Researchers have invented a prototype new form of high-performance air purifier that promises zero harmful waste and is 99.999% efficient in removing common bacteria and viruses::New purifier and filtering foam invented by University of Bath engineers is ready for commercialisation, seeking partners
We live in a small (12ftx28ft) house where we heat with a wood stove and have pets so our dust factor is pretty high.
I use 10x10 merv13 filters and a modified bathroom exhaust fan that sits in my rafters. It completely changed our air quality. I change the filters when they get gunked up every 10-14 days which may be a bit expensive at ~8 bucks each filter, but it is worth it for the clear nose and sinuses!