Created by John H. Emerson in 1931, the Emerson Respirator, or iron lung, was a large mechanical ventilator that helped polio patients suffering from respiratory paralysis breathe. A patient was placed inside the respirator with their head sticking out while air pressure changes in the inner chamber simulated breathing. More affordable and efficient than similar models of its kind, the Emerson respirator saved countless lives during the polio epidemics of the 1940s and 1950s.