An assembly and a method for measuring a gas concentration by means of absorption spectroscopy, in particular for capnometric measurement of the proportion of CO2 in breathing air in which IR light from a thermal light source is guided through a measuring cell with a gas mixture to be analyzed, and the concentration of the gas to be measured that is contained in the gas mixture is determined by measuring an attenuation of the light introduced into the measuring cell caused by absorption by the gas to be measured. The thermal light source is designed as an encapsulated micro-incandescent lamp with a light-generating coil.
