Superman's sight, stamina and breath powers were also similarly reduced, and the character was also shown as requiring an oxygen mask for prolonged travel in space or underwater.
Some believe his alcoholism and heavy smoking could have contributed to it; he was not wearing his oxygen mask, and matches were found near the oxygen machine, unignited.
The flight was possible by releasing stored oxygen into the cockpit, which was released directly into an enclosed cabin and not to an oxygen mask, which was developed later.
