Oxygen: a matter of life and death. Brian Cox and Robin Ince are joined on stage by chemist Andrea Sella, science broadcaster and writer Gabrielle Walker and comedian Sara Pascoe to look at the life and death properties of oxygen. It's the molecule we simply can't live without, but as fate would have it, oxygen is also the molecule that eventually leads to our death. Hailed as an elixir of life, and foundation of the atmosphere, oxygen is the revolutionary element that quickens life and hastens death through its ferocious reactivity. It's the molecule our cells need, but is actually highly toxic to them, and is in the end what causes us to age. Brian and Robin get to grips with the chemistry of this contradictory molecule, and Andrea Sella tries not to cause too big an explosion by demonstrating oxygen's reactive nature using a digestive biscuit. Producer: Alexandra Feachem.