Why is breath alcohol level a common measure of intoxication?

Breath alcohol level is commonly used as a measure of intoxication primarily because small amounts of ethanol are excreted in the breath. When alcohol is consumed, it enters the bloodstream and is eventually metabolized by the liver. As blood flows through the lungs, some of the alcohol evaporates from the blood into the breath, allowing for a non-invasive estimation of blood alcohol concentration (BAC). This relationship between blood ethanol levels and breath alcohol levels enables breathalyzers to provide a quick and reliable measure of intoxication, as the concentrations in breath correlate with those in the blood.

While the other options discuss aspects of testing methods, they do not directly convey the fundamental relationship that makes breath analysis for alcohol a common practice. For example, while breath testing can be faster than some blood testing methods, it is the specific process of ethanol excretion into the breath that forms the basis for its use in assessing intoxication levels. Also, breath testing is indeed less invasive than urine testing, but the primary reason for its prevalence lies in the biochemical nature of alcohol’s presence in the exhaled breath.