5 ms·

> The effectiveness of masks, however, is still under debate Effective for the mask wearer, or effective for others in the vicinity of the mask wearer? It's w

> The effectiveness of masks, however, is still under debate Effective for the mask wearer, or effective for others in the vicinity of the mask wearer? It's well established that cheap cloth masks and procedure masks don't protect the mask wearer very much. The rationale for cheap masks is that they drastically reduce the spread of particles from the wearer to everyone else nearby. If your goal is to protect yourself, wear an N95 or better. If your goal is to protect a population, and N95s aren't available, then the cheap mask help a lot when people wear them.

__blockcipher__ 5y ago
Except there is no convincing evidence that they actually do help others, and the whole theoretical mechanism is centered around catching large respiratory droplets which is at odd with the totality of evidence pointing towards aerosol being the dominant mode. I would add if droplet transmission is the dominant mode, which I very much doubt, then masks would still fail in a real-world setting when you look at the fact they make conversational partners stand closer or speak louder, and the massive cross contamination that happens to almost everybody wearing these pieces of cloth over their faces (hands touch mask, mask touches hands, etc)
- panarky 5y ago
  > no convincing evidence This MIT study [0] was pretty convincing. They conclude that "face masks can be an extremely effective indoor safety measure". For example: If an infected person was riding on a commercial airline with 100 other people, other passengers would be at risk of infection within 70 minutes. If all of the passengers wore masks, however, that space could be safe for up to 54 hours. [0] https://www.pnas.org/content/118/17/e2018995118 https://www.pnas.org/content/118/17/e2018995118
  - nradov 5y ago
    How can a model be convincing if it hasn't been extensively tested in the real world?
    - astrange 5y ago
      The model of wearing masks has been extensively tested in Asia. Meanwhile US doctors were telling me that putting on a mask would actually cause you to get infected faster because you'd do it wrong. (Then the CDC announced mask orders the next day and they mumbled something about new evidence to me.) And we can see who's done better in the last year.
      - makomk 5y ago
        It's looking more and more like a whole bunch of Asian countries just got lucky. Singapore, Taiwan and Vietnam have all currently got uncontrolled community spread again (possibly China too), and whilst the Taiwan outbreak could maybe be blamed on them getting sloppy Singapore has been aggressively enforcing mask wearing the whole time. There was already good reason to suspect this was the case over a year ago too. The early outbreaks mostly seemed to be a gradient emanating outwards from Italy, with genetic testing suggesting that even the US had done reasonably well at halting spread from China and its big outbreaks came from Europe; Asia is obviously a long way from Italy and it was suspicious that a bunch of countries that in reality had widely varying policies on things like masks, testing, etc showed such similar results. Including countries like Australia and New Zealand that were more or less western in terms of culture but were geographically close to the rest.
  - beagle3 5y ago
    Basically all convincing evidence for mask use is models (like the linked article) and in vitro unrealistic tests; whereas in real world data, the best I could find wrt covid is 2% reduction. Bacteria are a different matter, and possibly other viruses. But real world data about covid is that masks make very little difference either way, and are possibly harmful.
- Matumio 5y ago
  People touch their faces all the time, mask or not. And some non-physical effects of masks may be useful. If nothing else, fumbling around with masks is repeated reminder for all other measures. It may feel silly to wear a mask if you belief that this is the only effect. But you cannot deny that it is a causal effect, e.g. it would not happen without wearing the masks.
- deleted 5y ago
  [deleted]
xkcd-sucks 5y ago
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.
- simpleguitar 5y ago
  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 95% part). You can look it up, but it has something to do with the electrostatic media and physics. It definitely does not work like a sieve. (https://www.usatoday.com/story/news/factcheck/2020/06/11/fact-check-n-95-filters-not-too-large-stop-covid-19-particles/5343537002/ https://www.usatoday.com/story/news/factcheck/2020/06/11/fac...)
  - TylerE 5y ago
    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.
    - asabjorn 5y ago
      You are here talking specifically of N95 masks, not cloth masks, and this is only true for the very few that properly use masks. Doctors are required to not touch N95 mask and dispose of them after each use. Viruses can live for up to 24hrs on a mask and spread from you touching the mask then another surface. Covid survives for 30 seconds in sunlight, so wearing a mask outside is bad on balance as you breathe in your own CO2 and reduce oxygen intake which both have negative health effects (especially during exercise).
perryizgr8 5y ago
> then the cheap mask help a lot when people wear them. Are there any reliable and conclusive studies supporting this?
- astrange 5y ago
  There are not even any reliable studies showing that surgical masks help during surgery. The problem with public health agencies is that, apparently, if they don't have an RCT they immediately jump to make the worst possible decisions. So try not to do the same thing.
  - perryizgr8 5y ago
    > There are not even any reliable studies showing that surgical masks help during surgery. That's fine, because I am not a surgeon and I don't care. I do care about fogging up my glasses and having to speak up without any proper evidence that wearing a mask helps significantly against covid.
    - astrange 5y ago
      The kind with a bendable bar or tape at the top for your nose don't affect my glasses. Anyway, you're going to run into the same problem doctors' advice has, where everything not required is forbidden. If a 100-year problem like a pandemic comes up, try some unproven precautions, it's better than not doing anything until it's mandated.
asabjorn 5y ago
> The rationale for cheap masks is that they drastically reduce the spread of particles from the wearer to everyone else nearby. If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)?
- dragonwriter 5y ago
  > If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)? They...don’t (leaving out NYC because the other three things are large, diverse states and NYC is a single large city): California 3.7M cumulative cases & 1,336 case/day current 7-day average vs. 39.5M population Florida 2.3M cumulative cases & 3,007 case/day 7-day average vs 21.5M population. Texas 2.9M cumulative case & 2,034 case/day current 7-day average vs. 29M population. FL and TX are worse on per capita cumulative cases, and much worse on current per capita new cases than California. (case numbers from usafacts.org)
  - johbjo 5y ago
    Also consider age distribution/population density in areas you compare. Death rate is exponential in age, so small differences in age distribution gives big differences in relative deaths.
    - asabjorn 5y ago
      Death rate to confirmed cases is TX 1.7% (51k deaths over 2.9m cases), Florida 1.56% (36k deaths over 2296 cases), CA 1.64% (62k deaths over 3.74m cases) [source: google coronovirus stats]. So data does not confirm your conclusion.
      - dragonwriter 5y ago
        Without stats on the age distribution of confirmed cases (even before considering the absence of analysis of confounding factors, liking case timing within the pandemic, etc.), I’m not sure how you can say the data doesn’t confirm the conclusion since you don’t have data on the proposed independent variable at all.

