Because it's not an aggressive substance, i try to be calm about it and talk to the resident. Actual conversation: "Look, I'm not judging, but what you're doing is prohibited by law. You share space with other people - families, nurses, teachers. Some people can lose their jobs smelling like pot, and the odor is saturating their homes. It's so bad that i have people asking for the non emergency police number. You're gonna get caught. I need you to stop or give your notice to move out "