What term describes breathing air that is lacking oxygen?

The term that accurately describes breathing air that is lacking oxygen is hypoxia. This condition refers to a decrease in the amount of oxygen available to the body's tissues. It occurs when there isn't enough oxygen in the environment, which can happen at high altitudes, in enclosed spaces, or in situations where there is inadequate ventilation.

Asphyxia, while closely related, specifically refers to a condition where there is a deficiency of oxygen while there is an excess of carbon dioxide, often resulting in suffocation. While asphyxia results from low levels of oxygen, it is a broader term that encompasses various causes, including drowning and choking, not exclusively due to lacking atmospheric oxygen.

Hyperoxia is defined as an excess of oxygen in the tissues and organs, which is exactly the opposite condition of hypoxia. Oxygen deficiency could be a correct descriptor in some contexts, but it is not the technical term most widely accepted in medical or scientific literature to describe the condition of low oxygen availability.

Focusing on hypoxia allows for a clearer understanding of the physiological impacts and treatment approaches when oxygen levels drop, making it the more precise term in this context.