Smoking in garage help?

Alright so long story short i am in the garage for the day and its a seperated from the house.Im playing on medicating with some marijuana and hotboxing in here and watching some tv but im worried about starting a fire.There is a gas container on the other side of the garage (about ten feet away) and also a propan tank on the other side.There are three motorcycles in here as well.Would i need to worry about those? Ill be using a small bong and im not clumsy so i dont see any way for the gas to ignite and unless the fumes fill the room but the gas thing is empty and i dont smell gas.Would the smoke being in here be a problem? i dont care about the smell but could smoke pose a dangerous problem? Sorry for being a worry freak but better safe then dead.