Little truly unpolluted air exists on Earth today, but atmospheric scientists have found something close to it.

Air over some parts of the open southern oceans may be the last vestiges of almost pre-industrial skies. The only pollutants in that air are sea salt, a little mineral dust, a faint whiff of brimstone from volcanoes and a smidgen of smoke from wildfires.

It's not that someone is hoping to bottle the virgin air and sell it. Rather, the air is needed to understand how much dust was around to trigger cloud formation and rainfall before humans started inadvertently tinkering with the system.

http://dsc.discovery.com/news/2007/01/04/cleanair_pla.html?category=earth

[Actually, bottling that air could be a profitable idea. Sounds like a good stuff to get high.]