Doctor demonstrates for dummies that even six masks don't lower oxygen intake

The problem is, in their binary world, anti-maskers will use this nuanced bit of information to round off to “masks will kill you!”. They do the same thing with “masks don’t provide 100% protection, therefore they do nothing at all” type of logic. And it certainly didn’t help that this was the official message the public received early on, despite the fact it was only put out there to avoid a run on PPE that medical staff were struggling to get for themselves.

Then there’s the issue that if someone is not physically healthy enough to wear a mask, they should be exceptionally cautious going out since they are likely in the highest risk category to die from C19. But then these same people will claim they won’t wear a mask for “health reasons” as they insist on being inside a store or restaurant with 100s of other people.


Undoubtedly some will, yes, and it will be impossible to persuade everyone. But many of them already know about studies like the ones I linked to above, and if you don’t acknowledge the information in these studies then there’s no chance that they will take you seriously or listen as you make your argument that these effects are negligible and well worth the benefits that masks provide in halting the spread of this disease.

Edit to add:
Willfully withholding true information because you think it will help your effort to persuade people to act in society’s best interest very often backfires. I’m reminded of the early days of this pandemic when many health experts were trying very hard to get the message out that the general public should absolutely not wear masks, and that they would not be helpful to slow the spread. The goal at the time was to save the scarce PPE for medical professionals and those that needed it most, but it probably did more harm than good. I wish that they had instead focused on the message that PPE is desperately needed by the medical professionals and that everyone else should just focus on social distancing rather than hoard it.

You are intuitively correct.

No, they do not. As long as you can inhale, you are getting oxygen. The mask does not filter oxygen out. It is not a selectively permeable membrane. It does not keep people from taking a full, deep breath. It does not change your tidal volume. It does not change FiO2.

People might have to breath at a slower rate, bc it takes more time for air to pass through a mask. That effects exercise, not general everyday activity like walking. It clearly doesn’t stop people from talking (it is not a ball gag).

Last night I wore my mask for 12 hours. A FITTED N95. I ran down the hall. I helped move obese patients. I talked on the telephone. Luckily, I did not do CPR last night, but I have done CPR in my N95. I have worn an oxygen saturation probe, and my sat never changed. I have worn an ETCO2 monitor, and my ETCO2 did not change. I have worn a face shield as well as my N95 for over an hour at a time, in a plastic gown, in a closed patient room, while helping intubate patients and taking care of their nursing needs, while starting IVs, swabbing for covid19, with no breaks and no hydration. I did not die. I did not pass out. I did not get dizzy. I did not get hypercarbic, nor hypoxemic.

Yes, I am fit. Yes, I am not obese. Yes, I can run a marathon. Yes, wearing that N95 while doing CPR sucks, while running upstairs to the OR sucks, while pushing stretchers with 300# people on them sucks. So you go a little slower, you move a little more carefully, and you breathe a few more times per minute.

N95s, and masks in general, barely increase dead space. They are air permeable, and CO2 is a LOT smaller than a virus. CO2 passes through a mask, or everyone wearing a fitted mask would die.

Masks make people feel claustrophobic (me, too). Masks make our inhaled air warmer, and that also changes how we feel about breathing. Masks that are harder to pull air through (like an N95 compared to a surgical mask) mean you have to increase your inhalation period, and more forcefully exhale, which can change mask feel and definately change our perception of breathing. Masks are imperfect, even N95s. Even P100s. But the argument that someone can’t wear a home-made or surgical mask, at the grocery store, bc they have a “medical condtion” is raging nonsense. The argument that it affects your thinking goes against the reality of OR staff wearing masks throughout mutli-hour operations.

Here’s an overly specific, overly technical discussion of alveolar dead space, functional dead space, gas perfusion throughout these spaces during respiration, etc:


I’m not advocating withholding the truth in any way. I’m saying that some people need to be told what to do with that information so it doesn’t get misapplied. As I mentioned before, I completely agree with how the early official message about not wearing masks backfired because people were unequivocally told that masks were not necessary. And when the message changed, they were not told why and the level of trust deteriorated, and some people stuck with what they already “knew” - that “masks don’t work”.

I believe not ever wearing a mask because of these studies does not hold the same weight as wearing one for an hour at a time while shopping in a crowded indoor area to help prevent viral spread. If someone if concerned about inhaling too much CO2 or just because they’re claustrophobic then cover your face loosely with a bandanna instead of using an N95 mask. That is still better than nothing at all.

The paper doesn’t say that surgical masks would reduce your oxygen levels under normal use. The masks were tightly sealed against the face so the sm was acting as a filter. During normal use it just acts as a net to catch spray from your nose and mouth and does no filtering of the air you breath as that comes around the masks edges.
You are still correct that everyone should wear a mask as this is a communal effort.


