What is a breathalyzer?

A breathalyzer is a device for estimating blood alcohol content (BAC) from a breath sample. "Breathalyzer" is the brand name of a series of models made by one manufacturer of these instruments (originally Smith and Wesson, later it was sold to National Draeger), but has become a generic trademark for all such instruments. Intoxilyzer, Intoximeter, AlcoScan, Alcotest, AlcoSensor, Alcolizer, Datamaster are the other most common brand names in use today. The U.S. Government's National Highway Traffic Safety Administration maintains a "Conforming Products List" of breath alcohol devices approved for evidentiary use as well as for preliminary screening use.

Law enforcement

Breath analyzers do not directly measure blood alcohol content or concentration, which requires the analysis of a blood sample. Instead, they estimate BAC indirectly by measuring the amount of alcohol in one's breath. Two form factors are most prevalent. Desktop analyzers generally utilize infrared spectrophotometer technology, electrochemical fuel cell technology, or a combination of the two. Hand-held field testing devices, are generally based on electrochemical fuel cell analysis, and depending upon jurisdiction may be used by officers in the field as a form of "field sobriety test" commonly called PBT (preliminary breath test) or PAS (preliminary alcohol screening), or as evidential devices in POA (point of arrest) testing.

Consumer use

There are a number of models of breath alcohol analyzers that are intended for the consumer market. These hand-held devices are less expensive and can be much smaller than the devices used by law enforcement, and are less accurate, but can still give a useful indication of the user’s BAC. Almost all of these devices use less expensive tin-oxide semiconductor alcohol sensors (frequently called "Taguchi cell" based sensors), which are not as stable as fuel cell sensors or infrared devices, and are more prone to false positives. Breath alcohol analyzers sold to consumers in the United States are required to be certified by the Food and Drug Administration, while those used by law enforcement must be approved by the Department of Transportations National Highway Traffic Safety Administration.