4 ms·

FYI Grainger has N95s (not KN95s) in stock, is unlikely to have the systemic counterfeiting problems Amazon does, and in my experience delivers quickly: https:/

by geofft 5y ago

FYI Grainger has N95s (not KN95s) in stock, is unlikely to have the systemic counterfeiting problems Amazon does, and in my experience delivers quickly: https://www.grainger.com/category/safety/respiratory-protection/disposable-respirators-masks/general-purpose-disposable-respirators-dust-masks?attrs=Exhalation+Valve%7CNo&filters=attrs,shopItemsBy&shopItemsBy=In+Stock+Now&gwwRemoveElement=true https://www.grainger.com/category/safety/respiratory-protect... Price vary, but they run about $2 a mask give or take a bit. You can generally reuse them for a while, assuming you don't work in a hospital - the usual reason to dispose of them is if pathogens are on them, but if you're only using it for protection against covid, the virus dies quickly when outside a host. I don't go out a whole lot because I work from home so I usually use one mask for at least a week, often several weeks. If you're going out frequently, I've seen a recommendation to rotate through a couple of active masks, giving the virus a few days to die off.

prpl 5y ago
I bought 3M Aura masks at home depot today in Bay Area and there was a ton of them.
erik_seaberg 5y ago
I thought hitting the N95 spec relied on static charges on the non-woven fibers which are otherwise too coarse. Are they more effective than cloth even after that dissipates (within a day)?
- geofft 5y ago
  Interesting, I did not know this. I'm now curious! https://www.nature.com/articles/d41586-020-02550-8 https://www.nature.com/articles/d41586-020-02550-8 is a brief Nature post from Peter Tsai, who invented this electrostatic filter. In it he says that the charge are "permanent," and adds: > They wanted to sterilize the masks for reuse without damaging them or destroying the electrostatic charge. I knew that heat would not alter the charge, but that alcohol would erase it. The N95DECON project says that masks can be reused if stored at room temperature and do not lose efficiency: https://www.n95decon.org/publications#time https://www.n95decon.org/publications#time I see some studies that find that various decontamination methods (high heat, various disinfectants) can cause the charge to dissipate, e.g., https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724761/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724761/ - but I'm not advocating doing any of those, I'm just advocating leaving it hanging on a hook by your door when you get home. And, interestingly, those studies show that while filtration may drop below 95%, it's still pretty high, so I think that yes, a discharged N95 is still more effective than a cloth mask. But it'd be good to find a direct study. I'm having trouble finding a source that says the filtration performance drops after a day. I did find something that says that the N95 standard requires it must keep working for at least 24 hours, but that's the other direction. (And, anecdotally... the masks I ordered are shipped stacked together, not individually wrapped, in a cardboard box. They've presumably been in the box for a while at the warehouse. While it's true that cardboard is an insulator, so is air, and I'm not sure that the mask hanging by my door is losing charge any faster than the mask sitting in the box.) One thing that does seem to be true is that getting the mask wet can cause the charge to dissipate. If I'm wearing my mask in humid conditions and biking (I usually leave my mask on if I'm stopping frequently), I'll notice that it gets damp, and I do change it when that happens. If your home is extraordinarily humid, maybe put your mask in a brown paper bag or something.

by geofft 5y ago

prpl 5y ago

I bought 3M Aura masks at home depot today in Bay Area and there was a ton of them.

erik_seaberg 5y ago

I thought hitting the N95 spec relied on static charges on the non-woven fibers which are otherwise too coarse. Are they more effective than cloth even after that dissipates (within a day)?

geofft 5y ago
Interesting, I did not know this. I'm now curious! https://www.nature.com/articles/d41586-020-02550-8 https://www.nature.com/articles/d41586-020-02550-8 is a brief Nature post from Peter Tsai, who invented this electrostatic filter. In it he says that the charge are "permanent," and adds: > They wanted to sterilize the masks for reuse without damaging them or destroying the electrostatic charge. I knew that heat would not alter the charge, but that alcohol would erase it. The N95DECON project says that masks can be reused if stored at room temperature and do not lose efficiency: https://www.n95decon.org/publications#time https://www.n95decon.org/publications#time I see some studies that find that various decontamination methods (high heat, various disinfectants) can cause the charge to dissipate, e.g., https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724761/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724761/ - but I'm not advocating doing any of those, I'm just advocating leaving it hanging on a hook by your door when you get home. And, interestingly, those studies show that while filtration may drop below 95%, it's still pretty high, so I think that yes, a discharged N95 is still more effective than a cloth mask. But it'd be good to find a direct study. I'm having trouble finding a source that says the filtration performance drops after a day. I did find something that says that the N95 standard requires it must keep working for at least 24 hours, but that's the other direction. (And, anecdotally... the masks I ordered are shipped stacked together, not individually wrapped, in a cardboard box. They've presumably been in the box for a while at the warehouse. While it's true that cardboard is an insulator, so is air, and I'm not sure that the mask hanging by my door is losing charge any faster than the mask sitting in the box.) One thing that does seem to be true is that getting the mask wet can cause the charge to dissipate. If I'm wearing my mask in humid conditions and biking (I usually leave my mask on if I'm stopping frequently), I'll notice that it gets damp, and I do change it when that happens. If your home is extraordinarily humid, maybe put your mask in a brown paper bag or something.