Blood alcohol content or BAC is the amount of alcohol present in the blood. The breath alcohol tester is a BAC testing instrument that analyzes a sample of breath to determine blood alcohol content.  The concentration of the alcohol in breath will be proportional to its concentration in the blood.

While it is a good idea to be aware of alcohol consumption, it is very important to understand that many factors contribute to blood alcohol content or BAC. Factors that affect BAC include:

  • Gender – Women do not have as much of the enzyme dehydrogenase, which breaks down alcohol in the stomach. Female hormone levels also impact the body’s ability to process alcohol. Additionally, women tend to have a higher percentage of body fat and a lower percentage of water. For these reasons, women tend to have higher BAC levels than men drinking the same amount.
  • Rate of Consumption & Potency of Drinks – The faster alcohol is consumed, the faster BAC will rise. Drink strength is also a variable that will affect BAC.
  • Weight and Body Type – While people with lower body weight tend to be affected more by a given amount of alcohol; individuals with a lower percentage of body fat will have lower BAC levels than those with a higher percentage of body fat. Fatty tissue is low in water content and doesn’t absorb alcohol, so the alcohol remains in the bloodstream longer.
  • Mood – Mood can impact the way the body processes alcohol, which can affect BAC.  Stress may cause a diversion of blood from the stomach and small intestines to the muscles, and can temporarily slow down the rate of alcohol absorption into the bloodstream. Once the body becomes calm, however, a surge in your BAC may occur.
  • Food & Mixers – Drinking alcohol on an empty stomach will result in higher BAC levels. Food slows the absorption of alcohol into the bloodstream by keeping the alcohol in the stomach longer. Carbonated drinks such as mixed drinks with sodas may increase the rate at which alcohol passes through your stomach and result in a higher BAC.
  • Alcohol Tolerance – Alcohol tolerance is only a decrease in the body’s sensitivity to alcohol’s effects, and not a measure of how alcohol is processed in the body. While someone who demonstrates functional tolerance may not seem to be as intoxicated as someone without such tolerance, in both bodies the liver is eliminating alcohol at the same rate. That means someone who seems to be handling their drinks can have higher BAC levels than expected.

Additional Resources: Alcohol Testing