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BAC: What is it, and How is it Used?

beer alcohol

If you are like the typical individual, you probably are not aware of what BAC means. Everyone should be aware of BAC, how it is used, and the implications that come with it. 

What is Blood Alcohol Content?

Blood alcohol content (BAC) measures the amount of alcohol in a person’s system. As alcohol is consumed, it is absorbed from the stomach and intestines into the bloodstream. BAC is expressed as the weight of ethanol (pure alcohol) in grams per 100 milliliters of blood. For instance, a BAC of 0.08% means 0.08 grams of alcohol per 100 ml of blood.

BAC rises as more alcohol is consumed and falls as the liver metabolizes the alcohol. BAC and the effects of alcohol are influenced by factors like body weight, gender, medications, and stomach contents. Generally, higher BAC levels indicate greater impairment of motor skills. 

Fortunately, there is a legal limit to curb this. If you ever get hurt in an accident caused by a drunk driver, you should contact a drunk driving accident lawyer to help you evaluate your options.

How Different BAC Levels Affect Drivers

When you take alcohol, your BAC levels tend to rise. The average individual will experience the following effects at different BAC levels:

  • 0.02%: Some loss of judgment, relaxation of inhibitions, slight body warmth, altered mood.
  • 0.06%: Exaggerated behavior, may have a minor loss of balance and muscle coordination; usually a good feeling, lowered alertness.
  • 0.08%: Impaired muscle coordination and difficulty detecting danger, impaired judgment, possible dizziness, blurred vision.
  • 0.10%: Clear deterioration of reaction time and control, slurred speech, poor coordination, and slowed thinking.
  • 0.15%: Far less muscle control than usual, vomiting may occur, major loss of balance, impaired sensory perception.
  • 0.30%: Confusion, disorientation, loss of awareness, and memory blackout possible, impaired consciousness.
  • 0.40%+: Onset of coma, severe respiratory depression, memory blackout, possible death from alcohol poisoning.

How is BAC Measured?

There are several methods for measuring BAC:

  • Breathalyzer: This is the most common method. The person breathes into the device, which estimates BAC by analyzing the alcohol content of the breath. Police frequently use roadside breathalyzers for suspected drunk drivers.
  • Blood test: Drawing blood and directly measuring alcohol levels provides a highly accurate BAC reading. Blood tests are often done at police stations or hospitals.
  • Urine test: While not as precise as a blood test, a urine sample can indicate if alcohol is present in the body. This may be used in situations where a breath or blood test is unavailable.

Any of the methods above, provides an objective measure of intoxication. The results give insight into whether the person’s physical and mental faculties are impaired by alcohol.

Legal Implications of BAC


In the United States, the legal limit is 0.08%. If your BAC level is higher than this amount, you are deemed intoxicated in every state. For commercial drivers, the limit is 0.04%.

Additionally, most states have a zero-tolerance policy that applies to specific drivers. Usually, it is for teenage drivers below 21 years who are not supposed to be drinking alcohol.

Higher BAC levels result in more severe criminal charges, such as aggravated DUI or vehicular manslaughter. Refusing to submit to BAC testing may also lead to legal consequences, including license suspension.

Bottom Line

BAC quantification has proven vital for traffic safety and enforcing DUI laws. By setting legal limits on drivers’ allowable blood alcohol concentration, governments aim to prevent alcohol-impaired driving and its potentially fatal outcomes. However, if you are ever involved in a drunk driving incident, you should contact an accident lawyer to help you.

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