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
Historically, underground miners in the 19th century first used non‑air gas mixtures to avoid the accumulation
Safety guidelines for breathing gases involve monitoring of oxygen concentration, purging of CO₂ using carbon dioxide