The following article caught my eye a few weeks ago:

It deals with the call of an eminent scientist who is asking for the sale of Helium balloons to be banned as there is a shortage of the gas for instruments such as MRI scanners.

What I found particularly interesting is that Helium is mined – it is obtained as a by product from the extraction of natural gas. I had always pictured it being extracted from the air but (I guess) the concentration of it is too low and as it has such a low density, maybe most of it is found too high in the atmosphere anyway.

Would you be willing to pay £60 (approx 100€) for a balloon as this scientist is calling for?