4 ms·
No its because of Brownian Diffusion. Counter intuitively masks block particles smaller than 0.3 microns (such as virus’s) more easily than particles at around
by tangent-man 6y ago
No its because of Brownian Diffusion. Counter intuitively masks block particles smaller than 0.3 microns (such as virus’s) more easily than particles at around 0.3 microns in size.
It is particles that are around 0.3 microns in size that filters have the most difficulty blocking. N95 particles block 95% of particles of 0.3 microns in size. N99 Masks block 99% of particles at 0.3 microns.
As I understand it smaller particles get ‘stuck’ in the maze of fibres and are statistically unlikely to find there way through the mask. The best analogy I can think of is a spec of dust finding its way into a centre of a huge labarynth that is vibrating randomly in all directions (and coated in honey). Some respirator masks also contain anti viral coatings and are electrostaticaly charged.
- yibg 6y agoInteresting. Is it that particles smaller than 0.3 microns have more dynamic and random motion? I mean, why is it that particles smaller than 0.3 microns are likely to be "stuck" where as at 0.3 microns they aren't?
- tangent-man 6y agoI realized the original comment was about surgical masks.. I was commenting about the filtering properties of multi-layered polypropylene masks. I'm afraid its a bit beyond my Science / Engineering / Maths skills at the moment to try and explain it any better.. but maybe this link will help? https://www.tandfonline.com/doi/abs/10.1080/00022470.1980.10464592 https://www.tandfonline.com/doi/abs/10.1080/00022470.1980.10...