• Breathalyser calibration is crucial for accurate alcohol detection in workplaces, legal, or medical procedures. • It ensures the accuracy and precision of breathalyser results. • Regular calibrations are necessary to ensure compliance with company's alcohol and drug testing policy. • The process involves testing breathalysers using a breath alcohol simulator, ensuring the reading matches the known concentration within permissible errors. • Calibration can be triggered by built-up impurities, improper storage, regular use in alcohol-containing environments, improper handling, and post-alcohol consumption. • The calibration process involves three steps: measuring the simulated exhaled air, adjusting the calibration mode, and verifying the accuracy of the reading. • Calibration is essential to determine if the breathalyser sensor is faulty and requires repair or replacement. • Some breathalysers require passcodes for calibration, requiring calibration at an authorized calibration • Breathalyser calibration should be performed every six months, with frequency determined by manufacturer guidelines and frequency of use. • The Standard AS3547:2019 requires breathalysers to maintain accuracy for at least 6 months after each calibration. • Calibration should only be done by professional technicians, with a calibration report or certificate issued by the calibration centre.