Helium has become rare on Earth. If it gets free into the air it leaves the planet. Unlike hydrogen, which reacts with oxygen to form water, helium is not reactive. It stays as a gas. For many years after the 1925 Helium Act, the USA collected helium in a National Helium Reserve. American helium comes from wells in the Great Plains area. At present, more helium is supplied by Qatar than by the USA.