Written by Dr. Darko Butina

Or, What is the difference between the engine that runs the human body and the combustion engine? None!
The molecule carbon dioxide (CO2), a trace gas in our atmosphere is just about reaching concentration of 400 parts per million or 0.04{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117}, as measured at the Mauna Loa Observatory, better known as MLO. The current public view of CO2 is that of a villain causing practically everything that is wrong on our planet, from prostitution to tsunamis, from schizophrenia to earthquakes, from overheating to overcooling, from floods to droughts and so on.
Since well over one thousand peer reviewed papers say so, since all of the major television and newspapers outlets say so, since lot of national academies say so, surely it must be so? Surely, to accuse someone of mass murder and even genocide one would expect overwhelming evidence against the CO2 molecule; not by thousands of unreliable witnesses that never met or saw the murderer, but by the hard forensic data, in this case experimental data.
Since the standard definition of excellence in the climate sciences is ‘the less you know about CO2 and the calibrated thermometer, the more eminent scientist you are’, I will humbly present to you some basic facts about CO2 that all those “ignorant specialist” in respiratory mechanisms and carbon chemistry are using in their daily jobs of pushing the frontiers of science forward, not backwards.
This report is about toxicity of CO2 and I will answer that infamous $64,000 question, or the way that the things are going at the moment, $64 trillion question: At what concentration does CO2 become toxic to humans?
So let me start with the first question raised in the title of this report. You see, there is no difference between the engine that runs the human body and the combustion engine – they both run on the molecules that are based on the element called carbon with the symbol C, they both need the O2 molecules to break the fuel down to smaller chunks, or rather oxidise the fuel/food that is needed for the engine to run, and they both produce CO2 as a product of that oxidation process. For every single carbon that enters that engine (human body or combustion engine) one molecule of CO2 comes out.
Let us now turn to the medical sciences and our knowledge of the respiratory mechanism that is the key to our survival. For a long time scientists working in the field of human physiology have wandered why evolutionary forces made humans breathe out and assign the function of breathing in and out to the brain?Whether you are awake or asleep, every breath in is followed by the breath out – why is that?
We could easily understand breathing in – the human body cannot function without oxygen and therefore we should be OK by just breathing in. The answer became obvious once we realised that all life is based on the carbon atom with the molecules of DNA and proteins being the two main engines of that life. Since everything that supports life is based on carbon, it follows that the major fuel which runs the human engine needs to be based on carbon. For clarity, whether you eat meat or are vegetarian, you are consuming carbon! And then the knowledge of chemistry comes in – oxygen function is to ‘oxidise’ and since all the food is based on carbon, the result is CO2: C + O2 = CO2. It therefore follows that inside your body lots of CO2 has been produced as a by-product which needs to be taken out of the body – hence breathing out. As any textbook on respiration will tell you:
“The primary function of the lungs is to obtain oxygen for use by the body’s cells and eliminate the carbon dioxide that cells produce”.
The figure at the top of the page below shows the general principle of the exchanges of different gases that occur between the lungs and the blood stream: