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History of Breath Tests
Let Me Catch My Breath!
Before the invention of the modern breathalyzer in the 1950s, determining if someone was too intoxicated to operate a motor vehicle was incredibly subjective. It took decades for law enforcement technology to catch up with one of our most pervasive crimes. This post will take you through the history of breath tests, as used by prosecutors, in the United States.
The study of human breath originated in the classic studies of French chemist Antoine Lavoisier conducted between 1774 and 1785. Aside from defining respiration as the uptake of O2 and the output of CO2, Lavoisier’s invention, the “gasometer,” was the first instrument to make accurate measurements of the respiration gases. In the 1850s, physician John Hutchinson modified Lavoisier’s gasometer to make the first spirometer for measuring the volume of a patient’s breath. In 1874, British physician Francis Anstie, trapped the human breath and applied colorimetric analysis to study the fate of alcohol in the body. Building on this knowledge, actual analytical analysis of expired breath for blood alcohol concentration was first proposed in the 1920’s by Bogen. [Crow, K., Batt, R., Human Metabolism of Alcohol, Volume I; Pharmacokinetics, Medicolegal Aspects, and General Interests, CRC Press, 1977.]
Early versions of quantitative breath testing machines included the Drunkometer® (1938), Breathalyzer® (1954), and Alkotest® tube (1954). These early methods employed wet chemistry; generally, oxidation with potassium permanganate, potassium dichromate, or iodine pentoxide. Gas chromatography was employed in the early 1970’s, and, in 1974, infrared (IR) technology took the lead in popularity.
Breath Tests and Driving
In 1974, the National Highway Traffic Safety Administration (NHTSA) published the “Standards for Devices to Measure Breath Alcohol,” and listed devices that met the Federally mandated criteria. State programs applying for Highway Safety Funding were restricted to using equipment listed as meeting the Federal criteria. In 1984, state programs were no longer restricted to using devices listed as meeting the Federal criteria, though most states continue to limit their consideration to equipment on the list. And in 1993, NHTSA modified their specifications, changed the levels at which the machines were evaluated (0.020%, 0.040%, 0.08% and 0.160% instead of 0.050%, 0.101% and 0.151%), added a test for acetone detection, and expanded their definition of “alcohol” to included low molecular weight alcohol such as methanol and isopropanol.
There are a variety of breath alcohol testing instruments available to a user agency. Many of the evidential devices are listed in the Federal Register Conforming Products List of Evidential Breath Measurement Devices. [NHTSA, 2002, 67 FR 62091.]
Other devices (which may also be on the Conforming Products List) include alcohol screening devices designed to give an approximation of the alcohol level, passive alcohol sensors designed to detect the presence of alcohol only, and ignition interlock devices designed to prevent a driver from starting a vehicle if a certain breath alcohol concentration (BrAC) is present. Devices which are to be used as Ignition Interlock Devices must pass the Federal Specifications. [National Highway Safety Administration, Model Specifications for Breath Alcohol Ignition Interlock Devices (BAIIDs). 1992, Federal Register, 57(67), 11772-11787.]
Breath testing technology, on modern instruments, is either via a Taguchi semiconductor, fuel cell, infrared detection, or a combination of infrared and fuel cell. All of these technologies have been in use in science for decades. However, it has only been in the last few decades that the technology has been adapted for breath alcohol testing in a law enforcement setting. By far, the most common analytical technology utilized by these applications are, metal-oxide semiconductor [SC], infrared spectrophotometry (IR) and electrochemical oxidation/fuel cells (EC). In some machines both IR and EC technologies are employed.
Types of Breath Alcohol Testing Machines
Intoxilyzer® 5000 (64, 66, 68, EN)
Draeger® 7110 MK-III
IR and EC
IR and EC
Point to Note: There are two major categories of screening test devices:
- Passive. Passive devices merely measure the air space around the suspect, and do not require the subject to deliver a breath sample directly into the device.
- Active. Active devices require the subject to blow directly into the device. Active devices are especially popular in the law enforcement field, since they are portable, low cost, and can be used in the field with ease.
Pros and Cons of Screening Devices
Pros:When it comes to roadside testers, most agencies use either EC or SC technology since the analytical unit is small and compact, allowing its use in handheld devices. These screening devices, commonly called Preliminary Alcohol Sensors (PAS), are becoming an increasingly more popular investigative tool used by police officers in driving under the influence (DUI) cases.
Cons:There is no safeguard to ensure that the tested air is essentially alveolar in composition. Thus, the device can easily be measuring a sample contaminated with mouth alcohol, and the results will be falsely elevated.
In addition, there are several chemicals in the breath that are oxidized/detected in the fuel cell/Taguchi semiconductor and contribute to a true alcohol reading. For example, acetaldehyde, the breakdown product of ethyl alcohol is found in the human breath and gives a numerical reading on many screening devices. Some screening device manuals state that their device is “alcohol specific.” This generally means that the device detects the class of compounds called “alcohols” rather than ethyl alcohol specifically. Methanol, isopropanol and ethanol, all compounds which are chemically considered “alcohols” will also generate a reading on a fuel cell device.
To further complicate matters, small amounts of ethyl alcohol and other compounds are produced in the body as a by-product of normal body functioning even without alcohol consumption. This endogenous alcohol can register 0.01% or slightly more on a screening device. This fact is especially concerning, considering some states use 0.01% as their “zero tolerance” law limit for drivers under 21, and often allows the use of the screening devices for evidence, often absent the standard procedures generally in place to ensure reliability.
As you can see, this small device is a major player in any DUI case. It is imperitive that you have a skilled criminal defense attorney on your side. Call the Monder Law Group today.