At sea level, the partial pressure of oxygen should be between 75 and 100 millimeters of mercury, and the partial pressure of carbon dioxide should be between 38 and 42 millimeters of mercury, notes MedlinePlus. The oxygen saturation of the blood should be between 94 and 100 percent.
Doctors also test blood gas values to check the pH of a person's blood, according to MedlinePlus. Results indicate whether the blood is more acidic or more alkaline. The normal pH of arterial blood at sea level is 7.38 to 7.42, which means it is slightly alkaline. Normal levels of blood bicarbonate fall between 22 and 28 milliequivalents per liter.