Bronchitis, COPD and Emphysema are some of the diseases that can affect the respiratory system. COPD is a permanent lung condition, often caused by cigarette smoking. Emphysema consists of the destruction of the tiny air sacs (alveoli) in the lungs and the weakening of the support structure around them. Bronchitis is an inflammation of the airways, which causes a productive cough. Supplements that may support respiratory health include N-Acetyl Cysteine (NAC) and antioxidants.