Given the overwhelming association that most people in Florida make between roadside breath tests and drunk driving charges, one might think that having a test result indicating a blood-alcohol content greater than .08 (the near-universal standard for intoxication) is a good as a conviction. Yet that is not the case.
Indeed, according to the American Motorists Association, breath tests may have a margin of error as high as 50%. Such a high potential for inaccuracy may support one’s challenge of breath test results. However, to truly have a chance at such a challenge being successful, one needs to understand how breath tests actually work.
How alcohol gets on one’s breath
Ethanol alcohol is the particular form of alcohol that one ingests when they consume alcoholic beverages. Ethanol is a water-soluble compound, meaning that it can pass through membrane surfaces through a process known as passive diffusion. That is exactly what happens once it enters into one’s gastrointestinal tract. From there, it enters into the bloodstream and eventually finds its way to the lungs. In the lungs, a small portion of the ethanol vaporizes after coming into contact with the oxygen contained therein. One then expels that gaseous alcohol from their body when they breathe.
The blood-to-breath ratio
This process continues as the body metabolizes all of the ethanol, maintaining an equilibrium between the alcohol in one’s breath and their blood throughout. Hand-held breath testing devices assume a blood-to-breath ratio of 2100:1. Per the Alcohol Pharmacology Education Partnership, however, one’s actual blood-to-breath ratio may range between 1500:1 and 3000:1. This supports the earlier point as to the high potential for breath test inaccuracy, making one’s challenge all the more credible.
