A lot of people driving home after a night on the town dread the image of a policeman in the rear-view mirror, carrying a small device in his hand. This little device is an alcohol breath analyzer, and has probably saved countless lives since its invention.
Before we get to how breath analyzers work, take a look at this fact. Of all the road accident deaths in the United States, around 38 percent are because of alcohol. Roadside tests like reciting the alphabet backward, or walking a straight line, are often inconclusive, and a blood test is rarely feasible on the roadside. Here is where a breath analyzer helps; it can easily and quickly measure BAC (Blood Alcohol Concentration) levels, and if needed, the offending driver can be taken off the road. In most states, the permissible BAC level is 0.08.
Breath analyzers work on this principle: When alcohol enters the body, it does not change the chemical composition, but adds to it. What happens is that alcohol is absorbed by the stomach and intestines, and then gets into the bloodstream. It travels around the body with the blood, and eventually enters the lungs. There, alcohol mixes with exhaled air. When exhaled, the ratio of this air to the level in the blood has been shown to be about 2100:1; so, it’s easy to calculate how much alcohol you have in your blood by measuring how much is in your breath.
There are different kinds of breath analyzers used, all of which have slightly varying mechanics. Most of them look similar, and have a small tube for blowing into. The air then travels into the handheld unit, where it is analyzed.
The most common one is the Breathalyzer which uses a chemical reaction with alcohol molecules. It has two vials with a chemical mixture. One of these is exposed to the alcohol, and changes color based on the amount of alcohol present. The two vials are compared with an electric current, and a reading is given. Some other systems use ‘smart dust’ or oxidize sensors. These create a charge when exposed to alcohol, which is measured by a microchip. Yet other models measure infrared light to gauge absorption levels. Regardless of how they work, the basic principle is the same.
Your rights may differ depending in which state you live in. In some states, you can make a request for a blood test.