Mask questions

[cos]

Considering only their effectiveness at a) slowing the spread of covid-19 and b) protecting you from covid-19, in public and grocery stores and similar (that is, I'm not asking about bacteria, fungus, healthcare settings, etc.)...

• If an N95 mask doesn't quite fit as tightly as it should, is it still significantly better than all surgical & cloth masks? Or does the imperfect make it likely not much better than a surgical mask?

• I've seen it claimed that multi-layer cloth masks are better than actual approved surgical masks. I'm very skeptical. But is there some validity to this claim?

• Is there any difference between US N95 masks and Chinese KN95 masks for this purpose? Other than the fact that I've never figured out how to actually fit a KN95 to my face :) But aside from the fit, are they effectively exactly the same thing (for this purpose)?

If you have helpful references or sources for answers to any of these questions, I'd like to read!

Comments

[cos]

> From what I've garnered from various sources (sorry, no specific citations), most if not all "(K)N95" masks do not filter outflow -- so they don't help people nearby if you're infectious, but they do help you if people nearby are infectious.

I know for absolutely sure that is not true, because I use N95 masks frequently these days. Yes, definitely, there are N95 masks that have outflow valves. That's a feature you can choose whether you want or not, when selecting a mask. For obvious reasons, N95 masks without valves are the ones being mostly sold currently.

[macthud]

Good to hear about the N95 valves' decreased ubiquity.

Among same material masks, better fit is better.

I don't know what effectiveness factor should be applied to compare worse fitting N95 against better fitting cloth or surgical...