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Blood Alcohol Content (BAC) vs. Breath Alcohol Content (BrAC): What's the Difference?

Many people may be familiar with the concept and terminology of blood alcohol content, but when it comes to differentiating BAC from Breath Alcohol Content (BrAC) most people do not know the difference.

Both BAC and BrAC are methods of measuring a person's alcohol content, but there are important differences. Here is an overview:

  • Blood Alcohol Content (BAC): This is a straightforward measurement of alcohol content per milliliter of blood. For example, if a suspected DUI offender has a BAC of .05, this means that they have .05 grams of alcohol per 100 ml of blood. In Utah, this would be considered legally intoxicated. The other 49 states have a higher threshold of .08 BAC for legal intoxication. A measurement at or above .40 BAC is a potentially fatal amount of alcohol. BAC is measured via a urine or blood test. It can also be extrapolated via a BrAC test or breathalyzer. 
  • Breath Alcohol Content (BrAC): A BrAC test is also a method for measuring the alcohol content in your system. However, it differs from BAC because a BrAC test measures the alcohol content in your exhalations. Whenever you have a drink, the alcohol is absorbed into your blood. Then, it’s carried via your bloodstream to your brain and lungs. This means that the alcohol will be present in your breath when you breathe out after drinking. A breathalyzer can then measure the amount of alcohol in your breath and use that measurement to estimate your BAC.

As described, a BrAC test is used to get to Blood Alcohol Content, which is measured using blood or urine tests. Often, law enforcement will request a breathalyzer test if a driver is suspected of driving under the influence. A urine or blood test may follow to further strengthen the case.

If you’re unsure of the regulations around legal blood alcohol content, familiarize yourself so you can avoid a conviction for DUI, DWI, OWI, OUI, or OVI. Of course, the best way to avoid an issue is to avoid drinking and driving at all.

Guidelines and charts may help you know how to pace your drinking so you can remain under the limit, but these guidelines are not foolproof. Alcohol affects everyone differently, and a chart’s recommendations may not hold true for your own circumstances. Find an alternative way home if you are ever in doubt. The risk is not worth it.


How do various BAC levels impact you?

Most people are familiar with the concept of excessive intoxication and how it impacts them. The problem is, many are not aware of how much of an impact even a slight intoxication level can have. With just a .02 percent BAC (well below the legal limit in every state), your judgment can be impaired. You will be easily distracted, which is dangerous if you’re on the road. You may also not be able to keep up with tasks, which presents additional risk if driving. This amount of alcohol is not something most would consider intoxicated, but it can still create issues and render you unsafe to drive. 

There are tips and tricks you can employ to help keep your blood alcohol content from getting to a dangerous level, such as:

  • Make sure to eat: Drinking on an empty stomach means there is nothing in your system to absorb an influx of alcohol. Thus, it will hit your bloodstream fast and make you feel the impact more quickly. Food helps by absorbing the alcohol and preventing it from spreading so fast.
  • Take your time: Slamming drinks is a surefire way to get drunk fast. Even though everyone metabolizes differently, drinking multiple drinks in a short period is dangerous. Spread them out through the night and you will likely prevent over-intoxication. Additionally, you may not feel as hungover in the morning!
  • Drink plenty of water: Staying hydrated is beneficial for many reasons. For one, it prevents you from drinking as much alcohol. Also, it can help your body maintain proper hydration, preventing headaches in the morning. 
  • Familiarize yourself with any medications you take: Some medications interact with alcohol and make you feel the effects to a greater degree. Carefully read your medication to ensure that drinking while taking it is safe. If you’re unsure, your pharmacist will be able to answer any questions.


What can impact BrAC levels? 

As explained, BrAC is measured via your breath after drinking. Your BAC is then extrapolated from the BrAC level.

Ignition interlock users test their BrAC every time they start their vehicle, and during random retests on most trips. The device will measure alcohol in your breath, but there are some other factors that might impact your results. These seemingly harmless activities could result in a false positive:

  • Mouthwash or breath sprays: These products often contain alcohol in small amounts. Since you spray them directly in your mouth, the alcohol present in your breath may register a higher BAC than expected.
  • Hand sanitizer: Similar to mouthwash, most types of hand sanitizer contain alcohol. Using it just before testing can impact your results.
  • Perfumes and colognes: The fragrance in the air could linger and impact your test. Don't apply perfume or cologne right before testing. 


How to pass your BrAC or BAC test

Interlock users are required to test their BrAC before starting their car. Since all failures are reported to the state monitoring authority, it’s crucial to avoid these failures if possible. To avoid getting a high reading on your next test, try these tip:

  • Stay sober: This is the simplest, and surest, way to avoid a failed test. If you must drink, drink responsibly and follow the tips above for the best result.
  • Rinse your mouth and wait to test: If you have been drinking or using mouthwash, rinse your mouth with water and wait 10-15 minutes to take your BrAC test to avoid a positive reading. 


What should I do if I failed a BAC test?

If you’re facing criminal charges for DUI, you may want to consider hiring an attorney to assist you through the process. If you have an interlock device and have a failure you think is not accurate, you may want to contact customer support.