At what percentage of Oxygen does all flaming combustion cease?

Flaming combustion requires a specific concentration of oxygen to be maintained. The critical threshold at which flaming combustion ceases is approximately 12.5% oxygen. Below this concentration, the oxygen level becomes insufficient to sustain the chemical reactions necessary for combustion.

In practical terms, normal atmospheric air contains about 21% oxygen, which comfortably supports combustion. As oxygen concentration decreases, the ability of a substance to ignite and sustain a flame diminishes. At 12.5%, the available oxygen is no longer adequate to maintain the energy and reaction rates needed for continued flaming combustion, leading to the extinguishment of flames.

This threshold is significant in various safety scenarios, particularly in confined spaces or situations involving fire hazards, as it highlights the importance of maintaining adequate oxygen levels for any combustion processes to occur.