226

This is the meter used in the video: Note that the sensor is situated at the top, pointing upward. When the person in the video breathes out, the exhaled air will be directed into the sensor, but when the person inhales air will flow around the sensor with no strong tendency to enter it. This creates a strong bias for measuring exhaled air vs inhaled air, ...


85

Yes, of course. This was quite common. — The Evening News, Detroit MI Michigan, July 4, 1901 'Last train robbery of Butch Cassidy & the Sundance Kid' 'Original reporting' Sundance supposedly turned up again almost a year later in the town of Elko, Nevada. At midnight on April 3, 1899, Sundance, Harvey Logan, and George Currie, wearing masks, reportedly ...


81

This study has way too many problems to draw such a conclusion. It can only be taken as an indication that it may be worth further study, or may corroborate or contradict other, more carefully controlled, studies. The main problem is simply that by the nature of the study, the authors are comparing two groups of people, at two different times and ...


24

The study gets off on the wrong foot with the unqualified and unsubstantiated claim that Covid-19 is the world's deadliest pandemic. There is some discussion about that in the previous question Did COVID-19 take the lives of 3,100 Americans in a single day, making it the third deadliest day in American history? The study appears to make a correlation between ...


24

LangLаngС's answer has good examples of bandits/outlaws wearing masks in general, but the type is rarely mentioned - one image shows Zorro-style masks, and flour sack masks are also noted. Here are a couple of sources that specifically mention crimes committed while wearing bandanas as masks, since that's the claim from the article: The Big Springs train ...


15

We finally have a study that examines surgical masks and their effectiveness under different viral-load situations and compares their effectiveness to other types of masks. The research provides the mechanisms for surgical mask protection against COVID-19 infection and incorporates opposing findings The findings demonstrate that surgical masks are effective ...


10

As the other answers don't seem to make this link too clear from experiments (or at least the comments are in that direction); there aren't a lot of those it seems, but there's one cited in a review of Matuschek et al. (Aug 2020) the role of N95/FFP-2 masks was tested in 97 patients with advanced COPD while undergoing a 6-min walk test. Seven patients did ...


8

I'm not a hematologist, but I do ponder whether the statistically significant difference observed between those two groups, of 0.52 g/dl of hemoglobin (Hb) is of actual/much clinical relevance, let alone an indicator of "intermittent hypoxia" and (solely) attributable to the "mask mandate" as Setia et al. conclude. Their observed ...


7

As far as the WHO is concerned, they seem to only have changed their recommendation in June (much later than the CDC). Also note that it's a red herring what AAPS says about "respiratory protection" (which they define as excluding "source control") because e.g. the WHO never seems to have claimed that cloth masks act as PPE for the wearer ...


4

Regarding the first issue, whether the measurement method shown in the video is sensible (as this was challenged by mods as being unsourced speculation in the accepted answer), there are actually press articles in which the manufacturers of some such devices say that it isn't sensible... The France 24 Observers team contacted MSA, the company that ...


3

Looking at what other factors that cause hemoglobin concentration, I looked at smoking in particular to see how much that causes these levels to change. In doing so, I uncovered 2 major problems with the assumptions of the article in the Question. That article states that "mask wearers" have a Hb count of "15.01 ± 1.1 g/dl" (150.1 g/L) ...


3

Yes, there are several medical conditions that are directly triggered by wearing a mask. Physical problems are most commonly caused by the increased humidity (and temperature to a lesser degree) of the air that is trapped in the mask and gets breathed in again. Psychological problems can also be caused by the way the mask feels on your face (like ...


3

First, surgical masks (especially doubled up) work fine for keeping you safe from aerosols. Cloth masks also work to some extent, but not quite as much. This has been shown in a number of studies, but I'll link only a single recent one here that I think is well-performed. https://doi.org/10.4209/aaqr.210117 This is important to note, because it's a ...


3

It would appear to be difficult to test this with a single direct experiment, but we can approximations based on aerosol transmission models. A recent paper, SARS-CoV-2 aerosol transmission in schools: the effectiveness of different interventions is the best attempt to do this I've seen so far. Here's an excerpt of their summary: Methods: We ...


1

True The CDC changed course on April 3: "The Coronavirus Crisis: CDC Now Recommends Americans Consider Wearing Cloth Face Coverings In Public", npr,org April 3, 20205:49 PM ET On that day April 3 a webpage from the CDC went live called "Recommendation Regarding the Use of Cloth Face Coverings, Especially in Areas of Significant Community-...


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