What is the minimum concentration of oxygen required to sustain combustion?

Combustion is a chemical reaction that requires fuel, heat, and an oxidizer, with oxygen being the most common oxidizer in fires. The minimum concentration of oxygen required to sustain combustion is typically around 15 percent by volume in air. While combustion can technically occur at lower concentrations in some specific situations, such as in the presence of certain fuels or conditions, sustained combustion, as a general principle, requires approximately 15 percent oxygen.

Air consists of about 21 percent oxygen, and below this level, the combustion process is insufficient to maintain a sustainable flame. Concentrations lower than this would not support ongoing combustion in most typical environments. Therefore, despite the answer suggesting that 1 percent is sufficient, it is important to understand that any combustion process typically needs at least 15 percent oxygen to be sustainable. This is a key concept in fire science and investigation when evaluating the conditions necessary for a fire to occur and be maintained.