Preparing to survive in a nuclear environment following a nuclear attack or nuclear accident.
"This is the Wartime Broadcasting Service"
The message you never want to hear:
This country has been attacked with nuclear weapons. Communications have been severely disrupted, and the number of casualties and the extent of the damage are not yet known. We shall bring you further information as soon as possible. Meanwhile, stay tuned to this wavelength, stay calm and stay in your own homes.
Remember there is nothing to be gained by trying to get away. By leaving your homes you could be exposing yourselves to greater danger. If you leave, you may find yourself without food, without water, without accommodation and without protection. Radioactive fall-out, which follows a nuclear explosion, is many times more dangerous if you are directly exposed to it in the open. Roofs and walls offer substantial protection. The safest place is indoors.
Make sure gas and other fuel supplies are turned off and that all fires are extinguished. If mains water is available, this can be used for fire-fighting. You should also refill all your containers for drinking water after the fires have been put out, because the mains water supply may not be available for very long.
Water must not be used for flushing lavatories: until you are told that lavatories may be used again, other toilet arrangements must be made. Use your water only for essential drinking and cooking purposes. Water means life. Don't waste it.
Make your food stocks last: ration your supply, because it may have to last for fourteen days or more. If you have fresh food in the house, use this first to avoid wasting it: food in tins will keep.
If you live in an area where a fall-out warning has been given, stay in your fall-out room until you are told it is safe to come out. When the immediate danger has passed the sirens will sound a steady note. The "all clear" message will also be given on this wavelength. If you leave the fall-out room to go to the lavatory or replenish food or water supplies, do not remain outside the room for a minute longer than is necessary.
Do not, in any circumstances, go outside the house. Radioactive fall-out can kill. You cannot see it or feel it, but it is there. If you go outside, you will bring danger to your family and you may die. Stay in your fall-out room until you are told it is safe to come out or you hear the "all clear" on the sirens.
"The Wartime Broadcasting Service" was a service of the BBC that was intended to broadcast in the United Kingdom either after a nuclear attack or if conventional bombing destroyed regular BBC facilities in a conventional war. This service no longer exists and the UK has no agreed method of warning the population of an imminent nuclear attack. Few areas in the UK still have air raid warning sirens and there are no siren tests or drills in the UK anymore. If the country is attacked by nuclear weapons the first most survivors would know about it would be the flash although it is fair to assume that the government may try to warn people using radio, tv and social media if possible.
What happens when a nuclear bomb detonates?
Survive DURING an attack
If warned of an imminent attack, immediately get inside the nearest building and move away from windows.This will help provide protection from the blast, heat, and radiation of the detonation. See the FEMA advice and diagram below of presumed safest areas.
If there is no warning and you are outside the kill zone of a nuclear explosion there will be a bright flash like being bathed in bright hot sunlight and for a few minutes you may be temporarily blinded.
Take cover from the blast behind anything that might offer protection. Lie face down to protect exposed skin from the heat and flying debris. If you are in a vehicle, stop safely, and duck down within the vehicle.
After the shock wave passes, get inside the nearest, best shelter location for protection from potential fallout. You will have 10 minutes or more to find an adequate shelter.
Be inside before the fallout arrives. The highest outdoor radiation levels from fallout occur immediately after the fallout arrives and then decrease with time.
Stay tuned for updated instructions from emergency response officials. If advised to evacuate, listen for information about routes, shelters, and procedures.
If you have evacuated, do not return until you are told it is safe to do so by local officials.
Be Safe AFTER a nuclear attack
Immediately after you are inside shelter, if you may have been outside after the fallout arrived:
Effects of nuclear weapons
The destructive power of a nuclear weapon is manyfold. First comes a violent, rapid shockwave followed by a searing fireball. Ten minutes after the explosion comes invisible lethal radiation all contributing to injuries, deaths and damage. The largest nuclear free–fall bombs have a yield of 1.2 megatonnes, making them some 75 times more powerful than the bomb detonated over Hiroshima in 1945. The devastation produced by such a bomb depends on where it explodes, but also whether it detonates on the ground or in the air.
