I have set up my darkroom as much as a clean room as possible. In order to get into the darkroom you have to first pass through the archive room, this is a fire resistant room where I store my negs, prints and gear. The doors in and out are fire rated doors and have a gasket that creates a pretty air tight seal, it also makes the archive room light tight as well, so i could leave the darkroom door open if I liked, or just use the archive room as an "lightlock" room so people can enter the darkroom at any time. The room is ventilated with allergen rated air filters, and in the room a hospital grade air cleaner made by IQ Air runs constantly, it's a 180 sq foot room with a 900 sq foot rated air cleaner, so it changes the air very regularly. It has additional gas removal filters to absorb any fixer vapors that may come from the darkroom as well as any VOC's in the air.
You then pass through another set of gasketed fire doors to enter the darkroom. This 180 sq foot room also has an IQ Air cleaner with gas filters going and it's vented air is also filtered. I vacuum both rooms at least every other day. For MF negs I usually pass them through the orange Ilford cloth, it tends to do a very good job but one must be very careful about keeping it clean. For LF negs I have a Pro-Co dust stat. It's a charged anti static wand with a power supply. I use glass carriers so dust has 6 surfaces that it can cling to, and my wet negs just hang in the room to dry, hence all the precautions.
As little if any dusty air is allowed into the darkroom, the main source of any dust is me. I tend to wear cotton in the darkroom, jeans, t shirt, etc. and the clothes themselves create dust and lint. I have given thought to wearing clothes made of a synthetic but that's going too far and I think I have already been pretty thorough. With all of my precautions though, I still have to spot prints, but far less than I used to.