An object of the present invention to improve a system for monitoring the operation of the machine chamber atmosphere. This is the suction means (8) for sucking the aerosol / air mixture out of the machine's working chamber (4) and supplied to the light sensor unit having the same that at least one of the light meter 15, and at least one optical receiver (17) It is achieved by the measuring device (2) comprising. Photosensor unit is operated using an electronic device. Suction means for pressure supply (26), pneumatic nozzles (32), preferably funnel-being designed as through pressure release channel, and the negative pressure zone pneumatic injection pump (8) having a 10, a pneumatic nozzle 32 is substantially It has an outlet direction which is oriented in the direction of the pressure relief channel. Pressure supply 26 may be connected to a pneumatic source. A suction line (12) which can be connected to the machine's working chamber 4 is connected to the negative pressure zone (10). According to the invention, the optical sensor unit is light meter (15) and the light receiver 17 having a light path between, the passage is substantially vertically oriented, and a negative pressure zone relative to the outlet direction of the pneumatic nozzle 32 to pass through.