From a construction guys standpoint, these masks are only a novelty. The cost of the filters is the big deterrent. Plus I can tell these were never meant for such abuse like dirt and sweating. That's what the disposable ones are for. I wore my mask the one day I took pictures, and put it away. I didn't want to get it dirty. Hahaha. Plus, It didn't help with the main reason I bought it for. I guess the shape of my face still leaves gaps for my breath to get thru, and my glasses still fog. Oh well.