Law enforcement officers in Texas and throughout the nation often use breath tests to determine whether motorists are under the influence of alcohol. If an officer pulls you over on suspicion of drunk driving and your blood alcohol content level measures above the legal limit, you may get charged with a DUI.
Yet, studies show that breath test device readings are not always accurate, and may in fact lead to a wrongful DUI charge. According to researchers at the State University of New York at Potsdam, one in every four people tested using a handheld breath test device had inflated blood alcohol content results.
How do breath tests compare to blood tests?
While blood tests directly measure the amount of ethanol alcohol in your system, breath tests use an indirect method. When you blow into the breath test device tube, the machine detects the amount of ethanol alcohol in your exhaled sample. It then converts that number into a BAC level.
When researchers compared blood test results to breath test readings, however, they found a variance of up to 15%. This difference could lead to a wrongful DUI charge.
What factors play a role?
One factor that leads to the difference between readings is that breath test devices detect other substances that are similar in structure to ethanol alcohol. Other factors include the following:
- Pollution in the air
- Temperature and relative humidity of the air
- Cigarette smoke and fumes from gasoline, cleaners and paint thinner
- Residual blood, vomit and food in the mouth
- Electrical interference from officer radios and cellphones
In some cases, law officers do not use the devices properly or fail to calibrate the machines which could lead to wrongful results as well.
If you take a roadside breath test, keep in mind that the results may not be accurate depending on the circumstances of your situation.