I have always erred on the side of caution, figuring if one must neb, there is already a problem with the lungs. Another option is to replace the tubing frequently, for a while I had a ready source of disposable nebulizer mouthpieces with their own tubing, and replaced every couple weeks - since they were meant for only a few uses they weren't very durable and they broke easily. Once that supply ended I order several at a time on line, they're pretty inexpensive. Sue