Why is helium used to fill balloons instead of hydrogen?
Quick Answer
Helium is used because it is light and nonflammable, unlike hydrogen. It provides lift without the fire risk that made hydrogen dangerous in early airships.
The Full Story
Helium floats balloons because it is much less dense than air, so the balloon displaces heavier air and rises. It is preferred over hydrogen because helium does not burn, making it far safer for celebrations, weather balloons and many technical uses. Hydrogen is actually slightly lighter, but its flammability caused catastrophic accidents in early aviation, including the 1937 Hindenburg disaster. Helium is a finite natural resource on Earth because it is produced by radioactive decay and can escape into space over geologic time.
Key Facts
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