Containment airlock, particularly an airlock for working on a site on which radiological, asbestos, biological and/or chemical contamination may occur, comprising: a self-supporting frame, the frame being articulated so that it is expandable from a collapsed storage position and an extended work position, a flexible containment shell that is configured to be removably assembled to the frame, wherein the frame comprises a first collapsible plane frame, a second collapsible plane frame, and rigid single-piece reinforcing rods that connect the first plane frame to the second plane frame. the first plane frame and the second plane frame each containing vertices of the frame and articulated reinforcing rods that connect the vertices (6a, 6b, 6c, 6d) of the first plane frame to each other and the vertices (6e, 6f, 6g, 6h) of the second plane frame to each other, each of the articulated reinforcing rods comprising a first rigid segment, a second rigid segment and at least one intermediate articulation connecting the first segment to the second segment, the rigid single-piece reinforcing rods connecting the vertices (6a, 6b, 6c, 6d) of the first plane frame to the vertices (6e, 6f, 6g, 6h) of the second plane frame, the first plane frame and the second plane frame being located at opposite longitudinal ends of the rigid single-piece reinforcing rods, the first plane frame and the second plane frame being configured such that segments (72, 74) of the articulated reinforcing rods move towards the rigid reinforcing rods when the frame moves from its extended position to its collapsed position, and such that segments (72, 74) of the articulated reinforcing rods move away from the rigid reinforcing rods when the frame moves from its collapsed position to its extended position. a self-supporting frame, the frame being articulated so that it is expandable from a collapsed storage position and an extended work position, a flexible containment shell that is configured to be removably assembled to the frame, wherein the frame comprises a first collapsible plane frame, a second collapsible plane frame, and rigid single-piece reinforcing rods that connect the first plane frame to the second plane frame. the first plane frame and the second plane frame each containing vertices of the frame and articulated reinforcing rods that connect the vertices (6a, 6b, 6c, 6d) of the first plane frame to each other and the vertices (6e, 6f, 6g, 6h) of the second plane frame to each other, each of the articulated reinforcing rods comprising a first rigid segment, a second rigid segment and at least one intermediate articulation connecting the first segment to the second segment, the rigid single-piece reinforcing rods connecting the vertices (6a, 6b, 6c, 6d) of the first plane frame to the vertices (6e, 6f, 6g, 6h) of the second plane frame, the first plane frame and the second plane frame being located at opposite longitudinal ends of the rigid single-piece reinforcing rods, the first plane frame and the second plane frame being configured such that segments (72, 74) of the articulated reinforcing rods move towards the rigid reinforcing rods when the frame moves from its extended position to its collapsed position, and such that segments (72, 74) of the articulated reinforcing rods move away from the rigid reinforcing rods when the frame moves from its collapsed position to its extended position.