I really can't exercise very vigorously in below freezing weather--my lungs start to hurt, and I can't get enough oxygen flow. I tried wrapping a scarf around my face, as some websites have suggested, as a solution. This helps a bit, but only a little bit, and worse--my glasses start to fog up! This product, Polarwrap Warm Air Mask, claims to provide 80 degree air even when it is 20 degrees outside--and the one review is enthusiastic about it. Does anyone have experience with this product or others that perform a similar function?
I would think that those who live in places with severe winter storms might find this (or something like it) a useful addition to one's automotive emergency kit. A lot of the calories you burn in cold weather is spent warming up and humidifying incoming air before it gets to your lungs. While burning calories is usually a good thing, if you get stranded in your car for a couple of days, or lost in the wilderness, conserving calories may be the difference between life and death.
UPDATE: I'm not seeing any other competition in even close to the same price range, and other reviews were positive, so I ordered it up from Sierra Trading Post. (The local Sierra Trading Post doesn't have it--this is a clearance item.) I'll report back how it works out in a few days. At $24.95, if it even just turns 20 degree air into 50 degree air, that would be acceptable. The only question is whether I will sound like Darth Vader when using it.