Many BAC readings can be incorrect at the time you are tested following a DUI arrest, with the reading being as much as 23 percent higher than it should be due to inaccurate breathalyzer testing. There are a variety of reasons for these problems tracing back to the short comings of the machine design. A growing number of states across the country have begun to pull the black curtain back and look behind the rhetoric of the manufactures, including requiring the source code for the software that runs the machines; a growing number of courts are finding the truth regarding these machines and suppressing BAC results. The following are a few basic problems to look for.
Mouth Alcohol
Mouth alcohol can be caused for a variety of reasons including eating bread, certain medical conditions to burping or GERD. All of these have been shown to significantly raise BAC levels. If mouth alcohol has not been absorbed it can cause the instrument to yield an artificially high BAC number. It is very difficult for breathalyzers to determine where the source of alcohol in the mouth is coming from, and it makes a significant difference if the alcohol in the exhaled air is coming from the lungs or from the mouth and throat; the computer in the gizmo assumes that all the air it is analyzing is coming directly from the lungs, the alveolar air. This is problematic in mouth alcohol cases or oral hygiene products such as Listerine: the computer analyzes the exhaled air, but when the air passes through the mouth, it absorbs the alcohol particles from the mouthwash and leads to an artificially high BAC level which will then be used against you in court.
Homeostatic Variables
While incorrect alcohol readings secondary to mouth alcohol is a significant problem with breathalyzer machines, the machines likewise do not account for variable partition ratios in the subject which can result in substantially inaccurate readings. The partition ratio (ratio between BAC and breath alcohol content) is correlated at 2100:1, but subjects may range from 1500:1 to 2400:1 or higher, leaving a large margin of error. Consider, if one’s actual BAC level is .08, the breathalyzer could identify this range from a .065 to a .09. However, if one’s actual level is under the legal limit, .07, and the personal ratio is 1500:1, you will end up with a BAC level of .10, above the legal limit, through no fault of your own. A partition ratio can fluctuate far a variety of reasons including age, health, or whether the subject is in alcohol absorptive/post absorptive phase to name but a few. Dr. A.W. Jones, Assistant Professor in Experimental Alcohol Research at Sweden’s Karolinska Institute has confirmed the variations of blood to breath alcohol rations in different individuals and in the same person from time to time.
After conducting extensive studies, British physicians have concluded the following:
“the blood/breath ratio should be regarded as nothing more than a statistical convenience suitable for defining the limits of a particular universe. Its use to derive individual blood alcohol levels from breath alcohol levels has little scientific justification and its use in this way for law enforcement can only be deplored. We reiterate our view that breath analysis is not an acceptable method for accurately determining blood alcohol concentrations” [Alobaidi, Hill and Payne, Significance of Variations in Blood/Breath Partition Coefficient of Alcohol, 2 British Medical Journal 1479, 1481 (December 18, 1976)]
Interfering Components
Breathalyzers are designed to look for the ethyl alcohol molecule but they can be fooled by substances that appear similar in chemical composition to alcohol, thus misreading these substances as containing alcohol content. Acetone is one of the most common substances that can confuse breathalyzers and it is found in a large number of diabetics. Additionally, people who are exposed to certain types of paint fumes, ie. painters, can also confuse the breathalyzer and cause it to register a BAC level that is higher than it should be.
In addition to the foregoing, there are many other reasons why the results of a BAC reading may not be accurate; there will be ongoing debate as to the effectiveness of the machines continue to be tested, but as long as the machines allegedly assist the government in keeping drunk drivers off the road, much of the foregoing falls upon deaf ears.