A resting pulse rate of 75?
I’m 70 and I have a resting pulse rate of about 55.

On medical advice, I don’t wear a mask when racewalking. (I can’t run; I messed up a knee in a climbing accident about 45 years ago and it won’t take impact.) I have it at the ready and put it on if I’m about to pass anyone or they’re about to pass me. The trail I use is pretty wide and uncrowded, so I’m never within six feet of anyone in any case, but I put it on anyway.

The mask is usually improvised from a bandana, floral wire and rubber bands, but it fits closely enough that I get a decent seal. (My sunglasses don’t fog, which is a good sign that I’m doing it right - I’m not simply exhaling humid air around my nose.) The way I fold the bandana, I’m breathing through 6-8 thickness of cotton, which is pretty good tortuosity and a lot of surface on which droplets can adsorb.

I always wear the mask if I’m indoors with anyone but my wife. Including my adult daughter. I also don’t go anywhere except to the grocery store, to pick up takeout food, or I think I’ve visited my lab about 4 times since March because there’s been no alternative to being in there with a screwdriver.

And I’m old.

Anyone who can’t wear a mask indoors in public is too ill to go out in public. At all. Ever. Give me your order from the shop. I’ll fetch it for you. There’s your fucking disability accommodation, asshole.

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I would posit that your need to stop and take deep breaths while exerting yourself in an N95 is due to needing to cool your face off because you were overheating, rather than any oxygen deficit, because masks do not trap CO2. I, too, feel stifled when I wear a mask, particularly in summer. But I am not under the delusion that it is affecting my blood oxygen level, because the best evidence we have is that it isn’t. It is only uncomfortable.


That’s really what it all boils down to.

Masks itch, they can be hot, and having material that close to my nose often irritates my allergies, causing a runny nose… and I still wear them anyway, because I’m a responsible fucking adult who can comprehend the risks, and not a spoiled toddler who is only concerned with my own immediate comfort.


Ooh! Ooh! I can help with that! I’ve personally worn surgical masks for multiple hours under layers of PPE and it gets hot and stuffy, and it’s a relief to get it off, but not once have I had any sort of respiratory concern.

My wife currently wears a N95 for multiple greater than 12 hr shifts at her hospital each week, and her biggest complaint is the bands, and how the edges of the masks make your face sore.

There are people with pre-existing respiratory diseases that will make wearing a mask not medically safe, but this has to be a teensy tiny proportion of all of the covidiot douchenozzles out there who are promoting the mask conspiracy theories.

And no, I’m all for publicly shaming these assholes. By not wearing a mask, they are perpetuating a pandemic that is killing people. Let them feel shame and hide in the shadows or at home.


He took my breath away when he was wearing no masks.

I bet they must have fascinating opinions on birth control.


Doctor demonstrates for dummies that even six masks don’t lower oxygen intake

A doctor is not necessarily a scientist.

Here’s another one: [the same one @timd pointed out]

The relevant bit:

The data show that the so-called cardiopulmonary performance is significantly reduced by both mask types [surgical masks and FFP2 masks]. The masks affect breathing, especially the volume and the highest possible speed of the air when exhaling. The maximum possible force on the bike ergometer was significantly reduced. A faster acidification of the blood during exercise (lactate) was registered in the metabolism.

Disclaimer: That is no reason not to wear masks.


A friend of mine in the NHS has extremely uncomfortable dry patches behind her ears now, she has recently been offered masks that tie behind her head, still leave red marks on her cheeks though.

Yep. We forgot to add some chlorine to the gene pool, so Gaia is doing it for us. :smiley:

These are probably the same people that are anti-abortion*, and think that the Python song “Every Sperm is Sacred” was the truth instead of just a barbed poke at Catholicism in that time period.

(* No, we are NOT going to start that debate here. Don’t even try.)


I’ve got ones where the bands go all the way around your head, but then you get fun cheek marks.

My wife’s been using the around the ear type, but with an accessory strap that goes behind her head, and attaches to the ear band on either side. There are 3d printable designs out there, and if you don’t have a 3d printer, it’s pretty easy to jury rig something similar.

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When I had to get a blood test in June, the nurse had one of those extenders to keep pressure off the ears, so those are definitely worth the effort.

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I think whether or not the behind-the-ear ones are bothersome or not (for those who aren’t medical staff wearing them for 8 hours at a time) has at least something to do with fit. If you can find a mask that is physically big enough that it’s not pulling on your ears, but shaped enough that it seals off your face instead of hanging open, then your ears will be OK.

Easy for me to say, because I have a small head, so most adult masks run big on me anyway.

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I have modified one of my wife’s headbands with a couple of buttons and attach the straps to them. Takes the pressure off my ears, and makes a smart fashion statement as well!