Helium is so light that it constantly escapes Earth's atmosphere and drifts into space.

Helium is the second lightest element in the universe and exhibits a unique physical property called atmospheric escape. In Earth's exosphere—the outermost atmospheric layer—temperatures can exceed 1,000 degrees Celsius. This extreme heat gives helium atoms enough kinetic energy to reach approximately 11.2 kilometers per second, the escape velocity threshold needed to break free from a planet's gravitational pull.As a noble gas, helium does not react with other elements to form heavier molecules that might remain in the atmosphere. Instead, it stays as a light, individual atom that easily rises to the top of the atmosphere and leaks into the vacuum of space.Earth's helium supply is not found in the air but trapped in underground natural gas deposits. It forms over millions of years through alpha decay of heavy radioactive elements like uranium and thorium. According to the United States Geological Survey, once helium is extracted and released into the atmosphere, it is effectively lost to the planet forever.The global concern about helium shortages stems from this finite supply and the speed of its loss. Major facilities like the Federal Helium Reserve in Amarillo, Texas, have historically managed the world's supply, but reserves continue to decline. Because helium cannot be manufactured synthetically, every balloon released or industrial leak contributes to the permanent depletion of this non-renewable resource.