<sod>* Although abundant in the universe, helium is very scarce on Earth. The only commercially viable reserves are a few natural gas wells, mostly in the US, that trapped it from the slow [[alpha decay]] of radioactive materials within Earth. By human standards helium is a [[non-renewable resource]] that cannot be practically manufactured from other materials. When released into the atmosphere, e.g., when a helium-filled balloon leaks or bursts, it eventually escapes into space and is permanently lost.<eod>
<sod>* Although abundant in the universe, helium is very scarce on Earth. The only commercially viable reserves are a few natural gas wells, mostly in the US, that trapped it from the slow [[alpha decay]] of radioactive materials within Earth. By human standards helium is a [[non-renewable resource]] that cannot be practically manufactured from other materials. When released into the atmosphere, e.g., when a helium-filled balloon leaks or bursts, helium eventually escapes into space and is permanently lost.<eod>