The smoke's pretty bad for the plants.
Any kind of smoke...whether it be marijuana, tobacco, or a candle.
Don't get me wrong, I smoke a cigarette every once in a while in my grow room...
Am now.
If u have a very good air flow , just dont smoke next to the intake and the air shouldint make contact with the plants , i can literaly blow smoke at them and the air blows it away befor they get contact