A couple issues with that. ONe of these, is that if we use IRP scale, you would only gas a large city. Second, the blast would incinerate most of it, and shunt more out of the atmosphere. Third, you need prolonged exposure to generate phycical dependency. even if the gas hit a city, it would be a Physchological Dependence. They would go through -hell-, but it couldent kill them. To do that, you would have to drive -7- or so barges full of cardimine, which fusion reactors would probably have killed most people and or caused nuclear winter.