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Do breath test devices yield accurate results?

On Behalf of | Jun 4, 2020 | Firm News |

If you have been pulled over on suspicion of drinking and driving, you know firsthand the emotions involved with such an experience. You may feel overwhelmed when asked to submit to a breath test or a number of other tests law enforcement officers use to determine your blood alcohol content level. 

Law enforcement officers use breath tests to determine whether your BAC level is over the legal limit of 0.08. Yet, studies show that not all breath test results are reliable or even accurate. According to the State University of New York at Potsdam, one in four people who take a breath test will have inflated results. 

Breath test results 

When an officer asks you to exhale into a breath test device, the machine detects the amount of ethanol alcohol in the sample. It then converts this into a blood alcohol content level, rather than measuring the amount of alcohol in the blood directly through a blood sample. When comparing breath test device readings to blood test results, the results differed by more than 15% in some cases. This inflation could be enough to charge an innocent person of a DUI. 

Factors that affect results 

The problem lies in the fact that breath test devices measure more than just ethanol alcohol. It also picks up other methyl structures and can be influenced by other factors in the environment. These include the following: 

  • Static electricity from law enforcement radios and cellphones 
  • Pollution, cigarette smoke and dirt in the air 
  • Residual vomit, blood, food and drink left in the mouth 
  • Fumes from cleaners, paint, paint remover and gasoline 
  • Relative humidity of the air 

Breath test devices may give erroneous results if they are not calibrated correctly or if law enforcement officers use the machine properly.