I regularly go outside with my shirt off at -10C, as long as there's no wind and the sun's beaming, I'm nice and warm. Got a bit of a suntan last week. Wife thinks I'm crazy :)

> The only exposed skin is the center of my face.

Me too. And I have a beard. Do I have to take that into account? Do bald men get more D-vitamin out of the sun? Studies never talk about hairiness.