I opened a package of N95 masks to see how well one folded to see if I could put it in my mobile survival kit. Reading the enclosed literature, I learned to my dismay that it's good only for non-harmful particulates such as sanding dust. So, instead of my risking not being protected from something by taking "only a bandanna" for my air travel exposure kit, I actually wasted money by buying N95 masks instead of packing a simple cotton bandanna in my regular exposure kit.
I'm annoyed the Powers That Be advise us to buy bulky, expensive, specialty items we'll use infrequently, if not rarely, instead of inexpensive, easy to EDC items many people already use on a daily or other frequent basis.
Since N95 masks only filter out non-harmful particulates such as dust, more reasonable alternatives are cotton bandannas, those keffiyehs or shemaghs the military are finding so helpful in Iraq and Afghanistan, or cotton pareos. Shoot, when I encountered dust storms without protection, a dampened paper towel from the ladies' room held over my nose and mouth was enough although inconvenient because it wouldn't stay in place by itself.