The operation of an alcohol tester typically involves the following steps:

• Breath Sample Collection: The person being tested exhales into the device through a mouthpiece or a sensor. It is essential to follow the device's instructions on how to provide a proper breath sample.
• Alcohol Detection: The alcohol tester uses a technology called fuel cell or infrared spectroscopy to detect and measure the presence of alcohol in the breath sample. These technologies can differentiate between alcohol molecules and other substances, providing more accurate results.
• Alcohol Concentration Display: The device displays the alcohol concentration in the breath sample as a numerical value, such as blood alcohol content (BAC) percentage or breath alcohol units (BrAC). This reading is an estimation of the alcohol content in the person's bloodstream, which correlates with their level of impairment.
• Interpretation: The person conducting the test or the individual being tested can interpret the results based on legal or predetermined limits. It's important to note that different jurisdictions may have varying legal limits for acceptable alcohol concentrations. Alcohol testers are useful tools for determining if someone is under the influence of alcohol. However, it's crucial to remember that breathalyser results may not be as accurate as blood tests and can be affected by various factors, such as recent alcohol consumption, the calibration of the device, and individual physiology. If an accurate measurement is required, it is advisable to consult professional testing facilities or medical professionals.