In Germany they recommend to use it only in well ventilated areas and suggest to refrain from using it indoors. I take this as itīs not considered save to do so.
Agreed. Outside is best, unless you've got good ventilation. It wouldn't burn for long, so similar risk as a chaffing dish, maybe? Better safe than sorry, me thinks, so a backyard, front step, balcony, beside the snowed-in car are the target burn locations in my books.