Is a carbon dioxide level of 16 bad?

Answer 1

That depends.

If it is the CO2 level on an arterial blood gas test then it means the person is breathing at over twice the normal rate and likely has something very wrong with them.

Most likely you are looking at a chemistry lab report from more routine blood testing. In this case the "CO2" actually refers the bicarbonate level. Often, this is a lab error and will be normal on re-testing. If it is accurate it reflects a metabolic problem, most commonly a problem with the way the kidney regulates blood acidity.