Video: How Far Away Would You Need to Be to Survive a Nuclear Blast? (2024)

It's been nearly 80 years since two nuclear bombs were detonated over the Japanese cities of Hiroshima and Nagasaki, killing at least 129,000 people, and causing devastating, long-term health effects.

To date, those are the only instances of nuclear weapons being used for warfare, but the reality is there are roughly 12,700 warheads remaining in the world today. So, what would happen if nuclear war broke out tomorrow?

Don't panic – this is just a hypothetical. But in the video below, the team from AsapSCIENCE breaks down the science of nuclear bombs to predict how likely you'd be to survive. Let's just say, in the case of a nuclear blast, you would want to be wearing white.

First, let's get this out of the way – there is no clear-cut way to estimate the impact of a single nuclear bomb, because it depends on many factors, including the weather on the day it's dropped, the time of day it's detonated, the geographical layout of where it hits, and whether it explodes on the ground or in the air.

But, generally speaking, there are some predictable stages of a nuclear bomb blast that can affect the likelihood of your survival. (You can also explore this chilling interactive to find out how a nuclear blast would spread through the area where you live.)

As the video above explains, approximately 35 percent of the energy of a nuclear blast is released in the form of thermal radiation. Since thermal radiation travels at approximately the speed of light, the first thing that will hit you is a flash of blinding light and heat.

The light itself is enough to cause something called flash blindness – a usually temporary form of vision loss that can last a few minutes.

The AsapSCIENCE video considers a 1 megaton bomb, which is 80 times larger than the bomb detonated over Hiroshima, but much smaller than many modern nuclear weapons.

For a bomb that size, people up to 21 km (13 miles) away would experience flash blindness on a clear day, and people up to 85 km (52.8 miles) away would be temporarily blinded on a clear night.

Heat is an issue for those closer to the blast. Mild, first-degree burns can occur up to 11 km (6.8 miles) away, and third-degree burns – the kind that destroy and blister skin tissue – could affect anyone up to 8 km (5 miles) away. Third-degree burns that cover more than 24 percent of the body would likely be fatal if people don't receive medical care immediately.

Those distances are variable, depending not just on the weather, but also on what you're wearing – white clothes can reflect some of the energy of a blast, while darker clothes will absorb it.

That's unlikely to make much difference for those unfortunate enough to be at the center of the explosion, though.

The temperatures near the site of the bomb blast during the Hiroshima explosion were estimated to be 300,000 degrees Celsius (540,000 degrees Fahrenheit) – which is roughly 300 times hotter than the temperature bodies are cremated at, so humans were almost instantly reduced to the most basic elements, like carbon.

But for those slightly farther away from the center of the blast, there are other effects to consider aside from heat. The blast of a nuclear explosion also drives air away from the site of the explosion, creating sudden changes in air pressure that can crush objects and knock down buildings.

Within a 6-km (3.7-mile) radius of a 1-megaton bomb, blast waves would produce 180 metric tons of force on the walls of all two-story buildings, and wind speeds of 255 km/h (158 mph). In a 1-km (0.6-mile) radius, the peak pressure is four times that amount, and wind speeds can reach 756 km/h (470 mph).

Technically, humans can withstand that much pressure, but most people would be killed by falling buildings.

If you somehow survive all of that, there's still the radiation poisoning to deal with – and the nuclear fallout. AsapSCIENCE touches on this in the video above, but the ongoing effects on the planet are longer-lasting than you might expect.

For example, a simulation study published in 2019 found that a nuclear war between the United States and Russia would plunge Earth into a nuclear winter within days, due to the levels of smoke and soot released into the atmosphere.

We also know that radioactive particles can travel remarkably far; a recent study found that remnants of radioactive carbon from Cold War nuclear bomb tests have been found all the way down in the Mariana Trench, the deepest point of the world's oceans.

Again, all of this is hypothetical – there are international treaties in place to stop the spread and use of nuclear weapons, so we hope you never need to know any of this information for real.

However, to find out more about the current state of nuclear weaponry in the world, including the scale of the bombs, you can visit the Nuclear Notebook at the Bulletin of the Atomic Scientists.

A version of this article was originally published in January 2017. Due to overwhelming reader interest, we have now updated this article in February 2022.

Video: How Far Away Would You Need to Be to Survive a Nuclear Blast? (2024)


How many miles away is safe from a nuclear blast? ›

The resulting inferno, and the blast wave that follows, instantly kill people directly in their path. But a new study finds that some people two to seven miles away could survive—if they're lucky enough to find just the right kind of shelter.

