The highly toxic H2S (hydrogen sulfide) and CO2 (carbon dioxide) are removed along with excess water to get the gas below 7 ppm (parts per million).

FORBES: We're Headed To $8 Natural Gas

My guess is you saw a lot more -- people can recall seeing a lot more Hummer H2s on the road, say, three years ago than sort of post-late summer 2008.

WHITEHOUSE: Press Briefing