>>8508629>>8508634air purifiers do very little to keep dust down. I own three and even keeping one near a book shelf has no noticeable effect, despite me needing to clean the filter on a regular monthly basis.
I have two of these and another one that has a replacable carbon filter. Great for allergies and for dusting, but not minimizing it.
One way to keep dust down is just by vacuuming frequently. like twice a week. store anything fabric into drawers, cubbies, etc.
If you're in a dry area, a humidifier might work great for you.
Also, dandruff shampoo. A lot of dust is just your skin/hair flaking off.