Disclosed is a method and device for collecting particulate contaminants removed using a CO2 decontamination medium from an early step of a decontamination process. The device removes particulate contaminants from a contaminated subject by a decontamination stream, and simultaneously forms another stream for collecting such contaminants into a collecting filter, thus preventing such contaminants from diffusing into the atmosphere. The device forms streams between the nozzles and the surface of the contaminated subject to readily move the nozzles along the surface of the subject without frictional resistance, to reduce the sense of fatigue of the operator. The method and device are advantageous in that when the device is readily used with a conventional CO2 blasting decontamination unit to collect particulate contaminants, removal of particulate contaminants from a contaminated subject and collection of particulate contaminants contained in the decontamination stream are simultaneously performed, also allowing compressed gas blasted through air curtain blasting nozzles to prevent contaminated gas from diffusing into the atmosphere.