A breathalyzer is a device used to measure blood alcohol content (BAC). It is commonly used by law enforcement to test drivers for alcohol intoxication, but can also be used for personal use to monitor alcohol consumption.
Breathalyzers work by measuring the amount of alcohol in a person’s breath. Alcohol is absorbed into the bloodstream through the lungs, and then it is carried to the liver where it is metabolized. The amount of alcohol in a person’s breath is proportional to the amount of alcohol in their blood, so by measuring the alcohol in a person’s breath, a breathalyzer can estimate their BAC.