Zoo Panda gassed

Chinese zookeepers are in full apology mode after accidentally gassing a giant panda named Quan Quan with a mix of carbon dioxide and chlorine gas.
They were "disinfecting" a nearby bomb shelter that had air vents connected to the panda enclosure and the gases led to the panda's death.
It sounds like they were recycling (good) but have a lack of understanding when it comes to their infrastructure (bad).