Albert Widmann with the car engine running. He had nearly died of carbon monoxide poisoning from the exhaust fumes. This engine exhaust testing inspired the development of gas vans. Back in Berlin, Reinhard Heydrich immediately set to work within the RSHA for the development of, in the words of Heydrich's subordinate Walter Rauff, a "more humane method of execution" than the "Einsatzgruppen" firing squads which had been used. When a prototype gas van was driven to KTI, Widmann explained to his young chemists that by adjusting the timing of the ignition, one could maximize the amount of poisonous carbon monoxide in the
Gas chamber extermination camps at Bełżec, Sobibór, and Treblinka used exhaust fumes from stationary diesel engines. In search of more efficient killing methods, the Nazis experimented with using the hydrogen cyanide-based fumigant Zyklon B at the Auschwitz concentration camp. This method was adopted for mass killings at the Auschwitz and Majdanek camps. Up to 6000 victims were gassed with Zyklon-B each day at Auschwitz. Most extermination camp gas chambers were dismantled or destroyed in the last months of the World War II as Soviet troops approached, except for those at Dachau, Sachsenhausen and Majdanek. One destroyed gas chamber at Auschwitz was reconstructed