N95 masks Protection Physics

prior to March 2020, there’s a good chance you didn’t know what a 95 mask was, or at least didn’t think about them unless you were doing a home repair project with lots of dust or live in a part of the world with crazy pollution or wildfire smoke.

How N95 Mask Works?

And upon learning about them, you might think like I did that and 95 mask is basically a really, really fine strainer. A mesh of fibers with gaps too small for dust and other airborne particles to get through a strainer filter out particles larger than its openings, but not particles smaller than its openings. So you’d expect that with a mask after a particular point small sufficient particles will slip through. However, this isn’t how n 95 Masks work.

The particles they filter are generally much smaller sized than the gaps in between the fibers in the mask..

What’s more than a 95 mask is actually really good at filtering both the largest and smallest small particles, it’s medium sized small particles that are hardest for it to block. This isn’t at all like a strainer, because n 90 fives are much cleverer than strainers. The overarching goal of an N 95 mask is instead to get an airborne particle to touch a fiber in the masque.

Regardless of how big an airborne particle is, once it touches a fiber, it stays stuck to it and doesn’t become airborne.

Again, this isn’t anything special about the fibers, but about the size of the particles. At a microscopic scale. Everything is sticky because the weekly attractive force between molecules is more than strong enough to hold very, very small things in place.

So you shouldn’t think of N 95 masks like a fine windows screen that keeps insects of a particular size out, you should think about them more like a sticky spiderweb they can catch an insect of any size as long as it touches a strand

therefore and 95 masks utilize a lot of various creative physics and mechanical tricks to get particles to touch their fibers.

First, many spider webs are better than one. Unlike strainers were stacking many identical ones doesn’t improve the filtering at all.
more layers of sticky fibers mean more chances for particles to get stuck.
And how likely particles are to hit or miss a fiber depends in large part on their size. airborne particles larger than a 1,000th of a millimeter basically travel in straight lines because of their inertia. And because there are so many layers of fibers, their straight-line paths are essentially guaranteed to hit a fiber and stick. airborne particles that are really really small are so light that collisions with air molecules literally bounce them around, so they move in a random zigzag pattern and known as Brownian motion.
This zigzagging also makes it super likely that a particle will bump into a fiber and get stuck.