When the patient’s oxygen saturation is below 90%, mask oxygen is given immediately, and the etiology is identified based on the medical history. Diseases that may cause this phenomenon include bronchial asthma and chronic obstructive pulmonary disease (COPD). 1. Chronic obstructive pulmonary disease (COPD) is usually caused by an acute infection that leads to airway obstruction and decreased oxygen saturation. According to the patient’s condition, a combination of anti-infective (penicillin, cefixime), expectorant (acetylcysteine), and asthma-relieving (salbutamol, terbutaline) therapy is given to the patient. 2. Patients with bronchial asthma who have severe allergic reactions in the airways and bronchospasm can be treated with salbutamol inhalers as well as inhaled glucocorticoid combinations. Oxygen saturation is lower than 90%, which will seriously damage the function of the nervous system and circulatory system of the body, once found should seek medical treatment in time, give mask oxygen to improve breathing, treatment for the cause of the disease, the patient in the process of treatment need to strictly quit smoking.