Final answer:
A fire typically requires between 16% to 21% oxygen in the atmosphere to burn. The air in Earth's atmosphere contains about 20% oxygen, which is crucial for life and can be supplemented by oxygen tanks in low-oxygen environments.
Step-by-step explanation:
A fire needs approximately 16% to 21% oxygen in the atmosphere to sustain combustion. Atmospheric air is comprised of about 20% oxygen, which is essential for various chemical reactions in living organisms, such as the production of ATP—an important molecule for energy transfer within cells. Oxygen tanks can provide this essential gas in low-oxygen environments because gases are highly compressible, allowing a large amount of oxygen to be stored in a small container. When released, the oxygen expands in volume and is available for use at normal pressure.