Can You Beat a Breath Tester?

Myths and Truths About Changing Breath Tester Readings

Hang around any pub or party long enough, in any country where random driver breath testing exists, and you'll hear all sorts of pseudo-scientific babble about how you can beat breath testers, or the amazing story of a person who hadn't been drinking but was charged with drink driving due to breath tester quirks.

Strangely enough, not all of these stories are inaccurate! There is much truth in some of the 'urban legends' about breath testing - here we separate myth from reality.

Breath Testing Myths

MYTH - Mouthwashing will allow you to beat a breath tester Mouthwash will change a breath tester result, but not in the way that most people hope. Most mouthwashes contain alcohol, which will be blown into the tester and give a much higher than normal reading.

MYTH - Coffee lowers your BAC Coffee won’t change your breath tester reading. However, the caffeine in coffee can help offset the depressive effect of the alcohol.

MYTH - Eating will fool a breath tester Eating before or while drinking does help slow the rate of absorption of alcohol into your system ... but eventually, it all ends up in your blood and then your lungs, where breath testing will detect it just the same.

MYTH - Putting a coin under your tongue will fool a breath tester There is no chemical basis for truth in this.

MYTH - Wearing perfume gave me a reading It is true that environmental contaminants can affect readings on passive (speak-into) breath testers. However, the perfume would have to have been sprayed in the breath tester's vicinity immediately prior.

HALF TRUTH - Diabetics can give false positive readings on breath testers Diabetics often exhale large quantities of acetone, which is a by-product of the fact that their bodies must metabolise fat for energy, because they cannot utilise glucose properly. This acetone can create a breath tester reading - but only on the cheaper semiconductor style breath testing units.

Breath Testing Truths

TRUTH - Hyperventilating will fool a breath tester Studies have noted up to a 23% drop in breath tester reading after hyperventilating. However, if an officer suspects that you’re trying to beat a breath tester, they have the power to detain you for further testing. This is true, but pointless.

TRUTH - Women can have higher breath tester readings than men, but have the same BAC This is true. The ethyl alcohol to 'assumed BAC' conversion is accurate only at a certain hematocrit (red blood cell count). Women generally have a lower hematocrit than men, and will therefore produce higher breath tester readings at the same BAC.

TRUTH - People with dentures have higher breath tester readings This can be true, if the dentures have trapped small pockets of alcohol underneath them.