| Want to trick a breath machine into a low | | | | |
| test result? Or make sure that you're not | | | | Dr. Michael Hlastala, Professor of |
| causing a false high reading? Not that | | | | Physiology, Biophysics and Medicine at the |
| difficult, says a law firm of San Diego DUI | | | | University of Washington has gone farther and |
| attorneys and lawyers: just control your | | | | concluded: |
| breathing. | | | | |
| | | | "By far, the most overlooked error in breath |
| The simple fact is that these breath machines | | | | testing for alcohol is the pattern of |
| which determine guilt or innocence in DUI | | | | breathing... The concentration of alcohol |
| cases are not exactly the reliable devices | | | | changes considerably during the breath... The |
| that law enforcement would have us believe. | | | | first part of the breath, after discarding |
| There are dozens of factors that can cause | | | | the dead space, has an alcohol concentration |
| false test results. An example of that | | | | much lower than the equivalent BAC |
| unreliability is the fact that the results | | | | (blood-alcohol concentration). Whereas, the |
| will vary depending upon the breathing | | | | last part of the breath has an alcohol |
| pattern of the person being tested. This has | | | | concentration that is much higher than the |
| been confirmed in a number of scientific | | | | equivalent BAC. The last part of the breath |
| studies. | | | | can be over 50% above the alcohol level... |
| | | | Thus, a breath tester reading of 0.14% taken |
| In one, for example, a group of men drank | | | | from the last part of the breath may indicate |
| moderate doses of alcohol and their | | | | that the blood level is only 0.09%." 9(6) The |
| blood-alcohol levels were then measured by | | | | Champion 16 (1985). |
| gas chromatographic analysis of their breath. | | | | |
| The breathing techniques were then varied. | | | | Many police officers know this. They also |
| The results indicated that holding your | | | | know that if the machine contradicts their |
| breath for 30 seconds before exhaling | | | | judgement that the person they arrested is |
| increased the blood-alcohol level by 15.7%. | | | | intoxicated, they won't look good. So when |
| Hyperventilating for 20 seconds immediately | | | | they tell the arrestee to blow into the |
| before the analyses of breath, on the other | | | | machine's mouthpiece, they'll yell at him, |
| hand, decreased the level by 10.6%. Keeping | | | | "Keep breathing! Breathe harder! Harder!" As |
| the mouth closed for five minutes and using | | | | Professor Hlastala has found, this ensures |
| shallow nasal breathing resulted in | | | | that the breath captured by the machine will |
| increasing the blood-alcohol level by 7.3%, | | | | be from the bottom of the lungs, near the |
| and testing after a slow, 20-second | | | | alveolar sacs, which will be richest in |
| exhalation increased levels by 2%. ("How | | | | alcohol. With the higher alcohol |
| Breathing Techniques Can Influence the | | | | concentration, the machine will give a higher |
| Results of Breath-Alcohol Analyses", 22(4) | | | | -- but inaccurate -- reading. |
| Medical Science and the Law 275.) | | | | |