The bronchial tubes are chronically inflamed for various reasons, resulting in epithelial cell degeneration, necrosis and shedding, with the pseudo-replicated ciliated columnar epithelium being replaced by squamous cell proliferation. The etiology of ciliated epithelial cell damage and shedding: The etiology of this disease is not fully understood and may be the result of a combination of factors. Harmful gases and harmful particles such as cigarettes, smoke, dust, and irritating gases. These physicochemical factors can damage airway epithelial cells, leading to a decrease in airway purification function. They also stimulate submucosal receptors, parasympathetic hyperfunction, which causes contraction of airway smooth muscle, hypersecretion of glands, and increased airway resistance. Infectious factors Infections such as viruses, mycoplasma, and bacteria are one of the most important causes of the development of chronic bronchitis. Infectious factors cause damage to the airway mucosa and chronic inflammation. Viral infections such as influenza virus, rhinovirus, adenovirus and respiratory syncytial virus are common. Bacteria are often secondary to viral infections, and common pathogens are Streptococcus pneumoniae, Haemophilus influenzae, Catamorax and Staphylococcus. Other Immunity, age and climate are all associated with chronic bronchitis. The main cause of chronic bronchitis is the formation of chronic nonspecific inflammation of the bronchi by recurrent viral and bacterial infections. When the temperature drops, small blood vessels in the respiratory tract spasm ischemia, defense function decreases, etc. favorable to cause disease; smoke dust, pollution atmosphere and other chronic stimulation can also develop; smoking makes the bronchial spasm, mucous membrane variation, cilia movement is reduced, mucus secretion increases favorable to infection; allergy factors also have some relationship. In ordinary life, we should pay attention to the regular diet, avoid spicy food to stimulate the respiratory airway, causing airway spasm, the onset or aggravation of the disease. Luo Han Guo, fat sea and other lung laxative cough tea, etc., according to their own constitution to match.