In order to improve a system for monitoring the working area atmosphere of an operating engine, measuring devices (2) for determining readings for a gas and/or an aerosol in the working area (4) of an operating engine are used as a starting point. Each measuring device comprises a suction means (8) which extracts a gas and/or a mixture of an aerosol from the working area (4) of the operating engine and feeds it to a sensor unit (16, 17, 18). An electronics module for operating the sensor unit (16, 17, 18) is also present. The suction means is designed as a convection pump (8) preferably with a heating device (42) and a cooling device (44).