Aspen chips are relatively dust free and odor free. Pine chips may be moldy and dusty. Bell's book features photos showing nest boxes apparently filled with pine shavings, with no mention of the damage pine dust can do to ferret respiratory systems. The book also contains a picture of a ferret apparently housed in an aquarium-like structure. It is unsanitary and unhealthy to keep any animal except a fish in an aquarium.
Corncob bedding is dust-free and safe.