How A Breathalyzer Works
To simplify the breath alcohol tester process, alcohol is absorbed through your stomach into your blood stream. The blood then passes through your lungs. Some alcohol evaporates in your lungs and shows up in your breath as you exhale. When you blow into a breathalyzer your breath passes over a very sensitive sensor that interprets the level of alcohol and a formula is applied to extrapolate the blood alcohol content (BAC).
The Legal Limit
You may already know that the "Legal Limit" for adults in all 50 states is 0.08 BAC (for discussion purposes we will drop the leading “0” so 0.08 becomes .08). At .08 BAC or above you are considered legally intoxicated. If you are a truck driver with a CDL you are held to a much higher standard with .04 BAC being the legal limit in most states.
But beware. Many people become impaired at .04 BAC (and lower) and you can be charged with "Driving While Impaired" at .04 in many states. Although it is a lesser offense, it can still be costly and cause some major aggravation. More importantly, you could endanger yourself and others even at these lower BAC levels.
If you are under the age of 21 most states have “zero tolerance” laws in place and you are in violation at .01 or .02 BAC depending on the state.