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Do Breath Test Devices Yield Accurate Results?

April 22, 2020

Law enforcement officers in Indiana and throughout the country use roadside breath tests to measure your blood alcohol content level if they pull you over on suspicion of drinking and driving. Using exhaled air, the device measures the amount of ethanol alcohol contained in the breath sample. It then converts the amount into a BAC level.

Yet, studies show that readings from breath test devices can be inaccurate. Erroneous readings may lead to a wrongful DUI arrest and possible conviction. Knowing how these devices work may help you avoid wrongful charges.

Looking at the Facts

According to researchers from the State University of New York at Potsdam, one in four people who take a test will have inflated breath test results. Some readings may be as much as 15% higher than an actual blood test. What is to blame for the discrepancy between breath test readings and blood test results?

Accounting for the Factors

A multitude of factors can alter breath test readings. According to researchers, subjects that had no alcohol to drink had results of up to 0.05% after simply eating specific bread products. Other factors that can alter breath test readings include the following:

  • Inhaled cleaning fumes and gasoline fumes
  • Cigarette smoke and other types of pollution
  • Food, blood, drink or vomit in the mouth
  • Relative humidity and temperature of the air
  • Interference from officer radios and cellphones

Not only must law enforcement calibrate breath test devices regularly, but also they must adjust the machines to the specific temperature and climate. In addition, the officer administering the test must use the device correctly. Individual differences may also be to blame, such as your hematocrit level and activity level.

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