PROBLEM TO BE SOLVED: To provide a decontamination method capable of decontaminating a large space safely and in a short time compared with conventional methods without corroding contents in the space necessary to be decontaminated.SOLUTION: A decontamination method for removing contaminants by providing gas-phase chlorine dioxide to a closed space and reducing chemical corrosion of contents in the closed space includes a step for generating the chlorine oxide gas in the closed space under an environment of steam of 10 g/m3 or less and a step for introducing the chlorine oxide gas to the closed space at a chlorine oxide gas concentration of 230 ppm or less and a CT value of 50-2,000 ppm hr.SELECTED DRAWING: Figure 3COPYRIGHT: (C)2020,JPO&INPIT【課題】除染を必要とする空間内の内容物を腐食することなく、従来に比べ安全で短時間に大空間の除染が可能な除染方法を提供すること。【解決手段】閉鎖空間内での二酸化塩素の気相付与によって汚染物質を除去し、かつ前記閉鎖空間内にある内容物の化学腐食を低減する方法であって、水蒸気量１０ｇ／ｍ3以下の環境下とした前記閉鎖空間において、二酸化塩素ガスを発生させる工程と、二酸化塩素ガス濃度２３０ｐｐｍ以下、かつＣＴ値５０～２０００ｐｐｍ・時で二酸化塩素ガスを前記閉鎖空間へ導入する工程とを含む方法。【選択図】図３