__blockcipher__ 5y ago

Except there is no convincing evidence that they actually do help others, and the whole theoretical mechanism is centered around catching large respiratory droplets which is at odd with the totality of evidence pointing towards aerosol being the dominant mode. I would add if droplet transmission is the dominant mode, which I very much doubt, then masks would still fail in a real-world setting when you look at the fact they make conversational partners stand closer or speak louder, and the massive cross contamination that happens to almost everybody wearing these pieces of cloth over their faces (hands touch mask, mask touches hands, etc)

panarky 5y ago
> no convincing evidence This MIT study [0] was pretty convincing. They conclude that "face masks can be an extremely effective indoor safety measure". For example: If an infected person was riding on a commercial airline with 100 other people, other passengers would be at risk of infection within 70 minutes. If all of the passengers wore masks, however, that space could be safe for up to 54 hours. [0] https://www.pnas.org/content/118/17/e2018995118 https://www.pnas.org/content/118/17/e2018995118
- nradov 5y ago
  How can a model be convincing if it hasn't been extensively tested in the real world?
  - astrange 5y ago
    The model of wearing masks has been extensively tested in Asia. Meanwhile US doctors were telling me that putting on a mask would actually cause you to get infected faster because you'd do it wrong. (Then the CDC announced mask orders the next day and they mumbled something about new evidence to me.) And we can see who's done better in the last year.
    - makomk 5y ago
      It's looking more and more like a whole bunch of Asian countries just got lucky. Singapore, Taiwan and Vietnam have all currently got uncontrolled community spread again (possibly China too), and whilst the Taiwan outbreak could maybe be blamed on them getting sloppy Singapore has been aggressively enforcing mask wearing the whole time. There was already good reason to suspect this was the case over a year ago too. The early outbreaks mostly seemed to be a gradient emanating outwards from Italy, with genetic testing suggesting that even the US had done reasonably well at halting spread from China and its big outbreaks came from Europe; Asia is obviously a long way from Italy and it was suspicious that a bunch of countries that in reality had widely varying policies on things like masks, testing, etc showed such similar results. Including countries like Australia and New Zealand that were more or less western in terms of culture but were geographically close to the rest.
- beagle3 5y ago
  Basically all convincing evidence for mask use is models (like the linked article) and in vitro unrealistic tests; whereas in real world data, the best I could find wrt covid is 2% reduction. Bacteria are a different matter, and possibly other viruses. But real world data about covid is that masks make very little difference either way, and are possibly harmful.
Matumio 5y ago
People touch their faces all the time, mask or not. And some non-physical effects of masks may be useful. If nothing else, fumbling around with masks is repeated reminder for all other measures. It may feel silly to wear a mask if you belief that this is the only effect. But you cannot deny that it is a causal effect, e.g. it would not happen without wearing the masks.
deleted 5y ago
[deleted]

