We have created a range of breath CO monitors and testers which measure the small amounts of CO in exhaled breath. The more you smoke, the higher your COreading will be. The reading is given in ppm, which is the number of CO molecules in a million parts of air. The ppm reading can also tell you how much CO is in the blood (the %COHb) reading). %COHb is the percentage of red blood cells carrying CO instead of oxygen. This is a proven method to help motivate smokers quit smoking.