I'd agree with this general statement, too. Even when speaking about arguably one of the most toxic substances--plutonium from a dirty bomb--most of us would not be terribly at risk of dying. I elaborated on this particular threat a couple years ago here . (Unfortunately, one of the informative links in that post is now out-of-date) Actually, I had made a mental note to myself back then that if a dirty bomb went off in my vicinity, I would prefer to stay indoors (like at work) rather than trying to get out of Dodge in the minutes or hours immediately after, when the concentrations of plutonium suspended in the air outside would be highest. You'd be far more likely to die in a car accident with everyone else trying to make a mad dash to safety at the same time than from the plutonium.