When you drink alcohol, it goes into your stomach and small intestine. It is absorbed into your bloodstream and travels through your body to your brain and lungs. When you breathe, you exhale it.
Breath alcohol tests measure the amount of alcohol in the air you exhale. The device uses this measurement to estimate your blood alcohol content. This number is your BAC, or blood alcohol content.
The value may rise within 15 minutes of drinking. BAC is usually at its highest about an hour after drinking.
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Why use it?
As BAC rises, you may become clumsy and take longer to react. You may not make good choices. These things make driving dangerous.
In every state but one, it is illegal for a driver over the age of 21 to have a BAC higher than 0.08%. As of December 2018, Utah’s BAC level will be 0.05%. All states have zero-tolerance laws for drivers under the age of 21.
If you speed, have an accident, or are on the road, local police may suspect you of driving under the influence or under the influence. They can test your BAC at the scene of an accident or on the side of the road using a device called a breath analyzer (if they pull you over).
Are there different types of tests?
The test can also be manual or electronic. Most police officers use electronic devices the size of walkie-talkies. You blow into the mouthpiece and it gives you an instant reading. You may be asked to repeat this several times so that officials can get an average reading. It takes about a minute and doesn’t hurt.
The most common manual tests involve balloons and glass tubes containing yellow crystals. You blow air into the balloon and release it into the tube. The color of the crystal band in the tube changes from yellow to green, depending on the amount of alcohol in your system.
Check the instructions that came with the device to read the results. In general, a green band indicates that your BAC is below 0.05%, which is within the legal limit for driving. Two green bands mean your BAC is between 0.05% and 0.10%, and three bands mean more than 0.10%.
If you want to ensure your safety before driving, you can purchase either type of test for yourself. The manual one is cheaper.
Is that accurate?
Not always. There are a few things that can cause the readings to be wrong.
If you drink alcohol 15 minutes before the test, trace amounts of alcohol in your mouth may lead to inaccurate results. Smoking can also affect the results. The same goes for products that contain alcohol, such as mouthwashes and breath fresheners.
Sometimes the machine needs to be recalibrated or the battery replaced. These may interfere with reading.
Some of the software tested requires occasional updates, which can cause failures.
Professional breath alcohol tests (such as those conducted by the police) use fuel cell technology. They are the most accurate. But a breath test is more accurate than a blood or urine test.
Factors affecting BAC
How quickly BAC rises and how long it stays that way depends on several factors:
Your weight. The heavier you are, the more water you have in your body. The more water, the more alcohol is diluted.
Your gender. Alcohol affects men and women differently. Men have higher levels of stomach enzymes that help break down alcohol, so they process it faster. Women generally have less water and more fat. Hormonal changes in women can also affect BAC.
How much alcohol you drank, the strength of the alcohol, and how fast you drank it. The more you drink per hour, the faster your BAC rises.
How much you ate. A full stomach, especially high-protein foods, slows down alcohol processing.
What do the results mean?
If the police perform an alcohol breath test on you and your BAC is over the legal limit by 0.08%, you may be arrested and charged with driving under the influence.
You may also be asked to provide a blood or urine sample for further testing to determine a more accurate BAC.
