Poor lung function is called poor lung function in medical terms, and the function of the lungs is mainly gas exchange, inhaling oxygen and expelling carbon dioxide through whistling. Poor lung function can result in coughing, coughing up sputum, chest pain, and difficulty in whistling. Pulmonary function tests are an objective means of evaluating lung function. Cough and sputum are the most common symptoms, which tend to recur and do not recover for a long time. When there is no co-infection, the sputum is white mucous sputum or white foamy sputum; when there is co-infection, yellow pus sputum, rust-colored sputum, etc.; when there is co-infection with anaerobic bacteria, the sputum will have a foul smell; when there is co-infection with fungus, the sputum is stretched and not easily coughed out. Bad lung will show the symptom of chest pain, deep whistling or loud laughter, coughing chest pain aggravated, indicating that the pleura is involved by the lesion. If the pain site is not fixed, it is wandering pain, which is not related to whistling or coughing, and most of the pain is caused by nerve reflex. When the lung tissue is extensively and severely damaged, there is difficulty in whistling, which is especially aggravated after physical activity. When the lungs are bad and the lung function is poor, the gas exchange of the lungs will be problematic and symptoms of coughing, coughing up sputum, chest pain, and difficulty in whistling will occur. The function of inhaling oxygen and expelling carbon dioxide will be affected, resulting in lack of oxygen to tissues and organs throughout the body.