Moving to 4X5 compounds dust problems since each sheet of film is subject to more possibility of dust contamination. There are things that can be done to minimize the problem. I assume that you are speaking of dust on the film prior to or during exposure.

The measures include among others:

1. Check, and clean if necessary, your holders before loading film.

2. Attempt to make your loading area as dust free as possible. It seems that low RH makes dust more of a problem.

3. Store your holders in zip lock bags.

Even with pristine procedures dust will be more of a problem with sheet film. It is usually preferable to retouch the negative then to print a dark spot on a print and then bleach it prior to retouching. Retouch Methods (makers of Spotone) make a kit for retouching of negatives. There are other suppliers of these materials as well. I have heard of some photographers that use a fine point red Sharpee pen as their negative retouching material.

As an aside, in some instances with certain developers a stop bath will create pinholes in the negative emulsion. This will have the appearance of dust on the negative. I increase my stop bath dilution by double when using pyro developers.

If you are speaking of dust on the film after developing and when printing then that is another matter and should be fairly straightforward in corrective measures.