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When thinking of blood alcohol concentration (BAC), images of someone taking a breathalyzer on the side of the road may come to mind. But measuring one's blood alcohol level is more than just blowing into a breathalyzer and getting a more precise analysis of blood alcohol can often save lives.

Learn what BAC is, why it matters, and what it entails.

What is Blood Alcohol Concentration?

Blood alcohol concentration (BAC) is the metric used in measuring how much alcohol is in your bloodstream. More specifically, BAC measures how much alcohol per 100 milliliters of blood. If you have a blood alcohol level of 0.05, that means that there is 50 mg per dL of alcohol in your system, or 0.05%.

Almost every state has the same BAC limit: 0.08. Except for Utah, which rests at a lower 0.05. According to the Federal Motor Carrier Safety Administration (FMCSA), commercial drivers (like truckers) can only show 0.04 BAC.

Measuring Blood Alcohol Concentration

There are a few methods to measure BAC. With the aforementioned breathalyzer, a person blows air into an apparatus that measures BAC. Administering a blow test is ideal for determining if someone is driving under the influence or partaking in underage drinking.

While getting your blood alcohol level tested certainly pertains to legal matters and police suspicions, it's also useful for medical reasons. For example, if you've been drinking heavily and require immediate medical attention, doctors measuring your BAC can better treat you.

"We usually see the BAC test in drunk driving cases, but it can also help us determine if a patient is experiencing blood alcohol poisoning. A BAC above 0.3 percent can cause coma and respiratory depression. If we determine that your blood alcohol level is in the higher range and you are having signs and symptoms of ethanol intoxication, we need to consider immediate hospital evaluation, as the individual's life can be in extreme danger," says Dr. Long Q. Wang, a specialist in family medicine at Summit Health.

Standard ways of measuring blood alcohol levels via BAC are breathalyzers, urine samples, and blood samples.

Explaining BAC Levels

What does each standard measurement on the BAC scale correspond to? Here is a helpful guide:

  • 0.03 - This is just under the legal limit for commercial drivers in the United States. People with this BAC experience impairment in vision, judgment and feel "buzzed."
  • 0.05 - This is over the legal limit for commercial drivers and those driving in Utah. Those who register 0.05 are "loose," have a challenging time making decisions, and have slower reflexes.
  • 0.08 - This is the legal limit for drivers in the remaining 49 states. This is where you're considered legally drunk. Reflexes and reaction times are slower, and judgment is affected.
  • 0.10 - In addition to even slower reaction times, speech is slurred, and overall thinking is heavily impaired.
  • 0.20 - This is where people may become ill, vomit, feel confused, dizzy, and may even blackout.
  • 0.40 - Those with 0.40 BAC are in grave danger and likely require hospitalization. At this point, alcohol poisoning may set in, putting a patient's life at risk. It can result in coma and even death.

What Does This Mean?

When you take a drink, the excess alcohol absorbs into the bloodstream after being processed by the liver. Hence, the more you drink, the higher the alcohol level in your bloodstream.

Keep in mind there are a few key factors that can significantly affect BAC measurements. For example, your BAC increases the older you are, even if it's the same alcohol content.

Other factors include:

  • Gender
  • Food consumption before drinking
  • Weight
  • Genetics
  • Drug use
  • Medications
  • Alcohol content
  • Number of drinks consumed

The Dangers of Alcohol and How Summit Health Can Help

Determining a patient's BAC can be crucial in specific emergencies like altered mental status. If left unmeasured and untreated, an individual can experience severe impairment, alcohol poisoning, coma, and even death. There is never an acceptable BAC level to operating a car or other vehicles. Never drink and drive.

A significant issue regarding alcohol is its ties to masking stress and other negative feelings. Alcohol is a depressant so that it can provide temporary feelings of sedation and calm, depending on the individual. This can often lead to people depending on alcohol as a crutch, even helping them get to sleep at night.

However, getting in the regular habit of drinking to relieve stress is extremely dangerous and can have long-term adverse physical and mental effects. Regular alcohol consumption can lead to liver disease, heart damage, and birth defects. 

We highly recommend taking advantage of comprehensive mental health services to alleviate stress, depression, anxiety, and grief rather than depending on the temporary effects of alcohol.

Explore our various urgent care centers throughout the New Jersey and New York area.