Both and neither. Smoke in a "typical" structure fire is a nasty cocktail of chemicals. Almost everything in a modern home is manufactured from some sort of petrolium product. Have pvc pipe for plumbing? when it burns it produces phosgene gas. Phosgene was used in WW1. This is only one very small part of the make up of smoke. It does seem to make some sense that a n-95 mask will offer some limited protection from smoke particultes. My experience has only been with SCBA in the fire service. I have no experience with smoke hoods so I can't really offer any advice except that when the fire alarm goes off in your building LEAVE!