Are breath test machine readings accurate?

On Behalf of | Feb 14, 2021 | Firm News

Georgia law enforcement officers have several methods they use to determine whether you are driving under the influence of drugs or alcohol. One of the most common are roadside breath tests. These small machines use an exhaled breath sample to measure your blood alcohol content level, and if it is over the legal limit of 0.08, they may arrest and charge you with a DUI. 

Yet, researchers show that breath test readings are not always accurate, and a wrongful result could lead to a wrongful DUI charge. According to the State University of New York at Potsdam, one in four people who take a breath test show inflated breath test results when compared to an actual blood test. 

How do breath tests work?

In order to determine your BAC level, breath tests measure the amount of ethanol alcohol in your breath sample rather than measure it directly from your blood. The problem lies in the fact that they pick up other substances that have similar methyl structures, including substances found in your saliva. 

When comparing blood test results to breath test readings, researchers found more than a 15% discrepancy. 

What factors influence breath test results?

Breath test results may be inaccurate if an officer fails to calibrate the machine correctly or does not use the device properly. The following can also affect breath test readings: 

  • Relative humidity and temperature of the air 
  • Residual food, vomit, blood or drink in the mouth 
  • Fumes from gasoline, cleaners, paint or paint thinners 
  • Electrical interference from cellphones or officers’ radios 
  • Dirt or pollution in the air 

Your hematocrit levels or amount of physical activity can also affect breath test readings. 

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