Your blood oxygen level, also known as blood oxygen saturation, is a measure of how much oxygen is circulating in your blood. A healthy blood oxygen level is between 95% and 100% for most people. However, if you have a lung disease such as COPD or pneumonia, your normal oxygen saturation level may be lower. Your healthcare provider will let you know what levels are acceptable for you. If your blood oxygen level falls below 95%, it is considered low and may put you at risk of hypoxemia. Symptoms of low blood oxygen levels include shortness of breath, chest pain, coughing or wheezing, confusion, headache, rapid heartbeat, and a blue discoloration of your nail beds, skin, and mucus membranes. If you experience any of these symptoms, you should seek immediate medical attention. It is important to note that pulse oximeters are not always accurate, and your actual blood saturation level may be 2% to 4% higher or lower than what the oximeter reads.