According to the Mayo Clinic, a normal pulse ox reading is between 95 and 100 percent. The pulse ox reading tells of the saturation of oxygen in a person's blood. The reading is taken with a pulse oximeter, a device which is placed on a person's finger.
A low pulse ox reading represents low blood oxygen saturation. This low level of blood oxygen saturation is often a result of the condition hypoxemia. The proper functioning of a person's bodily organs depends upon an appropriately high level of oxygen saturated within his or her blood. The first sign that a person may be afflicted with low oxygen saturation in the blood is shortness of breath.