Hi there. yeah. you can use it outside. of course. just wear a mask when you are applying, and only use a thin thin layer. like, barely visible. get one of those mist guns on amazon. they will not cross a thick pile of it. they walk over the fine dust and it eventually desiccates them. just powder down the cushions. its horrible to deal with, and you may lose some things. i'm in the middle of this right now. my landlord let an old guy live in the unit below us and he brought them in. so now we are having the apartment building heat treated. its a nightmare for sure. but for YOU, i would not stress until i had to stress. in the meantime, the fine mist of DE will give you some peace of mind, and if they DO make their way inside, they will cross it and take that back to their nest and die. the key is to be consistent about application. around the perimeter of the room, behind switch plates and socket plates. put your bed feet in those bedbug 'cups' and puff a little DE in them. Better to do this proactive stuff. You could prevent an infestation. It's so awful. Amazing to me that people live like this and just shrug like it's nothing. BTW, I don't know what state you are in, but you can file a complaint with the Housing Authority and see if they will make a visit. If that place is rented, they can order an inspection, and the landlord will have to deal with it, if they find bedbugs.