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How Does A Breathalyzer Work?

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How Does A Breathalyzer Work

The AlcoHAWK PT500 is one of a variety of breathalyzer models Source: YouTube

We have all heard of a Breathalyzer, and we know that police officers regularly use them in the field in order to measure a driver’s blood alcohol levels (BAC), but how does a breathalyzer work?  Here we’ll examine what a Breathalyzer is, how it works, and just how accurate they are.

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Blood and urine tests are the most accurate tests for determining blood alcohol levels, but police officers needed a method more practical for testing alcohol levels in drivers while in the field. Often, by the time a driver is brought into a police station for blood or urine testing, alcohol levels have dropped. Today, police officers use breath alcohol testing as an accurate method of determining BAC in the field.

Alcohol consumed by a person is absorbed through the mouth, throat, stomach, and intestines into the bloodstream. As the blood moves through the lungs, some of the alcohol moves across the membranes of the lung’s air sacs, where the alcohol will evaporate into the air. The concentration of the alcohol in the lung’s air is related to the concentration of alcohol in the blood.

According to, the ratio of breath alcohol to blood alcohol is 2,100:1. This means that 2,100 milliliters (ml) of air from the lungs will contain the same amount of alcohol as 1 ml of blood. The legal standard in the U.S. for many years was 0.10, but today most states have adopted a legal limit of 0.08 (0.08 grams of alcohol per 100 ml of blood). According to the American Medical Association, a person can become impaired when the blood alcohol level hits 0.05.

Breathalyzers can also be purchased for personal use, so you can test your own breath before getting behind the wheel. It’s always better to be safe than sorry – if you plan on drinking, make sure you have backup transportation.

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