Low-Pressure-Arc (LPA) technology promises to be of use as a new surface decontamination technology for radioactive metal wastes. The radioactive dust generated during a LPA process can cause re-contamination of wastes, therefore the dust needs to be collected. As a fundamental study of the collection of radioactive dust, we applied a LPA to the oxide film at pressures of 13, 190, and 8000 Pa in an argon atmosphere, and investigated the frequency distribution of dust particle size adhering to the specimen. By establishing a method of evaluating the frequency distribution of dust particle size from SEM photographs using non-parametric test, we obtained the following results on the dust adhering to the specimen; (1) more than 80% of the measured particles are distributed within a size of 0.2-1.2 mu m to the total number of particles; (2) with the higher pressure, the number ratio of small particles declined, and the number ratio of large particles increased, especially near the track of cathode spot; (3) the further the distance from the removal area, the lower the number ratio of large particles becomes; (4) the ratio of the weight of the dust adhering to the specimen increased from 5% to 15% with the pressure. (c) 2005 Elsevier B.V. All rights reserved.