Air consists of nitrogen (N2, 80%) and oxygen (O2, 20%). They do not react at normal temperature, but produce nitrogen oxide at a higher temperature like in a combustion engine.

Life needs fixated nitrogen to produce amino acids (and in turn proteins) and nucleic acids (DNA).

Because N2 is hold by triple covalent bond, lots of energy is need to break it down. Humans and animals do not know how to break down nitrogen gas, so they need to eat greens.

Plants also do now know how to do it, but but bacteria and algae (diazotrophs) in soil can do nitrogen fixation by turning nitrogen gas (N2) into nitrates (NO3) and ammonia (NH3).

The Haber-Bosch process, invented in 1910, produces 30% of the total fixed nitrogen. Lightning does this naturally. Gaber was also responsible for creating chlorine, a poisonous gas heavier than air.