What is the minimum oxygen concentration required for combustion?

The minimum oxygen concentration required for combustion is typically around 15%. Combustion is a chemical process that requires a fuel source and an oxidizer, with oxygen being the most common oxidizer in many combustion reactions. When the concentration of oxygen in the environment falls below approximately 15%, the combustion process becomes insufficient to sustain a flame, leading to difficulties in ignition and maintaining combustion.

Oxygen levels around 20% are found in atmospheric air, which is conducive to normal combustion processes. However, combustion can begin to sustain at the lower threshold but relies heavily on the presence of sufficient heat and fuel. Therefore, while lower concentrations may allow for some reactions, 15% is recognized as the practical minimum required to maintain the combustion process effectively.