Have you checked out the MJ thread here?
Originally Posted by Smithie
I think a vaporizer or shutting himself in the bathroom with an air filter are both acceptable compromises. I wouldn't insist that a person spending all day alone with a child never ingest a little MJ or have a glass of wine (obviously, getting stoned off your ass or blind drunk are both very different than ingesting a moderate amount), but if he can't go outside then he can't just smoke in the same room as the baby.
My mother smoked dope, but was very conscientious about the actual smoke. I seem to have grown up unscathed. I do wish she had kept it a secret, though, because it was awkward for me to know that my parent was doing something illegal, esp. going through that fascist scare-tactic DARE program in school. Tell your dp from me that it's worth some inconvenience to spare your son that problem. Once he's old enough (teenager), he won't care.