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Getting pulled over by a law enforcement officer on suspicion of drinking and driving can certainly cause your heart to race. This is especially true if you have recently enjoyed a few drinks. You may get asked to participate in a roadside breath test, which officers use to determine whether you blood alcohol content level is over the legal limit of 0.08. Yet, what you may not know is that certain factors can cause breath test devices to yield inaccurate results.

According to research performed by the State University of New York at Potsdam, readings from breath test devices can vary by more than 15% when compared to the results obtained from actual blood tests. That means that at least one out of every four people who use a breath test device will show inflated blood alcohol content results. This may lead to a wrongful DUI arrest.

How do breath test devices work?

When you exhale into a breath test device, the machine measures the amount of ethanol alcohol in your breath sample. The device then converts this amount into a blood alcohol content level without actually taking a blood sample. The problem lies in the fact that other factors influence these breath test readings.

Factors that alter breath test results

In addition to measuring ethanol alcohol, the breath test device also picks up other substances with a similar molecular structure. Factors that can alter breath test results include the following:

  • Residual blood, vomit and food in the mouth
  • Inhaling gasoline and cleaning fumes
  • Cigarette smoke, pollution and dirt in the air
  • Static interference from officer radios or cellphones
  • The air’s temperature and relative humidity

Proper machine calibration is critical to breath test result accuracy, and to avoiding an unlawful arrest. Furthermore, if the officer using the device does not know how to use the machine properly, it can lead to unreliable readings.

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