Lung function includes a series of test indicators, different indicators standard value is different, common test indicators are lung volume, residual air volume/total lung volume, maximum ventilation, one-second rate and so on. 1. Spirometry: It refers to the volume of gas exhaled after breathing hard, and the standard reference value should be 2400-3400mL. 2. Residual air volume/total lung volume: Residual air volume refers to the amount of residual air that cannot be exhaled from the lungs after a calm expiration and then a forceful expiration; total lung volume refers to the amount of air contained in the lungs after a forceful respiration, including lung volume and residual air volume; the ratio of the two is used to determine the presence of emphysema, and the standard reference value is <25%. 3. Maximum Ventilation: It refers to the maximum volume of air that can be breathed per unit of time, and the reference standard value for normal adults is 80-106L/min. 4. One-second rate: refers to the percentage of the first second lung volume over the whole lung volume, which is often used to detect the presence of airway obstruction, and its standard reference value is >80%. For lung function, different hospitals have different testing indexes. Once symptoms such as breathlessness or chest tightness and shortness of breath appear, it is necessary to consult a doctor in time and be treated by the doctor through examination to avoid delaying the condition.