I have 130+ people in one building, so odors and noise effects everyone at my property.
At my property, (in Oregon) smoking is permitted and we have had similar issues in the past. The laws and rental agreement terms in your state may differ.
According to our attorney, offensive cigarette smoke is just like offensive noise.
Therefore, Residents can smoke inside their apartment or on their patio, but according to the rental agreement, they cannot "disturb the quiet enjoyment of other residents."
For the first offense, either call or post a note on their door as a friendly reminder. If it happens again, I make a copy of that portion of the rental agreement with the residents signature, highlight that section, and post it along with a non-compliance/disturbance notice to their door. Then I remind them that non-compliance notices have a derogatory effect on their rental history.
I've always recommended to my smokers that they use a smokeless ashtray, it does help.