A hydrogen peroxide sterilization process requires H2O2 vapor filling the sterilizer chamber, contacting and sterilizing exposed product surfaces. The design and progress of the decontamination cycle usually occurs upon completion in the OQ. USP3 again offers advice on this issue as does PIC/S6 which revealed a useful assistance document https://tailinscitech.blogspot.com/2026/02/vhp-sterilization-solutions-by-tailin.html