when a sharp air jet a dust separation blow p is blown out of the nozzle opening 20 which jet penetrates through the boundary layer and separates the particles of dust from the web face the separated dust is removed into the suction chamber 14 by a suction effect generated proximate to and before the nozzle opening 20 and the air that contains dust particles is then passed to a cleaning stage for example in a wet separator the blow pressure of the dust separation blowing may be regulated to be from about 2 kpa to about 50 kpa preferably from about 15 kpa to about 35 kpa for example when the dust removing device in accordance with the invention is used for removing dust from printing papers boards the blow velocity to be used in the dust separation blowing p may be regulated or controlled to be from about 50 meters per second to about 400 meters per second preferably from about 50 meters per second to about 300 meters per second of course the values to be used for the blow pressure and velocity may be outside of these ranges and depend on the strength of the web that is being run i e on the intensity of blowing that the web can endure and on the intensity of blowing that is necessary to separate the dust from the web face it has been recognized that when softer paper grades are being run lower values are.