[PaulKeeble]

Actually N95 is AT LEAST 95% effective. 95% is its worst case performance on a PM2.5 sized particle, at all other particle sizes it is better than 95% usually considerably. We also have N99 masks and even P100 respirators which do an even better job. We just need to start using them. We also need to educate ourselves how to fit and fit test a mask because if its leaking its not giving you that level of protection.

[hamburglar]

Well, the actual mask's performance is 95% effective, but you can't really make a guarantee about the overall worst case effectiveness when deployed by humans. N95 masks are not 95% effective on someone who has a big fluffy beard preventing a proper seal, for example. Or with people who use their gut feeling to decide where and when to put them on (like deciding if there's nobody in the elevator, you don't need it, ignoring the fact that someone may have gotten out of the elevator 20 seconds ago and left particulates in the air).

[avereveard]

I think that's about the material itself, then at the mask face interface you get all kinds of sealing issues

[weaksauce]

you're absolutely correct and furthermore smaller particles and larger particles are easier for the masks to catch to state it differently if it wasn't clear.