Frosted glass nodules in the left lower lobe of the lungs are not serious if they are caused by benign diseases such as pneumonia, but they are serious if they are caused by malignant tumors such as bronchopulmonary cancer. Milled glass nodules are cloudy, slightly dense shadows on chest CT. Ground-glass nodules can be caused by benign diseases such as pneumonia, tuberculosis, malignant tumor, etc. They can also be caused by bronchopulmonary cancer or metastatic lung cancer. If they are caused by benign diseases, they are generally not serious. Infectious diseases such as pneumonia and tuberculosis can be treated with anti-infectious drugs such as ceftazidime and isoniazid, and benign tumors such as malignant tumors can be treated with surgical resection, and only a small proportion of severe pneumonia and serious tuberculosis will be life-threatening. If it is caused by malignant tumors such as lung cancer, it is serious, mostly affecting survival and endangering life. Timely radical surgery, chemotherapy, radiotherapy and other comprehensive treatments are needed to improve the prognosis. Ground-glass nodules in the left lower lobe of the lungs also need to be evaluated for malignant risk in combination with the presence of a solid component, nodule size, morphology and other conditions. Patients are advised to consult a specialist for further examination, follow-up and treatment, and to take medication under the supervision of a physician.