What is the amount of oxygen in arteries?

Arteries carry oxygenated blood away from the heart and to the rest of the body. The amount of oxygen in arteries is usually measured as the partial pressure of oxygen (PaO2). Normal PaO2 levels in arterial blood range from 80 to 100 millimeters of mercury (mm Hg). A PaO2 level below 80 mm Hg is considered low and can indicate a variety of medical conditions, such as lung disease, heart disease, or anemia.