I’m amazed at the number of people I see wearing N95s or KN95s with a clear gap at the top. Why bother?
Uncharitably: People think it's a magical talisman; wear this mask and be protected. There's no grasp of the mechanism, so "wearing" the mask can be arbitrary.
Charitably: If people grasp how masks work, it's easy to forget, or not think of it, or not check that it's (still) on correctly.
(Bluntly, I think the former option more likely, but I try to think of charitable options)
In any case, we are talking about mitigation of risk, minimization of exposure. If my mask is only filtering 80% of the air at 95%, that still a lot fewer viral particles I'm exposing myself to than otherwise. I don't think that its a matter of whether 1 viral particle gets through, but how many that determines likelihood of an infection or serious illness.
And its effectiveness is backed up by studies of unfitted 95s.
IIRC, KN95s were designed for flatter, asian noses. I think I read somewhere that one of the motivating factors for the design was that it's harder for asians to get a good fit with some types of N95, because they were designed for caucasian noses.
I have a big nose, so KN95s never work for me, unless I retrofit a really long and beefy metal strip for the nose.
I suspect that the fabric’s motion doesn’t mean what you think. You’re just seeing motion from the pressure change. A non permeable plastic film will also move as the pressure changes. This doesn’t mean any air is going through it.
> If my mask is only filtering 80% of the air
If your mask is leaking around the edges, it is extremely unlikely that your mask is filtering anything close to 80% of the air.
My most important point though is that if your goal is to reduce your risk, then wearing an 95 type mask, even an unfitted one, achieves that goal. Its not all or nothing.
Consider how the fit can be pretty and still result in fogging up your glasses. In general but especially on cold days, you avoid fogging your glasses because the air you exhale is moving usually quickly enough that it is past your glasses by the time any of it starts diffusing and moving upward.
An N95 slows it down enough that some of the warm, moist air will make its way up to your glasses. It'll be especially noticeable if you're outdoors int he winter. Plus, the shape of some N95s and KN95s looks like it would cause some of your exhaled air to diffuse out through the mask in a more upward direction that it would if you were maskless.
So two of what I considered indicators of fit are probably wrong. I'll call that a good day. (:
I wouldn't read too much into fogging.
(That said, I do wish there were better options for people with giant noses like mine.)
More often, it's probably just a lack of training / reading the instructions on how to press-fit the nose bridge.
Then there's people like me with weird faces that fail fit tests no matter how careful with basically everything except the duck masks.
A lot of the people I see like this seem to have bent the nose piece so tight that it’s actually lifting the top edge off their faces (because the nose cannot fit in the tiny space created). I’m not sure if they think the absurdly tight nose piece is sealing better or if they are intentionally doing this to make it more “breathable”.
The too-tight nose piece is probably because that’s how the masks are packaged.
Ah, I see what you mean. I’m pretty sure that I’m not seeing an illusion most of the time, because I’m not looking at the cloth. I’m looking at the very visible skin beneath the gap. But it makes sense that the outer layer of cloth could be misleading.
> The too-tight nose piece is probably because that’s how the masks are packaged.
You’re probably right. I normally see this on the center-folded masks. This would mean that people are just throwing on the mask without fitting rather than doing an astonishing bad job at attempting to fit, or intentionally fitting to create a space. That’s certainly more understandable.
Suppose you buy a mask and it doesn't fit, what do you do, but random ones untill uou find one that works? They have no categorisation, even if you find one, often you cant but it again as shops change their stock randomly.
Also sometimes you buy a FP2 mask and if turns out it's not https://www.pcgamer.com/razer-rows-back-after-zephyr-face-ma...
I would imagine that if there’s a significant gap, most air would actually bypass the mask entirely. And “significant” here is still fairly small. I’m thinking you only need a cross section as large as your nostrils for most air to flow around the mask. And as you make the mask less breathable/more resistive, more air will bypass the mask.
But I don’t know how accurate my assumptions are.
I've worn an FFP3 throughout, don't see the point in cloth or surgical masks. (With my nose firmly inside...)