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 Optimum Health GSH+: The Best Defense Against Smoke Damage and Lung Irritation Levels of Reduced Glutathione (GSH) in Plasma and Lungs of Control and Download Table Lung glutathione and oxidative stress: implications in cigarette smoke induced airway disease American Journal of Physiology Lung Cellular and Molecular Physiology American Physiological Society What is glutathione and why must we protect patient access to it? Oxidants and Antioxidants Journal of The COPD Foundation