When prisoners arrived at the camp, they were either immediately selected to be sent to the gas chambers or chosen for forced labour. When deportees descended from the trains, families were divided and individuals lined up in two columns, one with men and older boys, the other with women and young children. A group of primarily Jewish prisoners was assigned to collect and sift through the confiscated possessions of those who arrived in Auschwitz, which were deposited in warehouses nicknamed ‘‘. Deportees were then examined by camp doctors or other camp officials. The main criterion for selection for gassing or for work was age: children below sixteen and the elderly were generally immediately sent to the gas chambers. Overall, approximately only 20 per cent of the people who arrived on transports to Auschwitz were selected for forced labour, and the rest were murdered on arrival., Auschwitz-Birkenau became the main extermination camp following the Wannsee Conference in January 1942, after which the Nazis moved the gassing of prisoners from Auschwitz I to Birkenau. The lethal gas Zyklon B was selected as the method of mass murder, after tests were conducted in Auschwitz I in September 1941., Living Conditions The reasons for the epidemics and contagious diseases that prevailed in Auschwitz concentration camp included the dreadful living conditions, which varied during the years that the camp operated, and were different in each part of the camp. In Auschwitz I, prisoners lived in old brick barracks..