Principles of Testing

When a person drinks alcohol it shows up in the breath because it gets absorbed from the mouth, stomach and intestines into the bloodstream. As the blood goes through the lungs, some of the alcohol moves across the membranes of the lung's air sacs called the alveoli, into the air as the alcohol evaporates as a volatile. The concentration of the alcohol in the alveolar air is related to the concentration of the alcohol in the blood being exhaled and can be detected by the breath alcohol-testing device - Intoxilyzer.

Now, these machines are monitored by a Quality Assurance Specialist (QAS) tested on a regular basis by the police agencies responsible for them. Like any piece of machinery, it is not uncommon for a machine to have a problem and to be pulled out of service for repair to the laboratory or sometimes back to the manufacturer. The only way to determine if the machine was working properly is to view its records from before and after the arrest.

Breath testing provides an alcohol concentration values printout to provide immediate results. However, like any piece of machinery there is variability in the scientific community over the accuracy and precision of these breath machines which include proper testing procedure, temperature, and individual human body variances.

Inherent Margin of Error: The Intoxilyzer 5000 and 8000 have an acknowledged possible 10% margin of error from the true reading.

Power Source & Radio Frequency Interference: The Intoxilyzer can be affected by its proximity to other devices emitting radio waves that may affect the accuracy.

Mouth Alcohol: Alcohol in your mouth from such things as, chewing tobacco, denture, and mouth wash may also result in incorrect alcohol readings.

Physical Condition: Your medical condition or exposure to certain substances may affect the accuracy of the Intoxilyzer such as diabetes.

The Average Person Myth: Body temperature for the Intoxilyzer assumes that expired breath temperature is 93.2 degrees Celsius where each degree of breath reading above that could result in a higher than the true breath reading. Then there is a person's breathing pattern of how an individual exhales into an Intoxilyzer can cause an artificially higher reading.