Surface Burst nuclear bomb effects
On impact with the ground, such a nuclear bomb would create a fireball nearly 3 km wide, with temperatures reaching many thousands of degrees Celsius. Humans and animals at the epicentre would vapourise instantly and further out in the 3 km circle people and animals would catch fire or sustain first degree burns. People and animals would be expected to suffer third degree burns more than 11 km from the epicentre
A powerful shockwave traveling faster than the speed of sound at sea level spreads out ahead of the fireball demolishing most buildings in its path. The shockwave could flatten sturdy concrete buildings within a 2.5 km radius with near 100% fatalities. Five kilometers out structurally weaker buildings would be flattened and more than 12 km out windows would shatter.
Within 2.5 km of ground zero most people and animals would suffer fatal acute radiation poisoning. More would be exposed as the radiation cloud, which can be many kilometres wide, is blown towards nearby populations. It is predicted that a 1.2 megatonne bomb dropped on London would instantly kill 700,000 people with nearly twice as many suffering serious injury.
Air Burst nuclear bomb effects
An air burst is an explosion in which a weapon is detonated in air at an altitude below 30 km but at sufficient height that the fireball does not contact the surface of the earth. After such a burst, blast may cause considerable damage and injury. The altitude of an air burst can be varied to obtain maximum blast effects, maximum thermal effects, desired radiation effects, or a balanced combination of these effects.
Burns to exposed skin may be produced over many square kilometers and eye injuries over a still larger area. Initial nuclear radiation will be a significant hazard but the fallout hazard can be ignored as there is essentially no local fallout from an air burst. The fission products are generally dispersed over a large area of the globe unless there is local rainfall resulting in localized fallout. In the vicinity of ground zero, there may be a small area of neutron-induced activity which could be hazardous to anyone living there. Tactically, air bursts are the most likely to be used against ground forces.
More detailed information on effects of nuclear weapons
The effects of nuclear weapons are classified as either initial or residual. Initial effects occur in the immediate area of the explosion and are hazardous in the first minute after the explosion. Residual effects can last for days or years and cause death mainly from cancers. The principal initial effects are blast and radiation. A nuclear explosion also emits an electromagnetic pulse (EMP), which creates damaging voltage surges in electrical equipment. The effect of the EMP depends upon size of explosion and the altitude of the blast. Key military equipment is shielded from the effect of EMP but civilian equipment is not and this means that communications could be destroyed up to 6 miles (1,000 kilometres) from a nuclear blast. Any electronic equipment will be rendered ineffective and this also means that most transport systems would be non–functional. Most modern cars would be ruined but an old farm tractor with no modern circuitry probably would still run. In real terms, there would be no electrical power, radio, TV, phone networks (or phones), computers, Internet, in fact, any electric equipment that uses an integrated circuit board would certainly fail. This would most likely mean there would also be no mains water supply, sanitation or electricity.
Blast is defined as the brief and rapid movement of air away from an explosion's centre and the pressure accompanying this movement. Strong winds accompany the blast of a nuclear bomb. Blast hurls debris and collapses buildings. Any person caught in the blast is killed or seriously injured depending on their proximity to the epicentre. Blast causes collapsed lungs, ruptured eardrums and crushing.
Thermal radiation is the heat and light radiation emitted by a nuclear explosion's fireball. Light radiation consists of visible light, ultraviolet and infrared light. Thermal radiation produces extensive fires, skin burns and permanent flash blindness caused by the reflexive glance, which is the normal reflex reaction that drives people and animals to look at the explosion.
Nuclear radiation breaks down into two categories: initial radiation and residual radiation.
