When a nuclear weapon detonates, everything changes instantly. For many, there is simply no time to react. For those not killed outright, the next seconds and minutes are critical – survival depends on immediate action.

The scale of destruction is difficult to justify in any terms: within hundreds of feet, everything is vaporized, and miles beyond that, buildings collapse under extreme force. But even for survivors of the initial blast, the ordeal is not over. Lethal radiation exposure follows, leading to catastrophic physical damage and death.

But research suggests survival could be possible for some, if you act fast and follow key steps, according to UNILad. First, they recommend resisting the urge to get into a car; it will not protect you from the blast or radiation. Instead, immediately seek proper shelter and follow survival guidance.

Step one: Do not look at the blast

A nuclear explosion produces a flash brighter than the sun. Anyone facing it risks immediate blindness, in some cases permanent. Even at distances of up to 10 miles, looking directly at the blast can damage the eyes.

The American Red Cross advises: “Do not look at the flash or fireball – it can blind you.Take cover behind anything that might offer protection,” according to UNILad.

Standing by a window is just as dangerous. What follows the initial, bright flash is powerful enough to turn glass into deadly projectiles within seconds.

Step two: Immediately get inside the nearest reliable shelter

The shockwave travels faster than sound and can arrive in under 30 seconds, depending on your distance from the blast. This wave, known as overpressure, can reach forces of around 20 pounds per square inch near the blast site, enough to reduce buildings to rubble.

As it moves outward, it weakens, but even at 5 psi, it remains powerful enough to collapse residential structures or kill anyone caught outside. As described by the Atomic Archive: “The air immediately behind the shock front is accelerated to high velocities and creates a powerful wind.

“These winds in turn create dynamic pressure against the objects facing the blast. Shock waves cause a virtually instantaneous jump in pressure at the shock front.

“The combination of the pressure jump (called the overpressure) and the dynamic pressure causes blast damage.”

Seek shelter immediately. Go to a basement if possible. If not, head to the deepest part of a large building and position yourself in a corner facing the blast. Move quickly and do not hesitate.

What comes next is slower – and just as dangerous

After surviving the blast itself, you have only a few minutes to find a better shelter, where you need to stay put for at least 24 hours, ideally up to 72. Radiation levels decrease over time, but the first hours are the most dangerous, and could be vital if you’re exposed.

The threat is invisible, but very deadly. Protection comes from distance and shielding. Thick layers of concrete or soil provide the best defense.

Move into a basement or enclosed structure. Once inside, seal the space by closing windows, doors, and vents. If possible, ensure you have water.

Step three: Remove outer clothing and wash exposed skin and hair with water to reduce radioactive contamination. Remain inside and wait for updates.

Stay sheltered. Then, conserve resources. Finally, follow any remaining official guidance.