When speaking of an NaCl solution, it is usually a physical saline solution with 0,9% salt / sodium chloride. The low salt content of the isotonic saline solution (0,9% NaCl) corresponds to the concentration of the body cells. This means that the upper and lower airways are moistened and at the same time protected from drying out. In addition, foreign bodies such as dust particles, viruses or bacteria are transported out of the respiratory tract. A higher salt concentration is called hypertonic and is useful for stubborn, viscous mucus. Water is withdrawn from the cells so that the mucus on the cells dissolves and can be transported away. A solution that contains at least 1,4% dissolved salts is referred to as brine. Due to the higher salt concentration, the removal of secretions is more effective, but it can also have an irritating effect due to the withdrawal of moisture. Therefore, a brine inhalation should be used as a cure and in a mask nebuliser like the SaHoMa-II the maximum brine concentration should be 3,5%. In brine chambers or brine trailers, the inhalation is distributed throughout the room and brine of 6% to 8% are also common here.