The system draws the driver’s exhaled breath into a sensor, which measures the concentrations of alcohol and carbon dioxide present. The known quantity of carbon dioxide in human breath serves as an indicator of the degree of dilution of the alcohol concentration in exhaled air. Molecules of alcohol and those of tracers such as carbon dioxide absorb infrared light at specific wavelengths. Infrared light beams sample the breath and analyse the wavelengths to quickly and accurately calculate the alcohol concentration.

The device is highly sensitive and able to analyse diluted breath samples from the driver’s natural breath.