An alcohol breathalyzer calculates the percentage of alcohol present in the human bloodstream by measuring the amount of alcoholic gases that are exhaled through the lungs. While first developed primarily as an aid to law enforcement officials administering sobriety tests in the field, they are now widely available on the open market and can be used for a wide variety of reasons.

Alcohol does not break down in the bloodstream and is easily transferred across the lungs’ air sacs into human breath at a known ratio to levels present in the blood. Today, most breathalyzers detect these percentages by infrared (IR) spectroscopy readings, through the chemical reaction in a fuel cell, or sensitive semiconductors.

Regardless of the type, each breathalyzer has a mouthpiece, a tube through which air is forcefully blown and a chamber where the air is held for testing. Once the air is tested, an LED or LCD panel displays an estaimated percentage of alcohol present in the blood. The calculations of levels are now so accurate that results from certain models have long been accepted as evidence in courts and many models now provide readings to with three decimal places. Over the past few years, the sizes and shapes of breathalyzers have also become more varied. Models can now be found that are smaller than the size of a cell phone and some are designed for easy placement on belts or key chains.

The most wide-scale use of breathalyzers is still within law enforcement personnel. These include police officers when there is suspicion of driving under the influence or public intoxication, booking officers during processing when a breathalyzer test was not administered at the time of arrest, probation officers verifying compliance with court orders and corrections officers verifying compliance during incarcerations.

But the common uses of alcohol breathalyzers is greatly expanding among businesses and individuals. Businesses and clinics utilize a breathalyzer when they need easy, fast and accurate ways to test for alcohol impairment. Bars and other establishments keep a breathalyzer on hand for use by patrons or to monitor problem drinkers. Parents give them as gifts to children to help keep them safe when they think they have had too much to drink, or use them as a tool to test for consumption in an under-aged child. College students are using a breathalyzer to monitor if friends are too drunk to drive or as a safeguard against alcohol poisoning. There are also now many individuals who routinely keep them handy for self-testing blood alcohol levels before driving after they have been consuming alcoholic beverages.