Jul 29, 2021Liked by Mathew Crawford

Hi Mathew,

Thanks for all your great work!

Here is a link to the pdf version of the article, for those who want to browse/review it per your suggestion but not pay for it:


I could not find the appendix; however.

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Fab share, the paywalls can be a huge obstacle. Lots of times Wayback is an effective bypass; some sources like MIT and misc media exclude URL capture but it's always worth the cost of a copy, paste, URL search to check. :~)


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Request to other readers:

Honestly, I am confused about masks...even after digging into the topic somewhat.

Anti-mask arguments (which, after my research, I find somewhat more compelling than the pro-mask arguments, like the one that Mathew just reviewed in this blog post) seem to go as follows:

SARS-Cov-2 is mostly spread by aerosols and not droplets Therefore, regular cloth masks are useless as they mostly prevent spread by droplets and are not effective in blocking aerosols.

However, another argument against masks is that they are dangerous because of the build-up of carbon dioxide.

Aren't these two arguments contradictory? Anyone who is well versed on this topic, please respond. Also, other resources (articles, videos, etc) that will help shed some light are welcome.

Thank you!

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Sep 21, 2021Liked by Mathew Crawford

I can see how they may appear to be contradictory on the surface, but in fact, they are not.

I'll make a couple of points before I get to a conclusion, which is that the key issue is that we are talking about two distinct types of functional dependencies.

First, there isn't a study that proves causation one way or the other.

All we can go on is clinical studies about the correlation between masks wearing and respiratory infections (symptoms and/or lab-confirmed cases) and medical opinion and regulatory documents from before 2020.

Which is, frankly, a lot.

For example, there are Guidelines for the prevention of surgical site infection.

The most recent version that mentions masks is from 1999 (https://stacks.cdc.gov/view/cdc/7160), and it plainly states that:

1) wearing surgical masks is a tradition,

2) their efficacy is questionable,

3) but they may protect against splashes of blood and fluids.

Again, masks protect the wearer from splashes.

And they don't even help protect surgical sites from bacteria -- forget the viruses.

Second, we know that the minimal infective dose of a respiratory virus is one (!) 1-5 mcm droplet.

Third, there are studies of the effects of prolonged mask-wearing in a hospital setting.

The vast majority of participants report experiencing headaches and other symptoms associated with hypoxia and hypercapnia.

Fourth, a few people (I saw four) recorded videos where they either

- measured blood oxygen after a brief physical activity while wearing a mask (or two) or

- used an OSHA-approved air quality meter at their mouth with and without a mask.

They found that blood oxygen can dip as low as 93% (!) after mere 10-20 seconds of exercise and that the air behind the mask becomes so bad, the device is beeping incessantly or even exceeding the limit it can measure again after no more than 10-20 seconds of regular breathing.

Thus, I personally come to these conclusions.

One. The probability of getting infected P as a function of the mask efficiency E is described by these equations:

P = C, if E < 1, where C is constant

P = 1, if E = 1

In other words, it does not matter if you're wearing a mask or not -- unless it's a gas mask rated specifically for virus filtration, in which case you're 100% protected.

It's a binary distribution.

Two. Any mask or even a face shield acts as a barrier that affects the diffusion of the gases around one's face, meaning that the air that one breathes out lingers around for a bit longer than it otherwise would.

This effect is slight -- if taken as an isolated episode.

However, with each consecutive breath, this effect becomes more and more pronounced -- in other words the air quality Q is inversely proportional to the barrier properties (efficiency) E of the contraption one wears on their face:

Q ~ 1/E

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Thank you! Very helpful.

I am now wondering about the mechanism behind the hypoxia and hypercapnia resulting from facemask use. Is there some electrostatic repulsion of CO2 (that is perhaps different from viruses?)

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Sep 21, 2021Liked by Mathew Crawford

No problem! First, based on your question, I see that I should perhaps make myself clearer.

You should not be comparing virus and CO2 permeability at all.

It doesn't matter, because unless you have perfect protection, you have effectively zero protection from the virus.

In regards to the mechanism of the gas exchange impediment, I reckon it's as simple as diffusion through a semi-permeable membrane, i.e., effectively, osmosis.

Here are indisputable facts that I believe result in the observed phenomenon.

1) All molecules of air flux either go through it, around it, or hit the threads.

2) All molecules of air that hit the threads lose velocity.

3) As one exhales through a mask, at that very moment, on the inner side they have CO2-rich air, and on the outer side, they have fresh, CO2-normal air.

Thus, one might conclude that whichever proportion of the exhaled air hits the mask fibers will (a) stay behind the mask and (b) be inevitably consumed during inhalation -- because it is also closest to the mouth.

The inhaled air will be also reduced in its volume by whatever proportion of it hits the mask fibers as one inhales.

So ultimately, I believe, a little bit of fresh air is replaced with a little bit of exhaled air at every inhalation, and since the exhaled air has a much higher concentration of CO2 and a lower concentration of O2, the resultant mixture (a little bit of exhaled with mostly fresh air) is enriched in CO2 and is depleted in O2.

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Thanks again for responding! Whew, I think I get it now. The key difference seems to be the following:

Per your first post: "we know that the minimal infective dose of a respiratory virus is one (!) 1-5 mcm droplet." So, breathing in one viral droplet puts you at risk of COVID-19. It does not matter that some viral particles may be blocked by mask fibers; many, many, many will still get in, as masks (esp cotton cloth masks, which most use) have pores of 100 mcm!

CO2 is a different problem - having one or few or even 'many' CO2 particles going in and out of masks is not a problem. Its the repeated exposure over time (although it could be a rather short period of time) that causes a huge , massive buildup thats the issue.

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What about this one? https://jamanetwork.com/journals/jama/fullarticle/2776536

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Are you asking me to read through it and spend 24 hours breaking it down like I did for this article?

That's a tough task on demand, and this topic is aside from my main research goals.

That said, the masking research hasn't impressed me this past year. And the strange disinterest in the level of aerosolization, which actually points to a weak viral cloud that can be easily killed with UV light, suggests to me that we're living through an intentional horror. I write enough to hopefully make that clear, and make clear the level of corruption of our institutions, but also want for people to understand how to protect themselves with medicine.

I will be receiving data on tens of thousands of patients over the next few weeks and plan to build a website displaying the results, whether or not the journals will allow it through the gates.

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May 21, 2021Liked by Mathew Crawford

I read through some of your texts and appreciate what you're doing. I look for independent analyses in these days of the COVID wars. It's post-normal science in a post-Trumpian world (or perhaps not). I'm an evolutionary biologist in Brazil watching irrational debates on masks, lockdowns, ivermectine and chloroquine, and the origins of SARS-Cov2. At the end of the day, the public will never be able to sort through all the arguments different sides throw into the pot, and everybody will just follow those that appear to have the right motivation. Perhaps just another case of "Contenders on the truth", the title of a great book by Ulrika Segerstralle.

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Indeed. It is all perplexing and maddening. Hopefully we can all make peace of it somehow.

Thank you for the recommendation.

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