Before fumigation, the person fumigating shall personally inspect all rooms and apartments ordered vacated under Section 19-97, and shall see that such rooms are unoccupied by persons or domestic animals, after which all doors to such rooms, excepting one exit door to the rooms or apartments to be gassed, shall be securely locked and sealed. In addition such windows or wall openings as might possibly be used to gain entrance shall be sealed and shall be locked or barred in such a way as to prevent entrance. Immediately upon generating or liberating the gas, the door through which the fumigator leaves shall be securely locked and sealed, and all keys obtainable to all the rooms or apartments ordered vacated shall be retained by the fumigator until all danger is passed. (Ord. 3281)