Lung nodules of 4-5 mm are not necessarily cancerous, but can also be due to pneumonia, tuberculosis, and other causes. Therefore, it needs to be determined in combination with other symptoms and tests. Generally, lung nodules smaller than 5mm are called microscopic nodules. Most of the microscopic lung nodules are benign nodules, and if the nodules grow slowly and have clear boundaries, dynamic observation is sufficient and no special treatment is needed. If they are accompanied by low fever, night sweats, hemoptysis, etc., tuberculosis will be considered and tuberculin tests will be performed. If there is a hairy glass-like shadow or solid lesion in the lung, lung cancer is suspected. For hairy glass-like lesions less than 8 cm in diameter, regular observation is sufficient, but if they grow faster, surgery should be actively performed. In addition to following the medical advice, patients should also pay attention to the comfort of their living and working environment and reduce the frequency and number of smoking or quit smoking, as smoking increases the risk of lung cancer and needs to be taken seriously.