yeah, buddy what is your ventilation like right there? if you are gonna be doing runs inside, you need some cfm to keep the air moving, as well as an exhaust that goes down to your floor.
Butane/Propane are heavier than air, so they fall when they evaporate. They begin to gather down by your feet until they find a pilot light, or any ignition source and then… boom.
please stay safe man.