Initial nuclear radiation consists of intense gamma rays and neutrons produced during the first minute after the explosion. This radiation causes extensive damage to cells throughout the body. Radiation damage may cause headaches, nausea, vomiting, diarrhoea and even death, depending on the dose received. The major problem in protecting oneself against the initial effects of radiation is time. A person may have received a lethal or incapacitating dose before taking any protective action. Personnel exposed to lethal amounts of initial radiation become a hazard to non–contaminated personnel as their bodies retain and emit lethal doses of radiation.
Residual radiation consists of all radiation produced after one minute from the explosion.
Types of nuclear bursts and their after affects
There are three types of nuclear bursts and the type of burst directly effects the chances of survival:
Most injuries following a nuclear explosion result from the initial nuclear effects of the detonation. These injuries are classed as blast, thermal or radiation injuries. Further radiation injuries may occur if proper precautions were not taken against fallout. Individuals in the area near a nuclear explosion will probably suffer a combination of all three types of injuries.
Blast injuries produced by nuclear weapons are similar to those caused by conventional high–explosive weapons, namely, collapsed lungs and ruptured internal organs. Blast injuries also include injuries from flying debris, which would typically be fractured limbs or massive internal injuries. Victims would also be thrown long distances by the blast and sustain impact injuries when they hit other objects or the ground. Substantial cover and distance from the explosion are the only protection against nuclear blast injury. Blast injury wounds must be covered as soon as possible to prevent the entry of radioactive dust particles.
The heat and light the nuclear fireball emits causes first, second or third–degree burns. Flash blindness also occurs. This blindness is usually permanent, depending on the degree of exposure of the eyes. Clothing provides some protection against thermal injuries. Covering as much exposed skin as possible before a nuclear explosion reduces the risk of thermal injury. First aid for thermal injuries caused by a nuclear blast is the same as for conventional burns. Open burns should be washed and covered to keep contaminated air from the wound; use food wrap if conventional first aid supplies are limited.
Neutrons, gamma radiation, alpha radiation and beta radiation cause radiation injuries. Neutrons are high–speed, extremely penetrating particles that actually smash cells within the body. Gamma radiation is similar to X–rays and is also a highly penetrating radiation. During the initial fireball stage of a nuclear detonation, initial gamma radiation and neutrons are the most serious threat. Beta and alpha radiation are radioactive particles normally associated with radioactive dust from fallout. They are short–range particles and protective clothing shields the body from their effect.
Residual radiation is all radiation emitted after one minute has passed from the instant of the nuclear explosion. Residual radiation consists of induced radiation and fallout.
This is a relatively small, intensely radioactive area directly underneath the nuclear weapon's fireball at ground zero. The irradiated earth in this area will remain highly radioactive and lethal for centuries.
Fallout consists of radioactive soil and water particles, as well as weapon fragments. During a surface detonation or if an airburst's nuclear fireball touches the ground, large amounts of soil and water are vaporized along with the bomb's fragments and are forced upward to altitudes of 15 miles (25 kilometres) or more. This is known as a "dirty bomb." When these vaporized contents cool, they can form more than 200 different radioactive products. The vaporized bomb contents condense into tiny radioactive particles that the wind carries and they fall back to earth as radioactive dust. Fallout particles emit alpha, beta and gamma radiation. Alpha and beta radiation are relatively easy to counteract and residual gamma radiation is much less intense than the gamma radiation emitted during the first minute after the explosion. Fallout is the most significant radiation hazard but provided one hasn't received a lethal radiation dose from the initial radiation, the chances of survival are reasonable if a person has protective clothing and knows how to survive.
How the human body reacts to radiation
The effects of radiation on the human body can be broadly classed as either chronic or acute. Chronic effects are those that occur some years after exposure to radiation, for example, cancers and genetic defects. Chronic effects do not effect immediate survival in a radioactive environment. Radiation sickness and beta burns are examples of acute effects to human tissue that occur within hours after exposure to radiation. Symptoms of radiation sickness include nausea, diarrhoea, vomiting, fatigue, weakness and loss of hair. Penetrating beta rays cause radiation burns; the wounds are similar to conventional burns.
Can a person recover?
