Face Masks: Much More Than You Wanted to Know | Hacker News Reader

Face Masks: Much More Than You Wanted to Know

slatestarcodex.com

57 pointsmonort13 comments

Side notes: I was trying to figure out how I could "help" by developing an N95 respirator with some online communities. I was prepared to be humbled by what I didn't know, but holy smokes, now I realize I can't even begin to know what I don't know.

* 3d printed PLA? Deforms at autoclaving temperatures. chemical sterilization not recommended b/c there's not many good ways to "know" it's worked correctly.

* Sealing? Good luck. There are some people working on using TPU to help seal, but again, sterilization is a problem.

* Porosity? 3d printed materials can barely pass 2psi. This also creates a LOT of places for bacteria to hide.

* Filter media? DO NOT cut up a HEPA filter! They're made with micron-scale fiberglass. This keeps getting suggested, but people don't realize that HEPA filters are not made of paper.

I'm confident an open source design and process can eventually be made, but it's much harder problem than it looks. There's a lot of people are adding a lot of noise (I'm in "read-only" mode for now to cut down on the noise level) so if you're thinking of contributing, the best thing you can do is just read atm.

Producing Face Shields has some interesting and unexpected requirements (head back leakage among other things), but is a much simpler problem to solve and there are some good designs (Google Prusa 3d Face Shield)

As usual, a great write up. I think one nuance that is important is:

> Does letting a single influenza virus through mean you will get infected? If so, any reduction short of 100% is useless. I have a vague sense that this isn’t true; your immune system can fight off most viruses, and the fewer you get, the better the chance it will win. Also, even respirators don’t claim to reduce particle load by more than 99% or so, and those work, so it can’t be that literally a single virus will get you

I was speaking with an ER doctor yesterday who said that aside from comorbities and age, the single biggest predictor of how severe a case may be is the viral load exposure. The reasons that N95 respirators are so important in a hospital setting is that when a dr or nurse are continuously exposed to the virus, those deltas in performance might mean they pstill get sick, but it’s mild and back to work in two weeks vs ending up in the hospital for a month.

This is exactly the reason the anti-mask people in the US or so frustrating. Yes, you might still get sick but the initial viral load is likely to be greatly reduced and the speed and intensity at which you get sick is likely to be milder.

I'm trying to decide if I should wear the mask or not, but whatever I read the only question is if a mask can protect me from getting the virus. But the question that interests me is if the mask protects people around me if I have the virus (and I don't have the symptoms yet). If it does, then everybody should wear a mask.

> But the question that interests me is if the mask protects people around me if I have the virus (and I don't have the symptoms yet).

Possibly, for the same reason you should cough or sneeze into your elbow. It reduces the number of droplets you spread into and around the environment around you, and before they aerosolize.

Once testing is widely available, I hope to see wearing masks in public as a precondition for ending lock-downs/quarantines and returning to normal life. This might be something most state governments of all stripes could sign onto.

Why? And for how long?

As long as the curve has been "flattened" and the health care system is under capacity, what are you hoping to achieve?

"As long as the health care system is under capacity" is about a week or so at best, in much of the U.S., and not much longer (or already past) in many other places. And it's going to stay that way for awhile - outside China and Korea, the best news we have so far is the rate of new cases in some places has stopped increasing exponentially.

Until new community-acquired infections disappear or are severely reduced. We want the epidemic to fizzle out by reducing R0 before the pressure to reopen the economy becomes so great that it begins to spread nationally again. The disease has already had a multitude of mutations. We really don't want to keep it circulating and coming back like the flu, especially if new strains overcome immunity.

Not being that guy in the ICU? I mean, seriously?

Old-school cotton masks help a lot too. We don't know exactly how much, but they do. They reduce viral loads by at least 30% and more likely by something like 70%.

Cover your mouths.

Citation please?

In response to a long article full of links to scientific papers and nuanced analysis, saying a blanket statement like this isn't helpful at all unless it's backed up.

https://smartairfilters.com/en/blog/best-materials-make-diy-...

not direct citation, but relevant

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