Glasses fogging isn’t reliable as even N95 masks allow water vapour to pass. With the huff test, a well sealed mask will collapse and expand slightly as you inhale and exhale, respectively. If it doesn’t do that, then it isn’t sealed properly.
Regular surgical masks aren’t designed to fit with a seal like N95s are.
HoobieHoo t1_itjo3r2 wrote
Reply to comment by randxalthor in MIT engineers develop sensors for face masks that help gauge fit by derpPhysics
Glasses fogging isn’t reliable as even N95 masks allow water vapour to pass. With the huff test, a well sealed mask will collapse and expand slightly as you inhale and exhale, respectively. If it doesn’t do that, then it isn’t sealed properly.
Regular surgical masks aren’t designed to fit with a seal like N95s are.