Which type of chemical test measures the alcohol content in a person's breath?

The breath alcohol test is specifically designed to measure the level of alcohol in a person's breath, which correlates to their blood alcohol concentration (BAC). This test involves using a device known as a breathalyzer, which analyzes the breath sample to provide an estimate of the amount of alcohol present in the body. Breath alcohol tests are commonly used by law enforcement during DWI (driving while intoxicated) stops because they are quick, non-invasive, and provide immediate results for the officer on the scene.

In contrast, the other types of tests listed serve different purposes or use different substances. For instance, urine alcohol tests measure alcohol present in urine, which can provide a broader time frame of alcohol consumption but is less immediate and less reliable for estimating current impairment. Blood alcohol tests analyze a sample of blood and are considered one of the most accurate methods for determining BAC, but they require medical personnel and more time to obtain results. Saliva alcohol tests are less common and are usually used for different contexts, as they are not as reliable for legal DWI enforcement.