I'm not aware that marijuana smoke lingers for more than a few hours. The difference between weed smoke and tobacco is vast--but I suppose if you are super sensitive and anxious about your baby this might be worrisome. Try opening your windows to let in some fresh air. Maybe buy a unit that neutralizes odors. Ozium is a spray that removes odors.

I like the way weed smells but cigarettes are super disgusting and cigars? Power stench.

Good luck!