If you put helium in a balloon and let go of the balloon, the balloon will rise until it reaches a height of just under 33,000 feet (10 kilometers), at which point it will burst because the atmospheric pressure and the strength of the balloon's skin won't be enough to withstand the pressure of the gas inside it [source: BBC Science Focus].
The helium that escapes is lighter than the other gases in the atmosphere, so has no reason to stop — it just keeps going and leaks out into space. That's why there's only a trace amount of helium — 0.0005 percent — in the atmosphere at any given time [source: Jefferson Lab].
Helium is abundant in space, where it's produced as a product of the fusion reaction inside stars such as the sun. The naturally occurring helium on Earth, though, comes from a different sort of process. Deep inside the Earth, radioactive elements such as uranium and thorium decay and turn into other elements. The byproduct of these reactions are tiny fragments called a-particles, which consist of two neutrons and two protons. Those particles pick up electrons from the environment around them and turn into helium, which gradually rises up through the crust and is emitted into the atmosphere, where it keeps rising until it gets into space [source: University of Pittsburgh].
Fortunately for us, helium also gets into the natural gas that oil and gas drillers extract from the ground for use as fuel [source: University of Pittsburgh]. That gives us a supply that we can use for blowing up balloons, as well as for a wide variety of other industrial processes, ranging from arc welding to MRIs to manufacturing silicon chips for computers. There has to be a certain amount of helium in the natural gas — at least 0.3 percent by volume – to justify all the trouble of separating it from natural gas. This is done through industrial processes that filter other impurities, such as water, carbon dioxide and hydrogen sulfide from the gas. Finally, a process called cryogenic processing is used to cool the gas and remove the methane that makes up most of it, leaving behind a crude form of helium that is about 50 to 70 percent pure, with small amounts of argon, neon and hydrogen making up the rest. Then, the crude helium is purified through another cooling and filtering process that results in a form of helium that's more than 99 percent pure [source: NAP].
The problem is that there aren't that many places with natural gas fields that have enough helium in them, and extracting helium is hard to do efficiently and affordably and most of it comes from just a few sources, including the U.S. government's National Helium Reserve in Texas. With so much demand for helium for industry, there just isn't enough to go around. That shortage has hurt businesses such as Party City, a party supplies company, which is set to close 45 of its stores in 2019 [source: Gibson].
- BBC Science Focus. "How high can a helium balloon float? " Sciencefocus.com. (May 13, 2019) https://www.sciencefocus.com/science/how-high-can-a-helium-balloon-float/
- Gibson, Kate. "Deflated by helium shortage, Party City to close 45 stores." CBS News. May 10, 2019. (May 13, 2019) https://www.cbsnews.com/news/party-city-helium-to-close-45-tores/
- Jefferson Lab. "The Element Helium. " Education.jlab.org. (May 13, 2019) https://education.jlab.org/itselemental/ele002.htmlNational Academies of Sciences, Engineering and Medicine. "The Impact of Selling the Federal Helium Reserve. " Nap.edu. 2000. (May 13, 2019) https://www.nap.edu/read/9860/chapter/7
- University of Pittsburgh. "Helium: Sources and Uses." Researchservices.pitt.edu. (May 13, 2019) https://researchservices.pitt.edu/helium/sourcesanduses