Is it bad if my apartment doesn’t get any drafts in it? I want to block the front door gap, but my dad got mad and said this would cause mold issues.

How and why? I mean I don’t live there so why would it become humid?

It’s not really an option to keep it open cause I’m allergic to some of the stuff that comes in from the neighbours

Follow up question: is it true that turning the bathroom fan on won’t do anything, if there isn’t somewhere outside the apartment that air can be drawn from?