If you are that worried you can go to extremes with the solution, Go get yourself some glade plug-in refills(small gel pack) peel back the plastic seal on it, under that there is another layer that is minutely permeable and allows the scent to escape in micro amounts. Poke some tiny holes in that layer then you will quickly learn why they put it there. Put them OUTSIDE about the place where smoke may escape cause it is soo pungent that it will coat your nose and throat. Fuck up and get that shit on ur skin n c what I mean. Combine that with a git-up like Cocoa said and unless ur neighbors are blood hounds then you should be good 2 go. Back in the day I made something similar to that but I used an acrylic tube with a container of activated carbon in it. Basically a big backwards flow bong with carbon in it instead of water. BTW..Since the 70's dope n incense go hand and hand even in the eyes of ignorent conservatives so that would be the last thing I would use.