Hey Turtle,

In my studies I've come across that technique, and the level is 5000ppm. Past that point is the level where humans can become a bit dizzy, so dont be in the room. I've never used it b/c my sanitary and vent design precautions have prevented even the smallest of infestations. Nobody ever believes me, but the only critter Ive ever seen is a millipede from the soil ive purchased. Never wear outdoor shoes in the room, I slip on a pair of sandals that are inside the room by the door.