If your studio is a home studio, I don't know if this applies. I'm looking at commercial spaces or dedicated commercial spaces in a home (e.g. add-on, basement, or other 100% studio space that is used by paid clients).
I had some clients give me grief because I refuse to let them smoke in my building. I wouldn't budge. For the health of my lungs and my gear, no smoking inside the building. What do you permit?