Analyzing how your breath can measure your BAC

On Behalf of | Sep 28, 2018 | Drunk Driving Charges

As you sit and contemplate the consequences a OUI arrest in Natick might bring, one question may creep into your mind: How is that law enforcement officials can determine what the alcohol content of your blood is by measuring your breath? Many have come to us here at the office of David. B Zirlen with the same question. To know the answer, you need to understand how it is that what you put in your mouth as a liquid can end up as escaping as breath. 

According to The Alcohol Pharmacology Education Partnership, the exact for of alcohol that you ingest in drinks is known as ethanol. Given that ethanol is a water-soluble compound, it is able to pass through the membranes of the organs of your digestive tract through a process known as passive diffusion. Ethanol molecules are thus able to pass through the lining of your stomach and small intestine and become caught up in the bloodstream, where they eventually reach your heart. 

In your heart, ethanol molecules are mixed into oxygenated blood and then sent to the lungs via the right ventricle. Upon coming in contact with the air in your lungs, some of the ethanol molecules vaporize into a gas, which is then expelled from the body as you breathe. This process continues in order to maintain equilibrium between the contraction of gaseous ethanol in your lungs with that in your blood. 

Ultimately, what this means is that with every breath, the blood-alcohol content of your body goes down. The constantly fluid nature of breath BAC measurements is often used as the basis of the argument challenging breath tests results used against you as evidence. More information on the relationship between alcohol and your body can be found here on our site.