CaCl2, calcium chloride can be very helpful in controlling excess moisture. It is cheap, environmentally gentle, readily available at Walmart, Home Depot, and even $ stores. Look for brand names like Damp rid. CaCl2 pellets are also used to melt snow and ice. People have been using it to help keep cabinets, basements, etc dry for many years. It also seems like a good solution for rv's, vans, cars, etc. It works for me.