Sometimes the stuff I read here is pretty funny. To everyone in this thread that says pot smoke is harmless to plants, well, in a nutshell, your mistaken.
Pot and Cig. smoke is bad for most plants. Doesn't matter if it's tobacco or marijuana smoke, you shouldn't smoke in your grow room if possible. Yes people do it all the time, I've done it myself but it's a fact that it's bad for them even in the best ventilated grow rooms. Smoke causes plants to drop or droop leaves and causes
epinasty. Smoke often contains pollutants like sulphur dioxide & nitrogen oxides that are also harmful to plants, plenty of other crap as well in pot smoke that isn't good for their happiness and well being.
Now with that said, Carbon dioxide in smoke is beneficial to plants, since carbon Dioxide is used in photosynthesis, but the particulates present, could coat the leaves and hinder the absorption of light, reducing the photosynthesis production.
There is caveats to this, for example, some pineapple growers, (Outdoors) smoke is used near their plants as an aid in fruiting or flowering, seen a couple studies on this, and like everything, there is two camps to this pineapple smoke debate.
The carcinogens and what not in pot and cig. smoke is detrimental to most plants. It clogs the Vacuole, clogs the plants cell structure and reduces the plants ability to conduct photosynthesis as it would with no smoke present.
Houseplants and such are effective in removing smoke and harmful gases from the atmosphere. Plants are natures air scrubbers. But anyone that tells you smoking pot in your grow room cannot do any harm, really is a bit misinformed. PLENTY OF Gov/ University studies that clearly show this as a fact and not my opinion.
Hey, their your plants, if you want to hinder their happiness, that's your prerogative. Blaze up all you want, just don't tell peope it's not harmful, because it is.