How is Blood Alcohol Content (BAC) measured?

Blood Alcohol Content (BAC) is measured by quantifying the amount of alcohol present in a specific volume of blood. This is generally expressed as a percentage, which indicates the ratio of alcohol to blood. For example, a BAC of 0.08% means that there are 0.08 grams of alcohol for every 100 milliliters of blood. This method provides an objective measurement that is crucial in determining a person's level of impairment and is widely used in DUI testing.

In contrast, monitoring heart rate, assessing breathing patterns, or observing physical coordination do not provide a direct measurement of alcohol in the bloodstream. While these factors can indicate impairment or the presence of alcohol, they are not reliable or scientific methods of measuring BAC. Therefore, measuring the weight of alcohol in a specific volume of blood is the most accurate and accepted approach for evaluating a person's blood alcohol concentration.