How do Alcohol Breathalyzers Actually Work?

The breathalyzer (also known as a breath tester and also at times spelt as breathalyser) is a device that measures breath alcohol content, or BrAC for short. The measurement is generally obtained by calculating the percentage weight per unit of volume.

A BrAC is considered as accurate as a Blood Alcohol Concentration (BAC). The breath alcohol to blood alcohol ratio of 2100:1 is used for converting BrAC to BAC. Meaning that 2100mg of deep lung air will contain the same amount of alcohol as 1ml of blood.

There are various types of alcohol breathalyzers but the predominant type available is a digital display, hand-held unit that can be reused multiple times.

The breath alcohol sample is taken by the user blowing for around 5 seconds into the breathalyzer. The volume of air required to fulfil a 5 second blow will need to come from the deep lung area, which is where accurate BrAC measurements can be taken. Quality alcohol breathalyzers will have what is known as effective breath capture where the unit will require a set amount of air and alcohol to take the sample. If the amount is not sufficient then the breathalyzer will not give a reading and will advise the user to try again.

Prior to the sample being taken a heating element contained within the breathlyzers sensor will raise the temperature of the sensor to 34 degrees Celsius. This temperature is approximately the same temperature as a person’s breath which is required for an accurate sample to be taken. Once blown the breath sample will pass from the mouthpiece, into the air intake tube and then over the alcohol breathalyzers sensor. The sensor will electronically measure and calculate the sample then relay the information to the digital display where it can be viewed.