5 ms·

>the empirical evidence for masking, especially vs. the new strains, is quite weak If you're wearing an N95 or KN95 the filtration efficacy is quite high. Most

by graeme 3y ago

>the empirical evidence for masking, especially vs. the new strains, is quite weak If you're wearing an N95 or KN95 the filtration efficacy is quite high. Most of the mask studies looked at whether mask policies lowered covid. If you wear a mask in class but then take it off in the cafeteria or outside of school, the mask no longer has an effect. If, however, you wear a mask with high filtration efficacy while outside of the house, that's a different story. To my knowledge we have no challenge trial of people wearing such a mask when exposed to an infectious agent. It is folly to ignore the physical mechanism of such masks when reasoning about them, and defaulting to only considering the studies we have, which simply cannot measure efficacy when the mask is worn. This study on parachutes is a good analogue: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC300808/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC300808/

tptacek 3y ago
N95 vs. KN95 seems like an instructive example: people equate the two based on the effectiveness of the filtering media, but the salient difference is in the attachment mechanism --- most KN95s are ear-loops, and don't achieve especially tight coverings (similarly: the reuse concerns about N95s are less that the filter media can't be "recharged" or whatever, but rather that the elastic gives out). At any rate: masks as worn in the real world seem pretty performative, for a variety of reasons. If you're wearing them carefully, that's great, and I appreciate it. Nobody should be messing with you regardless. You can look epidemiologically at this stuff and see that states with laxer regulations fared pretty well in the early COVID years, and appear to have fallen off only with the introduction of vaccines, which really seem like the high-order bit of COVID control.
- jeffbee 3y ago
  I don't know what's "performative" about it. The respirator has a clear mechanism of action. They filter out almost all airborne viruses and are even better at filtering bacteria (which are larger). They also have the side benefit of making the wearer not want to eat airline "food" which I've noticed leaves me feeling better when I arrive. They are designed to be worn effectively even by illiterate manual laborers, so it's not as if you need to be a PhD to get one on your face.
  - Scoundreller 3y ago
    What I like about wearing a mask on a plane is that I rebreathe some exhaled moisture. Though I did a flight in mid 2020 and I'd inhale, move mask, take bite/sip, exhale while putting mask back, and then breathe normally through mask. Was probably a bit unnecessary when the flights were basically empty, but reduced-risk eating/drinking is possible.
    - jeffbee 3y ago
      I noticed something similar: no nosebleeds. I have only taken a few flights in the last several years though and I can't rule out that maybe the 737 MAX has a more humid interior atmosphere or something like that. But before I started wearing masks on airplanes I used to shoot saline spray up my nostrils every hour to keep the nosebleeds away.
    - Krssst 3y ago
      Also: I find that the air feels warmer in winter when breathing through a mask.
      - Scoundreller 3y ago
        Yeah, it’s up there with water is wet. Ever wonder why your shoulders don’t get dry in winter but your face does?
- graeme 3y ago
  Completely agree that an ear loop is less effective than a headstrap. The question is: by how much? This beard length mask study is a good source of data. They actually measured fitted filtration efficacy at different beard lengths, including zero beard. N95 was near 100%. KN95 was between 80-90% (surprisingly, higher with a small bit of beard, around 0.5-1mm). Now, you could certainly argue that 80-90% filtration is performative, but on what evidence? We know from hepa filtration studies that lowering the concentration of virus in the air lowers infection amongst those in a room. So from physical mechanisms we would expect that reducing inhaled virus by 80-90% should likewise reduce risk of infection. https://pubmed.ncbi.nlm.nih.gov/34006963/#&gid=article-figures&pid=fig-2-uid-1 https://pubmed.ncbi.nlm.nih.gov/34006963/#&gid=article-figur...
  - tptacek 3y ago
    I don't know! But in mandatory masking regimes, ordinary people do a clownish job of masking (and some of the masking rules are themselves clownish, as with the "mask until you get to the dining table, and then unmask as soon as the water arrived", which was very much the regime in Chicago when dining opened back up in 2021). The bigger point would just be to look at the epidemiology. I get that questioning masking pattern matches to COVID nihilism. I'm not a COVID nihilist. It was a big deal for me and I take it seriously. But the data I see suggests that the most significant bit in controlling it is ensuring people are vaccinated, and that most of the rest of the controls don't seem to do much.
    - idlewords 3y ago
      One problem with "look at the epidemiology" as an approach is that the virus is such a moving target. I'm citing these figures from memory, so apologies if I mangle them, but with OG covid you could mask up properly and spend an hour in an enclosed space with viral particles in the air and have a low risk of infection, while with omicron you had maybe five minutes masked the same way before you'd catch an infectious dose. More generally, the trouble with evaluating masking is all the confounders. I spent the early pandemic in Japan, where ubiquitous masking was a highly effective barrier to spread. One reason it may have worked as well as it did is that people talked less with the masks on. But there were already strong social norms against talking in confined public places, and the public health authority stressed airborne spread. How much did that contribute? I feel like the mask issue is irretrievably lost at this point in the US, but it's important to stress that in places like Japan and Taiwan it worked quite well, at least until omicron got so infective that even stringent adherence was no longer adequate. But there's no way to untangle it from the changes in social behavior that accompanied it, some of them a physical result of the masks (less talking), some due to social signaling aspects of mask wearing, and many unrelated.
vlovich123 3y ago
Yes they are effective, but don’t forget that they’re not perfect - your eyes and ears remain as access ports for the virus even when wearing a mask. Probably eyes is the biggest after respiratory because glasses have been shown to decrease infections if I recall correctly.
- Sakos 3y ago
  It doesn't need to be perfect in order to be effective. What's your point?
  - Scoundreller 3y ago
    Personally, I think the ocular route has been under-investigated in transmission.
  - vlovich123 3y ago
    Just that the sequence of events is "I'm told masks prevent COVID" => "I was wearing a mask and got COVID" => "masks don't stop COVID" (or it happens to a friend or a friend of a friend etc). You have to explain that masks help prevent it but aren't perfect because your eyes & ears remain open (my hunch is that it's likely the eyes as the next major transmission vector so glasses or full goggles would be almost fully effective).

