It is something guaranteed to catch the eye of most young children on a day out – a huge bunch of floating, brightly-coloured helium balloons for sale. And for many people, a vital element in arranging a party is sitting down with a cylinder of helium to fill dozens of balloons with the lighter-than-air gas.
But according to one academic, such occasions may soon be a thing of the past. Tom Welton, a professor of sustainable chemistry at Imperial College, London, believes that a global shortage of helium means it should be used more carefully.