When someone drinks the alcohol it gets absorbed from the throat, stomach, mouth, and intestines into the bloodstream. Here we need to know one more point that is “Alcohol is not digested upon absorption, nor chemically changed in the bloodstream”. As of result, the blood goes through the lungs, some of the alcohol moves across the membranes of the lung’s air glands (also known as alveoli) into breathe, because alcohol will evaporate from the solution. The concentration of alcohol in the breath is related to the blood. As the alcohol is present in exhaled air, it can be detected by the testing of this air.