Natural and artificial radiation
Radiación natural y artificial
Ionising radiations from natural origins are present in the nature surrounding us. Apart from cosmic radiation, ionising radiations are also produced as a consequence of the presence of radioactive materials in the Earth's crust. Three-quarters of the radioactivity in the environment comes from natural elements.
Not all parts of the Earth have the same level of radioactivity. In some areas of India, for example, radioactivity is 10 times greater than the European average. The reason lies in the sand in India, which contains thorium, a natural radioactive element. The Alps and other mountain ranges also have a relatively high level of radioactivity due to the composition of their granite. As well as this geographical variation, certain activities such as, for example, the manufacture of ceramics, the production of fertilisers and the extraction of gas and petroleum, may increase the doses due to these radionuclides of natural origin, not only for the workers but also for the rest of the public.
In our homes, radioactivity may also exist, mainly from radon gas. This gas is produced as a consequence of the decay of the uranium contained in rocks. The amount of radon gas that accumulates in a house depends on its location, on the materials used to build it and on our way of life. Radon emanates from rocks and accumulates in closed places, so it is highly recommendable that homes and workplaces are well ventilated.
Cosmic radiation is generated in the nuclear reactions that occur inside the Sun and other stars. The atmosphere filters out these rays and protects us from their dangerous effects, since radioactivity is much higher outside the atmosphere, in space. When we climb a mountain, this protection decreases and cosmic radiation is more intense. The same situation occurs when we travel by plane; we are more exposed to radiation.
There are also radioactive elements in many food products and in drinking water. Even our bodies are a source of radiation since we store small amounts of radioactive potassium, a product that is necessary for the human body.
Radiation can also be produced artificially. In 1895, the physicist Roëntgen, experimenting with cathodic rays, discovered the first type of artificial radiation used by human beings – X-rays. These are electromagnetic waves caused by the impact of electrons with a certain material inside a vacuum tube.
Once the properties and potential of radiations started to become known, its applications were developed together with techniques to obtain artificial radioactive materials. X-rays and gamma radiation were used in medicine for diagnosis using multiple images of physical problems. Radiation is also used to treat cancer and other illnesses. Industry also benefits from the application of radiation in radiography techniques for industrial measurement, food sterilisation, pest control, etc. In addition, fission reactions are triggered in nuclear power plants to release a large amount of energy in the form of heat and radiations to produce electricity.