When using black fiberglass tissues in a baby's room, it's crucial to ensure that the fibers are not inhaled by the baby, as they can be harmful. Always ventilate the room well to disperse any airborne fibers. Avoid using these tissues if the baby is present, and clean up any mess immediately to prevent the baby from coming into contact with the fibers. It's also important to wash hands thoroughly after handling fiberglass tissues to prevent the transfer of fibers to the baby. If possible, consider using alternative materials that are safer for a baby's environment.