goMDnow Logo

A breath alcohol test is a non-invasive and rapid method of determining the amount of alcohol in an individual's bloodstream. It is commonly used to determine whether an individual has consumed alcohol and is therefore impaired. In this blog, you will explore what blood alcohol concentration is, why an alcohol breath test is used, the legal limit of it, and the factors that can affect its accuracy.

What is a BAC?

BAC stands for "blood alcohol concentration," which is a measure of the amount of alcohol that is present in a person's bloodstream. BAC is typically expressed as a percentage, and it is used as a way to determine a person's level of impairment due to alcohol consumption. BAC alcohol is typically measured using a Breathalyzer, which works by detecting the level of alcohol in the blood by testing the exhaled air after 15 minutes of alcohol consumption and converting it into an electrical signal.

Why is a Breath Alcohol Test Used?

Breath alcohol tests are used for a variety of reasons. One of the most common uses is in the enforcement of laws related to driving under the influence (DUI) of alcohol. In these situations, law enforcement officers use breath alcohol tests to determine whether a driver has a BAC level that exceeds the legal limit. Breath alcohol tests are also used in workplaces, such as in the transportation industry, where employees are required to have a BAC level below a certain limit while on the job.

What is the legal limit of BAC?

The legal limit for BAC levels varies by jurisdiction, but it is typically 0.08% in the United States for drivers who are 21 years of age or older. Commercial drivers, such as truck drivers, are subject to a lower legal limit of 0.04% BAC.

Factors That Affect Breath Alcohol Test

Out of several factors that can affect the accuracy of a breath alcohol test, a few most significant factors are mentioned below:

Body Weight

Body weight can have an impact on blood alcohol concentration (BAC) because the amount of alcohol a person consumes is distributed throughout the body's water content. In general, the more body weight a person has, the more water they have in their body, which can dilute the alcohol in their bloodstream and lead to a lower BAC.


Women tend to have a higher BAC than men after consuming the same amount of alcohol due to differences in body composition and metabolism. Men have low proportionality of body fats and more amount of water in their bodies as compared to women, due to which alcohol gets dissolved into it.

Rate of consumption

Drinking alcohol rapidly can lead to a higher BAC than drinking the same amount over a longer period.

Medical Conditions

Certain medical conditions affect the either by impairing the body's ability to metabolize alcohol or by altering the way alcohol is absorbed into the bloodstream. These conditions include liver diseases, diabetes, gastrointestinal disorders, and kidney diseases.

Read about:

Six Tips to Prepare for a Drug and Alcohol Test

Standard alcohol cut off level


Drug tests are commonly used in law enforcement and workplace settings to promote safety and prevent accidents. It's important to be aware of the factors that can affect the accuracy of these tests including breath and alcohol test and to understand that the results are not always a perfect indicator of a person's level of impairment.

goMDnow is committed to providing accurate and reliable drug and alcohol testing services to help individuals and organizations maintain safe and healthy environments.

goMDnow blog