If keeping your books dust free means buying some of those glass front book cases. That is fairly easy to do. You can also just create a dust free room environment. Don't go crazy over this. The standard book case is usually pretty good unless you share the house with furred creatures, or have a particularly dusty furnace. I justified buying my first barrister book case, separate shelves, and glass fronts, by realizing that adding the price of two of my books, came to more than the book case cost. I have also thought of making plexi-glass fronts for my large wooden book case, or some sort of vinyl hanging (strips of 4 inch wide hanging from the front.) Any of these solutions will provide a dust barrier. BUT, don't make the area completely air tight, because you may encounter some of the problems of moisture.