In the event of a nuclear explosion, the U. S. Department of Health and Human Services recommends staying inside for at least 24 hours. This is because the exposure rate to a 10-kiloton explosion (the kind that could damage but not destroy a city) drops to just 1% after 48 hours.
If something like this happens, you may be asked to enter a building and take shelter for a while instead of leaving. The walls of your home can block much of the harmful radiation, so staying indoors for at least 24 hours can protect you and your family until it's safe to leave the area. This is known as sheltering in place. Nuclear explosions can also produce clouds of dust and radioactive sand-like particles that disperse into the atmosphere, known as nuclear fallout.
It's important to know how far you live and work from major nuclear power plants and potential nuclear attack sites. Additionally, 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. In a nuclear attack, a nuclear bomb is detonated in the air or on the ground, causing a devastating explosion. To protect yourself and your family from the effects of such an attack, it's important to stay inside for at least 24 hours after the explosion.
This will help reduce your exposure to radiation and other dangerous elements.
