The purpose of filtering the air is to keep a house cleaner vacuum. It prevents the house from absorbing dust by filtering it from the air before it settles.

Unpopular opinion: I've worked in the food industry, and I much rather handwash my dishes, because it's just faster. I don't feel like placing dishes in a washer is faster then handwashing. I think people are just obsessive and slow when it comes to washing their dishes. I rather make space for a nice large sink and an air drying rack, then to make space for a dish washer and plumbing. I don't even technically need to put dishes away once they're on the drying rack, they just stay on the rack until I need the drying space. I also just hate the fact that I need to wait on a dishwasher to fill up (and then work) until I'm able to reuse the dishes.