How did the iron lung treat coal gas poisoning?

The Iron lung was essentially a pressure chamber in which the the pressure could be increased quite a lot over atmospheric pressure as a means of forcing the absorbed coal gas back out. Its other common use was in treating polio, and also divers with the 'bends'.


Coal-gas is poisonous by being chiefly Carbon Monoxide, which is fast acting as it binds much more readily than the intended oxygen to the blood's haemoglobin.


Also, the "iron lung" formerly used to treat polio, is a very different device from the hyperbaric or recompression chamber used to treat the "bends". The iron-lung is a an artificial respirator, the recompression chamber is not. Instead, it is a vessel large enough to accommodate the casualty, and filled with air at the pressure of the dive, then released very slowly.