Neighbors pot smoke coming in my kids window.

So I have a neighbor and she likes to some pot. I don't smoke and I don't care that she does. However, she places a fan in her window to blow it outside of her house and it blows right at my children windows. She is a renter and a piece of trash. We spoke to her landlord and it stopped for about 4 months and now it is back. Myself and the neighbors have called the police but they come and say that can't do anything because she is in the house. Why must I keep my children indoors and keep my windows closed? Does anyone have any ideas? We think she has a teenage son in the house but he never comes out and we think he smokes as well. Please help. My sanity depends on it.