The causes of lung atelectasis mainly include obstructive causes such as tumor and non-obstructive causes such as pleural effusion. 1. Obstructive pulmonary atelectasis: Obstructive pulmonary atelectasis can be caused by the following diseases, such as bronchial adenoma and other tumors of bronchial stenosis, fibro-cavernous tuberculosis, pulmonary mycosis and other infections and inflammation caused by bronchial obstruction, bronchial asthma, bronchial dilatation and other diseases, and also the inhalation of foreign bodies, bronchial stones and so on. 2. Non-obstructive pulmonary atelectasis: including compressive pulmonary atelectasis caused by intrapulmonary tumors, passive pulmonary atelectasis caused by pleural effusion, pyothorax, pneumothorax and intrathoracic tumors, and scarring pulmonary atelectasis caused by fungal infection and asbestosis, etc. In addition, there is absorptive pulmonary atelectasis. In addition, there are absorptive atelectasis, such as high concentration of oxygen may also cause atelectasis. Patients are advised to seek prompt medical attention for any discomfort.