Jeff Duntemann (jeff_duntemann) wrote,
Jeff Duntemann
jeff_duntemann

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More on Masks

I realize that I should have made the masks portion of yesterday's wander its own post. What was supposed to be a casual collection of odd impressions of current events and what I'm up to turned into a mildly angry rant. That's just how things work in the back of my head sometimes.

Anyway. I ran into some links this morning that are worth mentioning. The first one is a must-read: "Aerosols, Droplets, and Airborne Spread." It didn't answer all of my questions, but it answered a lot of them. It's a very long, dense article. (I think it was intended for medical professionals.) Read it anyway. Yes, it's almost three months old, but I sure don't get the impression that we've learned much since that time. The big takeaway is that SARS-CoV-2 spreads via aerosols; that is, naked virus particles or droplets so small that they remain suspended in the air for a long time. (A lot of supposed experts deny this.) Ever watch cigarette smoke? It doesn't drift toward the ground. It gradually spreads out until you can't see it anymore. But take a whiff of the supposedly empty air, and you'll know it's still there.

Most droplets fall to the ground fairly quickly. But it's true (as I mentioned yesterday) that in low-humidity environments, droplets evaporate quickly, and what may have been exhaled as a droplet large enough to fall can shrink to aerosol size before it hits the ground. We're having a cool day here to close out June in Arizona. It won't even break 100. The humidity is way up, at 16%. Tomorrow July comes in like a toaster oven (by most people's standards) at 103. The humidity will be 10% or less. Even a 100µm droplet will likely give up its water long before it hits the ground in that kind of humidity. After that, it floats for what may be 30,000 hours; i.e., indefinitely.

People are still getting into fistfights about whether there are enough viral particles in airborne aerosol droplets to cause infection. It's not a yes/no kind of question. Like a lot of other things associated with health, it's about probabilities. I'm thinking that if you spend an hour in a crowded bar where everybody is talking loud, laughing, and drinking, you're likely to get enough virus to become infected, even if everybody in the bar is wearing a mask. If you pass somebody in the baking aisle at Safeway, probably not. Why do I say this? Two things:

  1. There is something called "time in proximity." The longer you spend close to an infected person, the more likely you are to get sufficient viral load to come down with COVID-19. I don't go to bars much for the bar experience, but my writers' workshop took place in a sports bar for over three years. When there were important games, people were draped all over each other, talking loud and cheering when their side made a good play.
  2. You can catch this thing if you get enough viruses in your eyes. A couple of droplets is all it takes. Masks don't protect your eyes. Nor do I think masks eliminate all exhaled aerosols. Sit in a bar for an hour with hordes of people cheering into their masks, well, you'll probably get enough of the bad guy in your eyes to come down with it. Why? Badly fitted masks allow exhaled air to flow out the edges. I tried singing with a mask on to see if they leaked out the edges when I sang forcefully. They did.

I'm sure I'll get yelled at for my contention that masks don't help us anywhere near as much as our supposed health experts claim, but I'm past caring. Which leads us to another and probably more controversial link, which is one MD fisking a rah-rah hurray-for-masks post by another MD. This is a guest post on Sarah Hoyt's blog, and you're free to dial it down if that makes a difference to you. I don't agree with all the points made, but there are some solid numbers and good explanations about some of the downsides of wearing masks, few of which ever come up in the current debate.

Something else that I knew but forgot to mention yesterday: A real N95 mask filters inbound air only. N95's have one-way exhalation ports that remain closed until pressure in the mask indicates that the wearer has exhaled. Then it opens and releases the wearer's breath through the port. No filtering of exhaled breath is done. None. N95's exist specifically to keep patients from infecting medical personnel. They protect no one but the wearer. The tiresome bleat that "You wear a mask to reassure and protect others" simply doesn't apply for N95 masks.

So where do I sit in all this? I'll give you a list:

  1. We do not know a lot of things, particularly involving viral load, antibody generation, asymptomatic carriers, etc. Everything we know about SARS-CoV-2 and its effects (COVID-19) must be regarded as tentative. We'll learn more as we go, but right now there is a lot of arguing and handwaving over significant issues.
  2. Wearing a mask is no guarantee that you won't catch the virus, nor infect others. Everything is a matter of probabilities. The type of mask matters, some being worthless (handkerchiefs & bandanas etc.) and some a lot better. But none are any guarantee, especially if you wear a mask the wrong way. (I've seen a lot of that in grocery stores.)
  3. Time in proximity matters. It's the crowded bar thing again, or any dense meeting of bodies talking, laughing, or lor' 'elp us, cheering. Spend enough time cheek-by-jowl with virus carriers, and you will almost certainly get the virus, mask or no mask.
  4. Masks can be overwhelmed by strong exhalation. I've tried this myself, as I said before: Cheering or singing into a mask will just force air out the sides when the material of which the mask is made can no longer pass the volume of air presented to it. That air is not filtered.
  5. Masks don't protect your eyes. This should be self-explanatory, but it's rarely discussed. Getting droplets in your eyes is apparently less likely to lead to infection than breathing them in. However, after enough time in dense gatherings, your eyes could put your viral load over the top into infection territory.
  6. And my conclusion: Put as much distance between yourself and others as you can. Even that's no guarantee. Furthermore, for some people it may be all but impossible. But for people in my age bracket (I turned 68 yesterday) it could become a life-or-death issue.

Carol and I wear masks, and we stay home a lot. We certainly don't go to bars or political rallies or protests or anywhere else you have screaming crowds. If you pin me down on it, I'll express my opinion that masks don't protect you anywhere near as well as ten feet of clear air. But as with almost everything else about the virus, your guess is as good as mine.

Tags: covid19, health
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