A device for measuring the dust content of an air stream , wherein the device comprises: a supply line having an inlet opening for supplying the air stream in the device ; a measuring chamber for measuring therein the dust content of the air stream , wherein the measuring chamber is in fluid communication with the supply line ; a pump with adjustable flow rate for suctioning the air stream toward the measuring chamber via the supply line , wherein the flow rate of the pump is adjustable according to a predetermined control parameter; a first measuring system arranged for measuring, external to the supply line , at the inlet opening , the velocity, the temperature, the pressure and the moisture content of the air stream at the inlet opening of the supply line ; a second measuring system arranged for measuring, in the measuring chamber , the flow rate, the temperature, the pressure and the moisture content of the air stream in the measuring chamber ; a third measuring system arranged for measuring, in the measuring chamber , the dust content of the air stream , preferably by means of an optical measurement; and a control unit for controlling the device , wherein the control unit is operationally connected to the pump , the first measuring system , the second measuring system and the third measuring system , wherein the supply line and the measuring chamber have a predetermined shape and dimensions for establishing a predetermined relationship between the control parameter of the pump and the flow rate of the air stream in the measuring chamber at a given flow rate of the air stream at the inlet opening of the supply line . a supply line having an inlet opening for supplying the air stream in the device ; a measuring chamber for measuring therein the dust content of the air stream , wherein the measuring chamber is in fluid communication with the supply line ; a pump with adjustable flow rate for suctioning the air stream toward the measuring chamber via the supply line , wherein the flow rate of the pump is adjustable according to a predetermined control parameter; a first measuring system arranged for measuring, external to the supply line , at the inlet opening , the velocity, the temperature, the pressure and the moisture content of the air stream at the inlet opening of the supply line ; a second measuring system arranged for measuring, in the measuring chamber , the flow rate, the temperature, the pressure and the moisture content of the air stream in the measuring chamber ; a third measuring system arranged for measuring, in the measuring chamber , the dust content of the air stream , preferably by means of an optical measurement; and a control unit for controlling the device , wherein the control unit is operationally connected to the pump , the first measuring system , the second measuring system and the third measuring system , wherein the supply line and the measuring chamber have a predetermined shape and dimensions for establishing a predetermined relationship between the control parameter of the pump and the flow rate of the air stream in the measuring chamber at a given flow rate of the air stream at the inlet opening of the supply line . <EOS>