Posted on 06/26/2020 8:50:20 PM PDT by Grandpa Drudge
(excerpt copied from this article)
Furthermore, if there were any benefit to wearing a mask, because of the blocking power against droplets and aerosol particles, then there should be more benefit from wearing a respirator (N95) compared to a surgical mask, yet several large meta-analyses, and all the RCT, prove that there is no such relative benefit. Masks and respirators do not work.
In light of the medical research, therefore, it is difficult to understand why public-health authorities are not consistently adamant about this established scientific result, since the distributed psychological, economic and environmental harm from a broad recommendation to wear masks is significant, not to mention the unknown potential harm from concentration and distribution of pathogens on and from used masks.
(Excerpt) Read more at sott.net ...
“And what is the population density of South Dakota?”
It’s every bit as dense as any other town.
cotton is absorbent u til it is saturated by moisture from your breath. about 20 minutes. Not that any breathable material protects from the virus anyway
Who determines that the virus is contained in 1 um aerosols? If they are in that size, I would expect they would evaporate almost instantly. When the outer coating of water vapor goes, so does the virus.
- When the outer coating of water vapor goes, so does the virus.-
Where do you get that information?
Look it up.
Mark
Thanks, Jane. I guess I misinterpreted your reply, sorry.
I just don't trust people; I know there's tens of thousands of George Floyds out there, who know they're COVID-19 positive and are out and about anyway.
Had to do a pickup at the mall, some idiot who probably thought a face diaper was uncool turned and sneezed on me. Gee, thanks, bad enough being an essential worker, but you gotta do that too?
Friends made her finally put on a mask afterward. Always a smooth move after sneezing on a federal employee.
So, you know, you're welcome to ride your high horse on off into the sunset. Don't want to wear a face diaper, think they're useless, then stay the hell away from others and out of public spaces.
To be clear, rioters & looters and their cover decoys, the ‘peaceful protesters’ who aren't actually protesting anything, just making noise, who aren't wearing masks and aren't social distancing are total jerks. I'd be the guy who'd get arrested for running them over and you'd better believe I'd be going before a jury claiming I wasn't going to be held hostage against my will.
Anyone enabling those 'peaceful protesters' who simultaneously condemned people for protesting effective house arrest for the majority of the population without conviction are also jerks.
That would be by default pretty much every liberal out there.
indicates virus aerosol droplets could be as small as 1 μm. The size of the Covid-19 virus itself has been reported as 0.125 μm.
I don't know if anyone has indicated this virus is contained in 1 um aerosols, only that aerosol droplets could be as small as 1 μm.
The SOTT article referenced in this thread indicates the aerosol particles are less than 2.5 μm.
Good reply. You win!
And I read somewhere else (but can't find it now) that aerosol viruses can remain viable as long as 16 hours in enclosed spaces.
If you are infected and contagious the mask will not make you safe to be around.
Any aerosol virus you exhale will go out through your mask just as easily as it can come in, so the mask might slow the exposure a little, but it will NOT stop it.
A few days ago, I read a paper that stated that droplets evaporated by 95% in less than a second (I want to say 1/24 of a second) in a room at 50% humidity.
Clearly, ambient temperature and humidity are going to affect evaporation and virus survival rates.
Another paper said that viruses do not survive very long on the hands, I think it was only a few seconds.
I have read many papers, but unfortunately forget to bookmark them. I will look for the paper that discusses the evaporation rates and post a link if I find it.
Yesterday, I found three papers in which the efficacy of face masks in the context of Covid-19 was evaluated. Yep, the data actually shows that face masks, as well as social distancing and eye protection, work to reduce spread of Covid-19. The blog excerpted at the top of this thread was written by a physicist who has zero experience in infectious diseases. Two of the studies of mask efficacy were written by people in the field (MDs, PhDs, MPHs, MSs); the other was written by economists and statisticians but their references appear to be valid. I did bookmark these papers.
Any aerosol virus you exhale will go out through your mask just as easily as it can come in, so the mask might slow the exposure a little, but it will NOT stop it.
Actually, I found three review papers that specifically address the question of how masks affect transmissibility of Covid-19. All of them concluded that masks inhibit transmission of Covid-19.
