Natural Factors Lung, Bronchial & Sinus Health - A combination of herbal expectorants that work synergistically with NAC (N-Acetylcysteine) and Bromelain to break down and regulate the secretion of mucous, and herbal demulcents such as Marshmallow Extract that soothe irritated mucous membranes. Natural Factors Lung, Bronchial & Sinus Health helps reduce irritation and coughing, improves oxygen saturation to the lungs, clears airways and reduces the viscosity of respiratory tract secretions, as well as helping to relieve chest congestion and dry, irritating coughs.