What Can Trigger a “False Positive” on an Ignition Interlock Device?

What Can Trigger a “False Positive” on an Ignition Interlock Device?

Arizona requires anyone who has been convicted of a DUI to have a certified ignition interlock device installed in their vehicle for a period of time in order to be legally allowed to drive again.

A type of breathalyzer, ignition interlock devices are wired to a vehicle’s ignition and only allow the engine to begin running if a breath sample with a BrAC of under .02 is provided. The goal of these devices is to ensure that only sober drivers are behind the wheel.

However, ignition interlock devices are not capable of differentiating between alcohol contained in adult beverages and alcohol that occurs naturally in everyday items. Instead, they detect any methyl-alcohol components in an individual’s breath, regardless of the original source. This means that any of the following could potentially trigger a BrAC over the allowable limit:

  • Mouthwash
  • Breath mints
  • Cologne or perfumes
  • Inhalers
  • Auto fluids, such as coolant, windshield wiper fluid, and radiator fluid
  • Dark chocolate
  • Hand sanitizer
  • High yeast foods
  • Energy drinks
  • Non-alcoholic beer, wine, and liquors
  • Red wine vinegar
  • Spicy foods

False readings can also occur for the following reasons:

  • Smoking – Regular smokers produce extra acetaldehyde, which can be detected as alcohol.
  • Fevers – High body temperature can cause an inaccurate reading.
  • Poor breath sample – Failing to provide a breath sample in the exact manner required by the interlock device installed can trigger an incorrect reading.

Preventing False Positive Readings

Anyone with an ignition interlock device installed in their vehicle should take time to read the ingredients in the products they are using and the food and drinks they are ingesting. Anything that could potentially trigger a false reading should be avoided anytime they might need to drive.

If a positive breath sample is recorded as a result of possible contaminant, the driver should fully rinse their mouth with plain water and wait several minutes before providing a new breath sample.



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