The Caldarone Law Group, P.A.

The ABC's of BAC measurements

You know that no two people in Naples are alike. How, then, is a breathalyzer device able to come up with an accurate reading for different individuals? This is the question that many clients bring to us here at The Caldarone Law Group, P.A., and it is this question that serves as the basis for many defenses against drunk driving charges. While breathalyzer technology is advanced, that does that not mean it is infallible. Understanding how a breathalyzer device comes up with a BAC reading can help you understand how such a reading may be challenged. 

As has been detailed on this blog in the past, a breathalyzer measures the ethanol alcohol content of your breath. Your breath acquires its ethanol concentration as the ethanol absorbed into your blood vaporizes upon coming in contact with the oxygen in your lungs. As more ethanol is vaporized, its concentration in your blood decreases to the point of achieving an equilibrium with that which is in the air in your lungs. It is that assumed equilibrium that serves as the basis for breathalyzer BAC measurements. 

The blood-to-breath ratio represents how many milliliters of alcohol is in your blood compared to 1 milliliter in your breath. According to the Alcohol Pharmacology Education Partnership, the standard conversion factor that breathalyzer devices use in their measurements is 2100:1. However, in actuality, the blood-to-breath ratio in most can vary between 1500:1 and 3000:1. Factors that influence it can include: 

  • Your age, gender and your current state of intoxication
  • The times at which a measurement is taken
  • The type of breathalyzer device being used

Given the degree of variability that these factors indicate, it is easy to see how you might challenge the validity of a breathalyzer measurement. 

More information on challenging drunk driving charges can be found here on our site. 



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CLG - The Caldarone Law Group, P.A.

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2390 Tamiami Trail North, Suite 216
Naples, FL 34103

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Phone: 239-244-3242
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