There are methods you can try out.
1.Growing some plants underneath of racks. Water based loved plants.
2.I have seen laying some crushed granite on the floor area. how about keeping moisturizing trays.
I like the plant idea. Peace lilies (Spathiphyllum) would be great for this. They won't mind the low light under the bench at all. They use a good bit of water, therefore they should keep the humidity up.