1. Patients with a significant disease or condition other than the new coronavirus pneumonia, that is, a disease that, according to the investigator's judgment, may cause the subject to be at risk due to participation in the study, or affect the results of the study and the ability of the subject to participate in the study. 2. Women who are pregnant or nursing or plan to become pregnant during the study. 3. Have one of the following respiratory diseases: 1) Asthma: Based on the investigator's judgment, the subject is currently diagnosed with asthma. 2) Subjects with a previous history of COPD or long-term medication or imaging that showed significant lung structural damage (eg, giant pulmonary bullae). 3) Other respiratory diseases: subjects with other active lung diseases, such as active tuberculosis, lung cancer, wet bronchiectasis (high-resolution CT shows bronchiectasis, yellow sputum every day), sarcoidosis, idiopathic Interstitial Pulmonary Fibrosis (IPF), Primary Pulmonary Arterial Hypertension, Uncontrolled Sleep Apnea (ie, the severity of the disease will affect the implementation of the study at the investigator's discretion), combined with pneumothorax, pleural effusion and pulmonary embolism , Bronchial asthma, tumors, fever of unknown origin, etc. 4) Lung volume reduction: Lung volume reduction, lobectomy, or bronchoscopic lung volume reduction within 6 months (bronchial obstruction, airway bypass, bronchial valve, steam thermal ablation, biological sealant, Implants). 5) Patients who are critically ill or unstable. Definition of Severe Pneumonia: A. Increased breathing rate ( >= 30 beats / min), difficulty breathing, B. Peripheral blood oxygen saturation <= 93% when inhaling air, or arterial blood oxygen partial pressure (PaO2) / oxygen concentration (FiO2) <= 300mmHg, C. Lung imaging showed multi-leaf disease or lesion progression> 50% within 48 hours, D. Combined with pneumothorax. 6) Pneumonia risk factors: immunosuppression (HIV), severe neurological disease affecting upper respiratory tract control, or other risk factors that the investigator believes may put the subject at a significant risk of pneumonia. 4. Complicate serious primary diseases such as heart, liver, kidney, and hematopoietic system. 5. People with mental disorders and cognitive impairment. 6. Non-compliance: Subjects who did not comply with the study procedures, including non-compliance completion logs. 7. Questions about the effectiveness of informed consent: subjects with a history of psychosis, mental retardation, poor motivation, substance abuse (including drugs and alcohol), or other medical conditions that limit the effectiveness of informed consent in this study. 8. Those who use non-expectorant antioxidant drugs, including large doses of vitamin C and vitamin E. 9. Researchers consider it inappropriate to participate in this research.

1. Patients with a significant disease or condition other than the new coronavirus pneumonia, that is, a disease that, according to the investigator's judgment, may cause the subject to be at risk due to participation in the study, or affect the results of the study and the ability of the subject to participate in the study. 2. Women who are pregnant or nursing or plan to become pregnant during the study. 3. Have one of the following respiratory diseases: 1) Asthma: Based on the investigator's judgment, the subject is currently diagnosed with asthma. 2) Subjects with a previous history of COPD or long-term medication or imaging that showed significant lung structural damage (eg, giant pulmonary bullae). 3) Other respiratory diseases: subjects with other active lung diseases, such as active tuberculosis, lung cancer, wet bronchiectasis (high-resolution CT shows bronchiectasis, yellow sputum every day), sarcoidosis, idiopathic Interstitial Pulmonary Fibrosis (IPF), Primary Pulmonary Arterial Hypertension, Uncontrolled Sleep Apnea (ie, the severity of the disease will affect the implementation of the study at the investigator's discretion), combined with pneumothorax, pleural effusion and pulmonary embolism , Bronchial asthma, tumors, fever of unknown origin, etc. 4) Lung volume reduction: Lung volume reduction, lobectomy, or bronchoscopic lung volume reduction within 6 months (bronchial obstruction, airway bypass, bronchial valve, steam thermal ablation, biological sealant, Implants). 5) Patients who are critically ill or unstable. Definition of Severe Pneumonia: A. Increased breathing rate ( >= 30 beats / min), difficulty breathing, B. Peripheral blood oxygen saturation <= 93% when inhaling air, or arterial blood oxygen partial pressure (PaO2) / oxygen concentration (FiO2) <= 300mmHg, C. Lung imaging showed multi-leaf disease or lesion progression> 50% within 48 hours, D. Combined with pneumothorax. 6) Pneumonia risk factors: immunosuppression (HIV), severe neurological disease affecting upper respiratory tract control, or other risk factors that the investigator believes may put the subject at a significant risk of pneumonia. 4. Complicate serious primary diseases such as heart, liver, kidney, and hematopoietic system. 5. People with mental disorders and cognitive impairment. 6. Non-compliance: Subjects who did not comply with the study procedures, including non-compliance completion logs. 7. Questions about the effectiveness of informed consent: subjects with a history of psychosis, mental retardation, poor motivation, substance abuse (including drugs and alcohol), or other medical conditions that limit the effectiveness of informed consent in this study. 8. Those who use non-expectorant antioxidant drugs, including large doses of vitamin C and vitamin E. 9. Researchers consider it inappropriate to participate in this research.