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A breath alcohol test is an estimate of your blood alcohol concentration (BAC). The test measures the amount of alcohol in the air that you breathe out (exhale).
You can measure your own breath alcohol level with a simple handheld device. If the device is calibrated and used according to the manufacturer's directions, it can provide an accurate estimate of your blood alcohol level. There are different types of devices available. You can get simple devices meant for home use and professional devices like those used by police for suspected drunk drivers.
Within minutes after you drink alcohol, your blood alcohol concentration starts to rise. Unlike food, alcohol is absorbed directly through the walls of the stomach, goes into the bloodstream, and travels throughout your body and to your brain. This allows blood alcohol levels to increase quickly.
The amount of alcohol in your blood reaches its highest level about 60 minutes after you drink. But food in your stomach may increase the amount of time it takes for the blood alcohol to reach its highest level. Most of the alcohol is broken down in the liver. The rest of it is passed out of your body in urine and your exhaled breath.
You can buy breath alcohol devices to measure your BAC at many pharmacies or through the Internet.
Many bars and restaurants provide their customers with free alcohol breath tests using one of these two methods. The devices are also used to monitor people in an alcohol rehabilitation center or hospital.
The breath alcohol self-test is used to estimate your blood alcohol concentration (BAC). The results can help you decide whether it is safe to drive. This estimate of blood alcohol is not intended to represent your actual driving abilities. Your driving may be impaired even with a low BAC level, such as below 0.05.
The breath alcohol test offers one piece of information to help you make a safe decision about drinking and driving. The safest decision is always not to drive if you have been drinking.
BAC is commonly used by police and other legal authorities to determine whether a person is legally impaired and should not drive. A blood alcohol concentration (BAC) 0.08 or greater is considered legally impaired for adults in the United States. But the legal BAC limit for people under age 18 may be lower, such as 0.02.
To obtain a breath alcohol reading:
If your test has only the glass tube, blow through the tube for the amount of time in the instructions. Use one long breath, not several small breaths. Then look at the colored crystals to get the reading.
The amount of alcohol in your breath is based on the number of bands that change color and on the intensity of the color change.
Follow the specific instructions that come with the device. With most meters, you:
The results appear as a digital readout in a display window. It may show a red or green "traffic light" or an estimated blood alcohol concentration (BAC). After you obtain the first reading, press the reset button and do a second test.
There is no pain from a breath alcohol test.
There is no chance for problems from taking this test. You might feel slightly lightheaded after taking the test.
A breath alcohol test is an estimate of your blood alcohol concentration (BAC). The test measures the amount of alcohol in the air that you breathe out (exhale). Results are ready right away.
To read the glass tube breath alcohol test, count the number of yellow bands of crystals that turn green.
Some electronic devices have a "traffic light" display.
Some devices display the results as an estimated BAC numerical value.
No home test is 100% accurate. The results may not be helpful if you:
Your blood alcohol level depends on:
A blood alcohol test is more accurate than a breath alcohol test. To learn more, see the topic Blood Alcohol.
Driving under the influence of alcohol (DUI) can be deadly. Alcohol is involved in nearly half of all fatal highway accidents. Even mild intoxication can impair your ability to drive safely. At 0.06 BAC, your judgment and physical coordination are impaired. At a BAC of 0.08, your muscle coordination and driving ability are significantly impaired.
A person who drinks alcohol and takes certain medicines, such as antihistamines, sedatives (tranquilizers), or opioids, may feel more of the effects of alcohol. Also, a person who uses other drugs, such as marijuana, will feel the effects of both drugs more than if the drugs were used separately.
Having any amount of alcohol in the blood can cause poor judgment and slowed reflexes. BAC and the effects of drinking alcohol vary from person to person and depend upon body weight, the amount of food eaten while drinking, and each person's ability to tolerate alcohol.
Estimated blood alcohol concentration (BAC)
Relaxation, slight body warmth
Sedation, slowed reaction time
Slurred speech, poor coordination, slowed thinking
Difficulty walking, double vision, nausea, vomiting
May pass out, tremors, memory loss, cool body temperature
Difficulty breathing, coma, possible death
0.50 and greater
You can buy breath alcohol tests on the Internet, either directly from the manufacturer or from a company that sells this kind of product. If you have access to the Internet, you can find this information by searching for the type of test or the name of the manufacturer.
Other Works Consulted
Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
ByHealthwise StaffPrimary Medical ReviewerE. Gregory Thompson, MD - Internal MedicineAdam Husney, MD - Family MedicineMartin J. Gabica, MD - Family MedicineKathleen Romito, MD - Family MedicineR. Steven Tharratt, MD, FACP, FCCP - Pulmonology, Critical Care Medicine
Current as ofOctober 9, 2017
Current as of:
October 9, 2017
E. Gregory Thompson, MD - Internal Medicine
& Adam Husney, MD - Family Medicine & Martin J. Gabica, MD - Family Medicine & Kathleen Romito, MD - Family Medicine & R. Steven Tharratt, MD, FACP, FCCP - Pulmonology, Critical Care Medicine
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