New mathematical model tells you whether to stay put—or run like hell
It begins with a flash brighter than the sun. Trees, fences, and people immediately catch fire. The only reason you survive is because you run inside and dive into the cast-iron tub just as the shock wave arrives. You stumble to your lopsided front door and look out on the burning ruin of your neighborhood. The deadly radioactive fallout is on its way. Should you stay in your wobbling house or run across town to the public library to shelter in its basement? A new mathematical model may have the answer.
The model is the brainchild of Michael Dillon, an atmospheric scientist at Lawrence Livermore National Laboratory in California. He started exploring the topic about 5 years ago after the U.S. government called for more research on nuclear shelters. During the Cold War, scientists modeled almost every imaginable consequence of a nuclear explosion. But Dillon found a gap in the sheltering strategies for people far enough from ground zero to survive the initial blast but close enough to face deadly fallout. He focused on a single low-yield nuclear detonation like those that destroyed Hiroshima and Nagasaki. The world’s nuclear arsenal has grown far more powerful—today’s warheads can inflict thousands of times more damage—but security experts believe that low-yield bombs are the kind most likely to be used by terrorists.
Dillon simplified the calculation by assuming that you are totally exposed while running to safer shelter; he also ignored complexities such as limited shelter capacities. In the end, the math boiled down to a single critical number: the ratio of the time you spend hunkering down in your first shelter to the time you spend moving to the high-quality shelter. Then Dillon worked out what would happen with a variety of shelter options and transit times.
The results surprised him. For low-yield nuclear detonations, you can do far better than just sheltering in place, but you’ll need a watch and good knowledge of your surroundings. If your current shelter is poor and higher quality shelter is less than 5 minutes away, the model suggests that you should run there as soon as you can. If you have poor shelter but higher quality shelter is available farther away, you should get to that high-quality shelter no later than 30 minutes after detonation. Depending on the size of the city, if everyone follows this advice, it could save between 10,000 and 100,000 lives, Dillon reports online today in the Proceedings of the Royal Society A.