How Breath Test Machines Work

Instead of a dry, boring article, the following is an excerpt from a recent interview with Attorney Leckerman on the subject.

Interviewer: Before we continue with this-even on a treadmill, it will say what’s your height and weight and some personal factors about you. Would breath machines have parameters where you could dial in a person’s height, weight, sex and all the other stuff, so it has a remote chance of giving an accurate reading?

Kevin Leckerman: With some machines, you can input that information, but it doesn’t come into the equation per se. With breath test results, they’re not necessarily affected by height or weight, most likely weight, and a number of other scientific factors, which are utilized in what’s called the Widmark Equation or the Forrest Equation-this is called “retrograde extrapolation.” In other words, you can take a breath test result, program in somebody’s body mass, somebody’s alcohol intake, the concentration of that alcohol, the period of time over which the alcohol is consumed, and really come up with an idea of what the person’s breath or blood alcohol concentration was at the time of driving, in comparison to the time that the testing was done. The testing could have been done hours later.

That’s when those factors come into play. When it comes to breath testing itself, weight really doesn’t factor into it, gender doesn’t factor into it; although, gender and weight certainly do factor into a person’s ability to consume alcohol and eliminate it the body and not feel an alcohol peak that could affect one’s motor skills.

The partition ratio of 2100 to 1 is just an average. Some people’s partition ratio can be 1800 to 1 or 2500 to 1. In other words, the machine is programmed to assume that everybody has this same ratio; however, if you have a higher ratio, e.g. 2500 to 1, than what’s programmed into the machine, you would actually have more alcohol in your system than what the is measuring or calculating. If you have a lower partition ratio, then you may have essentially less alcohol in your system than what the machine is calculating.

Beyond that, you want to know if the person has physical issues such as reflux disease. Gastro-esophageal reflux disease could cause the person to regurgitate raw alcohol or alcohol laden gases into the mouth, which will then be mixed in with the breath sample. The machine cannot distinguish between the raw alcohol regurgitated and the actual breath sample.

Some of these machines have been equipped with or programmed with something called a slope detector or mouth alcohol detector. In the courses that I’ve taken, where I’ve been able to test these breath test devices, I have done my own experimentation essentially to see if the machine can detect raw alcohol. I’ve taken raw alcohol and swished it around in my mouth. The alcohol may have been drinking alcohol or simply mouthwash. I let it dissipate for about five minutes and then I breathed into the machines. On multiple occasions for two different machines, the device found me to be over the legal limit, when I didn’t have a drop of alcohol in my blood.

The other factor affecting results deals with blood. Fresh blood in a person’s mouth will have alcohol molecules present that could be mixed with the breath sample and artificially inflate the breath result. The machine is not going to be able to differentiate between the alcohol that’s in the blood in your mouth and the alcohol that’s in your breath.

Another factorwould be chemicals that you’ve been exposed to during the day that contain volatile organic chemicals or “VOCs.” You breathe them in and your bodybreaks down these chemicals. Potentially, the alcohol that results from the break-down of these chemicals can be misread by the breath test machine as alcohol in your body that is affecting your motor skills, when they actually have no effect.

Interviewer: Oh, so if you went to a nail salon and got your nails done and later that night you went out, you might have acetone in the nail polish remover from the nail salon in your lungs, let’s say. Or if you work in an industrial place where you deal with paint thinners and that kind of stuff.

Kevin Leckerman: That’s somewhat right. Acetone, paint thinners, paint, primer, and certain chemicals that are used for stripping paints or de-greasing motor engines all have volatile organic compounds in them. If you’re breathing them in for a long enough period of time, they will build to a certain level in your blood stream. Over time, your body’s going to break them down into basic chemical components that are exhaled, which could be misread by the breath test machine as something that’s either alcohol or a substance similar enough to alcohol thatcan’t be differentiated by the breath testing device.

Interviewer: What about if you burp or you belch or you throw up because you’re nervous or you’re upset when you’re doing a breath test? Will that affect it?

Kevin Leckerman: It certainly can. It all depends on if you had alcohol in your stomach at the time that you vomited or belched. Alcohol typically empties from the stomach within two hours from the time that it is ingested. If you don’t have any food in your stomach, then it’s going to be absorbed and eliminated from your stomach in a quicker manner. But after two hours, generally people don’t have alcohol in the stomach anymore. So, even if you belched or vomited, there may not be an effect on the breath test machine. If there still is alcohol remaining in your stomach,burping, vomiting or belching will have that same effect that the gastroesophageal reflux disease will have. You are putting raw alcohol into your mouth, which may not dissipate by the time that you’re breathing into the machine. In most states like New Jersey and Pennsylvania, there is a 20 minute observation/deprivation period that each officer must follow. This 20 minute period is supposed to give the raw alcohol that’s in a person’s mouth enough time to dissipate, so it won’t have an effect on the machine. According to the scientific studies, that 20 minute period is generally sufficient. Yet, if somebody has residual food in his or her mouth, the 20 minute deprivation period may not be enough time to allow that alcohol to dissipate.

Interviewer: Would someone eating bread, and let’s say they have dentures or gets caught, little pieces get caught in the back of their teeth, is that enough to significantly alter a breath test result?

Kevin Leckerman: Bread has yeast in it, and yeast does produce alcohol. There is a small amount of alcohol in bread. If you eat bread, chew it and have it in your mouth at the time that you blow into the breath test machine, some devices will register a small amount of alcohol. I’ve seen it in person. I’ve done it when I’ve tested some of these devices. The amount is generally not a large amount, but if there’s a situation with a breath test device where you may be on the borderline for the legal limit, then that little bit of alcohol from the bread could certainly affect the final result.

Interviewer: Since you said that different people have different partition ratios, depending on what they ate and all this other stuff their breath test result will be different, how accurate are these machines? Are they .1, .01? Are they very inaccurate? What have you seen as the level?

Kevin Leckerman: Yes, each machine does have a range of error. Each machine has a certain tolerance range or a certain range of error that the manufacturers know of and they should be giving that information to the police and to the defense attorney. The manufacturers have studied their machines to understand the range of error. It can be at 5%, or can be more than a 5% range of error. Many states will determine in their laws that a specific range of error is acceptable. If the breath test results fall within this calculated range of error, then they are valid breath test results. In places, such as New Jersey, the courts really have ignored the fact that there is a margin of error which could take the lowest breath test reading below the legal limit.

Interviewer: Practically, what have you seen or have been able to comment on the true error of the machine?

Kevin Leckerman: Well, its true error can only be established through study. So, as I said, the manufacturer should have conducted its own studies. When these machines are utilized by each state, they first have gone through a process with either the National Highway Traffic Safety Administration (NHTSA) or an international organization, like OIML, that is supposed to act as a third party to determine whether these breath test machines are meeting scientific. If they’ve passed the third party testing, then these products are placed on a conforming products list that the federal government puts out. The states will then choose, based on which products have been approved by the federal government, as to which one they want to utilize. Some states have no particular machine that’s used. Some states have a list of machines that each police department can individually determine will be used for their breath testing.

Interviewer: All right. In Pennsylvania and the counties that you practice in, what breath test machines are used?

Kevin Leckerman: In Pennsylvania the machines that I’ve come across have been the DataMaster, the Intoxilizer 5000, the Intoxilizer 5000 EN and Intoxilizer 8000.

Interviewer: How about New Jersey?

Kevin Leckerman: In New Jersey the machine that is exclusively used is the Alcotest 7110.

Interviewer: How long does it take for any alcohol you’ve drunk to get out of your stomach and into your bloodstream?

Kevin Leckerman: On the average, two hours or less.