A nuclear blast occurs when a nuclear bomb is detonated. This releases heat, light, and radioactive chemicals that contaminate the air, water, and ground for miles.
Nuclear attacks are a possibility, even though they are less unlikely to happen than other forms of terrorist attacks. It’s possible that a terrorist could create an improvised nuclear weapon that is smaller and less powerful than a nuclear bomb, but still dangerous, therefore you should know what to expect, and how to survive a nuclear attack.
The main factors in your safety during a nuclear attack is your distance from the blast, the surface that’s shielding you from the attack, and the amount of time that has passed since the attack occurred. You’ll want to be located in an area as far away from the blast as possible, surrounded by thick materials protecting you from the blast. A basement or in the middle of a building with thick walls is the best place to survive a nuclear attack.
After a nuclear attack, you may need to stay in shelter for up to a month before the radioactive fallout decays and there’s no longer a risk for radioactive poison. Within about two weeks the amount of radiation should be about 1 percent of what it was during the first 24 hours after the bomb.