Saunas (steam baths) are a Finish invention to boost the human immune system by alternating exposure to high heat and humidity to let the sweat wash out skin impurities, with cold showers followed by dips into cold-water pools afterwards. This method spread to Germany during World War II, and from there to the entire world.
The SS recognized the health benefits of saunas early on, and integrated them into the hygiene facilities for its troops, but then also for inmates in various concentration camps. In Auschwitz Birkenau, for instance, a sauna was built both for the guards, and also for the inmates. The latter was built inside the shower and disinfestation building BW 5b (see illustration).
Imagine what inmates must have thought of this device, meaning those who rarely or never had seen a shower, let alone a sauna, in their lives. Former Auschwitz inmates Erich Kulka and Ota Kraus wrote this about the sauna at Birkenau in their book Die Todesfabrik (The Death Factory, Kraus/Kulka 1958, pp. 47f.):
“Even without specialist knowledge, anyone will recognize that the Nazi doctors constantly committed crimes against humanity in the concentration camps. We cannot forget the SS officer, a doctor, who resided in Birkenau at the beginning of 1943. His little hobby-horse was the ‘Finnish sauna.’
This bath, in Birkenau, consisted of two rooms, separated from each other which could be hermetically sealed off from each other by means of a door.
The inmates had to undress in the corridor and give up their clothing and underclothing for delousing.
In the first room was a gigantic brick furnace, in which large stones were brought to white heat over a period of several hours before the beginning of the bath. Against the wall opposite the furnace was an extremely primitive bench, arranged in steps, reaching almost to the ceiling.
The naked inmates had to sit on these benches, as closely together as they could. One sat next to the other, the healthy ones pressed next to the sick ones, many of whom had infectious skin eruptions.
Then the heated stones were doused with water. As a result of the heat, the emaciated, sick, ruined bodies of the inmates began to sweat heavily. The new arrivals, who had to climb to the highest benches, sweated most of all. Sweat, mixed with dirt and pus from suppurating sores, ran down in streams.
When a few had already begun to lose consciousness, the hermetically-sealed door was opened to the second room, in which the naked inmates were driven under ice-cold showers with shouting and the blows of truncheons by the inmate trustees.”
To anybody who had never seen a sauna, and who was prepared to believe the worst about the Germans, this luxury installation naturally appeared as an instrument of torture. In some cases, it may even have given rise to the rumor that people were killed by the Germans in steam chambers, as has been alleged for the Treblinka Camp (see that entry).
This example shows how beneficial health measures introduced by the Germans were misconstrued into instruments of torture by ignorant and/or malicious witnesses.