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Find Out about the possibilities and causes of a false positive Breathalyzer test in Arizona and the importance of Breathalyzer testing in DUI proceedings.

It’s against the law though out the U.S. to drive with a blood or breath alcohol concentration (BAC) of . 08% or more.  A driver who fails a Breathalyzer test can be arrested and tried on Driving Under the Influence (DUI) charges. Some legal and science experts question the validity of Breathalyzer tests because it is a machine and can be affected by several things that can cause a false positive reading.

What is a Breathalyzer?

A breath alcohol test is used to measure how much alcohol is in the air you exhale. This device uses the measurement to estimate how much alcohol is concentrated in your bloodstream. That number, known as your BAC, is your blood alcohol content.

Ethanol (alcohol) is a water-soluble compound. It dissolves readily in water-based solutions, and once it is swallowed, it moves into water spaces throughout the body, including the bloodstream. Ethanol in the veins travels to the heart, then the lungs, where a portion is exhaled.

As the more alcohol you consume increases; the more vaporized alcohol passes out of your lungs. A you breathe out into the Breathalyzer, the devicemeasures the amount of alcohol in your blood.

The average blood-to-breath ratio is about 2100:1. One milliliter of blood has 2100 times more ethanol than 1 milliliter of air from the lungs. This value is used to calculate the blood alcohol level (BAC) from the Breathalyzer test.

How Does A Breathalyzer Test Work?

Most police use a portable electronic Breathalyzer device about the size of your hand for a driver suspected of intoxication to blow into a mouthpiece. The Breathalyzer gives an immediate reading. The Breathalyzer test doesn’t directly measure blood alcohol content. For that to happen, a blood sample is needed. Instead, the Breathalyzer measures the amount of alcohol in someone’s breath.

The handheld device uses a chemical reaction to indicate the level of alcohol-based on a color change. There is a mouthpiece, a tube to blow through, and a sample chamber.

3 Types of Breathalyzers

Most breathalyzers use one of three technologies.

Fuel cell Breathalyzers. A fuel cell measures a subject’s alcohol content by creating a chemical reaction that oxidizes the alcohol in the breath and produces an electrical current. A fuel cell has two platinum electrodes partitioned by a porous acid-electrolyte material. As a subject’s exhaled air passes through the fuel cell, the platinum oxidizes any alcohol present and produces acetic acid, protons, and electrons, which flow through a wire from the platinum electrodes and register the Blood Alcohol Concentration.

The strength of the electric current corresponds to the volume of alcohol present in the sample. Fuel cell Breathalyzers are used by individuals desiring the highest level of accuracy, as well as law enforcement officers for roadside screenings, in substance abuse centers, clinics, and businesses.

An ethanol-specific sensor measures a subject's Blood Alcohol Concentration. Semiconductor sensor technology often involves a tin-oxide material, which is less expensive than platinum fuel cell sensor technology. 

Infrared Spectrometry Spectrometers work by identifying molecules based on the way they absorb infrared light. The ethanol level in a sample is singled out and measured and can determine a subject's alcohol level. Infrared Spectrometry is used in large, tabletop Breathalyzers often found at police stations.

Reliance on Breathalyzer test results

Breathalyzer machines are the most common law enforcement tools used to evaluate an individual’s Blood Alcohol Concentration. Law enforcement agencies rely heavily on Breathalyzer tests to charge individuals with Driving Under the Influence of Alcohol. Prosecutors use Breathalyzer results as the basis for DUI convictions.

A wide variety of outside factors can directly affect the accuracy of breath test results. Studies estimate that 23% of individuals tested using this method will have an actual BAC significantly lower than the BAC reading. Research shows that breathalyzer tests vary at least 15% from actual blood alcohol concentration.

Are Breathalyzer Tests Accurate?

A significant problem with some machines is simple. They identify the ethanol found in alcoholic beverages. But they also identify other substances containing the methyl group structure. Over a hundred compounds are in the human breath at any one time, and 70 to 80 percent contain the methyl group structure. Breathalyzer machines can incorrectly report them as ethyl alcohol. The more different ethyl group substances the device detects, the higher will be the false BAC estimate.

A significant cause of false Breathalyzer results is acetone in the breath. Acetone exists in the breath of most individuals. The Acetone can be high enough to cause false readings in alcohol-breath testing machines.  

Diabetics and people on a diet can have acetone levels hundreds and even thousands of times higher than that in others.

Dieting or Fasting can also cause very high levels of acetone. Research has shown that fasting can increase the acetone level high enough to give a false reading of .06 BAC.

A low-carbohydrate diet can increase acetone levels. The body produces more acetone to compensate for the reduced glucose in the diet. Those who follow the KETO, Atkins, and similar diets intentionally seek to achieve a low carb ketosis condition. This condition promotes the “burning” of fat.

There are many other things known to cause a false positive Breathalyzer reading.

• Trace Amounts of Alcohol in our mouth. If you drank 15 minutes before the test, trace amounts of alcohol in your mouth could lead to an inaccurate result. 
• Smoking can also affect results. So can products that contain alcohol, like mouthwash and breath fresheners.
• Foreign Substances present in the mouth that contain alcohol can produce false positives because the amount of alcohol vapor they emit may be greater than the amount exhaled from the lungs. For example, some mouthwashes, breath fresheners, and toothache medicines contain alcohol and can skew readings. 
• Calibration. Breathalyzers must be calibrated periodically, and batteries must be replaced to maintain accuracy.
• Software. Breathalyzers run on special software, just as computers rely on operating systems, resulting in occasional bugs and glitches. 
• Human Error.   As easy as breathalyzers are to use, they still require some attention to detail. 
• Environmental Factors can cause false results. Errors can be triggered by the presence of paint fumes, varnish, and chemicals such as plastics and adhesives.

A False Positive Test Result May Be Able to Be Suppressed

Two major pieces of evidence are used to convict a person of DUI. The first is the testimony of the arresting police officer regarding their initial reasons for stopping the driver, the results of their field sobriety test, and their reason for administering the Breathalyzer test. The second is the results of the Breathalyzer test.

Arizona’s implied consent laws state that, you are presumed to have implied consent to chemical testing if you are arrested for drunk driving. If you refuse testing, your driving privilege can be suspended. 

The lack of accuracy in Breathalyzer test results can be an integral part of a strong defense to dispute DUI charges. Many different circumstances can affect a BAC reading taken from a Breathalyzer test, so there are many alternatives for challenging the test results. These challenges can lead to negotiating a lesser charge or penalty, or even dismiss of charges in some cases.

If you face drunk driving charges in Arizona because you failed a breath test, you owe it to yourself to speak to an Arizona DUI defense lawyer. An experienced attorney specializing in DUI defense should have the expertise necessary to challenge the Breathalyzer testing procedure, the numerical test results, and the reliability of the Breathalyzer device itself.