I built a coop inside an old barn, well after looking up in the hay mound of the barn, there is some straw bales that are dark brown and kinda have a damp smell. The chickens will live down below the straw. Will it hurt the chickens to live in an area around molded straw or wild bird droppings? They wont be stepping in it but they will be breathing some of the fumes even if keep all the vents open.