That's a touchy subject these days. I personally never asked the powers that be if it was ok since they are never around except for an occasional announced visit every 3-4 months. I did however ask my co-workers in my office if they would mind. They couldn't care less, and for the most part enjoy the aroma from many of my juices.
So... I decided what they didn't know wouldn't hurt them and that I wouldn't give them the option to say yes or no. There is a strict No Smoking policy throughout the company as well as company vehicles but they will supply, for free' smoking cessation products such as patches, gums, lozenges, etc.
So in the event I should ever be confronted, I could argue the tobacco side, they (technically) cannot use the "No Nicotine" angle since they provide Nicotine laced alternatives, and it's simply just an "easier to ask for forgiveness than permission" thing.