Cardboard boxes are handy and convenient, and tend to be used frequently for storing stuff - we all have lots of stuff. But when the head to the basement, trouble can ensue - as moisture + cardboard = opportunities and food sources for mold to grow. Store your items in plastic totes with lids, and ditch the cardboard. If your cardboard boxes get wet, empty the box, dry out the contents 100%, then replace with a plastic container and toss the water damaged box, even if it appears to have dried.