User's Guide

Alcohol and Its Effects on the Human Body
When alcohol is consumed, it is absorbed from the mouth,
throat, stomach, and intestines into the bloodstream. Blood
carries the alcohol throughout the body - including to the lungs.
As alcohol-laden blood moves across the membranes of the
lung’s air sacs (alveoli), it permeates the breath. The concentration
of the alcohol in the alveolar air is directly related to the
concentration of alcohol in the blood.
The ratio of breath alcohol to blood alcohol is generally estimated
to be 2,100:1. Therefore, every 2,100 ml of alveolar air contains
approximately the same amount of alcohol as 1 ml of blood.
The breathalyzer uses this ratio in order to make an accurate
estimate of your BAC.
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