The chance of recovery depends mainly on how much and for how long the body was exposed to radiation, as well as on a person's general level of health and ability to recover. The brain and kidneys will not recover. Other parts (skin and bone marrow) have a greater ability to recover from damage. Usually, a dose of 600 centigrams (cgys) to the entire body will result in almost certain death. If, for example, only the hands received this same dose, a person's overall health would not suffer much, although the hands would be severely damaged.
External and internal damage to the body
Highly penetrating gamma radiation or the less penetrating beta radiation that causes burns can cause external damage. The entry of even a very small amount of alpha or beta radiation–emitting particles into the body can cause internal damage to critical organs, such as, the gastrointestinal tract, thyroid gland and bone. These radiation–emitting particles can enter the body through consumption of contaminated water or food, by inhalation of contaminated dust or by absorption through cuts or abrasions. Internal radiation damage can be reduced by good personal hygiene and careful decontamination of food and water. The symptoms of internal radiation injuries include nausea, diarrhoea and vomiting. The severity of these symptoms is due to the extreme sensitivity of the gastrointestinal tract to radiation. The severity of the symptoms and the speed of onset after exposure are good indicators of the degree of radiation damage. The gastrointestinal damage can come from either an external or an internal radiation hazard.
Protecting against penetrating external radiation
Understanding the radiation hazards and knowing how to protect against the most dangerous form of residual penetrating external radiation, is critical to survival in an area of nuclear fallout. Time, distance and shielding are critical factors to survival. The level of radiation can be reduced and chances of survival increased by controlling the duration of exposure. It is important to get as far away from the radiation source as possible, as fast as possible. Finally, protecting the body using shielding material (ideally a NBC suit and respirator), is the best defence against nuclear fallout.
Time is a critical factor to the survivor because radiation dosages are cumulative and radioactivity decreases or decays over time (radioactive half–life). Thus, a radioactive element decays or loses half of its radioactivity within a certain time. Obviously, the greatest hazard from fallout occurs immediately after detonation and the hazard decreases quickly over a relatively short time. Avoiding fallout areas until the radioactivity decays to safe levels gives the greatest chance of survival. The rule of thumb for radioactivity decay is that it decreases in intensity by a factor of ten for every sevenfold increase in time following the peak radiation level. For example, if a nuclear fallout area had a maximum radiation rate of 200 cgys per hour when fallout is complete, this rate would fall to 20 cgys per hour after just 7 hours; it would fall still further to 2 cgys per hour after 49 hours.
Because radiation intensity of penetrating gamma radiation decreases by the square of the distance from the source, the further away from the blast area, the greater one's chances of survival. For example, if exposed to 1,000 cgys of radiation standing 12 inches (60 cm), you would only receive 250 cgys, thus, when you double the distance, radiation decreases to (0.5)/2 or 0.25 the amount. While this formula is valid for concentrated sources of radiation in small areas, it becomes more complicated for large areas of radiation such as fallout areas. Putting science to one side, to survive one has to get as far away from the blast area as fast as possible but this is easier said than done, bearing in mind, the total infrastructure will be destroyed. It is best to travel overland or by river and avoid the sea, as all the salt in it will be highly radioactive.
Shielding oneself from radiation provides the greatest protection and is, perhaps, the only feasible thing to do under survival conditions. If shielding is not possible, get as far away from the blast area as quickly as one can.
Shielding means placing a barrier between oneself and the penetrating radiation. Shielding material either absorbs or weakens the penetrating radiation, thereby reducing the amount of radiation reaching the body. The denser the material, the better the shielding effect; lead, iron, concrete and fresh water are good examples of shielding materials.
The thickness required to weaken gamma radiation from fallout is far less than that needed to shield against initial gamma radiation. Fallout radiation has less energy than a nuclear detonation's initial radiation. For fallout radiation, a relatively small amount of shielding material can provide adequate protection.
