I do this all the time without issue. You will be fine so long as you have adequate ventilation. I wouldn’t blast it for hours on end or fall asleep with it going, but simply taking the chill off when you get out of wet clothes or when getting out of the Fart sack in the early AM to go hunting is what this thing is designed for.

Heats the cap of a truck or small tent very fast. I love this thing. Once fall hits and the mornings get crisp I don’t leave home without it.