What is the primary purpose of a breath test?

The primary purpose of a breath test is to measure the concentration of alcohol in a person’s system, which is directly related to their level of intoxication. When a breath test is administered, it quantifies how much alcohol is present in the breath, which correlates with the blood alcohol concentration.

While some might think that measuring alcohol presence is a valid answer, the precision of the breath test goes beyond mere detection; it provides a quantifiable measure of how much alcohol is in a person's system at that moment. This measurement is critical in legal contexts, such as determining whether a driver is above the legal limit for operating a vehicle.

Other choices do not align with the function of a breath test. It does not measure blood pressure or analyze drug metabolites, as those would require entirely different testing methods and equipment. Therefore, the breath test is specifically designed to assess alcohol concentration, making the proper understanding of this process vital in law enforcement and public safety related to alcohol consumption.