To access the PCRM storage facility, one would need to pass through a long series of locked doors that are only accessible to specific PCRM medical and laboratory staff. Our facility also has an independent security system and security guards for the building 24 hours a day. The storage tanks are filled with liquid nitrogen, and the levels are checked and recorded weekly. The holding time for these tanks is several weeks, meaning that if for some reason it was not possible to top up the liquid nitrogen, the samples could still stay frozen. Also, because we use liquid nitrogen, and not electricity, samples will remain safely frozen during power outages.