Propane is a bi-product of natural gas as it’s separated out when natural gas is refined. Most propane comes from this process and the remaining comes from crude oil refining. Propane is considered a clean burning fuel (EPA Clean Air Act).
Propane is used for indoor home heating using propane efficient furnaces as well as for propane energy efficient appliances including tankless water heaters, ranges/stoves, clothes dryers, and fireplaces. Propane is used outdoors including generators, patio heaters and outdoor fire pits. Propane appliances are certified by nationally recognized independent testing laboratories. 
The propane gas industry has an outstanding safety record. The industry operates under voluntary, self-imposed rules governing safety. Anytime safety needs to be addressed or reexamined, the industry responds quickly and effectively. Due to these efforts, there are very few federal government standards regulating the use of propane gas.