[Trex]

Most of what the man on the street calls ‘chemicals’ are made up of carbon (C), hydrogen (H), oxygen (O) and nitrogen (N), plus a bunch of other elements - C, H, O and N are the biggies. Depending on the chemical reaction and the way the various elements are combined, different things are produced.

If there is insufficient oxygen for complete combustion, one typically gets carbon monoxide (CO) as one of the products. This is Bad as it interferes with blood oxygen transport.

A typical product of even complete combustion (including animals’ breathing) is carbon dioxide or CO2. This is present in the natural air we breath, but at a very low level, say 0.05%. If that level rises to a given level, animals find it poisonous. Top tolerable limit (without dying, ie) is somewhere around 5% but effects are felt well below that and safety standards, depending on where you are, call for something on the order of 0.5% maximum. CO2 is happy juice for plants, which breath it and release pure oxygen (O2) – it’s a good relationship between plants and animals, ie.

CO2 is, significantly, a greenhouse gas, directly tied to global warming.

It might also be noted that while pure nitrogen (N2) comprises something like ¾ of the air we breath and is quite harmless, combustion products containing nitrogen are often Bad and contribute directly to the pollution we can smell and even see in smog.

This is why I am so impressed with the potential of hydrogen power. Burn pure hydrogen in the presence of pure oxygen and you get pure water, totally nonpolluting. As noted by Seafarer, there are problems in the way we make hydrogen at present, but the potential is there. Hypothetically, we could use sunlight as the power to break down water (H2O) into its components of hydrogen and oxygen. It’s not quite that simple as the infrastructure is going to be a pain, but it is possible.

But he’s right – TNSTAFL still reigns.