Tracheitis is the inflammation of the bronchial mucosa caused by viral or bacterial infections, physical or chemical irritation, or allergic reactions, and usually occurs during cold seasons or sudden changes in temperature; Asthma, or bronchial asthma, is a chronic airway inflammation participated by many kinds of cells, especially mast cells, eosinophils, and T lymphocytes; Emphysema refers to the pathological state where there is a reduction in elasticity, over-expansion, over-inflation, and increase in lung volume distal to the terminal bronchioles (respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli), or concurrently with destruction of the airway walls.