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Ionizing Radiation

Viimati uuendatud: 25.02.2017

Ionizing Radiation

Depending on their ability to harm the organism, radiations are divided into ionizing and non-ionizing radiation.

Non-ionizing radiation includes infrared radiation, radio- and microwaves, UV-radiation. Short-wave UV-radiation could also be ionizing, but can easily be shielded with clothing or skin. Read more about the mentioned radiations in other sections of this website.

Ionizing radiation or radioactivity or radioactive decay characterizes particles or energy bursting out of atoms. Such substance is called radioactive material. For illustration purposes, a radioactive substance could be compared to an open popcorn machine, chaotically emitting pieces into all directions. Differently from a popcorn machine, radioactive particles are tiny yet bear a great amount of energy. Should this particle hit a human, it has an ionizing effect on the atoms of living tissues – meaning, it can harm these atoms.

Ionizing radiation is a daily phenomenon for humans. It has accompanied humans during the entire evolution and, according to some scientists, even helped in the development of humans. In addition to natural sources of radiation, the modern human is also exposed to radiation emanating from artificial sources.

Natural radiation dose consists mostly of radiation emanating from soil and building materials, cosmic radiation, and radionuclides and radon which have entered the human body. The latter two make up approximately half of the natural radiation dose. In Estonia, the radon percentage can be even greater, in places with higher radon occurrence. Radionuclides enter the body with consumed food and water.

Professionally, the cosmic radiation background can provide great input in the yearly radiation dose of employees. For example, 15 km above ground where airplanes fly, the radiation level is 10 μSv/h (micro Sieverts per hour). The same indicator on sea level is 0.03 μSv/h (IAEA).

Table. Radioactive radiation is divided into three classes.






Alpha particles bear a strong energy but do not last   long. They cannot even penetrate through a sheet of paper. Skin also stops an   alpha particle.

Beta particles are much smaller than the alpha   particles and can penetrate much deeper into materials and live tissues. They   have more energy and can thus cause much more harm. Beta particles are   stopped by aluminium paper, plastic, glass or a piece of timber.

Photons with a large amount of energy; radioactive   radiation with a great penetration ability. Gamma particles can be stopped by   a thick layer of thick substance (lead or steel), or a thick layer of soil or   concrete.


Poses a small danger when it comes into contact with   a body externally. Is more dangerous when inhaled or swallowed, for example   radon (is dangerous when inhaled).

Poses a danger:
  1) internally, when consumed, and
  2) externally, on the skin. Can cause dangerous “beta-burns” on skin and   damage the blood system below the skin. Usually does not penetrate deep   inside the skin. Is more dangerous when inhaled or swallowed (e.g., when food   is contaminated).

Gamma radiation can greatly damage internal organs   without having to consume it. Poses a danger:
  1) externally, on the entire body, and
  2) internally, on the entire body. Can greatly and irreversibly damage the   entire organism.


1) closed containers.

Alpha radiation is usually stopped by clothes or the   external skin layers.

Hygiene requirements and contamination cleaning   procedures must be adhered to in positions with an increased level of risk   stopped by ordinary clothes.

1) closed containers,
  2) local shielding, and
  3) monitoring the time of exposure.

Positions with higher beta radiation risk, must   follow hygiene requirements and contamination cleaning procedures.

1) move away from the source of radiation;
  2) shielding;
  3) minimizing the exposure time.

Chemical protective clothing does not provide any   protection against gamma radiation itself, but the use of breathing masks   (filters) and protective clothing helps to prevent radioactive particles from   entering the body.

Gamma radiation cannot be completely stopped with   shielding – its’ intensity can only be decreased. The shielding coefficient   of the gamma radiation depends on the material and thickness of the shield.

 Main sources of radioactive radiation are, for example:

  • medical X-rays,
  • radioactive contamination that originates from testing nuclear      weapons in the atmosphere,
  • the release of radioactive waste from the nuclear industry into the      environment,
  • industrial gamma radiation,
  • other generators, such as commodities.

In Estonia, professional contact with radioactivity can mostly occur in two cases:

  • accident or neglect of safety requirements when handling or      transporting radioactive waste,
  • neglect of safety requirements when working with a radiation source.

In addition to the aforementioned, risk can also originate from nuclear power plants located in neighbouring countries which jeopardize also Estonian population in the case of accidents (Loviisa in Finland, Sosnovoy Bor in Russia, and Ignalina in Lithuania).

Health Effects

Radioactivity can influence humans mostly in two ways: internally and externally. In the case of external influence, the radiation emits from a radioactive material which radiates the human body with alpha, beta or gamma radiation. Internal radiation occurs after visiting a radioactively contaminated environment – radionuclides that entered the body via inhaling or swallowing continue their radiation “work” inside the human body. For example, radionuclides can reach the ground from the atmosphere with rain and enter the food chain or drinking water.

Illustration. Average yearly radiation dose emanates from these sources (IAEA) (click on the image to enlarge)

Energy emitted by radioactive decay poses a danger to biologic tissues (human beings). The radiation damages genetic material inside the cell, which creates a risk of tumours. The more radiation is the received, the greater the damage on body cells. Genetic damage reaches from generation to generation and represent a health risk also for future generations.

Great amount of radiation is followed in a few days by severe illness symptoms and, in the case of extra-large dose, even death (if the incident exposed the human to more than 1,000-times the yearly dose). Contact with moderate radiation might not have any immediate effects and health problems may begin after some years.

All people are daily exposed to small doses of radiation from the environment, but this does not damage health.

The harmfulness of exposure to radiation depends mostly on the dose and length of exposure. The dose depends on the intensity of the radiation source, how far the person is to the source, and how much personal protective gear is used.

After contact with radioactivity, the following symptoms may appear:

  • skin damage ranging from redness to burns,
  • wounds and bleeding on the mouth, nose or digestive tract epidermis,
  • nausea, vomiting, diarrhoea,
  • shaking hands, spasms,
  • headaches, weakness, palpitation,
  • losing hair and other body hair,
  • lack of appetite, apathy, depression (indicators of a damaged      haematogenous system).

Pregnant women are in the risk group as radioactivity could negatively influence the development of the foetus. Exposure to large doses of radiation can result in prenatal death or severe damage to the child. According to ICRP, there is a direct connection between the child’s later level of intelligence and the dose of radiation received as a foetus. The risk of malicious tumours also grows, if a person was exposed to radioactive radiation prior to birth.

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