The Science Behind Breathalyzers

We often associate breathalyzers with roadside stops, flashing police lights, and the anxiety of whether one is under or over the legal limit. But how do these small devices translate human breath into a measurable blood alcohol concentration (BAC)? Let’s dive into the intricate science behind breathalyzers, exploring their mechanics, reliability, and margin of error.

History of the Breathalyzer

The first breathalyzer, named the “Drunkometer,” was developed in 1938 by Dr. Rolla Harger. However, it was Robert Borkenstein’s invention in 1954, aptly named the “Breathalyzer”, that became the basis for modern devices used worldwide. While there have been developments to the breathalyzer, such as the infrared absorption to measure alcohol, the technology is largely identical to its original iteration.

How Does a Breathalyzer Work?

The principle behind a breathalyzer is relatively straightforward, yet ingeniously scientific. When you consume alcohol, it enters your bloodstream and eventually reaches your lungs. As you breathe out, a small fraction of this alcohol travels out through your breath. The breathalyzer’s primary task is to measure this alcohol content and equate it to your BAC.

There are primarily three types of breathalyzer technologies:

  1. Semiconductor Oxide-based Breathalyzers: These have a sensor coated with a material that reacts to alcohol. When alcohol comes in contact with this sensor, its resistance changes, producing a reading. While they are affordable, they are less accurate and more suited for personal use.
  2. Fuel-cell Breathalyzers: These are commonly used by law enforcement. When alcohol in the breath reacts with the fuel cell, it produces an electric current. The intensity of this current is directly proportional to the alcohol content in the breath, giving a more accurate reading.
  3. Infrared Spectrophotometer Breathalyzers: Used mainly in police stations, these machines identify molecules based on the way they absorb IR light. Different substances, including alcohol, have unique absorption patterns, allowing the machine to determine BAC.

The Margin of Error

While breathalyzers offer a quick and non-invasive method to estimate BAC, they are not without their limitations:

  • Interfering Substances: Other substances, like mouthwash, medications, or certain foods, can trigger a false positive due to their alcohol content.
  • Breath vs. Blood: Breathalyzers estimate BAC based on breath, making them less accurate than direct blood tests. This disparity can sometimes lead to discrepancies between the device’s reading and an individual’s actual impairment.
  • Calibration: Just as a musical instrument needs regular tuning, breathalyzers require frequent calibration to ensure accuracy. A device not calibrated correctly can give erroneous readings.

The Science Isn’t Settled

The breathalyzer, while an incredible feat of scientific engineering, is not infallible. Its readings, though useful for quick assessments, have inherent limitations. Anyone facing legal consequences based on a breathalyzer test should be aware of these nuances and might consider seeking legal and scientific expertise to ensure accurate interpretation and fairness.

If you’re facing a DUI charge, then use the form at the top of this page or call (800) 384-5297 for a free consultation.