by graeme 3y ago

tptacek 3y ago

N95 vs. KN95 seems like an instructive example: people equate the two based on the effectiveness of the filtering media, but the salient difference is in the attachment mechanism --- most KN95s are ear-loops, and don't achieve especially tight coverings (similarly: the reuse concerns about N95s are less that the filter media can't be "recharged" or whatever, but rather that the elastic gives out). At any rate: masks as worn in the real world seem pretty performative, for a variety of reasons. If you're wearing them carefully, that's great, and I appreciate it. Nobody should be messing with you regardless. You can look epidemiologically at this stuff and see that states with laxer regulations fared pretty well in the early COVID years, and appear to have fallen off only with the introduction of vaccines, which really seem like the high-order bit of COVID control.

jeffbee 3y ago
I don't know what's "performative" about it. The respirator has a clear mechanism of action. They filter out almost all airborne viruses and are even better at filtering bacteria (which are larger). They also have the side benefit of making the wearer not want to eat airline "food" which I've noticed leaves me feeling better when I arrive. They are designed to be worn effectively even by illiterate manual laborers, so it's not as if you need to be a PhD to get one on your face.
- Scoundreller 3y ago
  What I like about wearing a mask on a plane is that I rebreathe some exhaled moisture. Though I did a flight in mid 2020 and I'd inhale, move mask, take bite/sip, exhale while putting mask back, and then breathe normally through mask. Was probably a bit unnecessary when the flights were basically empty, but reduced-risk eating/drinking is possible.
  - jeffbee 3y ago
    I noticed something similar: no nosebleeds. I have only taken a few flights in the last several years though and I can't rule out that maybe the 737 MAX has a more humid interior atmosphere or something like that. But before I started wearing masks on airplanes I used to shoot saline spray up my nostrils every hour to keep the nosebleeds away.
  - Krssst 3y ago
    Also: I find that the air feels warmer in winter when breathing through a mask.
    - Scoundreller 3y ago
      Yeah, it’s up there with water is wet. Ever wonder why your shoulders don’t get dry in winter but your face does?
graeme 3y ago
Completely agree that an ear loop is less effective than a headstrap. The question is: by how much? This beard length mask study is a good source of data. They actually measured fitted filtration efficacy at different beard lengths, including zero beard. N95 was near 100%. KN95 was between 80-90% (surprisingly, higher with a small bit of beard, around 0.5-1mm). Now, you could certainly argue that 80-90% filtration is performative, but on what evidence? We know from hepa filtration studies that lowering the concentration of virus in the air lowers infection amongst those in a room. So from physical mechanisms we would expect that reducing inhaled virus by 80-90% should likewise reduce risk of infection. https://pubmed.ncbi.nlm.nih.gov/34006963/#&gid=article-figures&pid=fig-2-uid-1 https://pubmed.ncbi.nlm.nih.gov/34006963/#&gid=article-figur...
- tptacek 3y ago
  I don't know! But in mandatory masking regimes, ordinary people do a clownish job of masking (and some of the masking rules are themselves clownish, as with the "mask until you get to the dining table, and then unmask as soon as the water arrived", which was very much the regime in Chicago when dining opened back up in 2021). The bigger point would just be to look at the epidemiology. I get that questioning masking pattern matches to COVID nihilism. I'm not a COVID nihilist. It was a big deal for me and I take it seriously. But the data I see suggests that the most significant bit in controlling it is ensuring people are vaccinated, and that most of the rest of the controls don't seem to do much.
  - idlewords 3y ago
    One problem with "look at the epidemiology" as an approach is that the virus is such a moving target. I'm citing these figures from memory, so apologies if I mangle them, but with OG covid you could mask up properly and spend an hour in an enclosed space with viral particles in the air and have a low risk of infection, while with omicron you had maybe five minutes masked the same way before you'd catch an infectious dose. More generally, the trouble with evaluating masking is all the confounders. I spent the early pandemic in Japan, where ubiquitous masking was a highly effective barrier to spread. One reason it may have worked as well as it did is that people talked less with the masks on. But there were already strong social norms against talking in confined public places, and the public health authority stressed airborne spread. How much did that contribute? I feel like the mask issue is irretrievably lost at this point in the US, but it's important to stress that in places like Japan and Taiwan it worked quite well, at least until omicron got so infective that even stringent adherence was no longer adequate. But there's no way to untangle it from the changes in social behavior that accompanied it, some of them a physical result of the masks (less talking), some due to social signaling aspects of mask wearing, and many unrelated.

vlovich123 3y ago

Yes they are effective, but don’t forget that they’re not perfect - your eyes and ears remain as access ports for the virus even when wearing a mask. Probably eyes is the biggest after respiratory because glasses have been shown to decrease infections if I recall correctly.

Sakos 3y ago
It doesn't need to be perfect in order to be effective. What's your point?
- Scoundreller 3y ago
  Personally, I think the ocular route has been under-investigated in transmission.
- vlovich123 3y ago
  Just that the sequence of events is "I'm told masks prevent COVID" => "I was wearing a mask and got COVID" => "masks don't stop COVID" (or it happens to a friend or a friend of a friend etc). You have to explain that masks help prevent it but aren't perfect because your eyes & ears remain open (my hunch is that it's likely the eyes as the next major transmission vector so glasses or full goggles would be almost fully effective).