The common causes of bronchial dilatation are as follows: 1, infection: bacterial and viral infection destroys bronchial tissues, resulting in irregular dilatation of the bronchial tubes; 2, physical and chemical: inhalation of gastric acid, toxic gases, or the presence of tumors in the trachea, enlarged lymph nodes outside the trachea, and structural changes in the lungs cause obstruction; 3, immune: rheumatoid arthritis, desiccation syndrome, Crohn’s disease, and other systemic disorders cause dilatation; 4, genetic factors; and 5, the six obscenities, namely, wind, cold, heat, dampness, dryness, and fire trigger disease.