The normal CO2 or carbon dioxide levels in the body range from 23 to 29 milliequivalent units per liter of blood, according to Healthline. The test for CO2 determines the level of bicarbonate, which is the chemical that balances the pH of blood, notes WebMD.
More than 90 percent of carbon dioxide in the blood is in the form of bicarbonate, while the rest exists as carbonic acid or carbon dioxide gas, states WebMD. The lungs and the kidneys balance these forms. Causes of high carbon dioxide levels include vomiting, heart disease and overuse of medicines that contain bicarbonate. Low levels of carbon dioxide occur from kidney disease, severe malnutrition and uncontrolled diabetes.