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Breath Alcohol Test – Indications, Procedure, Results

Last updated: February 8, 2026 Medically reviewed by: RxHarun Orthopedic Specialist Doctor Reading time: 3 min read

A breath alcohol test determines how much alcohol is in your blood. The test measures the amount of alcohol in the air you breathe out (exhale).

How the Test is Performed

There are many brands of breath alcohol tests. Each one uses a different method to test the level of alcohol in the breath. The machine may be electronic or manual.

One common tester is the balloon type. You blow up the balloon with one breath until it is full. You then release the air into a glass tube. The tube is filled with bands of yellow crystals. The bands in the tube change colors (from yellow to green), depending on the alcohol content. Carefully read the instructions before using the test to make sure you get an accurate result.

If an electronic alcohol meter is used, follow the instructions that come with the meter.

How to Prepare for the Test

Wait 15 minutes after drinking an alcoholic beverage and 1 minute after smoking before starting the test.

How the Test will Feel

There is no discomfort.

Why the Test is Performed

When you drink alcohol, the amount of alcohol in your blood goes up. This is called your blood-alcohol level.

When the amount of alcohol in the blood reaches 0.02% to 0.03%, you may feel a relaxing “high.”

When that percentage reaches 0.05% to 0.10%, you have:

  • Reduced muscle coordination
  • A longer reaction time
  • Impaired judgment

Driving and operating machinery when you’re drunk (intoxicated) is dangerous. A person with an alcohol level of 0.08% and above is considered legally drunk in most states. (Some states have lower levels than others.)

The alcohol content of exhaled air accurately reflects the alcohol content of the blood.

Normal Results

Normal is when the blood alcohol level is not elevated.

What Abnormal Results Mean

With the balloon method:

  • 1 green band means that the blood-alcohol level is 0.05% or lower
  • 2 green bands mean a level of 0.05% to 0.10%
  • 3 green bands mean a level between 0.10% and 0.15%

Risks

There are no risks with a breath alcohol test.

Considerations

The test does not measure the driving abilities of a person. Driving abilities vary among people with the same blood-alcohol level. Some people with a level below 0.05% may not be able to safely drive. For people who only drink sometimes, judgment problems occur at a level of just 0.02%.

The breath alcohol test helps you to know how much alcohol it takes to raise the blood-alcohol level to a dangerous level. Each person’s response to alcohol varies. The test may help you make better decisions about driving after drinking.

 

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area later with a custom field named _rx_references.

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Written by Dr. Harun Ar Rashid, MD - Arthritis, Bones, Joints Pain, Trauma, and Internal Medicine Specialist

Dr. Md. Harun Ar Rashid, MPH, MD, PhD, is a highly respected medical specialist celebrated for his exceptional clinical expertise and unwavering commitment to patient care. With advanced qualifications including MPH, MD, and PhD, he integrates cutting-edge research with a compassionate approach to medicine, ensuring that every patient receives personalized and effective treatment. His extensive training and hands-on experience enable him to diagnose complex conditions accurately and develop innovative treatment strategies tailored to individual needs. In addition to his clinical practice, Dr. Harun Ar Rashid is dedicated to medical education and research, writing and inventory creative thinking, innovative idea, critical care managementing make in his community to outreach, often participating in initiatives that promote health awareness and advance medical knowledge. His career is a testament to the high standards represented by his credentials, and he continues to contribute significantly to his field, driving improvements in both patient outcomes and healthcare practices. Born and educated in Bangladesh, Dr. Rashid earned his BPT from the University of Dhaka before pursuing postgraduate training internationally. He completed his MD in Internal Medicine at King’s College London, where he developed a special interest in inflammatory arthritis and metabolic bone disease. He then undertook a PhD in Orthopedic Science at the University of Oxford, conducting pioneering research on cytokine signaling pathways in rheumatoid arthritis. Following his doctoral studies, Dr. Rashid returned to clinical work with a fellowship in interventional pain management at the Rx University School of Medicine, refining his skills in image-guided joint injections and minimally invasive pain-relief techniques.