I had the same question no ones to sure but passive smoking is bad for people so i would think for beardies too. im also a smoker and when i smoke in the same room as roo i open up the window.
Also if ur worried try putting him in a room where you dont spend large amounts of time like ur bedroom as opposed to the lounge room. Or if ur house has many windows open a window if the room he is in starts to get too smoky.
Basically just use ur brain dont blow smoke in his face or at his tank...
i follow these rules and roo is fine, happy and healthy!!