Sulfur hexafluoride

From Conservapedia

Sulfur hexafluoride (SF₆) is a colorless gas soluble in alcohol and ether, and slightly less soluble in water. It is used as a dielectric in electronics and in the making of plastics for toys.

Sulfur hexafluoride possesses the highest 100-year global warming potential of any gas (23,900).

It is also incredibly toxic, requiring only a few grams to to be lethal.