Propane can be either a liquid or a gas.
At normal atmospheric pressure and temperature, it is a non-toxic, colorless and odorless gas. Just like natural gas, an identifying odor is added so it can be readily detected. Under moderate pressure, propane becomes a liquid that vaporizes into a clean-burning gas when released from its storage container. Propane is 270 times more compact as a liquid than a gas, making it economical to store and transport as a liquid. As opposed to relying on foreign sources, approximately 90 percent of the United States propane supply is produced domestically.