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Face masks effectively limit the probability of SARS-CoV-2 transmission

science.sciencemag.org

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Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#181

Post by TylerE »

simpleguitar wrote: post #177
xkcd-sucks wrote: post #165

Earlier quoted context omitted.

I wear "n95" masks while sanding drywall, obviously trying to make the fit as good as possible, and still my boogers end up with tons of plaster in them. I would assume these particles to be bigger than any virion.

A properly fit N95 should block out all dust. If you are getting plaster in your nose, try different types of masks (folding), or a half-face respirator. One of the justification for not advising N95s to the public was the fact that most people don't know how to properly wear one. As if they couldn't be trained in a few weeks, or duration of the pandemic. Also, N95s filter out particles smaller than .3 microns (the 9…

Actually it DOES work like a sieve on larger particles. The electrostatic mechanism works on smaller particles, while the larger ones are indeed filtered "mechanically".

The 0.3 micron size is used in the specification because it's the "worst" case... too large for maximum electrostatic attraction, too small for mechanical filtration...it's the worst case.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#182

Post by ddingus »

solarengineer wrote: post #176
mattm wrote: post #153

Earlier quoted context omitted.

"Some people with swine flu travelled on a plane from New York to China, and many fellow passengers got infected. Some researchers looked at whether passengers who wore masks throughout the flight stayed healthier. The answer was very much yes. They were able to track down 9 people who got sick on the flight and 32 who didn’t. 0% of the sick passengers wore masks, compared to 47% of the healthy passengers. Another wa…

What is astounding to a lot of us in South East Asia is the reluctance of the West in learning from our lessons. How many deaths and personal trauma experiences do people in general need to go through in order to learn from others?

There is a strong culture of individuality, and that is coupled with an extreme reluctance to just do what we're told, and what I mean by that is more about trust than Authority. Trust is low here, which is problematic for a scenario like this.

Many of us did learn those lessons.

For me personally when this all began, checking out what the world is doing seemed the natural thing to do.

The US is also very insular, in that a smaller percentage of people travel abroad than is typical for many Western Nations. And a small percentage of people seek news produced outside the nation too.

Both of those stats are better elsewhere in the West, so make of that what you will.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#183

Post by simpleguitar »

anonymousiam wrote: post #35

Here's the manufacturer's (3M) label: WARNING: This respirator helps protect against certain particulate contaminants but does not eliminate exposure to or the risk of contracting any disease or infection. Misuse may result in sickness or death. For proper use, see supervisor, or User Instructions. https://multimedia.3m.com/mws/media/1837275O/3m-9132-healthc...

Notice the word 'eliminate'.

Nobody could claim something would 'eliminate exposure or risk of contracting any disease' and not get sued immediately by someone who got sick.

In Wuhan, something like 10,000 doctors were sent in to treat the thousands in field hospitals. None of them caught covid during that time.

N95s work, if worn properly (and pass a fit test, even a crude one).

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#184

Post by Grimm665 »

jonas21 wrote: post #85
joshuaengler wrote: post #74

The VAST majority of mask wearing I have seen in California has been average cloth-covers. I have only seen a handful of people out of thousands actually wearing N95 masks, so perhaps N95 is highly effective at stopping viruses, but I see basically nobody wearing that. Stores, offices, buildings, all are completely fine with you wearing a bandana over your face. There is effectively no point in even mandating mask la…

I've never seen anyone wearing a coffee filter over their face. What are you talking about?

I haven't either but I did have to drive several miles out of my way a few months ago to get coffee filters at the only store in the state that seemed to have them in stock. I was told during checkout people were buying them in bulk to use as masks.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#185

Post by raverbashing »

rsj_hn wrote: post #75
tgsovlerkhgsel wrote: post #39

This entire study seems to be centered around a theoretical, mathematical model, and I didn't see any attempt to actually validate that model. Basically, the authors seem to assume that the virus behaves according to their formulas, and show that under their assumptions, face masks work, but don't actually prove that their assumptions match reality - or did I miss something?

Indeed this is the money paragraph: "The effectiveness of masks, however, is still under debate. Compared to N95/FFP2 respirators which have very low particle penetration rates (around ~5%), surgical and similar masks exhibit higher and more variable penetration rates (around ~30-70%) (2, 3). Given the large number of particles emitted upon respiration and especially upon sneezing or coughing (4), the number of respi…

Ah yes the "randomized controlled" studies 5 and 6.

