Bronchitis is a lung disease in which bronchial and tracheal secretions increase and can be caused by either infectious or non-infectious factors. Patients who smoke are far more likely to develop bronchitis than non-smokers. The classification of bronchitis can be divided into two types: acute and chronic. The main causes of bronchitis are viral and bacterial infections. Triggering factors are inhalation of dust, fine particles and toxic gases, inhalation of cold air and smoking. The self-inflicted causes are usually a decrease in immunity and respiratory dysfunction. The clinical symptoms of bronchitis are: (1) cough. In acute cases, the onset is rapid and usually manifests as a dry cough, while in chronic bronchitis the cough is long and easily recurrent; (2) coughing sputum; (3) shortness of breath can be present, commonly in the acute phase. The disease has a long and slow and continuous course, with mild symptoms in the early stage, usually without obvious symptoms; the late stage tends to affect the health of the organism and the function of the lungs. In the early stages, there is no abnormality in lung auscultation, or only coarse breath sounds can be heard, and as the disease progresses, scattered dry and wet rales can be heard. People who are susceptible to bronchitis should take precautions against bronchitis by quitting smoking, staying away from smoky places, wearing a mask when they go out, and keeping indoor air flowing to prevent colds and keep warm. Do early detection and treatment to prevent the occurrence of the disease.