Study material

The effects of nuclear weapons

Damage to human beings

Of the direct effects of nuclear weapons, the heat, blast and the ionising radiation are the causes of damage to human beings.

Damage by thermal radiation

Within a certain distance from the site of explosion, the heat is so intense that practically everything is vaporised. In Hiroshima, all that was left of some humans, sitting on stone benches near the centre of explosion, was their outlines.

Konturerna efter offer f–r atombombsexplosionen i Hiroshima
Outlines of victims of the nuclear explosion in Hiroshima


Outside the area where wounds are mortal, many humans will suffer severe burns. Heat radiation on bare skin causes burns directly. The skin will also be indirectly damaged when their clothes catch fire.

The thermal radiation causes damage to the eyes so that many people will be blinded by the explosion. For most of them, sight will return within a few minutes, but some will suffer permanent damage to the eyes, such as retina burns.

Many people will also be wounded or killed by the fires that result from the thermal radiation. These fires may grow together and become immense firestorms, spreading out from the site of explosion. Within these areas, even people in underground shelters will die because of heat, lack of oxygen or from carbon monoxide or -dioxide poisoning.

Blast damage

Humans can be killed by the sheer force of the blast if they are close to the explosion. At a greater distance, the shock may cause damage to the lungs or burst eardrums.

Most of the wounds caused by the blast will be indirect. People are most likely to die under collapsing buildings or by being hurled into solid objects. Further extensive damage will be caused to humans by flying shrapnel in the form of shattered glass, brick, concrete or wood.

Radiation damage

One of the things that set nuclear weapons apart from conventional arms is that the former kill and wound through radiation. This damage is caused by gamma and neutron radiation in both initial radiation and radioactive fall-out.

The damage caused by radiation is suffered by the cells of the body. When a somatic (body) cell is irradiated, the energy carried by the radiation is transferred to the cell. There is a risk that the DNA molecule contained in the cell is damaged, either directly by the radiation or by so-called free radicals, molecules that are harmful to DNA, that are formed in the cell. Unless the DNA molecule can be repaired, the cell will either die or become a cancer cell.

Pregnant women exposed to high doses of radiation suffer the risk of deformation of their children.

When a human body is exposed to a lethal dose of radiation, three syndromes appear:

  1. The gravest syndrome is the one that concerns the central nervous system (brain). The symptoms are headache, weariness, apathy, muscle tremors, coma, seizures and shock. This syndrome is an effect of high doses of radiation and inevitably ends in death within a few days.
  2. The second syndrome affects the gut and is characterised by nausea, vomiting, bleeding diarrhoea, dehydration and high fevers. The radiation victim dies within 1-2 weeks as a result of blood poisoning, intestinitis and disturbed water balance.
  3. The third syndrome concerns the blood-forming organs of the body. It occurs at lower dose levels than the syndromes (1) and (2), but still limited to persons relatively close to the epicenter. The bone marrow is damaged, decreasing its capacity to form white blood cells and blood platelets. Since the white blood cells defend the body against infections, the radiation victim becomes very sensitive to infection. The platelets bring about the coagulation of the blood, so a decrease in their number will increase bleeding. Thus, the risks are great that the victim will bleed to death. Depending on how much the bone marrow is damaged and how the victim is treated, he/she may return to health. Otherwise, death comes within a few months.

    Updated September 25, 2005

Quick review (Click to read the answers)

  1. What damage is done by the heat in the area closest to the detonation?
  2. The blast will kill people close to the explosion. What damage can be caused by the blast at greater distances?
  3. The radiation from a nuclear explosion causes damage to the cells of the human body. What happens to a cell when it is irradiated?

Continue to read about the indirect effects of nuclear war

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