Oh yes, dust. It used to be a nightmare. For a long time my models were exposed to dust on open shelves. Every Saturday cleaning was the name of the game. Then I had a cabinet with hinged doors but not tight enough. It helped slightly but dust still got inside. To make it worse, it was not a blowable dust, especially the matt and satin surfaces of models seemed to be sticky, I had now idea how to remove it. Brush, blowing, nothing helped.
And for a couple of years now I have my models in two cabinets, again with hinged doors fitted with glass windows. They were custom made by a master carpenter. Let it suffice to tell that he cuts the wood pieces with 0.5mm accuracy! It is a solid wood-like plate, not deforming (unlike natural wood, which usually reacts to even slight variations of humidity, temperature and is just creeping in time). He made it almost perfectly tight and the inevitable gap between the doors is additionally sealed with a plastic strip. I have not removed dust from my models for 5 or 6 years. After this time I see some thinny layer on the glass shelves, but it is not visible on models at all. I reckon, it is due to occasional opening of the cabinet, for instance to put the new roll-outs inside or to allow some visitors to see the models better.