Absolutely, even when dipping outdoors. That stuff is NASTY and will get you high as a kite in a few minutes. The first time I used it (indoors without a respirator), I couldn't see the color red for about an hour and was pretty dizzy. With the proper filters you can't smell a thing.
It literally takes 5 seconds to slap on the mask and if you get a well fitting one you will forget you are wearing it. I walked upstairs to get a drink of water once while painting and put the glass up to the mask.