Breathalyzers Discriminate Against Women -- Part 1

If you have a BAC above .08 in Colorado, you are guilty of drunk driving. Your age, race, and gender do not matter. Perhaps they should. Several scientific studies have indicated that Breathalyzer machines discriminate against women.

In Colorado, if you refuse to take a breath test, you automatically lose your driving privelige. Also, the fact that you refused the test can be used as evidence of your guilt. Trying and failing to blow enough air into the machine is also treated as a refusal. Women have a higher rate of "refusals" reported by the machines than do men.

Breathalyzer machines do not directly measure the amount of air blown by a suspect. They measure the pressure of the suspects breath using a pressure sensor and the amount of time that the pressure is present. As air flows faster, its pressure increases. Mathematically, volume is the quotient of air flow and time. The machine makes assumptions about how hard the suspect is blowing and calculate the volume based on those assumptions. When those assumptions are incorrect, so are the results.

In a study of Breathalyzer test results in Florida, on average, women produced samples that were 20% to 40% lower than men. Women with lower lung capacities are not able to produce the minimum volume of air that the machine needs to complete its analysis. When it doesn't get enough air, the machine reports a refusal. In that same Florida study, women in every age group are twice as likely to be penalized for failing to produce a sufficient breath sample as men.

An equally troubling problem occurs when the machine reports an result, which has been inaccurately calculated. Because the machines computer software does not consider the subject's age, gender or the presence of medical conditions. The machines are inherently inaccurate.

Studies have shown that a 1 degree Centigrade change in body temperature can produce a 7.5% change in the reported BAC. Suspects with higher body temperatures have higher readings while those with lower body temperatures have lower readings.