NAC is a great supplement. It's awesome stuff to support healthy lungs. NAC is a known mucolytic. That is a fancy term meaning breaking up mucus. Now, research does show that NAC NAC Precursor to Glutathione, Support Lungs Liver 600 MG 3 BOTTLES 180 Caps eBay Lung glutathione and oxidative stress: implications in cigarette smoke induced airway disease American Journal of Physiology Lung Cellular and Molecular Physiology American Physiological Society Adding glutathione to parenteral nutrition prevents alveolar loss in newborn Guinea pig ScienceDirect Oxidative Stress and Histopathological Evaluation of Rat Lung Tis Lung Cancer Targeted by Photoacoustic Imaging of Elevated Glutathione