Oxygen is the basis of human metabolism and the source and foundation of life and health. Human beings need oxygen because the source of human energy is provided by the aerobic decomposition of sugars, which can oxidize substances into energy to meet the needs of human tissues and organs. Lack of oxygen can affect metabolism, which in turn leads to physical discomfort, causes various diseases and endangers health.

        Long-term hypoxia can lead to reduced sensitivity of peripheral chemical receptors and reduced pulmonary ventilation ability, resulting in respiratory depression, irregular respiratory rhythm, and central respiratory failure. Long-term hypoxia can also cause the continuous contraction of the small pulmonary artery, increase the resistance of pulmonary circulation, cause pulmonary hypertension, and eventually cause right heart failure. Long-term myocardial hypoxia can cause the reduction of myocardial contraction and diastolic function, causing bradycardia and premature beat. In severe cases, it will induce the occurrence of malignant arrhythmias such as ventricular fibrillation. Long-term hypoxia in the blood system can lead to an increase in the number of red blood cells, an increase in blood viscosity and an increase in blood flow resistance, thus increasing the burden on the heart. Chronic hypoxia in the nervous system can be manifested in symptoms such as inattention, drowsiness, fatigue, and depression.

        Nowadays, the oxygen content in the air is about 21%. When the oxygen content is too low, the human body will have hypoxia, which will endanger life when severe hypoxia. When the oxygen content is too high, it will also cause certain damage to the human body. If people breathe pure oxygen, it will cause the phenomenon of oxygen poisoning. Therefore, from the perspective of human physiology, there is no need to inhale high concentrations of oxygen. Generally, diluted oxygen is inhaled. The following table shows the effect of oxygen concentration on the human body.