When assessing whether someone is over the limit for alcohol consumption, it is based on a threshold of blood alcohol concentration. So, this is set to 0.08% blood alcohol concentration.
With a breathalyser, it is not measuring the blood alcohol level in your blood. It’s measuring the amount of alcohol, or ethanol, in your breath. Therefore, a breathalyser test can only give you an indication of whether you are over the limit. If you have, it’s very efficient at measuring ethanol within your breath, but that’s not to say it’s not as accurate as a blood test.
A blood test will always give you a more definitive answer to whether you are above that threshold of 0.08% blood alcohol concentration.
