... they're unhealthy.
I was just working with my tippi foam cutter, melting some rock forms in some blue foam. I was doing this outside, nice breeze, no problem, I thought, until I stood up. Asthma attack, light-headedness, headache, a decent buzz.
Moral of the story, I have killed some more of what obviously precious few brain cells I have left ... and, ... what was i saying?, Oh yeah, really make sure you have good, no make that great, ventilation when melting foam with a foam cutter.
Well, gotta go lay in my spinning bed and turn blue!