A normal blood oxygen level, as measured by a pulse oximeter, is between 95% and 100% for most people. However, for individuals with lung diseases such as COPD or pneumonia, the normal oxygen saturation level may be lower, and their healthcare provider will determine what levels are acceptable for them. A lower-than-normal blood oxygen level is called hypoxemia, which can lead to serious conditions and damage to individual organ systems, especially the brain and heart. Hypoxemia is often concerning because oxygen is essential to all of the body's functions, and the lower the oxygen level, the greater the likelihood for complications in body tissue and organs. If blood oxygen saturation levels fall below 92%, it may be a sign of hypoxia, and if they fall to 88% or lower, immediate medical attention is needed
. Hypoxemia, or low blood oxygen, can be caused by various conditions and circumstances, including insufficient oxygen in the air, an inability of the lungs to inhale and send oxygen to all cells and tissues, and an inability of the bloodstream to circulate to the lungs, collect oxygen, and transport it around the body. Some medical conditions that can lead to hypoxemia include asthma, chronic obstructive pulmonary disease (COPD), interstitial lung disease, pulmonary hypertension, and bronchiectasis
. Pulse oximetry is a noninvasive method of measuring the saturation of oxygen in a person's blood. A resting oxygen saturation level between 95% and 100% is considered normal for a healthy person at sea level. People with known lung disorders such as COPD may have resting oxygen saturation levels below the normal range. Pulse oximeters are used to measure how much oxygen is in someone's blood, and a pulse oximeter reading for oxygen saturation level is between 95% and 100% for most people. However, the accuracy of pulse oximeters may be lower for people with darker skin
