||What are the sources of radiation?
The primary sources of radiation to which people are exposed are the natural radioactive background and manmade sources. There is natural radioactivity in the world in which we live. The majority of cosmic radiation comes to the Earth from the Sun. The atmosphere protects the Earth against the cosmic rays and substantially reduces their transmission. The other sources of natural radiation are radioactive isotopes which are widespread in the natural environment. Uranium (U), radium (Ra), and radon (Rn, gas) are examples of the naturally radioactive elements. They occur in rocks, soil, and in a number of minerals. The natural radioactivity level varies with different locations.
Fig. 2. Weighted-average, effective annual doses of natural irradiation and contributions of primary dose-forming sources (in %).
Source: Lukyanova, Ye.M., Clinic and paraclinic aspects of children's health 9 years after the Chernobyl disaster. Proceedings of the Ukrainian Academy of Medical Sciences, Vol. 1, 1995.
Alongside the influence of natural radiation, people are affected by radioactivity from manmade sources. The majority of exposure to radiation is accounted for by medical and dental procedures associated with X-ray and gamma-ray treatment; the rest is associated with previous testing of nuclear weapons, X-ray security units in airports, and nuclear and coal-fired power stations. Those who reside or who have resided in territories contaminated during the Chernobyl Nuclear Power Plant accident were exposed to radiation from emissions. The exploded reactor emitted about 1018 Bq of radioactive substances and a multitude of radioactive nuclides (Iodine-131, Iodine-132, Iodine-133, Cesium-134, Cesium-137, Strontium-89, Strontium-90, Plutonium-238, Plutonium-239, Plutonium-240, etc.) into the atmosphere.