The breath alcohol analyzer, or breathalyzer, has been used for years to measure blood alcohol content, or BAC. "Breathalyzer" was actually once used only as a brand name, but has come to be used for all machines of this type in most cases and is now used as a generic term in addition to the brand itself.
The first breath alcohol analyzer was invented as early as 1938. Called the "Drunkometer," the machine collected breath in a balloon and then pumped it through a solution of potassium permanganate; if ethanol was present, the solution, sensitive to the chemical construction, changed color.
Although revolutionary for its time, the Drunkometer had one significant drawback; it was difficult or impossible to tell how much alcohol was present in the sample, and therefore most prosecutors had to rely on other evidence to secure a conviction of drunkenness, such as eyewitness testimonies. It was clear that a way of quantifying the amount of alcohol in a sample was necessary.
In 1954, the first analyzer was marketed; this machine used chemical oxidation and photometry, and could determine not only the presence of alcohol but also the concentration of ethanol in the sample. While many of today's breathalyzers rely on infrared spectroscopy to determine concentrations, there are several different types on the market now. Another type, such as AlcoHAWK breath alcohol analyzers, uses semiconductors or fuel cells to do the monitoring.
Although it is commonly assumed that a breathalyzer test proves BAC, this is not true. What a breathalyzer does is estimate the amount of ethanol in a sample; it requires a blood test to prove BAC. However, the breathalyzer does provide law enforcement officers with a powerful field tool that allows them to estimate BAC and determine if a blood test is in order.
If an individual is tested and receives a score of .08 or higher, he or she is usually considered to be under the influence. This translates into .08 grams of alcohol per 210 liters of breath. It is generally agreed that people with a BAC of .08 or higher are impaired in their ability to operate a motor vehicle. In most states, breathalyzer results are admissible in court and are used to back up blood tests, which may be performed at a later time than the breathalyzer, thereby lowering the results as the body metabolizes the alcohol.
Some breathalyzers have limitations and do not always give accurate results. Recent studies have shown that heavy breathing precipitated by exercise can significantly lower the BAC reading obtained by a breathalyzer. In one study, 20 seconds of hyperventilation decreased the BAC reading by 32%. On the other hand, holding the breath may increase the reading by 28%. It is obvious that false readings can be obtained in some cases, although most breathalyzer results are confirmed by blood tests.
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