What Is a Breath Alcohol Test? When you drink alcohol, it goes into your stomach and small intestine. It gets absorbed into your blood, which carries it through your body and into your brain and lungs. You exhale it when you breathe. A breath alcohol test measures how much alcohol is in the air you breathe out. The device uses that measurement to estimate how much alcohol is in your blood. That number is known as your BAC, or blood alcohol content.
Hide player controls
Hide resume playing