Alright, I’ve had to read about face masks and N95s until my brain cries for work, so I’m going to do a thread on them. So first of all, what’s the difference between an N95 and a face mask? A huge problem right now is that there are like 5 terms for each.

Face masks are simple barriers that go over your mouth and nose and fits fairly loosely. They usually have ear loops. If you make a cloth face mask, this is what you have.

An N95 is cup-like, and seals to the face. It also covers the mouth and nose, but that seal is a big difference. The straps usually go around your head (more on that later).

Face masks are to prevent you from coughing or sneezing on others. It may provide some slight filtering, but you should basically assume these are doing absolutely nothing to actually protect you.

Like, literally nothing. Aerosols are good at following the path of least resistance, and since there’s no seal stuff just goes in through the edges.

Is wearing a mask good? Jury is definitely still out, there haven’t been any conclusive studies, but as long as it doesn’t give you false sense of security it won’t make things worse. So to be clear, if you wear a face mask, you should still social distance as if you weren’t

N95s are very different. Since they seal to your face, the air HAS to go through the filter. The filter technology is really neat, it’s basically a mish-mash of polypropylene bits that have electric charge, and that charge is mainly what grabs stuff and filters it.

So how do you get a seal, or know you have one? It’s an absolute pain in the ass. There’s a tedious ~15 minute fit test that has to be repeated annually. Facial hair, weight change, etc. will change the fit. I’ve found that N95s deform as you wear them so a used one may not fit

The key thing with N95s is that not only do they protect others from you, they protect you from others. So, should everyone go get N95s? No.

Remember how I said they’re a pain to fit? If you haven’t been fit tested you don’t know if yours fits or not. It’s not trivial to check. And if it doesn’t fit, then it’s doing maybe not quite nothing, but very little. And that assumes you’re wearing it right.

Ok so imagine an N95. Imagine how you would put it on. I feel confident saying that no matter what you thought, probably >50% of people just imagined the wrong way. Wearing them properly is a pain in the ass. You have to adjust the nose just so, and the straps just right

When I went to the grocery store this weekend, I’d say about 75% of all the white people there were wearing the N95s they had wrong. POC, it seems like y’all have this down.

So, the N95 shortages. Usually, you don’t wear an N95 in a health care setting unless your patient has tuberculosis or something like that. So usually, very little usage, maybe once a year for a few staff. Now suddenly, all staff have to wear them all the time. See the issue?

Demand skyrocketed 10x, 100x, I don’t know exactly, but a huge amount. And there are very few N95 manufacturers because it’s really hard to make ones that pass government standards. The problem isn’t the public buying them (tho that doesn’t help), the system was just unprepared

So why can’t they just reuse them, or clean them? Well, N95s are generally made to be used once for a short period and then trashed. Like I said, they deform over time, so over time they get less effective. Also, as that filter does its job, it slowly gets clogged.

As for the filter getting clogged, well, it isn’t easy to breath with an N95 to begin with. You’re used to there being zero resistance to your inhalation, so having a barrier makes it harder. I’ve seen people have asthma attacks during the fit testing from the difficulty.

So you can only use one respirator for so long. Plus, it can pick up germs and virus etc. along the way (referred to as fomites). So, why can’t we just wash them?

Again, these are made to be disposable. The materials are meant to do some very specific things for a very short time. Imagine if you put plastic forks in the dish washer. It’d wreck them, right? Well, most sterilization methods are way harsher than that.

You can ruin an N95 a ton of ways. You can oxidize the metal nose clips (an issue with bleach), melt them (issue with microwave), destroy the charge of the filter (issue with alcohol), ruin the straps (issue with a ton of things), any number of things.

Plus, there had been virtually no research into this. Why would there be? Until about a month and a half ago, we had plenty!

So how can you sterilize your N95? Bluntly: you can’t. Every method out there right now requires specialized equipment (hydrogen peroxide vapor is currently in the lead) or high heat (major fire risk). Your best case scenario is your N95 no longer fits. Worst case is injury.

How can hospitals sterilize, that’s a whole ‘nother ball game. That’s what I’ve read about for ~50 hours over the last ~10 days. Long story short vaporized H2O2 is in the lead for 3M 1860 model N95s, by far the most common for medical settings. But might not work for other models

So let’s say you have a face mask. Great! Wear it outside. If it’s cloth, wash it FREQUENTLY. Soap and water should do but I haven’t looked deeply into that.

If you have N95s (maybe you’re a Californian like me with left overs from fire season) let’s talk. First, don’t go buy any. One you’ll get extorted, two I’m not exaggerating when I say every single mask matters. Exception: if you have underlying health conditions, might need some

How do you wear them? Follow the instructions on the box. For most, you’ll have two elastic bands. One goes high up on your head, across the crown, the other goes under your ears. They should not be crossed, you can’t use only one strap, etc.

Push the nose piece in with both hands, one on each side. Don’t just pinch! The way you pinch usually leads to unequal force which leads to a bad fit.

Perform a user seal test. Cover the filter with your hands and give a short sharp exhalation. If you feel air come out the nose area or chin area (or anywhere else) it isn’t sealed. If you wear glasses, your glasses should NOT fog.

Follow the instructions on the box for how to take it off properly. Yes, this makes a difference. Wash your hands immediately after removing.

If you have N95s, set aside 5. When you’re done with it for the day, put it in a clean paper bag. Leave it there for five days. After that time, all the COVID should be dead so you can reuse it! Note that this does not mean it is sterile! COVID just doesn’t live long on them.

Keep track of how many times you’ve worn each mask, best practices is putting rallies on the bands. Discard when you can’t get a seal or if it gets too hard to breath. The end! Until I think of other stuff.

Oh, I referenced in the first tweet all the different names. So what are they? Sorry, I genuinely can’t keep track. The terms “medical face mask” and “surgical mask” particularly are used ambiguously.

Even N95 isn’t a sufficient designation because of differences between medical N95s and standard N95s (e.g., ones used for construction)