During the Cold War, the U.S. government recommended that schoolchildren "duck and cover" in case of a nuclear attack. Those days and that anxious cartoon turtle are now behind us, but the threat of nuclear war still lingers. In 2014, an atmospheric scientist published a paper suggesting that victims of a nuclear attack do something unexpected: instead of hunkering down at home, they should leave to find better shelter. His recommendations have their critics, however.
Hole Up Or Head Out
Lawrence Livermore National Laboratory atmospheric scientist Michael Dillon, Ph.D. published an analysis in Proceedings Of The Royal Society A where he crunched the numbers to determine a person's best course of action in case of a low-yield nuclear attack — the kind like that of Hiroshima and Nagasaki, which experts think would be on par with the size of bomb a terrorist could detonate. If a bomb like that exploded, it would first produce a giant radioactive fireball, followed by a flash of light that can blind and burn skin, and finally a blast of superheated air that can crush buildings and send clouds of debris flying. Dillon's analysis, however, deals with the aftermath: the deadly radioactive fallout. What's the best way to avoid it?
Guidelines generally recommend to take shelter in the closest, most protective structure you can: a basement, a parking garage, or a tunnel, which FEMA says can reduce radiation doses by a factor of at least 10. But what if your house doesn't have a basement? Dillon has an answer: if your house isn't very protective and you know you can get to a quality shelter in five minutes, run to that shelter. If the nearest shelter is 15 minutes away, stay put for a half-hour, maximum, then run to that shelter.
That's because your radiation dose is a balance of how much you get in an improper shelter and how much you'll get when you're outside reaching a better shelter. According to Dillon's calculations, a five-minute run is worth reaching a nearby shelter. But if it's further away, waiting pays off, since environmental radiation intensity decreases over time. The researcher estimates that these guidelines could save between 10,000 and 100,000 lives.
Not everyone agrees with this advice. Critics say that telling everyone to leave can force too many people out on the streets, where they'll be slowed by gridlock and exposed to radiation for longer than they planned. That's one reason the U.S. government recommends that people shelter for at least 12 hours after the blast. Even barring a mob of people running for safety, an individual can't predict how long it'll take to get to a shelter after a blast based on how long it would take on a normal day. There will most definitely be debris in the way, slowing you down.
Still, it's important to crunch the numbers because that helps government agencies create better recommendations and evacuation plans. Knowing that there's a tradeoff between how much radiation you get in a poor shelter and how much you'd get by running to a better one is useful in policy decisions, and could indeed save lives. But if the they do drop the big one, try your best to hole up in a basement (or at least a fridge, Indiana Jones style), and feel free to duck and cover.