4 ms·

Masks that don't seal tightly against skin vent (backwards as well as up and down). You feel "quite safe from aerosols" but the empirical studies don't back thi

Masks that don't seal tightly against skin vent (backwards as well as up and down). You feel "quite safe from aerosols" but the empirical studies don't back this up across real world large-N groups. So mandating an insufficient mask is worse than mandating one that might make a measurable difference, but in any event: mandates are not justified in my view, on also not advised by long-term WHO and CDC guidance, and they are in a legal "gray area" in the US. Germany and USA: https://twitter.com/ianmSC/status/1359677558829191169 https://twitter.com/ianmSC/status/1359677558829191169

kodah 6y ago
Just going to preface with I don't agree that masks didn't help. The clean fit to a face is pertinent to zero exposure. This is a common test in the military: dawn your mask, cover the vents, and suck in. If you don't feel immense pressure on your face, if you can't shake your head and do it again then you're metaphorically dead. Part of this fit is having a mask that fits your face and being clean shaven. I don't know that COVID protection needs to hit this mark, since this is designed for nerve agents and nuclear fallout. It seems like trapping quantities of the virus is good enough, since it takes some threshold of exposure to get someone infected.
- BrendanEich 6y ago
  Microdroplets, aerosol flows. This isn't a matter of stopping large droplets, where masks are more effective provided they don't nebulize. See also https://link.springer.com/article/10.1007/BF01658736 https://link.springer.com/article/10.1007/BF01658736 https://ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/annrcse01509-0009.pdf https://ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/annrcse... for surprising null or even slightly negative result of surgeons masking vs. surgery patient wound infections. Assuming linear scaling or other naive-model benefits from masks runs into large-scale gen-pop experience, which has now been studied by enough RCTs to cast doubt on the assumption. Long-term WHO and CDC policy guidance was based on empirical science showing non-pharmaceutical interventions are not very effective against respiratory viruses.
blub 6y ago
I am not a large-N group though, so my main interest is whether a properly worn FFP2 mask can protect me. Everything indicates that it can. My only worry was FFP2 vs FFP3, since the former is not actually recommended to be used to protect against aerosols, but it seems that it's the default even for medical personnel - high aerosol inducing procedures aside. The fact that others are wearing surgical or even FFP2 masks is a protective bonus for me, even if the former vent or it doesn't protect them in all cases. I believe this was the reasoning of the German original fabric mask mandate starting spring/summer 2020: mask + no mask = 0, but mask + mask = good protection against droplets. Whether that made any significant difference with the transmission in aggregate is probably impossible to tell now, but it probably did prevent at least some infections. More importantly it made masks more normal, compared to spring where you were looked at like a maniac for wearing one. Regarding the graph, Germany was and still is in a lockdown, so numbers will be going down masks or not. Upgrading the mandate to surgical/FFP2 was done more out of fear of the new mutations and it wasn't FFP2 only because it's economically / socially not tenable. I don't know why the US decreased, but the US is way ahead on vaccines and also had more infected, so I assume it will continue to do so.

kodah 6y ago

Just going to preface with I don't agree that masks didn't help. The clean fit to a face is pertinent to zero exposure. This is a common test in the military: dawn your mask, cover the vents, and suck in. If you don't feel immense pressure on your face, if you can't shake your head and do it again then you're metaphorically dead. Part of this fit is having a mask that fits your face and being clean shaven. I don't know that COVID protection needs to hit this mark, since this is designed for nerve agents and nuclear fallout. It seems like trapping quantities of the virus is good enough, since it takes some threshold of exposure to get someone infected.

BrendanEich 6y ago
Microdroplets, aerosol flows. This isn't a matter of stopping large droplets, where masks are more effective provided they don't nebulize. See also https://link.springer.com/article/10.1007/BF01658736 https://link.springer.com/article/10.1007/BF01658736 https://ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/annrcse01509-0009.pdf https://ncbi.nlm.nih.gov/pmc/articles/PMC2493952/pdf/annrcse... for surprising null or even slightly negative result of surgeons masking vs. surgery patient wound infections. Assuming linear scaling or other naive-model benefits from masks runs into large-scale gen-pop experience, which has now been studied by enough RCTs to cast doubt on the assumption. Long-term WHO and CDC policy guidance was based on empirical science showing non-pharmaceutical interventions are not very effective against respiratory viruses.

blub 6y ago

I am not a large-N group though, so my main interest is whether a properly worn FFP2 mask can protect me. Everything indicates that it can. My only worry was FFP2 vs FFP3, since the former is not actually recommended to be used to protect against aerosols, but it seems that it's the default even for medical personnel - high aerosol inducing procedures aside. The fact that others are wearing surgical or even FFP2 masks is a protective bonus for me, even if the former vent or it doesn't protect them in all cases. I believe this was the reasoning of the German original fabric mask mandate starting spring/summer 2020: mask + no mask = 0, but mask + mask = good protection against droplets. Whether that made any significant difference with the transmission in aggregate is probably impossible to tell now, but it probably did prevent at least some infections. More importantly it made masks more normal, compared to spring where you were looked at like a maniac for wearing one. Regarding the graph, Germany was and still is in a lockdown, so numbers will be going down masks or not. Upgrading the mandate to surgical/FFP2 was done more out of fear of the new mutations and it wasn't FFP2 only because it's economically / socially not tenable. I don't know why the US decreased, but the US is way ahead on vaccines and also had more infected, so I assume it will continue to do so.