If you have been arrested and charged with drunk driving, you may feel as though contesting such charges would be futile given the evidence against you. After all, a roadside breath test indicating intoxication is fairly ironclad, right? Yet what if subsequent testing shows your blood-alcohol content to be below the legal limit? Could the initial measurement have been incorrect? This has prompted many in your same situation to come to us here at Beebe & O’Neil asking how a breath test can even give an accurate measurement of the alcohol content of your blood anyway.
The Alcohol Pharmacology Education Partnership offers the answer. The exact form of alcohol you consume in drinks is called ethanol, which is a water-soluble compound. This means that after ingesting it, it is able to pass through membranes through a process known as passive diffusion. Thus, ethanol molecules permeate the lining of your stomach and enter into your bloodstream, where they are eventually carried to your heart.
From your heart, blood is pumped into your lungs via the right ventricle. Once the blood carrying the ethanol molecules arrives there, some of them are vaporized upon coming into contact with the oxygen contained therein. That vaporized ethanol is then exhaled as you breathe.
This process continues, with the alcohol concentration in your blood lowering as more is exhaled in order to maintain equilibrium. Breathalyzer devices make assumptions about this concentration in your blood in order to generate readings. Yet in reality, your actual BAC is lowering with each breath. It is for this reason why such a large margin of error is attributed to breathalyzer devices, and why their results are often disputed.
You can learn more about challenging drunk driving charges by continuing to explore our site.