5 is about influenza and 6 is not even worth the paper it's printed on.

No kidding, 6 is "recommending" people to wear a mask (and not even trying to control for the actual number).

So no, I have no qualms in calling study 6 useless, I've seen science fair projects with more scientific rigor and relevance than that.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#186

Post by maxerickson »

addicted wrote: post #161
rsj_hn wrote: post #75

Earlier quoted context omitted.

Indeed this is the money paragraph: "The effectiveness of masks, however, is still under debate. Compared to N95/FFP2 respirators which have very low particle penetration rates (around ~5%), surgical and similar masks exhibit higher and more variable penetration rates (around ~30-70%) (2, 3). Given the large number of particles emitted upon respiration and especially upon sneezing or coughing (4), the number of respi…

Considering that the vast majority of cases of COVID are asymptomatic, it’s pretty apparent that the viral load needed to infect someone enough that they even exhibit symptoms, never mind need to be hospitalized, is not easy to achieve. As such, it’s likely even a 30% reduction (which is on the lower end of the range) in the viral load inhaled by someone could drastically reduce the chance of symptomatic COVID. And w…

That's not how infections work though. A high initial load can cause the infection to peak higher (because more replication occurs before the immune response), but a lower initial load doesn't necessarily lead to a low peak infection (because replication is exponential with a large exponent).

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#187

Post by crocodiletears »

solarengineer wrote: post #176
mattm wrote: post #153

Earlier quoted context omitted.

"Some people with swine flu travelled on a plane from New York to China, and many fellow passengers got infected. Some researchers looked at whether passengers who wore masks throughout the flight stayed healthier. The answer was very much yes. They were able to track down 9 people who got sick on the flight and 32 who didn’t. 0% of the sick passengers wore masks, compared to 47% of the healthy passengers. Another wa…

What is astounding to a lot of us in South East Asia is the reluctance of the West in learning from our lessons. How many deaths and personal trauma experiences do people in general need to go through in order to learn from others?

In the US, it's more to do with the way the CDC's messaging throughout the pandemic than any rejection of the evidence concerning a mask's efficacy.

People refusing to wear masks rarely question whether or not it works, and more to do with a low estimation of the disease's threat, as well as contempt for both the technocrats who chose to mislead the public about masks early on, and leaders who they believe are overstepping their authority by mandating them.

Our leadership has been doing everything possible to burn through its perceived legitimacy, and this is the result. Childish, spiteful, somewhat understandable behavior.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#188

Post by listless »

splitrocket wrote: post #3

Not that this will settle anything. Anecdotally, I've not gotten even a slight cold while being socially distanced while consistently masked.

Objectively, it doesn’t seem to matter if an area is masked or not. The virus won’t be stopped. Just compare Florida to California or Georgia to Washington state.

I know what the models say. But my eyes deceive me.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#189

Post by slver »

alvah wrote: post #142
simpleguitar wrote: post #116

Earlier quoted context omitted.

Absolutely. Considering how long it took CDC and WHO to even acknowledge airborne transmission, even though the Chinese were very clear about it from very early on. https://www.nytimes.com/2021/05/07/opinion/coronavirus-airbo...

"even though the Chinese were very clear about it from very early on" I'm not sure this adds as much credibility as you seem to think. See (for example) - propaganda videos of people dropping dead in the street in Wuhan in early 2020.

Why on Earth are you calling them “propaganda” videos, when China was trying to downplay the pandemic at the time?

See, this is one big reason we’re collectively dumb. Everyone and their big conspiracy theories.

Re: Face masks effectively limit the probability of SARS-CoV-2 transmission

#190

Post by lostlogin »

jasonlaramburu wrote: post #148
function_seven wrote: post #113

Earlier quoted context omitted.

> On the other hand, "observational data show that regions or facilities with a higher percentage of the population wearing masks have better control of the coronavirus disease 2019 (COVID-19) (7–9)." So how to explain these contrasting results and apparent inconsistencies? My hypothesis regarding surgical mask prevalence and how it correlates with better virus control: People who wear masks--however effective they m…

It’s worth also considering the case of ski helmets. Since these have became common on the slopes head trauma has actually increased because wearers take more risks.

I had previously read that WW1 saw an increase in head injuries when helmets were used, due to victims surviving previously fatal injuries. However on searching it doesn't seem that clear-cut.
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