"On Sunday morning, hundreds of thousands of pounds of toxic gas were accidentally released from the Shell Oil facility in Deer Park [Texas].

According to reports from the Texas Commission on Environmental Quality, 326,166 pounds of butadiene escaped through an open valve on a spherical tank between 10:40 am and 11:35 am.

Neil Carman, a chemist with the Sierra Club of Texas and a former power plant inspector for the TCEQ, said that butadiene is a known human carcinogen, but that its molecular structure allows it to dissipate quickly in the hot summer air. The chemical is commonly expelled in car exhaust, but Carman said the quantity in the Shell incident was concerning."

Dylan Baddour reports for the Houston Chronicle August 12, 2015. [2]