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What Causes False Breath Test Results?

By , March 28th, 2019

All breath tests used in the Criminal Justice system work on basically the same principle. A sample of a person’s breath is introduced to the electrochemical cell and the alcohol reacts with the cell to produce electricity. The breathalyzer measures the amount of electricity produced and uses a mathematical formula to convert that to an estimated blood alcohol level.

These breathalyzers are used at the police station to test drunk drivers, on the side of the road to justify arresting someone for DUI, by probation officers screening offenders, in ignition interlock devices installed in the vehicles of person’s convicted of DUI and in many other situations as well. All of these machines work on the same basic principles and are (to some degree) vulnerable to the same problems.

Breathalyzers measure minute amounts of alcohol in a subject’s breath and are extremely sensitive. Exposure to even trace amounts of alcohol can trigger a result. That is why trace amounts of alcohol in your saliva, on your skin or in the air can trigger or elevate alcohol readings.

Mouth alcohol is a term used to define, alcohol that is trapped in your saliva, mouth or throat rather than your blood. After you consume alcohol there is a significant amount of alcohol trapped in your saliva for up to 40 minutes after drinking. If a person blows into a breathalyzer during this 40 minute window then the machine will measure the alcohol in the saliva and add that to any blood alcohol reading. Wearing dentures, braces, chewing gum, retainers ect. are all items that can trap mouth alcohol in your mouth for longer than the 40 minutes period.

Mouth alcohol sources include: Drinking alcohol, using alcohol based mouth washes, or eating items that contain trace amounts of alcohol such as processed breads (white bread or honey buns), fruit cups, vanilla extract and some juices. If you would like to see a video where we test foods and measure their affect on a breathalyzer check out this video.

Burping, belching, vomitting, GERDs, acid reflux ect. can all effect a breathlayzer by introducing stomach alcohol. Breathalyzers are designed to detect faint traces of alcohol in your breath, the fumes from alcohol in a person’s stomach are much more potent then the fumes in your breath. If a person burps, belches, vomits or regurgitates after consuming alcohol, those more potent fumes will be introduced into their breath sample and increase the breathalyzer results.

Acid re-flux, GERD’s and other medical conditions can increase the chances that stomach fumes are being released into the esophagus and thus into the breath. This can happen without a person being aware that it is happening, unlike burping or vomiting where you can feel it happening. Burp, belching, regurgitating, vomiting,  GERD’s, Acid re-flux ect will only affect a breathalyzer if there is alcohol inside a person’s stomach. This condition will not affect readings unless a person has been consuming alcohol recently.

Ambient alcohol is alcohol that gets introduced into the breathalyzer from the air. When these products get used on your skin or in the air around you, the alcohol can evaporate and be introduced into the breath sample. This can be from many difference sources including alcohol based windshield washer fluid, hand sanitize, sunscreen, various cosmetics and aerosols. Check out this video where we demonstrate how various cosmetics create false readings on a breathalyzer.

Breathalyzers will measure many different types of alcohols including ethol alcohol, methanol, denatured alcohol and even some other chemicals. While most of these types of alcohols are poisonous and are not likely to be found in mouth alcohol, they are common in ambient alcohol situations. There may even be some other non-alcohol chemicals that create false positives, like the chemicals found in Banana Boat Cool-Dry Sport Sunscreen.

Breathalyzer tests at the police station (like the EC/IR II) have many checks and procedures designed to catch or limit the affect of these false readings. However, the portable breath tests used by police and ignition interlock tests do not have most of these safe guards and these tests are particularly vulnerable to these types of false readings. 

If you have been charged with crime in Northern Virginia, contact Nichols & Green Pllc to find out whether any of these defenses or issues may apply in your situation.



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