As a medical professional with expertise in respiratory health, I can tell you that an oxygen level of 90 is generally considered to be on the lower end of what's normal, but it's not necessarily bad. Normal arterial oxygen levels are approximately 75 to 100 millimeters of mercury (mm Hg). However, when we talk about oxygen levels in terms of pulse oximetry, which is a non-invasive way to measure oxygen saturation in the blood, the normal range is typically from 95 to 100 percent. Values under 90 percent are considered low and could indicate that a person is not getting enough oxygen. It's important to note that oxygen levels can be influenced by various factors, including altitude, health conditions, and the method of measurement. If someone has a consistent oxygen saturation level of 90 percent, it may not be a cause for concern if they are at a high altitude or have a medical condition that naturally results in lower oxygen levels. However, if the level drops suddenly or is accompanied by symptoms such as shortness of breath, chest pain, or confusion, it could be a sign of a health issue and should be evaluated by a healthcare provider. read more >>

Normal arterial oxygen is approximately 75 to 100 millimeters of mercury (mm Hg). Values under 60 mm Hg usually indicate the need for supplemental oxygen. Normal pulse oximeter readings usually range from 95 to 100 percent. Values under 90 percent are considered low.read more >>