I was not allowed to have a blackboard in my office because the boss said the chalk dust gets into the computers and causes problems (or makes you have to clean them frequently). We were a software company, so there were a bazillion computers around.
I don't know if this is true or not, and if it is true whether or not with careful use you can avoid the problem, but if you ever do ask for a blackboard, make sure you have some answer for this in case someone brings it up as an objection.
I was at a university some years ago that had blackboards in all the rooms except the computer labs, which had whiteboards instead, also citing this reason. At the time I believe whiteboards were more expensive (and less familiar), so they were put only where "needed", i.e. rooms with computers. These days I see mostly just whiteboards everywhere, though.
It is nothing compared to the quantity of chalk dust generated. I've used chalkboards for years though in computer labs and around other electronic equipment, it has no noticeable effect.
I don't know if this is true or not, and if it is true whether or not with careful use you can avoid the problem, but if you ever do ask for a blackboard, make sure you have some answer for this in case someone brings it up as an objection.