breathalyser

A breathalyser is a device that estimates the concentration of alcohol in a person’s blood by measuring the ethanol content of exhaled breath. It is commonly used by law enforcement to determine intoxication levels, and also by employers or medical facilities to monitor abstinence or compliance with policies or treatment.

Most modern breathalysers operate using one of two technologies. Electrochemical sensors, often referred to as fuel cells, detect ethanol via a chemical reaction that generates an electrical signal proportional to the alcohol concentration. Infrared spectrometry devices detect specific absorption wavelengths of ethanol in the breath sample. Earlier, some devices relied on colorimetric chemical reactions that produced a visible change. Some portable models combine different sensing approaches, and there are more advanced “evidential” instruments used by authorities that adhere to regulatory standards.

Operation and interpretation typically involve providing a clean, deep-lung breath into a mouthpiece. The device displays a breath alcohol concentration and, in many jurisdictions, converts this to a corresponding blood alcohol concentration (BAC) using standard ratios. Readings are usually given as BrAC or BAC and cover a range sufficient to indicate legal impairment in many settings.

Accuracy and limitations must be considered. Readings depend on proper technique, regular calibration, and sensor maintenance. Factors such as residual mouth alcohol, recent smoking, mouthwash, temperature, and ambient humidity can affect results. A breathalyzer reading is an estimate and may be subject to verification by a blood test in legal or critical contexts.

History and terminology: The term breathalyser traces to the Breathalyzer developed in the 1950s by Dr. Robert B. Borkenstein. In British English, the term breathalyser is common, while “evidential breath tester” or “portable breathalyser” describes devices used for official testing.