Fallout is the radioactive particles that fall to earth as a result of a nuclear explosion. It consists of weapon debris, fission products, and, in the case of a ground burst, radiated soil. Fallout particles vary in size from thousandths of a millimeter to several millimeters. Much of this material falls directly back down close to ground zero within several minutes after the explosion, but some travels high into the atmosphere.
A nuclear blast is different than a dirty bomb. A dirty bomb, or radiological dispersion device, is a bomb that uses conventional explosives such as dynamite to spread radioactive materials in the form of powder or pellets. It does not involve the splitting of atoms to produce the tremendous force and destruction of a nuclear blast, but rather spreads smaller amounts radioactive material into the surrounding area.
The main purpose of a dirty bomb is to frighten people and contaminate buildings or land with radioactive material. While a serious event such as a plane crash into a nuclear power plant could result in a release of radioactive material into the air, a nuclear power plant would not explode like a nuclear weapon. There may be a radiation danger in the surrounding areas, depending on the type of incident, the amount of radiation released, and the current weather patterns. However, radiation would be monitored to determine the potential danger, and people in the local area would be evacuated or advised on how to protect themselves.
Local emergency management officials will tell people when to take KI. If a nuclear incident occurs, officials will have to find out which radioactive substances are present before recommending that people take KI.
If radioactive iodine is not present, then taking KI will not protect people. Taking KI will not protect people from other radioactive substances that may be present along with the radioactive iodine.
Skip directly to site content Skip directly to page options Skip directly to A-Z link. Radiation Emergencies. Section Navigation. Facebook Twitter LinkedIn Syndicate. Minus Related Pages. What is a nuclear blast? What are the effects of a nuclear blast? How can I protect my family and myself during a nuclear blast? Following are some steps recommended by the World Health Organization if a nuclear blast occurs: If you are near the blast when it occurs: Turn away and close and cover your eyes to prevent damage to your sight.
Drop to the ground face down and place your hands under your body. Vehicles offer almost no protection from radiation , including fallout, and a driver can experience dazzle — or flash blindness — for 15 seconds to a minute. If you happen to be driving at speed on the roadways, and you and all the other drivers around you are suddenly blind, I think that would probably result in crashes and injuries and road blockages.
If there's a missile alert, the best move is to get to the closest place where you can safely pull over, get out, and make your way into a building. The deeper and lower in the building you can get, and the farther from windows which can shatter , doors which can fly open , and exterior walls which can cave in , the better your odds. At home, a three-story condo building, he'd head toward the first floor and move as much toward its center as possible. Staying inside can also limit how much invisible nuclear radiation produced by a blast will reach your body.
Too much exposure over a short time can damage the body enough to limit its ability to fix itself, fight infection, and perform other functions, leading to a dangerous condition called acute radiation sickness or syndrome. Typically, about millisieverts of exposure over several hours or less can make a person sick. This is roughly times the amount of natural and medical radiation that an average American receives each year. A kiloton blast can deliver this much exposure within a radius of about a mile , inside the "moderate damage zone.
But Buddemeier says most exposure assumptions are based on test blasts in the desert. The next danger to avoid is radioactive fallout , a mixture of fission products or radioisotopes that a nuclear explosion creates by splitting atoms. Nuclear explosions loft this material high into the atmosphere as dust-, salt-, and sand-size particles, and it can take up to 15 minutes to fall to the ground.
High-altitude winds can make it sprinkle over hundreds of square miles , though it's most intense near the blast site. The danger is from fission products that further split up or decay. During this process, many shoot gamma rays, an invisible yet highly energetic form of light that can deeply penetrate the body and inflict significant radiation damage.
But a nuclear attack would probably create more radioactive fallout than a missile-launched warhead. That's because warheads are often designed to explode high above a target — not close to the ground, where their fireballs can suck up and irradiate thousands of tons of dirt and debris. Regardless, Buddemeier says sheltering in place for at least 12 to 24 hours — about how long the worst of this radiation lasts — can help you survive the threat of fallout.
He added that, depending on your distance from the blast, you might get 10 to 15 minutes to move to a better shelter — ideally, a windowless basement, where soil and concrete can help block a lot of radiation. Buddemeier said that at his basement-less condo, he'd move to the center of the middle floor after a blast "because the fallout is going to land on the ground around my house, and that first floor would have slightly higher exposure than the second floor.
Because some of the isotopes in fallout from weapons testing were the long-lasting type, a small amount of radioactive fallout remains in the environment today, and people can continue to be exposed. However, scientists were able to estimate the dose to which an average person might have been exposed.
All people who were born since have received some exposure to radiation from weapons testing-related fallout. Some people who received higher radiation doses may have an increased risk of cancer from this exposure, although CDC and NCI scientists believe this risk is small for most people. Your individual dose from fallout will depend on a number of factors such as where you lived when the testing occurred, how much time you spent outdoors, the weather, how much milk you drank and fresh fruits and vegetables you ate, and other personal lifestyle and individual factors.
Because all people in the United States who were alive since received some radiation exposure from fallout, some people may have an increased risk of cancer from this exposure, in particular, thyroid cancer. CDC and NCI scientists believe that although the potential for developing thyroid cancer from exposure to global fallout is small, it is important for people to be aware of the risks.
People exposed to I, especially during childhood, may have an increased risk of thyroid disease, including thyroid cancer many years later. Thyroid cancer is uncommon and is usually curable. NCI has more information about I and thyroid disease at its Web site at www. However all studies have shown the risk to be very small. Scientists continue to study the risks from exposure to these isotopes and others.
In , Congress asked CDC and NCI to see if it would be feasible to estimate whether Americans have suffered health effects from nuclear weapons tests in the atmosphere.
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