What is evaluated when a subject takes the Preliminary Breath Test (PBT)?

The Preliminary Breath Test (PBT) specifically evaluates the breath alcohol concentration of an individual. When the subject exhales into the device, it measures the amount of alcohol present in the breath, which is then used to determine the approximate blood alcohol concentration (BAC). This is crucial in the context of suspected driving under the influence, as it helps law enforcement assess whether the driver is above the legal limit for alcohol consumption.

The focus of the PBT is solely on detecting alcohol levels rather than examining other physical or cognitive capabilities such as visual acuity, balance and coordination, or reaction time. Each of those factors may be important in assessing a person's overall impairment when suspected of driving under the influence, but they are not the direct purpose of the PBT, which is designed to provide immediate, quantitative results related to alcohol consumption.