Law enforcement officers in Kentucky and throughout the United States often use roadside breath test machines to determine whether motorists are drinking and driving. If you have taken a breath test, you know first hand how easy it is to blow into the device and get the results.
What you may not know is that breath test results obtained from these machines are not always accurate and could lead to a wrongful arrest and DUI charge.
How do breath tests work?
Roadside breath test machines detect ethanol alcohol in an exhaled breath sample. It then converts this amount into a blood alcohol content level. Studies show, however, that breath devices detect substances with similar methyl structures as well. These substances can alter the BAC level reading leading to inaccurate results.
According to the State University of New York at Potsdam, factors that affect breath test readings include the following:
- Residual food, drink, blood and vomit in the mouth
- Cigarette smoke, gasoline fumes or pollution in the air
- Static interference from cellphones and officer radios
- Temperature of the air
- Relative humidity of the air
- Physical activity
Not only must breath test devices be calibrated regularly for the environment for which they are being used, but law enforcement officers must use the machines properly.
How do breath test readings compare to blood test results?
Studies show that breath test readings may vary by more than 15% from BAC level results obtained from an actual blood test. Furthermore, one in every four people tested using a breath test device will have inflated results.