Great discussion going here, solid facts and hard to back up opinions. I don't have much to add other than the fact I have been using cat heaters since the seventies and still alive. First cat was a green mushroom Coleman which was used for ski bumming, and if a cat was going to kill me that would have been the one. Used it in a van covered inside mostly by sprayed on expanding foam, very air tight. Always left two windows cracked a bit which at below zero temps was a hard but needed decision. Only drawback to the mushroom was resort security it drew when I lit it off in parking lots because of the two foot flame while getting started.
