The yahoo news item gives better insight. http://news.yahoo.com/ga...-024755078--finance.html It may do reputational damage to one of the leading lubricant additive companies as this does not appear to be a gas leak but apparently a product that has decomposed "...........Internal operations director Pierre-Jean Payrouse said the company was battling to plug the leak, as the cloud spread over some 350 km (220 miles), but said it might take until the evening. The cause of the leak was still unknown." "It's not so much a leak as a product that has decomposed, which smells very bad and which is escaping," Payrouse told RTL radio. "An investigation is under way (into what happened) but our priority is to deal with the problem." There is a lubricant additive, Zinc dithiophosphate (ZDDP) that can decompose giving off Hydrogen Sulphide and mercaptans on heating above 80 to 90 degrees C http://en.wikipedia.org/wiki/Zinc_dithiophosphate http://en.wikipedia.org/wiki/Zinc_dithiophosphate