The principle of "half–value layer thickness" is useful in understanding the absorption of gamma radiation by various materials. According to this principle, if 5 cm (2 inches) of brick reduce the gamma radiation level by one–half, adding another 5 cm (2 inches) of brick (another half–value layer) will reduce the intensity by another half, namely, to one–fourth the original amount. Fifteen centimetres (6 inches) will reduce gamma radiation fallout levels to one–eighth its original amount, 20 cm (8 inces) to one–sixteenth and so on. Thus, a shelter protected by 1 metre (3.3 feet) of dirt would reduce a radiation intensity of 1,000 cgys per hour on the outside to about 0.5 cgys per hour inside the shelter.
Getting under cover
Bearing in mind the shielding material's effectiveness depends on its thickness and density, an ample thickness of shielding material will reduce the level of radiation to negligible amounts. Because it is vital to stay in a shelter for at least seven days, at the minimum, make sure you have at the very least a supply of bottled water; the body can survive without food for longer than seven days.
It is essential to get protection against the high–intensity radiation levels of early gamma fallout within five minutes of a bomb exploding. Without shelter, the dosage of radiation received in the first few hours will exceed that received during the rest of a week in a contaminated area. The dosage received in this first week will exceed the dosage accumulated during the rest of a lifetime spent in the same contaminated area. This means, one has to stay shielded for a minimum of seven days following a nuclear explosion.
Good examples of terrain that provides natural shielding and easy shelter construction are ditches, ravines, rocky outcrops, hills and riverbanks.
In level areas, without natural protection, the only option is to dig a slit trench. When digging a trench, work from inside the trench as soon as it is large enough to cover part of your body to reduce exposure to radiation. In open country, try to dig the trench from a prone position, stacking the dirt carefully and evenly around the trench. On level ground, pile the dirt around the body for additional shielding. The faster one digs and gets under cover, the greater is one's chance of survival.
Other emergency shelters
An underground shelter covered by 1 metre (3.3 feet) or more of earth provides the best protection against fallout radiation; the following unoccupied structures (in order listed) offer the next best levels of protection:
It is not essential to roof over a shelter. Only do this if the materials are readily found with only a brief exposure to outside contamination. If building a roof would require extended exposure to penetrating radiation, it would be wiser to leave the shelter roofless. A roof's sole function is to reduce radiation dropping directly down, which is only a great risk in totally still weather conditions and these are unlikely following a nuclear blast. Unless you used a thick concrete roof covered in earth it would provide very little shielding anyway.
A simple roof can be made from a groundsheet or plastic sheet anchored down with dirt, rocks or other refuse from your shelter. Large particles of radioactive dirt and debris from the top of the sheeting can be beaten off the sheeting from the inside at frequent intervals. This cover will not offer shielding from the radioactive particles deposited on the surface but it will increase the distance from the fallout source and keep the shelter area from further contamination.
Selecting and preparing a site for a shelter
To reduce exposure to radiation, remember the following factors when selecting and setting up a shelter:
To avoid contamination:
Treating casualties and survival issuesIn the UK there is no triage system for handling fatalities following a nuclear explosion, there is guidance available, but currently no internationally agreed upon medical triage systems specifically for radiation mass casualty incidents. In standard triage, the most severely injured are given first priority. After a nuclear detonation, priorities are likely to change. It may be necessary for those with less severe injuries (e.g., those who are ambulatory, responsive and only moderately injured) to receive priority in order to provide the greatest good to the greatest number of victims. This means that First Responders will need to change accepted conventional triage methods from treating the most severely injured first to ignoring the severely injured and leaving them to die.
Rudimentary treatment of the wounded
All wounds must be covered to prevent contamination and the entry of radioactive particles. Burns from beta radiation have to be washed first and then treated as ordinary burns. Extra measures have to be taken to prevent infection because the body will be extremely sensitive to infections due to changes in blood chemistry. Close attention should be paid to the prevention of colds or respiratory infections. Personal hygiene becomes essential to prevent infections.
