[en] The aim of this study is to propose action levels for chelation therapy in the case of inhalation of plutonium compounds using nose swabs. The relationship between the activity found in the nose swabs and early faecal excretion was investigated using actual cases at JAEA-NFCEL. The ratio was found to be in log-normal distribution. The action levels based on the activity of nose swab corresponding to 10 ALI (5200 mSv) are determined for the facilities at JAEA-NFCEL by using the relationship and specific information such as isotopic ratio and physicochemical characteristics of plutonium compounds. (authors)