breathalcohol

Breathalcohol refers to the concentration of ethanol present in a person’s exhaled breath, which is used to estimate the amount of alcohol in the bloodstream. The measurement is typically expressed as breath alcohol concentration (BrAC) and is converted to an equivalent blood alcohol concentration (BAC) using a standard partition ratio, commonly cited as 2100:1 at body temperature. This method provides a noninvasive, rapid indication of alcohol exposure and potential impairment.

Breath alcohol is measured with breath testing devices, often called breathalyzers. Modern devices use methods such as fuel-cell sensors, infrared spectroscopy, or semiconductor sensors to detect ethanol in a breath sample. Evidentiary breath-alcohol tests used by authorities may require calibration against reference standards and follow strict operating procedures. Many personal devices also estimate BrAC but vary in accuracy. Users blow into a mouthpiece, and the device analyzes a deep, long exhalation to minimize contamination from mouth alcohol.

Accuracy can be influenced by several factors. Mouth alcohol from recent drinking, residual mouthwash, or tobacco use can produce falsely elevated readings. Physiological differences, breathing pattern, temperature, humidity, and device calibration also affect results. Proper testing procedures, including device maintenance and standard calibration, are essential to ensure reliability. Breath tests are a legal proxy for intoxication in many jurisdictions but do not measure impairment directly; impairment can occur at BAC levels lower than legal limits, and individual tolerance varies.

In practice, breathalcohol testing is widely used by law enforcement and in workplace safety programs to screen for alcohol use, guide further evaluation, and enforce regulatory limits.