breathinggas

Breathing gas refers to any gaseous mixture that is inhaled by living organisms to obtain the necessary constituents for respiration. In humans, breathable air is primarily composed of about 21 percent oxygen, 78 percent nitrogen and traces of argon, carbon dioxide, water vapor and other gases. The definition of breathing gas expands to include any engineered or natural mixture that satisfies the organism’s metabolic demands, such as scuba breathing mixtures (nitrox, trimix), hyperbaric oxygen therapy gases, and medical anesthetic gases like oxygen‑nitrous oxide blends.

The key characteristics of a viable breathing gas are sufficient partial pressure of oxygen to sustain oxygen consumption, absence of toxic concentrations of other components, and compatibility with the target organism’s physiological tolerance. For example, the partial pressure of oxygen in water must be substantially higher than ambient to allow a mammal to extract enough oxygen through lungs, prompting the development of hyperbaric chambers or oxygen-rich inhalation covers for diving.

Historically, underground miners in the 19th century first used non‑air gas mixtures to avoid the accumulation of flammable gases. By the early 20th century, the invention of sealed breathing apparatuses and oxygen concentrators enabled controlled breathing gas delivery for medical and industrial use. In modern applications, breathing gas mixtures are essential in aviation, underwater exploration, spaceflight, and anesthesia.

Safety guidelines for breathing gases involve monitoring of oxygen concentration, purging of CO₂ using carbon dioxide absorbents, and maintaining pressure within acceptable limits to prevent hypoxia, hypercapnia, or oxygen toxicity. Regular testing of gas supplies and personnel training are standard protocols across professions that utilize breathing gases.