy with zero nuance. I choose to ignore the unreasonable and do what I think is good and reasonable and above all charitable, despite the discomfort.

Good for you. Fortunately where I live mask wearing is not a political statement and therefore people use common sense and their brain to evaluate when and where to wear a mask and everything is very relaxed and fluid. When mask wearing becomes a political symbol then all logic is out of the window and you get crazy mental ideologists on both sides destroying it for everyone. We should make a list of all those people on both sides and maybe one day that list might become useful lol.

If you don't have Covid then the only way to get Covid is to be exposed to someone who is contagious. I know that's stating the obvious. The point is, if you're outside and with no one but yourself, and not close to anyone else, there's no risk. A passing squirrel or a bird is not going to infect anyone.

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.

Reading your comment, it's unclear how far you're keeping from others. The only information is that other people don't feel safe given your distance and lack of mask.

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.

That's the last statement of the conclusion sections of the paper:

> 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.

The paper was about aerosolized virus. The title here misleadingly implies any kind of outdoor transmission (including droplet not just aerosol transmission) is unlikely.

The Federal Government is completely failing here. States can't run deficits, usually by force of law. They'd rather confirm judges than pass legislation to help, all of this damage is completely self-inflicted.

Masks are one part of risk management, but they're not 100% effective. An effective strategy might involve wearing masks and social distancing and limiting how far you can travel and limiting the size of gatherings and banning indoor gatherings.

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.

Wow. Where is this, if I may ask?

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.