Most water sources will be contaminated in an area covered by nuclear fallout. Running water in rivers and streams will be less contaminated forty–eight hours after the last nuclear explosion, but avoid using water that has high sediment content. Water from springs, wells or other underground sources that undergo natural filtration will be the safest. Any water found in the underground pipes or containers of abandoned houses or stores will also be free from radioactive particles. This water will be safe to drink, although it will have to be boiled before use.
Snow taken from 15 cm (6 inches) or more below the surface of a fallout area is also a safe source of water.
After several days, all fast flowing streams and rivers should be free of contamination (unless they flow through the area where a bomb exploded). If at all possible, filter water before use to get rid of any radioactive particles. The best filtration method is to dig sediment holes or seepage basins along the side of a water source. The water will seep laterally into the hole through the intervening soil that acts as a filtering agent and removes the contaminated fallout particles that settled on the original body of water. This method can remove up to 99% of the radioactivity in water. You must cover the hole in some way in order to prevent further contamination.
Water from lakes, pools, ponds and other standing sources is likely to be heavily contaminated, though most of the heavier, long–lived radioactive isotopes will settle to the bottom. Use the settling technique to purify this water. First, fill a bucket or other deep container three–fourths full with contaminated water. Then take dirt from a depth of 10 cm (4 inches) or more below the ground surface and stir it into the water. Use about 2.54 cm (1 inch) of dirt for every 10 cm (4 inches) of water. Stir the water until you see most dirt particles suspended in the water. Let the mixture settle for at least 6 hours. The settling dirt particles will carry most of the suspended fallout particles to the bottom and cover them. You can then carefully remove the clear water. Purify this water using a filtration device.
Treat all water with water purification tablets from your survival kit or boil it as an additional precaution against disease.
It will be difficult to find edible food in a radiation–contaminated area. On foraging trips, look in abandoned buildings for any processed foods. These are safe for use after decontaminating them by washing their containers thoroughly in running water. Look for canned and packaged foods; if they have outer wrappers remove these and wash the inner wrappers or containers free of fallout particles. A good place to look for food is in the storage areas of shops and supermarkets, as food stored there will still be in pallet wrapping or in boxes.
If little or no processed food is available in your area, you may have to forage for plants and hunt for animals as you work your way to a safer place.
Animals as a Food Source
Assume that all animals, regardless of their habitat or living conditions, were exposed to radiation. The effect of radiation on animals is similar to its effect on humans. Thus, most of the wild animals living in a fallout area are likely to become sick or die from radiation during the first month following the nuclear explosion. Even though animals may not be free from harmful radioactive materials, you can and must use them in survival conditions as a food source if other foods are not available. With careful preparation and by following several important principles, animals can be safe food sources. Rabbits exist almost everywhere and they live in deep burrows, this doesn't guarantee they are not contaminated but the risk is less. Earthworms are a valuable source of protein.
First, do not eat an animal that appears to be sick. It may have developed a bacterial infection as a result of radiation poisoning. Contaminated meat, even if thoroughly cooked, could cause severe illness or death if eaten.
Wash in running water and then carefully skin all animals to prevent any radioactive particles on the skin or fur from entering the body. Do not eat meat close to the bones and joints. A contaminated animal's skeleton will contain over ninety per cent of the radioactivity. The remaining animal muscle tissue, however, will be safe to eat. Before cooking it, cut the meat away from the bone, leaving at least a 0.12 inch (3 mm) thickness of meat on the bone. Discard all internal organs (heart, liver and kidneys) since they tend to concentrate beta and gamma radioactivity.
Cook all meat until it is very well done. To be sure the meat is well done, cut it into strips of less than 0.5 inch (13 mm) before cooking. This will also reduce cooking time and save fuel.
Fish and other aquatic animals will be highly contaminated. This is also true for water plants, especially in coastal areas. Use aquatic food sources only in conditions of extreme emergency. The salt in seawater will be highly radioactive.
