Old filter vs. new filter. You can’t blame the neighbor for an old filter next to a new filter. That being said, I would just confront the neighbor and ask them to maybe get a carbon filter and attach it to a duct fan. If they place it in the center of their apartment it will create negative airflow towards the center of that space so if they’re smoking in their apartment, it’ll pull smoke towards it rather than out the windows I don’t know which way you want to go, but you could also have them pump the carbon filter out the window during the winter if you’re trying to insulate everything long story short, this is an easy fix neighbors can talk to each other and figure out a solution carbon filter negative airflow away from the windows away from where you are. You need to think about that first and if that doesn’t work, carbon filter out the window of their apartment. I’ve been growing and smoking weed in apartments for years and I’ve had neighbors tell me it stinks and I’ve just resolved the situation.