What is the radius of death from a nuclear bomb? ›

The initial radiation pulse from a 1 KT device could cause 50% mortality from radiation exposure, to individuals, without immediate medical intervention, within an approximate ½ mile (790 m) radius. This radius increases to approximately ¾ mile (1200m) for a 10 KT detonation.

How deep do you need to be to survive a nuclear blast? ›

A fallout shelter needs to protect you from radioactive particles and blast impact: compacted dirt is great at both. Building down to a depth of about ten feet will provide ample protection, but any deeper makes it hard to dig out in the event of a collapse.

How many miles can a nuclear bomb destroy? ›

Thus 1 bomb with a yield of 1 megaton would destroy 80 square miles. While 8 bombs, each with a yield of 125 kilotons, would destroy 160 square miles. This relationship is one reason for the development of delivery systems that could carry multiple warheads (MIRVs).

How long after a nuke is it safe to go outside? ›

Radiation levels are extremely dangerous immediately after a nuclear detonation, but the levels reduce rapidly, in just hours to a few days. This is when it will be safest to leave your shelter and participate in an orderly evacuation.

Where is the best place to live in the US if nuclear war breaks out? ›

Parts of California, Florida and Texas that are away from their big cities like San Francisco, Miami and Houston are ideal because they are near water and have good weather. 'If you're near water you will always be near food and water that can be ingested after it has been desalinated,' said Ragusa.

How far does the radiation of a nuke go? ›

Even though there is very little fallout that still exists in the environment, it is important to remember that recent fallout, within about 10 to 20 miles downwind of the detonation, can be very dangerous. This section talks about the different ways we can be exposed to radiation if a nuclear detonation occurs.

How far would a nuclear bomb spread if it went off? ›

Although details about how far fallout travels are highly dependent on weather conditions, the most dangerous concentrations of fallout particles (i.e., potentially fatal external exposures to those outdoors) occur within 10 to 20 miles downwind of the explosion (from a 10 kT detonation).

How far would a nuke reach if it hit NYC? ›

Maps produced by Alex Wellerstein, a professor and historian of nuclear technology, show that if detonated over downtown Manhattan in New York City, it would effectively vaporize SoHo and the surrounding neighborhoods, with a main blast radius that would level most buildings up to the southern end of Central Park and ...

Where is the safest place in the house during a nuclear war? ›

In a study published in Physics of Fluids, scientists simulated an atomic bomb explosion to determine the best and worst places to be in a concrete-reinforced building during such an event. The safest place: the corners of a room, author Ioannis Kokkinakis of Cyprus' University of Nicosia said in a statement.

How long would it take for radiation to clear after a nuclear war? ›

Seven hours after a nuclear explosion, residual radioactivity will have decreased to about 10 percent of its amount at 1 hour, and after another 48 hours it will have decreased to 1 percent.

Can you survive a nuclear bomb in a house? ›

Seek shelter indoors, preferably underground and in a brick or concrete building, per the Red Cross and FEMA. Go as far underground as possible, per the Red Cross and FEMA. If that's not possible, try to stay in the center of the building, for example in a stairwell.

Are you safe 100 miles from a nuclear blast? ›

Here, it's important to stress that even if the nuclear event doesn't happen in your immediate area—even if it's hundreds of miles away—the fallout could still potentially reach you in a day or less.

At what distance are you safe from a nuclear bomb? ›

Severe shockwave damage could extend to about a half mile. Severe thermal damage would extend out about a mile. Flying debris could extend up to a few miles. Initial (prompt) nuclear radiation for a 10-Kt blast could expose unprotected people within about 3/4 mile of the explosion site to lethal radiation dose.

How many states can a nuclear bomb destroy? ›

Theoretically there is no real limit to the yield of a thermonuclear bomb. Also, the Tsar bomba which was detonated in 1961, could have easily wiped out Rhode Island, Delaware or most of Maryland so, yes, you could potentially destroy an entire state with one thermonuclear bomb.

How long does an area stay radioactive after a nuclear blast? ›

Although the dangerous radiation levels will subside rapidly over the first few days, residual radiation from the long half-life fission products (such as 90Sr, 106Ru, 137Cs, 147Pm, and 155Eu) will become the main contributions to exposure (after about 10 years).

How far would a nuke on NYC reach? ›

Maps produced by Alex Wellerstein, a professor and historian of nuclear technology, show that if detonated over downtown Manhattan in New York City, it would effectively vaporize SoHo and the surrounding neighborhoods, with a main blast radius that would level most buildings up to the southern end of Central Park and ...

Would being underwater protect you from a nuke? ›

It is easy to see that normal water pressure from deep submergence would complement the overpressure from a nuclear blast.

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