What self cleaning windows, deodorizing lights and your skin have in common
Self cleaning windows are a marvel of modern technology. They are capable of breaking down grime and organic matter on their surface, thus reducing the amount of effort you need to spend cleaning them. This is all achieved through the use of a relatively benign compound: titanium dioxide (or TiO 2 for you chemistry freaks). TiO 2 is fairly inert and non-toxic. However, don't push it, everything is toxic in the sufficient amounts or if irresponsibly used - just think of dihydrogen monoxide (H 2 O). It is used almost everywhere as a whitening agent – toothpaste, icing, paint, plastics, etc – because it is incredibly white and non-toxic. It does have one interesting property: it is a photocatalyst. That means it interacts with light and facilitates a chemical process, while not actually taking part in the chemical process. For example, nickel is used as a catalyst in the process of hydrogenating margarine (adding an extra hydrogen atom to a liquid fat and making it a not so good sol...