What is the minimum percentage of oxygen required to sustain a fire?

The minimum percentage of oxygen required to sustain a fire is 16%. This figure is based on the fact that for combustion to occur effectively, a certain concentration of oxygen is necessary in the atmosphere. Typically, the normal concentration of oxygen in the air is about 21%. When the oxygen concentration drops to around 16%, it is still sufficient to support combustion, allowing most materials to burn. Below this level, the ability to sustain a fire diminishes significantly, as the combustion process requires adequate oxygen to maintain the chemical reactions that generate flames.

Understanding this threshold is important for safety training and practices, especially in construction and confined spaces, where oxygen levels can fluctuate and put workers at risk of fire hazards.