Abstract: A light beam generated by a light source having a wavelength corresponding to the ethanol absorption spectrum, preferably in the wavelength range of 3.28-3.52 ?m or in one or more wavelength ranges 6.49-7.46 ?m, 7.74-8.33 ?m, 8.84-10.10 ?m, 10.7-12.00 ?m, is sent through a measuring space containing a sample of exhaled breath, and then the intensity of the light beam passing through the measuring space is measured. Based on the spectral analysis of the dependence of the light intensity to the alcohol concentration, the concentration of ethanol vapor is determined and the information about the level of the ethanol content is provided to a suitable display or device.

Abstract: A light beam generated by a light source having a wavelength corresponding to the ethanol absorption spectrum, preferably in the wavelength range of 3.28-3.52 ?m or in one or more wavelength ranges 6.49-7.46 ?m, 7.74-8.33 ?m, 8.84-10.10 ?m, 10.7-12.00 ?m, is sent through a measuring space containing a sample of exhaled breath, and then the intensity of the light beam passing through the measuring space is measured. Based on the spectral analysis of the dependence of the light intensity to the alcohol concentration, the concentration of ethanol vapor is determined and the information about the level of the ethanol content is provided to a suitable display or device.