The clinical degree of impaired lung function is mainly divided into mild, moderate, severe and very severe, previously divided into grades I-IV, with moderate belonging to grade II. Generally, lung function is divided according to FEV1, the percentage of one second rate to the expected value, which is often greater than or equal to 50% in moderate, and FEV1 <80% of the expected value, which is called moderate lung function impairment, and the impairment is relatively severe. For most chronic diseases, such as COPD with chronic obstructive pulmonary disease and interstitial pneumonia, this condition often suggests that lung function has been impaired, which is generally more severe, or at least reminds or suggests that the patient must be seen in a hospital and that regular treatment is required. If left untreated, lung function may progress from moderate to severe or toward very severe, so it is important to undergo aggressive treatment.