Yeah, I had a similar trial & error phase managing indoor AQ. I figured out that blocking the front door fully across the door frame with a blanket plus using a door snake (draft stopper) helped drastically decrease amount of air getting pulled in. Crude but effective. Less work for my air filters.
Thanks for this. Glad I’m not alone in the trial and error phase, but admittedly, mine was protracted. Thanks for these other solutions. I take it you’re also in an apartment-style building?
Yes, a very drafty apartment! So no built in hvac, I have two portable air filter units that I use (and love). I have a little indoor AQI monitor that I used to see what a difference they make & how quickly, and was pleasantly surprised!