The Temperature Problem in Breath Alcohol

Posted On June 12, 2023 Charles Ramsay

There’s a major problem in breath alcohol testing— the problem of breath temperature. 

You can have a higher alcohol measurement, due to no fault of your own, simply by having a slightly elevated breath temperature. 

In the lab, breath alcohol machines are tested against breath simulators that create a reference alcohol vapor at 34 °C. But this isn’t the temperature of normal human breath. Most studies find that the breath temperature varies from 32 - 36 °C, with the average coming in at around 35 °C.

For every degree (°C) increase in body temperature, your breath alcohol increases by ~ 8.6%. 

In one study, scientists immersed subjects into a hot tub and measured the increase in breath alcohol as their body temperature increased. Scientists found that as the temperature of the subject increased, their breath alcohol increased to be 23% higher than their blood alcohol.

What’s the solution to variable breath temperatures?

Some states, like Alabama, correct for breath temperatures that are higher than the reference value of 34 °C. One of their breath machines, the Draeger Alcotest 7110 MKIII, automatically measures and lowers the final value of the breath alcohol based on the person’s breath temperature.

If a person’s breath temperature is running high, the machine will automatically calculate and adjust the final measurement downward. When the breath alcohol is measured on Alabama’s DMT (which doesn’t measure breath temperature), they automatically subtract 10% from the lower of the two samples to account for the possibility of a higher breath temperature.

Unfortunately, Minnesota’s breath machine (the DMT) doesn’t adjust for breath temperature, and the state fails to compensate for the variability in any way. 

Justice and fairness demand that the appropriate adjustment takes place. A person shouldn’t be penalized because their breath temperature was different than the reference value.

At Ramsay Law, we hold the state to a higher standard. If the state wants to use the numbers from a machine to take away your license or liberty, they must account for the variability of your breath temperature.

If you’ve been affected by the state’s inadequate breath machines, call Ramsay Law — we get results.

Daniel Koewler