Measuring Blood Alcohol Concentration

To determine your BAC or blood alcohol concentration you need a breath alcohol test. This measures your breath and the amount of alcohol in your breath when you exhale.

With a handheld breathalyser device you can measure your alcohol level from a sample of your breath. You need to follow the manufacturer’s directions to ensure the device is set up properly for the right reading. You will get an estimate of the blood alcohol level in your system. These devices are like the ones uses by law enforcement officers although they aren’t as precise as those units.

Your blood alcohol concentration goes up once you consume alcohol. The alcohol is absorbed through the walls of your stomach and then directly into your bloodstream. The alcohol moves through your body and then into your brain. Your blood alcohol level goes up quickly because of the way you absorb alcohol into your system.

After 60 minutes the amount of alcohol in your system will reach its maximum level. If you eat food it may take longer for the alcohol to reach its maximum level. We exhale the alcohol in our breath, it’s broken down in tһe liver, and secreted in the urine too.

To measure your BAC you can buy various types of device. The Zoom Testing Rapid Alcohol Screening Test will give you an estimate of your blood alcohol in about two minutes, just from a swab of saliva from your mouth. Results of the test can be seen by checking the colour of the test strip against the colour chart provided.

There are two types of  device that measure breath alcohol. These are:

  • Disposable Breath Alcohol Detector – The device is a glass tube. There are crystals that change colour when they encounter alcohol on your breath. This device costs less than the electronic meters. This device comes in two versions – one detects alcohol at 0.08%, the other detects BAC at 0.02%.
  • Another way to measure BAC is with an electronic breathalyser. You see the BAC in an electronic display once you blow into the mouthpiece of the unit. You’ll spend more for this type of unit to measure BAC.

Why use the Test?

The BAC is a self-test so you can figure out the concentration of alcohol in your blood. This can tell you if you are at a safe level for driving so you don’t go to jail or get a ticket for being impaired. It’s not intended to figure out if you can drive, you need to judge that. The level of alcohol in your blood might be low but you can still be impaired according to the law of your country or state.

This is just a tool you can use to figure out if you should drive or not. If you have been drinking it’s always better to take a cab if you have had more than one or two drinks or haven’t eaten any food. If you have any doubts, don’t drive.

The police use the BAC test to determine if you have been drinking and are over the legal limit in your area. In England a level of 0.08 is the legal limit, in Scotland it is just 0.05.

Photo Credit: “Breath test” (CC BY 2.0) by OregonDOT

This post has been updated since its original publication in 2013.


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