What is Radioactive Fallout? Definition, Concept and Effects

What is Radioactive Fallout?

Radioactive rain. It is defined as the deposition of radioactive particles, released into the atmosphere from nuclear explosions or leaks from nuclear installations and power stations, on the Earth’s surface.

Radioactive fallout is the accumulation of radioactive particles that are deposited on the ground and transported by water and can occur after an atomic bombing, a nuclear weapons test or an accident at a nuclear plant (such as Chernobyl).Radioactive Fallout

They are also composed of radioactive fragments and isotopes of other chemical elements, activated by the radiation of the explosion, as well as of the radioactive offspring of these isotope fragments.

The material is transported by water droplets that are in the atmosphere. In this way, it can be inhaled or reach the ground contaminating crops, wildlife and drinking water.
It can also contaminate crops, marine life, and drinking water.

Cow’s milk is also particularly vulnerable, according to experts, if cattle graze in areas exposed to radiation.

Depending on the type of atomic explosion, the earth may be contaminated for decades and possibly centuries. Contaminated buildings, soil, and vegetation must be replaced for cleaning.

Nuclear tests cause radioactive rains

This phenomenon has been observed since the period of large-scale atmospheric nuclear testing in the 1950s and early 1960s.

Allegations of its harmful effects were made for many years, but it was not until 1984 that a landmark decision was made when a Utah federal judge ruled that 10 people had fallen ill with cancer because of the government’s negligence in exposing citizens to the radioactive fallout in that state.

In 1985 the English and Welsh Pension Court of Appeal reached a similar conclusion in the case of a veteran of the British nuclear tests in the Christmas Islands during the 1950s.

Since the signing of the nuclear test limitation treaty in 1963, levels of radioactive fallout have decreased worldwide.

Weather conditions have a major influence on radioactive fallout, particularly local rainfall. Atmospheric winds are capable of carrying the precipitation of radioactive particles to large areas.


The individual radioactive particles are invisible and so light that they could spin around the planet again and again without ever descending to the surface.

However, this situation would only occur if a nuclear bomb were detonated at a considerable distance from the atmosphere.

When a nuclear weapon is detonated near the earth’s surface, the violence of the explosion pulverizes vast amounts of material, much of which is absorbed into the fireball and therefore into the hot mass that rises to form the characteristic mushroom cloud.

Inside the fireball and on the stem of the pump cloud, the radioactive particles adhere to heavier particles, which act as ballast.

The particles of higher mass matter fall back to Earth in a matter of minutes, forming a highly localized radioactive fallout.

The Local Rain

Particles of smaller but easily visible mass, carried by the wind, fall to the earth’s surface after several hours and are called local radioactive fallout.

The nature and extent of the explosion depend on the type and strength of the explosion, the altitude of the detonation and the speed and direction of the wind.

Microscopic particles remain suspended for longer periods. If the explosion is low or medium power, the bomb cloud may not reach the tropopause, i.e. the atmospheric layer between the troposphere and the stratosphere.

In such cases, so-called tropospheric fallout occurs, and the bomb fragments move around the Earth following the latitude where the detonation occurred, falling to the surface when rain and other forms of precipitation carry foreign matter from the atmosphere.

Radiative rain can cause different effects

Biological effects

the long-term retention of radioactive waste in the atmosphere allows some of the short-lived products to disappear.

In the event of tropospheric rain (which occurs in the troposphere, the layer closest to the Earth’s crust), disintegration occurs in the atmosphere, which partly reduces the dose of radioactivity.

Long-lived radioisotopes do not disintegrate and remain in the stratosphere and can remain a risk for years, especially in contaminated food.

Genetic effects

To evaluate the effects of this rainfall it is important to study the genetic effects of radiation.

It can produce mutations (changes in the reproductive cells that transmit characteristics from one generation to another), almost all of which are harmful and are passed on from generation to generation over a long period of time.

In case of exposure to high levels of radiation.

what should be done with contaminated clothing and shoes?

In case of irradiation, undress before entering the house or shelter, so as not to contaminate them. Take off your clothes and shoes and put them in a plastic bag.

Close the bag tightly and place it in a safe place away from living areas and children and pets.

A shower or bathe with hot (not boiling) water and soap.

Notify authorities that you have clothing and personal items that may have become contaminated so that they can be handled properly and disposed of in accordance with accepted national procedures.

What are potassium iodide tablets?

In the event of an accident at a nuclear power plant, potassium iodide tablets are administered to saturate the thyroid gland and prevent the fixation of radioactive iodine. If taken before or shortly after irradiation, the risk of cancer may be decreased in the long term.

Potassium iodide tablets are not“radiation antidotes”. They do not protect against external radiation or radioactive substances other than radioactive iodine.

They can cause complications in certain people, for example, those suffering from kidney disorders, so the administration of potassium iodide tablets should only be carried out if expressly recommended by public health authorities.

What effect does radioactive fallout have on food?

Food may be contaminated with radioactive material as a result of a nuclear or radiological emergency.

The surface of fruits and vegetables, or food of animal origin, can become radioactive if airborne or rain-borne materials are deposited on them.

Over time, the interior of food can also become radioactive, as radionuclides pass from the soil to crops and animals, rivers, lakes and the sea, where they can be captured by fish and shellfish.

The severity of the risk depends on the combination of radionuclides and the amount of pollutants emitted.

Radioactivity cannot contaminate canned foods; for example, canned or plastic-wrapped foods are protected from radioactivity as long as the container is intact.

What to do in case of radioactive fallout?

The response to a radioactivity emergency should be the same as to any emergency due to contamination of food by a dangerous product.

In the early stages of an emergency, and as long as it is safe, immediate action can be taken to prevent or minimize contamination of food by radioactive material. For example, you can do the following:

  1. PROTECT vegetable and forage crops by covering them with plastic or tarpaulins.
  2. STABLE the livestock or put it under cover.
  3. HARVEST crops that are ripe and put them under cover.

Many other short, medium and long-term measures need to be considered in severely contaminated areas, such as the following:

  1. Avoid consuming locally produced milk or vegetables.
  2. Avoid fishing, hunting or harvesting mushrooms or other fruits of the forest.

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