Union Carbide, a chemicals firm, has a link to information on the deadly Bhopal gas leak in India on its home page, for example.

ECONOMIST: Corporate history

"The methane 'leak' claim just got a lot more difficult for opponents" of natural gas, noted Steve Everley, with Energy In Depth, an industry-funded group.

NPR: EPA Methane Report Further Divides Fracking Camps

Last August a gas leak at the Amuay refinery in western Venezuela led to an explosion and fire that burned for days and killed more than 40.

FORBES: What Does Chavez's Death Mean For Venezuelan Oil Giant Pdvsa?