h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Denser inert gases exist. For details, read down the right hand side (group 8, or group 0, depending on your standpoint) of the periodic table.

Information on the periodic table can be found here: http://www.theodoregray.com/PeriodicTable/

See also referencing article (plug! plug!) at A973677

Xenon is another inert gas. Inhalation of which, while hideously expensive, should not be dangerous providing sensible precautions (like breathing out properly) are taken.

Radon, on the other hand, is somewhat radioactive. http://www.theodoregray.com/PeriodicTable/Elements/086/index.s7.html has the following to say about Radon:

1. It is radioactive, and seeps out of the ground all over the world, more in some places than others (those of you in Cornwall should be particularly aware of this)
2. There was a brief period of time during the twentieth century during which people thought radon was a good thing (yikes!)

After Radon, there is (or isn't) Element 118, which doesn't exist, atleast not such that it can be measured. Various people are working on it, and these people can be identified by the bright blue glow they emit in the dark. Inhaling element 118 is probably best avoided.

There is of course also SF6 (sulfur hexafluoride, cheap and HEAVY, and inert...) But it's waaaay more dangerous.

(That's also the reason why I didn't mention the heavier gases explicitly in the Entry, one could 'drown' in them)

HELL

WARNING! WARNING! WARNING!

DO NOT TRY THIS WITH XENON!

There is very little danger of 'drowning' in xenon (one good breath out empties much more than the normal tidal volume of the lungs). However, xenon is a very good anaesthetic. Indeed, if it were cheaper it would be very widely used as such.

How do I know this? I was stupid and tried it out. Friends said the dizziness I felt was due to my lungs being full of xenon. So I repeated the experiment standing on my head - and the dizziness was worse. Only later did I find that I'd been sending myself to sleep.

Oh - and it did have a marked effect on my voice.

Ref: http://www.anaesthetist.com/anaes/drugs/xenon.htm

Righto, I withdraw my earlier suggestion. Where did you get Xenon gas from anyhow? I would have thought the cost would be fairly high..

I also wonder what element 118 would be like...

(We should also add a note for the common-sense-impaired: These gases, while present in things like neon lighting, are not present in any significant volume, and what is in there is at a pressure way below atmospheric. If you are looking at flourescent lightbulbs as a source of recreational gas, DONT. Not to mention the interesting effects the other compounds in the tube, and the broken glass particles can have on your system. Eeuuuwww!. But hey, why not; Kkill yourself stupidly and contribute to the intellectual development of the human race! Win a Darwin Award (www.darwinawards.com))

(Ps, that wasn't aimed at you, but if you thought it was, perhaps it was after all )

Mmmm. Darwin awards. Time for another guide entry, methinks...