Radiation can be described as energy or particles from a source that travel through space or other mediums. Light, heat, microwaves and wireless communications are all forms of radiation. The kind of radiation discussed here is called ionising radiation because it can produce charged particles (ions) in matter.
Ionising radiation is emitted by a large range of natural materials, can be produced by everyday devices such as X-ray machines, and can also be emitted by unstable atoms. Atoms become unstable when they have the wrong amount of mass required to keep them stable, an excess of energy, or both. Unstable atoms are said to be radioactive.
In order to reach stability these atoms give off, or emit, energy and/or mass. The energy is emitted in the form of electromagnetic radiation (i.e. light) and the mass is in the form of tiny particles. These emissions are ...view middle of the document...
One is living indoors. In surrounding ourselves with bricks and mortar, we increase the concentration of a radioactive gas called radon in the air we breathe. Radon arises naturally from the radioactive decay of uranium and thorium, normally present in rocks, soil, bricks, mortar, tiles and concrete. Reducing ventilation in order to conserve energy may increase radon concentrations even further. Using bore water, especially in a hot shower or in thermal springs, also increases your radiation dose.
Another source of radiation is medical use –X-rays in radiography and tomography and radioactivity in nuclear medicine. Some therapeutic uses of radiation give a dose to certain organs many times higher than our annual background radiation dose.
Small extra doses of radiation occur in a number of ways. The higher you go, the less shielding the atmosphere affords from cosmic rays. On a mountain top the air may be cleaner, but the radiation dose is higher. Air travel increases radiation dose; astronauts receive even higher doses. Fallout from atmospheric nuclear testing in the 1950s and 1960s is still present in the environment. Many industries release otherwise locked-in radioactivity into the environment. This is especially true of a coal-burning plant, and to a lesser extent the fertiliser, mining and building industries.
Other common, but minor, sources of radiation are some older luminescent clocks, watches, compasses and gunsights, exit signs, certain paints and pigments, dental porcelain, fire alarms, smoke detectors and television sets.
Although some radiation is capable of travelling large distances, it may be stopped by appropriate absorbers. Starlight traverses galaxies, but may be stopped by a piece of paper. Radio waves, too, are capable of travelling great distances, but may be absorbed by materials such as metals. Like light, ionising radiation travels in straight lines until absorbed or deflected. The material used to absorb ionising radiation depends on the type and energy of the radiation.