Which device is commonly used to measure alcohol levels in the blood?

The Intoxilyzer is a device specifically designed for measuring blood alcohol content (BAC) in the breath. It works on the principle that alcohol in the breath correlates with the alcohol level in the bloodstream. When a person breathes into the machine, it analyzes the breath sample and provides an estimate of the BAC, making it a vital tool in law enforcement for assessing whether a driver is under the influence of alcohol.

Other options, like a blood pressure monitor, do not measure alcohol levels and are intended for tracking cardiovascular health instead. A urine sample can also be used to detect alcohol, but it does not provide immediate results like the Intoxilyzer does, nor is it as widely used by law enforcement during traffic stops. Physical tests, such as field sobriety tests, evaluate a person's coordination and balance rather than directly measuring alcohol concentration in the body. Each of these alternatives serves a different purpose and is less effective for the specific task of measuring blood alcohol levels compared to the Intoxilyzer.