5 ms·

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 woul

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).
- beagle3 5y ago
  Unless you have a valve, and hardly breath at all, exhaling pushes the N95 away from your face enough to let some unfiltered air in. There’s a similar (though smaller) effect with the thin paper valves, but regardless of how good the fit is, you need a much better valve than that to actually filter all air through the fabric.
  - La1n 5y ago
    Are there N95's without a valve? Cause all I've owned before the pandemic had a valve.
    - beagle3 5y ago
      Yes. I’ve had both with and without valves since 2015. Would never buy one without a valve again if I can find one with a valve (in the last year at some times could only find valveless) Fwiw, in Israel it was illegal to use a valved mask without covering the valve with cloth/paper/surgical mask. The official statement was that the pressure out of the valve disperses virions much farther, and is thus more dangerous to people around you if you are presymptomatic than having no mask at all.
lostlogin 5y ago
When wearing a mask in a hospital setting I had to have a fitting done. A test was run and a machine measured particles getting through. Properly fitted, nothing got though down to a very small size (which I don't recall). An earlier version of the test saw some particle released into the room and a properly fitted mask wouldn't let it though. If people could smell the chemical, the fit was poor.
- asabjorn 5y ago
  And I assume you were also trained in how to use the masks properly so that they didn't increase chance of virus spread and only used N95 masks? E.g. don't touch mask and dispose/clean the mask after each use. Almost nobody does this, and many use cloth masks.
chimprich 5y ago
> I would assume these particles to be bigger than any virion. The masks aren't expected to stop individual virus particles. They are supposed to catch salivary droplets containing the virus. These are probably bigger than particles of drywall dust.
jaclaz 5y ago
Yep, what most people forget when talking about N95 and similar is how a "standardized" fit test is performed, basically the 95% is theory and only IF the mask is properly fitted. You will have deep signs on your face after wearing a fitted N95 a feww hours. Previous posts with some more details and link to a US Department of labour video: https://news.ycombinator.com/item?id=27129984 https://news.ycombinator.com/item?id=27129984 https://news.ycombinator.com/item?id=23957506 https://news.ycombinator.com/item?id=23957506

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).
beagle3 5y ago
Unless you have a valve, and hardly breath at all, exhaling pushes the N95 away from your face enough to let some unfiltered air in. There’s a similar (though smaller) effect with the thin paper valves, but regardless of how good the fit is, you need a much better valve than that to actually filter all air through the fabric.
- La1n 5y ago
  Are there N95's without a valve? Cause all I've owned before the pandemic had a valve.
  - beagle3 5y ago
    Yes. I’ve had both with and without valves since 2015. Would never buy one without a valve again if I can find one with a valve (in the last year at some times could only find valveless) Fwiw, in Israel it was illegal to use a valved mask without covering the valve with cloth/paper/surgical mask. The official statement was that the pressure out of the valve disperses virions much farther, and is thus more dangerous to people around you if you are presymptomatic than having no mask at all.

lostlogin 5y ago

When wearing a mask in a hospital setting I had to have a fitting done. A test was run and a machine measured particles getting through. Properly fitted, nothing got though down to a very small size (which I don't recall). An earlier version of the test saw some particle released into the room and a properly fitted mask wouldn't let it though. If people could smell the chemical, the fit was poor.

asabjorn 5y ago
And I assume you were also trained in how to use the masks properly so that they didn't increase chance of virus spread and only used N95 masks? E.g. don't touch mask and dispose/clean the mask after each use. Almost nobody does this, and many use cloth masks.

chimprich 5y ago

> I would assume these particles to be bigger than any virion. The masks aren't expected to stop individual virus particles. They are supposed to catch salivary droplets containing the virus. These are probably bigger than particles of drywall dust.

jaclaz 5y ago

Yep, what most people forget when talking about N95 and similar is how a "standardized" fit test is performed, basically the 95% is theory and only IF the mask is properly fitted. You will have deep signs on your face after wearing a fitted N95 a feww hours. Previous posts with some more details and link to a US Department of labour video: https://news.ycombinator.com/item?id=27129984 https://news.ycombinator.com/item?id=27129984 https://news.ycombinator.com/item?id=23957506 https://news.ycombinator.com/item?id=23957506