What is the normal blood oxygen level for humans?

　　Blood oxygen value generally refers to blood oxygen saturation, which is further divided into arterial blood oxygen saturation and venous blood oxygen saturation. The normal range for arterial blood oxygen saturation is 95% to 98%, while the normal range for venous blood oxygen saturation is 64% to 88%. If abnormalities occur, timely medical attention is recommended. A detailed explanation is as follows:

　　Arterial blood oxygen saturation refers to the percentage of oxygenated hemoglobin relative to total hemoglobin in arterial blood. It is usually measured through arterial blood gas analysis or a pulse oximeter. Under normal circumstances, arterial blood oxygen saturation should be between 95% and 98%, a value that reflects the efficiency of oxygen exchange in the lungs and the circulatory system's ability to supply oxygen.

　　Venous blood oxygen saturation refers to the percentage of oxygenated hemoglobin in venous blood, typically measured by collecting a blood sample via a central venous catheter. Venous blood oxygen saturation reflects the oxygen utilization status of tissues, with a normal range of approximately 64% to 88%. Low venous blood oxygen saturation may indicate inadequate tissue oxygen supply or increased oxygen consumption, commonly seen in conditions such as heart failure, shock, or severe infections.

　　In daily life, it is important to maintain a healthy lifestyle, improve dietary habits, engage in appropriate physical exercise, enhance blood oxygen saturation levels, and reduce the risk of illness.