When referring to drunk driving laws in Roanoke, one number is often repeated: 0.08. This number the blood-alcohol content level recognized almost universally as being the standard at which you are considered legally drunk. Take note of how this test is a measurement of your blood. Yet if and when you are pulled over for suspicion of driving under the influence, law enforcement officials do not test a sample of your blood, but rather your breath. How is, then, that the alcohol you drink ends up in your lungs?
It has everything to do with the composition of the alcoholic compound found in your drinks. Ethanol is a form of alcohol that is water soluble, meaning that it not only dissolves in water, but also can move through membranes in the body. The Alcohol Pharmacology Education Partnership offers a detailed explanation on how the ethanol found in the drinks you consume makes its way in and out of your body.
After being ingested, ethanol molecules are able to move across the membranes lining both your stomach and small intestine, where they then enter into the bloodstream. Blood flow meanders throughout your body, supporting the organs and tissues. Eventually, its circuitous journey makes it back to the heart, where it is then is pumped by the right ventricle into the lungs.
Another compound is present in the lungs which is vital to BAC measurement: oxygen. upon coming into contact with oxygen in the lungs, some of the ethanol in your blood is then vaporized into a gaseous state. That gas is eventually exhaled as you breathe, carrying an ethanol concentration with it. This process repeats until the ethanol in the blood makes its what out of your body. This is why breath is said to offer an indication of your impairment.