The breathalyzer device has become the de-facto symbol for drunk driving enforcement in the U.S. Yet many in Naples may wonder how alcohol (which people consume as a liquid) can be measured through one's breath. The answer to this question lies in understanding the unique nature of alcohol and the pathway it travels through the human body.
The alcohol component of alcoholic drinks is ethanol. This is a water-soluble compound (meaning that it dissolves completely in water). Once dissolved in the stomach's fluids, ethanol molecules permeate the linings of the organs of the gastrointestinal tract (the stomach, the intestines) and enter into the bloodstream. Veins then carry them throughout the body (including to the brain, which triggers many of the effects of intoxication) before finally arriving at the heart, which then sends the deoxygenated blood to the lungs.
According to the Alcohol Pharmacology Education Partnership, once in the lungs, the ethanol molecules remain in liquid form in the blood in the mucous lining of the alveoli (the lung sacs). Above them is open space which is filled with oxygen brought in when one inhales. Upon coming in contact with that oxygen, some of the ethanol molecules are vaporized into a gas, which then escape the lungs (along with the carbon dioxide vaporized from the blood) with each breath. Breathalyzer devices measure this concentration of alcohol in one's breath and use a conversion factor to estimate its concentration in the blood.
Yet the complexities of this process introduce a number of factors that could impact breathalyzer accuracy. A study cited by ZDNet.com showed that something as simple as one's breath temperature could inflate readings. Combine that with the potential human error in correctly calibrating a breathalyzer device, and one can see why the results they generate are often challenged.