xkcd-sucks 5y ago

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.

simpleguitar 5y ago
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 95% part). You can look it up, but it has something to do with the electrostatic media and physics. It definitely does not work like a sieve. (https://www.usatoday.com/story/news/factcheck/2020/06/11/fact-check-n-95-filters-not-too-large-stop-covid-19-particles/5343537002/ https://www.usatoday.com/story/news/factcheck/2020/06/11/fac...)
- TylerE 5y ago
  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.
  - asabjorn 5y ago
    You are here talking specifically of N95 masks, not cloth masks, and this is only true for the very few that properly use masks. Doctors are required to not touch N95 mask and dispose of them after each use. Viruses can live for up to 24hrs on a mask and spread from you touching the mask then another surface. Covid survives for 30 seconds in sunlight, so wearing a mask outside is bad on balance as you breathe in your own CO2 and reduce oxygen intake which both have negative health effects (especially during exercise).

perryizgr8 5y ago

> then the cheap mask help a lot when people wear them. Are there any reliable and conclusive studies supporting this?

astrange 5y ago
There are not even any reliable studies showing that surgical masks help during surgery. The problem with public health agencies is that, apparently, if they don't have an RCT they immediately jump to make the worst possible decisions. So try not to do the same thing.
- perryizgr8 5y ago
  > There are not even any reliable studies showing that surgical masks help during surgery. That's fine, because I am not a surgeon and I don't care. I do care about fogging up my glasses and having to speak up without any proper evidence that wearing a mask helps significantly against covid.
  - astrange 5y ago
    The kind with a bendable bar or tape at the top for your nose don't affect my glasses. Anyway, you're going to run into the same problem doctors' advice has, where everything not required is forbidden. If a 100-year problem like a pandemic comes up, try some unproven precautions, it's better than not doing anything until it's mandated.

asabjorn 5y ago

> The rationale for cheap masks is that they drastically reduce the spread of particles from the wearer to everyone else nearby. If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)?

dragonwriter 5y ago
> If so, why does states with the highest mask use (CA, NYC) have much higher covid rates than states with some of the lowest mask use (Florida, Texas)? They...don’t (leaving out NYC because the other three things are large, diverse states and NYC is a single large city): California 3.7M cumulative cases & 1,336 case/day current 7-day average vs. 39.5M population Florida 2.3M cumulative cases & 3,007 case/day 7-day average vs 21.5M population. Texas 2.9M cumulative case & 2,034 case/day current 7-day average vs. 29M population. FL and TX are worse on per capita cumulative cases, and much worse on current per capita new cases than California. (case numbers from usafacts.org)
- johbjo 5y ago
  Also consider age distribution/population density in areas you compare. Death rate is exponential in age, so small differences in age distribution gives big differences in relative deaths.
  - asabjorn 5y ago
    Death rate to confirmed cases is TX 1.7% (51k deaths over 2.9m cases), Florida 1.56% (36k deaths over 2296 cases), CA 1.64% (62k deaths over 3.74m cases) [source: google coronovirus stats]. So data does not confirm your conclusion.
    - dragonwriter 5y ago
      Without stats on the age distribution of confirmed cases (even before considering the absence of analysis of confounding factors, liking case timing within the pandemic, etc.), I’m not sure how you can say the data doesn’t confirm the conclusion since you don’t have data on the proposed independent variable at all.