What Can Cause A False Breath Test Result?

Residual alcohol in a suspect’s mouth or throat is a common cause of falsely inflated breath test results.  The breath test device assumes when it captures a breath sample that the alcohol in the sample came from the deep lung or “alveolar” air.  The breath test device applies a formula to translate the results from the breath sample in an attempt to measure how much alcohol is in the suspect’s blood.  The formula is based on an average ratio of alcohol in the breath to alcohol in the blood.  This is the partition ratio and it assumes that there will be 2100 units of alcohol for every one unit measured by the breath testing device.

The residual or mouth alcohol causes some serious problems, but one not recognized by the breath testing device.  When a suspect has mouth alcohol present at the time he gives a sample of his breath, the breath testing device will read that alcohol as part of the breath sample, assume it came from the person’s deep lung air, and produce a falsely high test result.

This is a common problem when the suspect has recently drank alcohol, or recently used a breath freshener or mouthwash.  Other causes can be dentures, chewing tobacco, vomiting, acid reflux, or periodontal disease.  However, mouth alcohol will usually dissipate due to saliva naturally rinsing one’s mouth.  In Ohio, police are required to observe the suspect for at least 20 minutes before giving a breath test. 

If you are charged with drunk driving, OVI, or DUI in Ohio, it is critical for you to contact an experienced Columbus DUI attorney.

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