* diagnosed as mild, severe, critical or asymptomatic type of covid-19. * subjects in the treatment or active stage of malignant tumor. * subjects who are intolerable to inhalation treatment. * subjects with mental disorders or cognitive impairment who are unable to provide consent. * subjects with any immunodeficiency requiring chronic treatment with any corticosteroid or other immunosuppressants. * complicate serious primary diseases such as heart, liver, kidney, and hematopoietic diseases; acute exacerbation phase of chronic obstructive pulmonary disease, or acute attack of bronchial asthma. * subjects who are using any non-expectorant antioxidant drug, including large doses of vitamin c and vitamin e. * subjects who are participating any other clinical study of any investigational drug or medical device. * pregnant or lactating women. * any other condition judged as inappropriate to participate in this study by the investigator.

* diagnosed as mild, severe, critical or asymptomatic type of covid-19. * subjects in the treatment or active stage of malignant tumor. * subjects who are intolerable to inhalation treatment. * subjects with mental disorders or cognitive impairment who are unable to provide consent. * subjects with any immunodeficiency requiring chronic treatment with any corticosteroid or other immunosuppressants. * complicate serious primary diseases such as heart, liver, kidney, and hematopoietic diseases; acute exacerbation phase of chronic obstructive pulmonary disease, or acute attack of bronchial asthma. * subjects who are using any non-expectorant antioxidant drug, including large doses of vitamin c and vitamin e. * subjects who are participating any other clinical study of any investigational drug or medical device. * pregnant or lactating women. * any other condition judged as inappropriate to participate in this study by the investigator.

diagnosed as mild, severe, critical or asymptomatic type of covid-19. subjects in the treatment or active stage of malignant tumor. subjects who are intolerable to inhalation treatment. subjects with mental disorders or cognitive impairment who are unable to provide consent. subjects with any immunodeficiency requiring chronic treatment with any corticosteroid or other immunosuppressants. complicate serious primary diseases such as heart, liver, kidney, and hematopoietic diseases; acute exacerbation phase of chronic obstructive pulmonary disease, or acute attack of bronchial asthma. subjects who are using any non-expectorant antioxidant drug, including large doses of vitamin c and vitamin e. subjects who are participating any other clinical study of any investigational drug or medical device. pregnant or lactating women. any other condition judged as inappropriate to participate in this study by the investigator.

diagnosed as mild, severe, critical or asymptomatic type of covid-19. subjects in the treatment or active stage of malignant tumor. subjects who are intolerable to inhalation treatment. subjects with mental disorders or cognitive impairment who are unable to provide consent. subjects with any immunodeficiency requiring chronic treatment with any corticosteroid or other immunosuppressants. complicate serious primary diseases such as heart, liver, kidney, and hematopoietic diseases; acute exacerbation phase of chronic obstructive pulmonary disease, or acute attack of bronchial asthma. subjects who are using any non-expectorant antioxidant drug, including large doses of vitamin c and vitamin e. subjects who are participating any other clinical study of any investigational drug or medical device. pregnant or lactating women. any other condition judged as inappropriate to participate in this study by the investigator.