Understanding the intricacies of breathalyzer testing and its potential implications is crucial in ensuring justice in DUI cases. Here, we delve into a recent study exploring the impact of the volume of air provided during testing on breath alcohol readings.
There are numerous factors that can artificially elevate or artificially lower breath alcohol readings when compared to a true blood alcohol concentration. A recent study has shown that the sheer volume of air that you provide can have a significant impact on what the ultimate reading is. Really, we shouldn’t be too surprised at the results of the study considering the fact that breath alcohol concentration is looking at what is colloquially known as deep lung air, the alveolar air above the blood vessels at the bottom of the lungs. The more air that you produce, the closer the air is going to be to the bottom of the lungs.
There is, however, a lot of debate in the scientific community about whether or not that alveolar error is actually a true approximation of blood alcohol concentration, as opposed to a higher concentration of alcohol because it is collected and stored in the mucus for longer periods than it would be just eliminating and evaporating from the blood vessels at the bottom of the lungs. The recent study looked at breath testing equipment from California, Missouri, Iowa, and Minnesota. The volume requirements of the equipment ranged from 1.3 L maximum to an unlimited maximum amount of air, and the study looked at individuals who provided breath samples into the instruments to determine how the volume of air that they provided contributed to the ultimate reading.
Individuals with the same blood alcohol concentration blew into four separate instruments, producing larger volumes of breath each time they blew. For an instrument used in California that required 1.35 L of air, the breath alcohol concentration registered on the instrument was .06. The Missouri instrument, using 1.5 L of air, got a reading of .06 but slightly higher on the third digit. The Iowa instrument, which had a maximum breath volume requirement of 3 L, got a reading for the same individual of .072, and in Minnesota, where there is an unlimited volume of air that can be provided at a 1.5 L minimum, the breath alcohol reading was .083.
The result of this study clearly demonstrates that a person who might otherwise be tested to be innocent in one jurisdiction may be tested to be guilty in another, simply based on the volume of air provided. In British Columbia, the roadside breathalyzers that are used have a collective volume of 1.3 L of air, but there is also no maximum requirement. These are just the minimum sampling requirements, and you can continue to blow breath into the device after the amount of air that is required has been provided. I’ve often demonstrated this myself by blowing before the device clicks to automatically capture the sample because the click engages at a later point in time than the minimum volume has actually been achieved.
For a person naïve to the mechanism to provide a sample into a roadside breathalyzer, however, they’re not necessarily going to be able to produce the type of volume. They may not know that they’ve hit the minimum volume requirements and naturally taper off their breath before the click engages, and police officers are going to direct a person to continue blowing until the click engages. This means that people are going to provide samples that likely overestimate the reading that they would’ve got had they stopped once they achieved the minimum volume. This demonstrates that innocent people can be issued immediate roadside prohibitions in Canada simply because an officer tells them to keep blowing into the roadside breathalyzer.