Why are noble gases nonflammable?

Noble gases are nonflammable primarily because of their extreme chemical stability, which stems from their unique electronic structure.12

Each noble gas possesses a complete outer shell of electrons—a configuration often referred to as an octet (or a filled shell in the case of helium). Because these shells are already full, the atoms are exceptionally stable and do not readily gain, lose, or share electrons to form chemical bonds with other elements, such as oxygen.234

Since combustion is a chemical reaction that typically involves the oxidation of a substance, the noble gases' profound indifference toward oxygen and other reactive elements renders them inherently nonflammable. This chemical inertness is why they are frequently used to create protective, nonreactive environments for industrial processes like welding and electronics manufacturing, where preventing unwanted reactions is essential.2