Breathalysers

Breath Alcohol Analyser is a device for estimating blood alcohol content (BAC) from a breath sample. The U.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.

A breath analyser can detect BAC because alcohol does not change chemical  composition within the body. Instead, it is absorbed by the stomach and intestines to enter the bloodstream. Inside the bloodstream it travels throughout the body, including lung sacs called alveoli, where alcohol molecules are mixed with exhaled air.

The ratio for alcohol found in the breath to alcohol in the blood is 2,100:1. Hence, by measuring the concentration of alcohol in the breath, the breath analyser can easily calculate blood alcohol content. The legal limit in most states is 0.08% BAC.

Law enforcement has used breathalysers for many years, but a breath analyser can also be handy for individuals. Party guests can avail themselves of a breathalyser to ensure they can legally and safely get behind the wheel to drive home. If the reading is still too high, a simple waiting period can help one avoid a costly DUI (driving under the influence violation) or worse. Institutions and business with policies of random drug testing might use a breath analyser, especially among employees that are entrusted with the care of others, work with potentially dangerous machinery or operate vehicles.

There are many models of consumer or personal breath alcohol testers on the market. These hand-held devices are generally less expensive than the devices used by law enforcement. Most retail consumer breath testers use semiconductor-based sensing technology, which is less expensive, less accurate, and less reliable than fuel cell and infrared devices. While semiconductor devices can sense the presence of breath alcohol, they do not provide as reliable measures of BAC.

Infrared instruments are also known as “evidentiary breath testers” and generally produce court-admissible results. Other instruments, usually hand held in design, are known as “preliminary breath testers” (PBT), and their results, while valuable to an officer attempting to establish probable cause for a drunk driving arrest, are generally not admissible in court.

Originally published here.

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