how big is your room bm? I run 3 hours in a 12'x20'x9.5'h and it seems to be the sweet spot only needing one burn to do the job.i set mine up to start 10 mins after lights out and I don't turn anything back on until the end of my 12 hour dark cycle.i do use a real small fan on low to blow some of the vapor to the far side of my room but that's the only thing running.the longer it sits without fans moving it off the plants the better job it will do.
as far as the sulfer getting in your body question,its already there lol.most chem ferts are made from some form of sulfer,as well as many other things around us.but that doesn't mean you should go back into your room right after a burn without a respirator or at least something cotton over your mouth.you can od on water if you drink enough lol.2-3 hours after a burn is safe,by then the vapor should have settled.if its bad in your room,do another burn in a few days like 3 or 4.but if your room is as big as mine 1 hour wont knock it out.gl bm