I have a KN95. I can't get it to fit on the top. Always fogs my glasses. But when I breathe in, I can clearly see by the fabric's motion that air is substantially being pulled through the material rather than around it (edit: or that might just be pressure differential).
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.
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.
> I can clearly see by the fabric's motion that air is substantially being pulled through the material rather than around it.
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.
> I have a KN95. I can't get it to fit on the top. Always fogs my glasses. But when I breathe in, I can clearly see by the fabric's motion that air is substantially being pulled through the material rather than around it.
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.
Depends on degree; I was thinking of people who aren't even covering their noses when I wrote my comment. Good point, though; I hadn't thought of "physically doesn't fit".
Lately, I've been using FFP3 masks with N95-style double headbands. All the FFP3 masks I've seen have a foam nose bridge that makes it much easier to get a good seal than any of the KN95s I've seen.
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.