I have vacation scheduled to Arizona 7/25, rafting in the Grand Canyon for a week. There are forest fires all around, and the smoke travels and settles in the canyon in the heavier night air. I am allergic/sensitive to all kinds of smoke, so am worried about having respiratory problems breathing at night . Does anyone know of a good mask that protects against smoke? I'll probably need one that I can sleep in (comfortable and easy to breathe through). I will not have access to a store to get a new one if the mask I bring isn't working, so I am hoping your suggestions will help me make a good first pick. Thanks to any and all suggestions!