It all began with Einstatzgruppe
Gas vans were used on a large scale by the Einstatzgruppe in Byelorussia and the Ukraine. Thousands of jew were crammed into the wagon, with hoses from the car exhaust connected into the van. They were then driven around until the noises stopped. Gas vans were used, particularly at Chelmno extermination camp, until gas chambers were developed as a more efficient method for killing large numbers of people. There were two types of gas vans in operation, used by the Einsatzgruppen in the East.
Drivers could hear them yelling in the back, finding it distracting and disturbing.
Also, some people would take up to 25 mins to die.
The Gas van was created by the Soviet Union in 1936. The gas van was created because of the the psychological effects of shooting the women and children. The Einstatzgruppen were ordered to come up with a more effective way of killing the jews. They came up with the gas van. They were used up until the time until gas chambers were invented. The gas van was sold in 4 models. 30, 70, 90, and 100 people.