Originally Posted by
S.o.S.
Justapax1 Given that you have now revealed your true self - I shall probably have to ban you permanently from PPRuNe. After all, we can't have people in here spouting actual, real knowledge and like, you know, facts man. 
Is that what they call purple prose
?
I am duly admonished.
Helium is constantly released into the atmosphere by natural processes. To put it in context, if you are reading this in a typical living room, most of the air is nitrogen, oxygen, and water vapour, but the argon would fill an inflatable armchair, the helium would fit in a shoebox, and the carbon dioxide in two shoeboxes. If you live in a city centre, there will also be NOx and SO2, in teaspoonful quantities.