Phosphorus and Helium
Phosphorus and helium are two very different chemical elements with one big thing in common - one day the world could find them much more difficult to get hold of.
Helium and phosphorus are two very different elements of the periodic table. One is a highly reactive solid, the other a completely inert gas. Yet they have one big thing in common - mankind is frittering them away and could one day find them much more difficult to get hold of.
Without helium, the fight against cancer would become far more daunting. And a world without phosphorus... well, that hardly bears thinking about! We find out where we get these two critical elements from, and - far more disconcerting - where they end up.
And as for what can be done to conserve them? Listen to find out.