Can anyone point me to data on the dangers of mask reuse? Masks block droplets from entering, but it's unclear whether those droplets attach to the mask or "bounce off". And if they attach, then it seems like those droplets would eventually be displaced by others. It seems like whatever concentration of particles is in the outside air would also become the concentration of particles on your mask, and thus no more dangerous.
According to a video I watched some time back, N95 works by statically attracting the particles to stick to the fibers. Over time, the static electricity is neutralized in the same way it is with, say, your laundry. This is why you can't simply wash the mask, and also why they become ineffective after a time of use, even if they never once come in contact with coronavirus particles. Basically, your skin is gradually causing the static to discharge.
The video I was watching was about why N95 masks aren't interchangeable with PM2.5 masks, and vice versa, but they can be (and are) combined for some purposes. PM2.5 can let coronavirus through if it isn't in a medium large enough to be filtered, and n95 can let some gases through that pm2.5 would block. But noting that viral particles rarely fly around on their own (they are usually in an aerosol liquid which may or may not have a surface area that will be filtered by either one), the effectiveness isn't as drastically different as it might initially seem when only talking about particle size.
The video argued that due to how the masks work, N95 is 95% effective, and pm2.5 is 93% effective (and some argued 80-some-odd percent). PM2.5 can pretty much be decontaminated with strong UV light, but N95 can't because no amount of UV will make it statically charged again. Once discharged, an N95 is pretty much toast, and cannot be re-used.
But, caveats be given, that is a single study and might not be representative of "out there in the wild." It comes down to how much the charcoal filter and other layers can hold onto versus how much the statically charged (and shorter lived) N95 fibers last before being discharged. They have completely different end-of-life profiles.
Also there are 2 parts to "effective" - ingress air and egress breath. N95 is quite a bit more effective at filtering your breath than PM2.5, which is important when avoiding you spreading the germs. This is the part a lot of people get confused about, because it often sounds conflicting when reports don't define what is "effective." The dangers of re-use also get confounded by this detail.
[+] [-] jaredtn|5 years ago|reply
[+] [-] ksaj|5 years ago|reply
The video I was watching was about why N95 masks aren't interchangeable with PM2.5 masks, and vice versa, but they can be (and are) combined for some purposes. PM2.5 can let coronavirus through if it isn't in a medium large enough to be filtered, and n95 can let some gases through that pm2.5 would block. But noting that viral particles rarely fly around on their own (they are usually in an aerosol liquid which may or may not have a surface area that will be filtered by either one), the effectiveness isn't as drastically different as it might initially seem when only talking about particle size.
The video argued that due to how the masks work, N95 is 95% effective, and pm2.5 is 93% effective (and some argued 80-some-odd percent). PM2.5 can pretty much be decontaminated with strong UV light, but N95 can't because no amount of UV will make it statically charged again. Once discharged, an N95 is pretty much toast, and cannot be re-used.
But, caveats be given, that is a single study and might not be representative of "out there in the wild." It comes down to how much the charcoal filter and other layers can hold onto versus how much the statically charged (and shorter lived) N95 fibers last before being discharged. They have completely different end-of-life profiles.
Also there are 2 parts to "effective" - ingress air and egress breath. N95 is quite a bit more effective at filtering your breath than PM2.5, which is important when avoiding you spreading the germs. This is the part a lot of people get confused about, because it often sounds conflicting when reports don't define what is "effective." The dangers of re-use also get confounded by this detail.
[+] [-] refresher|5 years ago|reply