Ground glass shadow in the lungs may be caused by infection, tumor, air pollution and so on. 1. Infection: when the patient’s immunity is lowered, it will lead to microorganisms such as bacteria or viruses invading the lungs and causing inflammatory reactions, such as pneumonia and tuberculosis. If left untreated, it will cause inflammation to stimulate the surrounding tissues, which in the long run will cause grinding glass shadow in the lungs. 2. Tumor: when the patient’s lung tissue develops malignant lesions that lead to cancer, it will affect the lung function, and the cancer cells will continue to grow along the alveolar wall, resulting in ground-glass shadows in the lungs. 3. Air pollution: living in areas with outdoor air pollution or working environment with a lot of dust for a long time, fine dust can not be adsorbed and discharged by lung alveoli and deposited in lung tissues, which may be an important factor leading to the emergence of ground-glass shadow in the lungs. Severe urban air pollution can aggravate the condition of people with lung disease. There are more reasons leading to the appearance of grinding glass shadow in the lungs, patients should go to the hospital in time for examination, to clarify the specific conditions of the lungs, and choose the appropriate method of treatment.