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Blood test vs. breath test: Comparing the results

On Behalf of | Feb 27, 2020 | Dui/dwai |

Getting pulled over by law enforcement can certainly make your heart race, especially if the officer asks you to take a breath test. Law enforcement officers use roadside breath tests to determine whether your blood alcohol content level is at or above 0.08, the legal limit in Colorado. While the best way to obtain your blood alcohol content level is to take an actual blood sample, it is impossible to do so while pulled over on the roadside. Studies question the accuracy of breath test device readings. 

According to the State University of New York at Potsdam show that blood test results and breath test readings may vary by more than 15%. Furthermore, one in every four people who take breath tests show elevated results. This discrepancy could result in a wrongful DUI arrest and potential conviction. 

Breath tests work by measuring the amount of ethanol in an exhaled breath sample. This substance is found in alcoholic beverages, yet, there are other substances in the body and in the environment that have similar methyl structures and may skew the results. This includes the following: 

  • Residual food, drink, vomit or blood in the mouth 
  • Dirt, pollution in the air 
  • Relative humidity and temperature of the air 
  • Cigarette smoke, gasoline fumes, cleaning fluids and paint removers 

Officers administering the test must do so properly in order to obtain accurate results as well. Furthermore, breath test devices must be calibrated regularly. It is important to keep these in mind when and if officers ask you to submit to a breath test.