Across the United States, it is illegal to operate a motor vehicle with a blood alcohol content (BAC) of 0.08 percent or higher. If a driver’s BAC is over this legal limit, he or she may be charged with drunk driving.
How do law enforcement agents determine your BAC? This is where breath tests come in to play. Breath alcohol tests measure your blood to breath ratio. In theory, the breath alcohol/blood alcohol ratio should be 2,100:1.
Since the days of Socrates, doctors have known that the study of human breath was important to diagnosing a patient. In fact, breath is one of the most accurate ways to measure someone’s BAC. This is because blood flows through the lungs, where gas is exchanged. The molecules from the alcohol in the blood are transferred to the lungs and expelled during breathing.
The first breath alcohol test was developed in 1938 by Dr. R. N. Harger. It was appropriately named The Drunkometer. In 1941, the Intoximeter was invented by Glenn Forrester. This device was closely followed by the Alcometer, invented by Professor Leon Greenberg. All of the machines measured the breath alcohol to blood alcohol levels of lung air samples.
Before these breath-testing devices were invented, the only way to determine BAC was through blood or urine testing, both of which were expensive and time-consuming. In 1954, Robert Borkenstein, an officer with the Indiana State Police, invented the Breathalyzer. Due to its portability, the device quickly became popular at police departments across the country.
The early breath testers obtained samples by requiring the individual to blow up a balloon. This provided the tester with a deep air lung sample. The air from the balloon was then let out over photoelectric chemicals, which changed color if there was alcohol present. The deeper the colors changed, the higher the BAC. However, the results of this device were often challenged because the test was known to produce false results. Indeed, just using mouthwash that contained alcohol before giving the breath sample could result is a false, inflated reading.
By the 1980s, as attorneys successfully challenged the results in court, these chemical breath tests became less common and today, infrared breath tests are used by police departments around the country.
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