Also, I found another paper about the survivability of viruses in different environments. One limitation of this paper was that most of the studies were looking for viral RNA remaining in the environment, but the presence of RNA is not an indicator of infectivity. The following passage from that paper, Stability and infectivity of coronaviruses in inanimate environments leapt out at me:
Infectivity of HuCoV- 229E was undetectable after drying on aluminum, sterile latex surgical gloves, and sterile cotton gauze sponges at RT for 3 h; HuCoV OC43 survived 1 h or less[34]. Contaminated droplets will be absorbed faster on cotton materials than on fluid-repellent materials, and cotton gowns offer protection against droplets bearing viruses. Droplets or fomites that persist on a nonabsorbent disposable gown or gloves may be a risk to contaminate the environment.
SARS-CoV strain GVU6109 was isolated from a lung tissue specimen of a SARS patient during the SARS outbreak in 2003[35]; its infectivity at 10^4 tissue culture infection doses (TCID50)/mL vanished within 5 min after drying on paper or a cotton gown at RT[35], showing that the viral infectivity perished faster on the cotton gown than on an impervious surface (e.g., the disposable gown) (5 min vs 60 min at 10^4 TCID50/mL, 1 h vs 24 h at 10^5 TCID50/mL )[35].
Note: these studies used commonly circulating coronaviruses; the behavior of the Covid-19 virus should be similar.
In other words, the cotton material used in masks helps to dry (and kill) the virus quickly. This is nice to know, since I just ordered 8 yards of pure cotton cloth to use to make masks.
Dynamics of infectious disease transmission by inhalable respiratory droplets
And the relevant passage: "Evaporation, being a molecular process, is very fast (Nicas et al. 2005; Morawska 2006); for example, a 20 µm droplet evaporates to a 1 µm diameter droplet within 0.24 s−1 (at 50% ambient relative humidity). Henceforth, we neglect droplet evaporation, and we follow Nicas et al. (2005) to take the post-evaporation diameter (approximately) half the pre-evaporation diameter."
I have never worn a surgical or cloth mask that became saturated, no matter how long I wore it. In any case, even if they become damp, water has a wonderful property of sticking to itself. Therefore, even a damp mask would attract any droplets containing virus. And if a mask became so wet that breathing became even more difficult than it normally is while wearing a mask, I suspect that most people would change it out.
Oh, and here are three papers that specifically address the question of mask efficacy in reducing the spread of Covid-19:
SARS-CoV-2 Infections and Serologic Responses from a Sample of U.S. Navy Service Members — USS Theodore Roosevelt, April 2020 [From the CDC's weekly publication, Morbidity and Mortality Weekly Report. And I know one of the authors.]
Face Masks Considerably Reduce COVID-19 Cases in Germany: A Synthetic Control Method Approach [Written by three economists and a statistician; however, their reference list looks solid.]
Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis [Published in The Lancet; most of the MD and MPH/MS authors are affiliated with Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, ON, Canada.]
All of these reviews concluded that masks (and social distancing and eye protection) are effective to reduce the spread of Coronavirus.
In addition, on the survivability of virus in different environments, I found this review: Stability and infectivity of coronaviruses in inanimate environments. Now, most of the studies examined in this review only looked for the presence of viral RNA in the environment, which tells nothing about whether there are infective particles in the environment. However, what that paper had to say about the survivability of virus on absorbent vs. non-absorbent surfaces was very interesting:
Infectivity of HuCoV- 229E was undetectable after drying on aluminum, sterile latex surgical gloves, and sterile cotton gauze sponges at RT for 3 h; HuCoV OC43 survived 1 h or less[34]. Contaminated droplets will be absorbed faster on cotton materials than on fluid-repellent materials, and cotton gowns offer protection against droplets bearing viruses. Droplets or fomites that persist on a nonabsorbent disposable gown or gloves may be a risk to contaminate the environment.
SARS-CoV strain GVU6109 was isolated from a lung tissue specimen of a SARS patient during the SARS outbreak in 2003[35]; its infectivity at 10^4 tissue culture infection doses (TCID50)/mL vanished within 5 min after drying on paper or a cotton gown at RT[35], showing that the viral infectivity perished faster on the cotton gown than on an impervious surface (e.g., the disposable gown) (5 min vs 60 min at 10^4 TCID50/mL, 1 h vs 24 h at 10^5 TCID50/mL )[35].
So it actually looks like cotton is the best choice for reducing virus spread.
But, don't tell me, I already know: what can a bunch of researchers who actually examine data and evidence possibly know about the real world?
I have seen similar reports on droplets holding covid. I don’t have the time to find them again. Thanks for your good info.
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