As regards N95 masks and influenza, a number of folks in the Flu Thread have indicated they don't work or don't give a good seal -- whatever. I've seen a number of news photos of folks wearing their masks with their nostrils exposed. What's the point of wearing a mask if you leave your breathing holes on the outside? Maybe they don't breathe through their noses.

The isolation masks we have here (99% EFF at .1 Microns) can be shaped around the bridge of your nose and they provide a good fit.