View Single Post
Old 03-24-2020, 02:03 PM
Stranger On A Train is offline
Join Date: May 2003
Location: Manor Farm
Posts: 19,882
Respirator masks are used for more than just medical applications. Guide to a few different types of respirator masks. Some of these masks may be N95-grade masks, which are often used in 10000K or better clean-room environments where even aerosols exhaled by workers can pose a serious contamination problem.

It is important to understand that these masks don’t work simply by physically blocking the passage of virional and most microbal pathogens by aperture size alone. The filtering material is a type of meltblown polypropylene which is used to make non-woven textile layers that have a high volumetric throughput but with very small aperature size. However, it is actually electrostatic attraction which grabs virion, sticking it to the material and letting the liquid of the aerosol droplet evaporate, which then causes the virus to desiccate and become inactive as the protein capsid literally falls apart. As the material becomes saturated with moisture, it becomes less effective. This is also why alcohol or other solvents cannot be used to sterilize for reuse. There is a paper from a study in China which indicated that exposure to a 70 C temperature for 30 minutes would cause the virus to break down. However, there are many other pathogens found in hospitals, like the dreaded MRSA, which can survive that environment so some additional work needs to be done to quantify the risk (though obviously if the choice is between working with a moderately contaminated mask and working without any protection, I’d pick the mask).

Homemade masks using natural woven fibers like cotton, linen, or silk may be worse than useless as aerosol particles might initial stick to them and then pass through with reduced size, settling deeper within the lungs and leading to a more virulent and difficult to fight infection.. As a side project I’ve looked at a number of concepts for 3D printed mask frames and sealing materials like 3 mil contractor bags but the Achilles heel is an useful filter material which just doesn’t exist in natural or commonly available textile materials.

Originally Posted by What Exit? View Post
3M has already doubled production and plans to increase it even more and some other US Manufacturers are regearing to make N95 masks so the supply chain should improve.
I wouldn’t put a lot of hope in that, at least in the near term. NPR: “ COVID-19 Has Caused A Shortage Of Face Masks. But They're Surprisingly Hard To Make”


Last edited by Stranger On A Train; 03-24-2020 at 02:06 PM.