You wake up in the dead of night as a flash brighter than the sun streaks through your windows. Was it car headlights? No, you realize something isn’t right when all the electronics in your house are dead. Then you hear emergency sirens outside and you realize; it was a nuclear explosion.

Now what?

New research suggests rather than “sheltering in place” as many emergency programs insist, your best bet for survival after a nuclear detonation might be to run away from the blast zone and the deadly fallout, rather than staying in a building with only moderate protection from radiation.

Make a run for it? The mathematical model of nuclear fallout suggests that sheltering in place (first option above) is not always the best survival strategy. If you can reach higher quality shelter in less than 30 minutes (second option), you should go for it. And if you are out in the open, you need to find any shelter at all, and soon (third option).

Michael Dillon, an atmospheric scientist at Lawrence Livermore National Laboratory in California, created a mathematical model of nuclear fallout survival after his relatives – who were curious about his work – asked what they should do if they saw a mushroom cloud.

“I realized that I really didn’t have a great answer,” Dillon said. The official U.S. government advice is to “take shelter in the nearest and most protective building.” For most people, that would be the basement of their home. But, Dillon says, “out in California there just are not that many basements,” offering little protection from fallout.

For those people, the official recommendations suggest “early transit” to find better shelter, ideally one with thick layers of concrete over your head and plenty of food and water.  But if you spend too much time outside in the fallout, you’re toast. Dillon’s mathematical model results surprised him, Science reports:

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 claims, in the Proceedings of the Royal Society A.

Dillon’s strategy addresses gaps in 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 portable, low-yield bombs are the most likely terrorist threat.

Not everyone is on board with Dillon’s run-like-the-wind strategy, however.

“I disagree with the conclusions,” says Lawrence Wein, an operations research scientist at Stanford University in Palo Alto, Calif. “He fails to account for several important issues that are vitally important for policy recommendations.”

Such as, most injured, confused and panic-stricken people likely won’t be able to execute a flawless evacuation strategy. Simply stumbling to the basement sounds like a better mass plan than suggesting hundreds of thousands of people head into the apocalyptic wasteland without idea how long the transit time will really be.

Because of this uncertainty, Wein says, the official U.S. government recommendation is “to shelter for at least 12 hours” after the blast.

In TheBlaze’s example at the beginning of the article, the situation is made even worse at night. Without sunlight to assist in the “early transit” stage, a survivor would have little hope in making their way to a fallout shelter unless they had mapped out and practiced an escape route.

So, for example, this woman would need to start running fast away from the blast. If this were real. Not sure if those sunglasses are much help at this point. (Credit: Shutterstock)

Public health researchers at the U.S. National Institutes of Health in Bethesda, Md., say Dillon’s models are useful.

“As someone working with government and state and local planners, we find models extraordinarily useful to help us develop concepts of operations,” C. Norman Coleman, a researcher at USNIH says. For example, knowing how long the window of opportunity is for people to reach better shelter can help rank future evacuation plans. At the very least, Coleman says, Dillon’s model reveals what is “possible to do and what is not likely to be useful.”

(H/T: John Bohonnan, Science)