The importance of breathalyser calibration and how it is done

Regular breathalyser calibration ensures reliable breath alcohol data for the proper execution of alcohol and drug testing policy in the workplace.

The importance of breathalyser calibration and how it is done

Calibration is the important process of configuring measuring devices, especially ones that are used in scientific and medical procedures, to make sure that the results produced are accurate and precise at all times. As the breath alcohol concentration of an employee will determine whether they have passed workplace screening, it is crucial to perform regular calibrations on breathalysers so that proper action can be taken based on the alcohol and drug testing policy of your company.

Ensures the accuracy and performance of breathalysers

Be it a handheld or wall mounted breathalyser, the best way to check its reliability is by calibration. In the process of calibration, the breathalyser will be tested using a breath alcohol simulator where simulated exhaled air with a known concentration of alcohol is blown into the breathalyser. The reading shown should match the known concentration within the maximum permissible errors to confirm its accuracy.

These are several reasons for sensor drift where the breathalyser becomes less accurate over time:

  • Built-up impurities on the breathalyser sensor.
  • Improper storage of the breathalyser under unfavourable conditions, such as high temperature and high humidity.
  • Usage or storage of the breathalyser in an environment where products containing alcohol, such as hand sanitisers and cleaning sprays, are regularly used.
  • Improper handling of the breathalyser; damages incurred from accidental dropping and shock.
  • Improper usage of the breathalyser, such as when a test was done right after alcohol was consumed, causing a high level of alcohol to be blown into the breathalyser.

How a breathalyser is calibrated

The breathalyser calibration process can be summarised in 3 steps:

  1. Measure the simulated exhaled air with a known concentration of alcohol and take down the reading.
  2. Turn on the calibration mode of the breathalyser and measure the simulated exhaled air again. The accuracy of the breathalyser will be adjusted should there be a sensor drift. This step may vary according to the breathalyser model.
  3. Repeat step 1 to verify that the breathalyser reading is accurate.

These steps may be repeated several times if required. Calibration is essential as it determines whether the breathalyser sensor is faulty, in which case it would have to be sent for repairs or be replaced entirely.

Depending on the manufacturer of the breathalysers, some breathalysers require passcodes to access their calibration mode; hence, you would need to send the breathalysers to their authorised calibration centre for calibration.

The frequency of a breathalyser calibration

The frequency of a breathalyser calibration is determined based on your company’s needs, frequency of use, and specifications stated by the manufacturers. As a general rule of thumb, the more frequent the breathalysers are used, the more frequently they should be calibrated. The Australian Standard AS3547:2019 requires breathalysers to maintain their accuracy for at least 6 months after each calibration. To ensure that this requirement is met, breathalysers should be calibrated according to the manufacturers’ advice.


As specific skills and equipment are needed for breathalyser calibration, it should only be done by professional technicians. A calibration report or certificate will be issued by the calibration centre after calibration is done as proof that the breathalysers have been calibrated and can perform optimally. Breathalyser calibration is not an optional process. It should be done regularly to ensure reliable breath alcohol testing data, which in turn allows for the proper execution of your company’s alcohol and drug testing policy.

Disclaimer: The information provided in this article is for general reference only. Please seek advice from professionals according to your business’s needs.

Jaka Exstrada

Jaka Exstrada

Since 2017, Jaka has been providing consultation for alcohol and drug testing policies to companies in various industries, such as mining, transport, construction, and medical, in Australia. As an accredited Drug and Alcohol Officer for Drug Abuse Testing, he brings valuable insight to companies that want to create and maintain an alcohol and drug-free working environment for the safety of their employees, as well as to ensure the efficiency of on-site operations.