All eggs, even if laid during the period of fallout, will be safe to eat. Completely avoid milk from any animals in a fallout area because animals absorb large amounts of radioactivity from the plants they eat.
Plants as a food source
Plants absorb contamination through their roots and all plants will be covered in radioactive fallout. For this reason, search for potatoes, turnips, carrots and other tuberous plants. These are the safest to eat once you scrub them and remove their skins.
Next best are plants that can be decontaminated by washing and peeling their outer surfaces. Examples are bananas, apples, tomatoes, prickly pears and other such fruits and vegetables.
Any smooth skinned vegetable, fruit or plant that you cannot easily peel or effectively decontaminate by washing should only be eaten if there is absolutely nothing else to eat.
The effectiveness of decontamination by scrubbing is inversely proportional to the roughness of the fruit's surface. Smooth surfaced fruits lose 90% of their contamination after washing, while washing rough surfaced plants removes only about 50% of the contamination. Eat rough surfaced plants (such as lettuce) only as a last resort because one cannot effectively decontaminate them by peeling or washing. Other difficult foods to decontaminate by washing with water include dried fruits (figs, prunes, peaches, apricots, pears) and Soya beans.
In general, you can use any edible plant food if you can effectively decontaminate it. Plants that are growing, however, can absorb some radioactive materials through their leaves as well as from the soil, especially if they have grown during or after the fallout period. Avoid using these plants for food except in an emergency.
Lessons from Chernobyl
Chernobyl before and after the explosion.
Following the Chernobyl nuclear reactor disaster in April 1986, a saturated solution of Potassium iodide (SSKI) was given to 10.5 million children and 7 million adults in Poland as a prophylactic measure against the build–up of radioactive iodine–131 in the thyroid gland. (Potassium iodide (KI) is prepared by reacting iodine with a hot solution of potassium hydroxide. It is mainly used in the form of a saturated solution, 100 gm of potassium iodide to 100 ml of water. This equates to approximately 50 mg/drop. The solution is usually added to water, fruit juice or milk before drinking.)
Approximately 18 million doses were distributed, with follow up studies showing no known thyroid cancer among KI recipients. With the passage of time, people living in irradiated areas where KI was not available have developed thyroid cancer at epidemic levels, which is why the US Food and Drug Administration (FDA) reported, "The data clearly demonstrates the risks of thyroid radiation. KI can be used to provide safe and effective protection against thyroid cancer caused by irradiation."
Soviet authorities distributed KI in a 19 mile (30–kilometre) zone around the plant. The purpose was to protect residents from radioactive iodine, a highly carcinogenic material found in nuclear reactors, which had been released by the damaged reactor. Only a limited amount of KI was available, but those who received it were protected. Later, the US Nuclear Regulatory Commission (NRC) reported, "thousands of measurements of I–131 (radioactive iodine) activity suggest that the observed levels were lower than would have been expected had this prophylactic measure not been taken. The use of KI was credited with permissible iodine content in 97% of the evacuees tested."
Chernobyl also demonstrated that the need to protect the thyroid from radiation was greater than expected. Within ten years of the accident, it became clear that thyroid damage caused by released radioactive iodine was virtually the only adverse health effect that could be measured. As reported by the NRC, studies after the accident showed that "As of 1996, except for thyroid cancer, there has been no confirmed increase in the rates of other cancers, including leukemia, among the public, that have been attributed to releases from the accident."
But equally important to the question of KI is the fact that radiation releases are not "local" events. Researchers at the World Health Organization accurately located and counted the cancer victims from Chernobyl and were startled to find that "the increase in incidence of thyroid cancer has been documented up to 311 miles (500 kilometres) from the accident site (Chernobyl is 1,489 miles (2,396 kilometres) from London). Significant doses from radioactive iodine can occur hundreds of kilometres from the site, beyond emergency planning zones. Consequently, far more people than anticipated were affected by the radiation, which caused the United Nations to report in 2002 that, "The number of people with thyroid cancer has exceeded expectations. Over 11,000 cases have already been reported."