qwizoking might have the best answer, I dont do many ISO runs and hes the king. but when I purge ISO and everclear though, I put them into a nice dish, set the dish AND a griddle outside. set the griddle at about 120F, set a fan on it, and let it do its thing. outside is 1 thing, but inside is just asking for trouble.
also, those evaporated ISO fumes can also fuck you up. get you feeling drunk and probably do brain damage too. that shit is NOT good to be breathing in.
look at this video... these guys werent using much ISO either. and their explosion, although a fairly small one, happened within 5 or 10 seconds.... imagine if you let those ISO fumes cook off and collect for 10 minutes, then the explosion happen.. ouch.
http://www.youtube.com/watch?v=cvYIFNX_n7U