The primary gas used in air balloons is helium. Helium is a lighter-than-air, non-flammable gas that makes it an ideal choice for filling balloons, allowing them to rise and float. Unlike hydrogen, which is also lighter than air but highly flammable, helium is safe and does not pose a fire risk. Its unique properties enable helium-filled balloons to ascend, providing a fun and eye-catching way to celebrate occasions like parties, parades, and festivals. The use of helium balloons is popular in both recreational and commercial applications.