Measuring device for performing safety tests at a workbench which is formed as a containment and is in operating mode, wherein: a) the workbench , surrounded by a housing , has an internal working chamber with a working surface and also a working opening affording access to the working chamber ; b) the measuring device has a distributor element for introducing a test medium ( T m ) into the working chamber and external sensors for measuring the concentration of test medium ( T m ) reaching the outside through the working opening ; and c) the test medium ( T m ) is a liquid or a particle substance which allows itself to be distributed by means of compressed air as a test aerosol in the working chamber by way of the distributor element , characterized in that d) the distributor element comprises at least one nozzle , preferably a number of nozzles , which are positioned on a nozzle carrier ; wherein da) the nozzle carrier can be displaced along a widthwise extent of the working chamber on a transversal axis ( x-x ) and is connected to a carriage ; and db) the carriage is arranged on a guide ; and e) connected to the carriage is a dummy , which can be positioned substantially outside the working chamber and is facing the working opening , wherein: ea) the dummy represents a replica of an upper body of an operator working at the workbench ; and eb) the side of the dummy that is facing the working opening serves as a carrier for the external sensors . a) the workbench , surrounded by a housing , has an internal working chamber with a working surface and also a working opening affording access to the working chamber ; b) the measuring device has a distributor element for introducing a test medium ( T m ) into the working chamber and external sensors for measuring the concentration of test medium ( T m ) reaching the outside through the working opening ; and c) the test medium ( T m ) is a liquid or a particle substance which allows itself to be distributed by means of compressed air as a test aerosol in the working chamber by way of the distributor element , characterized in that d) the distributor element comprises at least one nozzle , preferably a number of nozzles , which are positioned on a nozzle carrier ; wherein da) the nozzle carrier can be displaced along a widthwise extent of the working chamber on a transversal axis ( x-x ) and is connected to a carriage ; and db) the carriage is arranged on a guide ; and da) the nozzle carrier can be displaced along a widthwise extent of the working chamber on a transversal axis ( x-x ) and is connected to a carriage ; and db) the carriage is arranged on a guide ; and e) connected to the carriage is a dummy , which can be positioned substantially outside the working chamber and is facing the working opening , wherein: ea) the dummy represents a replica of an upper body of an operator working at the workbench ; and eb) the side of the dummy that is facing the working opening serves as a carrier for the external sensors . ea) the dummy represents a replica of an upper body of an operator working at the workbench ; and eb) the side of the dummy that is facing the working opening serves as a carrier for the external sensors . <EOS>