How Far Away is Safe from a Nuclear Bomb?

The threat of nuclear weapons has been a frightening reality since the Atomic Age. With recent threats of terrorism, many people have expressed concern about the likelihood and effects of a nuclear explosion. To understand how far away you need to be to be safe from a nuclear bomb, it's important to consider the size of the bomb, the distance from the explosion, and the potential for nuclear fallout. Minor first-degree burns can occur up to 11 km (6.8 miles) away, while third-degree burns, which destroy and blister skin tissue, can 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 medical attention is not received immediately. The U. S. Department of Health and Human Services recommends staying home for at least 24 hours in the event of a nuclear explosion.

After 48 hours, the exposure rate to a 10-kiloton explosion (the kind that could damage but not destroy a city) drops to just 1%. Nuclear explosions produce a powerful phenomenon called a nuclear electromagnetic pulse (PEM), an invisible burst of energy that can cut off power lines, telephone and Internet. This marked the beginning of a frightening new era known as the Atomic Age, and the threat of nuclear weapons never disappeared. The 1963 Limited Nuclear-Test-Ban Treaty ended atmospheric testing for the United States, Great Britain and the Soviet Union, but two major non-signatories, France and China, continued nuclear testing at a rate of approximately 5 megatons per year.

A bomb case would produce a very destructive nuclear explosion, but not as large as that of a nuclear weapon developed for strategic military purposes. For survivors of nuclear war, this persistent radiation hazard could pose a serious threat for up to 1 to 5 years after the attack. Nuclear explosions can produce clouds of dust and radioactive sand-like particles that disperse into the atmosphere, known as nuclear fallout. Essentially, it is best to avoid countries with access to nuclear weapons and those involved in nuclear agreements. To be safe from a nuclear bomb, it is important to consider the size of the bomb, distance from the explosion, and potential for nuclear fallout.

Minor first-degree burns can occur up to 11 km (6.8 miles) away while third-degree burns can affect anyone up to 8 km (5 miles) away. Department of Health and Human Services recommends staying home for at least 24 hours in the event of a nuclear explosion.