We all agree: Oxygen is vitally important to us, if we stop breathing it, we will be dead in a matter of minutes. And yet, how much does the average person know about it? What exactly is Oxygen and where does it come from? Is it an elixir or poison or both?

Oxygen is a gas with the chemical symbol O, the third- most abundant element in the universe that constitutes 20.8% of the Earth’s atmosphere. The name Oxygen was coined only in 1777 and the element itself had been „discovered“ only several years earlier but curiously enough, even before that, had been know to the Alchemists, the ones that tried to turn iron into gold.

The unusually high concentration of Oxygen gas in the atmosphere of the Earth is the result of Photosynthesis, a process in which light is used by organisms to split water and convert CO2 into glucose, emitting Oxygen as a waste product in the atmosphere. Photosynthesis emerged 3.5 bln years ago. Why is this a big deal?

It is thanks to this emission of Oxygen as a waste product of photosynthesis that the Earth preserved its oceans while the other planets lost them. How come? Here is how. There is water in gas form in the atmosphere. The ultraviolet sun rays split the water molecule (H2O), Hydrogen being a light gas escapes the gravity, while Oxygen, being much heavier, is retained by gravity and reacts with iron in the rocks and oceans, forming crust, the net result being loss of water. This is what happened on the early Earth before the emergence of photosynthesis, this is what cost Mars and Venus their oceans. On the other hand, the Oxygen emitted as a result of photosynthesis combines with the Hydrogen from the split water molecules in the atmosphere and in this manner locks it back in, recaptures it so to say and this is what conserved the water on our planet.

Another peculiar thing about oxygen is that it is toxic. Very high concentrations of oxygen cause convulsions and death in a matter of minutes. The toxicity of oxygen is what drove the emergence of complex organisms adapted to tolerate so much oxygen in the air. The first multicellular organisms probably evolved from clumps of cells which clustered together to deal collectively with the rising amount of atmospheric Oxygen.

The toxicity of Oxygen results from the formation of free radicals (fleeting electrons from the Oxygen atom) and the formation of intermediary Oxygen compounds that are highly aggressive and damaging. This formation of free radicals is caused both by the ultraviolet radiation of the Sun and also, by our own respiration. When we use Oxygen to extract energy from food, we produce free-radical intermediates that are the exact same ones that result from radiation. Oxygen‘s free radicals are formed inside us all the time. Over a lifetime the cells in our bodies gradually deteriorate and this is called ageing. Hence, the process of aging is a process of slow Oxygen poisoning akin to radiation poisoning.

In an nutshell: Oxygen is both a life elixir and poison at the same time, subjecting us to slow poisoning akin to radiation poisoning that causes ageing and ultimately death.

© Teodora Rudolph. All rights reserved 2016, Zurich, Switzerland

Picture Rafaela Beddig