To get to the bottom of this, a chemist recently took bone from the mummy of a Nubian child and dissolved it in hydrogen fluoride, a nasty acid that helps extract tetracycline.

The system, made by Linde, splits hydrogen fluoride into fluorine.

Finally, refineries emit many gases like sulphur dioxide (SO2), nitrogen oxide (NO2), carbon dioxide, carbon monoxide, methane, dioxins, hydrogen fluoride, chlorine, benzene and others.