Oxygen

The Delhi High Court asked the Centre to immediately ban industrial use of oxygen due to the ongoing shortage of medical oxygen in hospitals

Most patients with Covid-19 have a respiratory tract infection, and in the most severe cases their symptoms can include shortness of breath. In a small proportion of such cases, this can progress to a more severe and systemic disease characterised by Acute Respiratory Distress Syndrome (ARDS).
The lungs enable the body to absorb oxygen from the air and expel carbon dioxide. When a person inhales, the tiny air sacs in the lungs — alveoli — expand to capture this oxygen, which is then transferred to blood vessels and transported through the rest of the body.
Respiratory epithelial cells line the respiratory tract. Their primary function is to protect the airway tract from pathogens and infections, and also facilitate gas exchange. And the SARS-CoV-2 coronavirus can infect these epithelial cells.
To fight such infection, the body’s immune system releases cells that trigger inflammation. When this inflammatory immune response continues, it impedes the regular transfer of oxygen in the lungs. Simultaneously, fluids build up too. Both these factors combined make it difficult to breathe.

Oxygen is the chemical element with the symbol O and atomic number 8
At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2.
It is a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds.
After hydrogen and helium, oxygen is the third-most abundant element in the universe by mass.
Oxygen constitutes about 65% of the mass of the human body and most of this is in the form of water.
Oxygen also makes up about 30% of the Earth and 20% of the atmosphere.
Another form (allotrope) of oxygen, ozone (O3), strongly absorbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation. However, ozone present at the surface is a byproduct of smog and thus a pollutant.

- Plants: During photosynthesis, plants use sunlight, water, carbon dioxide to create energy and oxygen gas is liberated as a by-product of this process.
- Sunlight: Some oxygen gas is produced when the sunlight reacts with water vapour in the atmosphere.
Artificially–
- Oxygen is produced in large quantities and at high purity as a gas or liquid by cryogenic distillation

Industrial uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.
Smelting of iron ore into steel consumes 55% of commercially produced oxygen

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