Welcome to brain Stuff from how Stuff Works dot com where smart Happens. Hi, I'm Marshall Brain with today's question, how are people able to breathe inside a submarine? The air we breathe is made up of significant quantities of four gases. There's nitrogen at about oxygen at about argon it maybe one percent, and a little bit of carbon dioxide. Plus there's almost always some amount of water vapor in the air. When we breathe in air, our bodies consume
the oxygen and converted to carbon dioxide. Exhaled air, it contains about four to five percent carbon dioxide. Our bodies don't do anything with the nitrogen or the argon. A submarine, or a spaceship for that matter, is a sealed container that holds people in a limited supply of error. There are three things that have to happen in order to keep the air in a submarine breathable. First, the oxygen has to be replenished as it's consumed. If the percentage
of oxygen in the air falls too low, a person suffocates. Second, the carbon dioxide must be removed from the air. As the concentration of carbon dioxide rises, it becomes a toxin. Third, the moisture that we exhale in our breath has to be removed. Oxygen is supplied either from pressurized tanks, an oxygen generator which might get oxygen from electrolysis of water, or some sort of oxygen canister. Oxygen is either released continuously by a computerized system, or it's released in batches
through the day. Carbon dioxide can be removed from the air chemically using soda lime, which is sodium hydroxide and calcium hydroxide. The carbon dioxide is trapped in the soda line by a chemical reaction and removed from the air. Other similar reactions can accomplish the same thing. The moisture can be moved by a de humidifier or by chemicals. This prevents the moisture from condensing on the walls and equipment inside the ship. Do you have any ideas or
suggestions for this podcast? If so, please send me an email at podcast at how stuff works dot com. For more on this and thousands of other topics, go to how stuff works dot com.