What is radiation? Radiation is various types of energy in the form of particles or electromagnetic waves that travel through space. The radiation has different compositions and origins.

Radiation is a physical process of emission (output) and propagation (displacement) of energy by moving particles or electromagnetic waves. This process can occur in a material medium or in space (vacuum).

The following are examples of well known and commented upon radiations:

  • Alpha
  • Beta
  • Gamma
  • X-rays
  • Ultraviolet
  • Visible light
  • Radio waves
  • Infrared
  • Microwaves, etc

Classification of radiation

According to their origin, radiations are classified as natural or artificial.


These are radiations that originate from a source not generated by human technology and occur spontaneously. An example is nuclear radiation, which emanates from inside the atomic nucleus of a chemical element.

Naturally radiating elements are found, for example, in rocks or sediments. Another example of natural radiation is cosmic radiation:

  • Protons
  • Electrons
  • Neutrons
  • Mesons
  • Neutrinos
  • Atomic nuclei
  • Gamma rays, which comes from solar and stellar events


These are radiations produced by electrical devices in which particles, e.g. electrons, are accelerated. This is the case with X-ray tubes used in radiodiagnosis.

There are also radiations produced by non-electrical devices, i.e. chemical elements irradiated by the acceleration of particles.


These are radiations coming from inside the nucleus of an unstable atom. The nucleus is unstable if the atom has 84 or more protons in it on average. There are only three nuclear radiations: Alpha (α), Beta (β) and Gamma (γ).

Types of radiation

Depending on their ability to interact with matter, radiations are classified as ionizing, non-ionizing and electromagnetic.


These are radiations that, upon contact with atoms, promote the escape of electrons from their orbits and transform the atom into a cation, i.e., an electron-deficient atom.

These radiations can cause ionization and excitation of atoms and molecules, changing the structure of the molecules (at least temporarily). The most important damage is that which occurs in DNA.

The most important examples of ionizing radiation include:

  • Alpha radiation: it consists of two protons and two neutrons and has low penetrating power.
  • Beta radiation: It consists of one electron and has a higher penetrating power than alpha, gamma and X-rays.
  • Gamma radiation and X-rays are electromagnetic radiations that differ only in their origin (gamma radiation is nuclear and X-rays are artificial) and have a high penetrating power.


These are radiations that are unable to remove electrons from the orbitals (electrospheres) of their atoms. Thus, they remain stable atoms. These radiations cannot cause ionization and excitation of atoms and molecules. Thus, they do not cause any (at least temporary) change in the molecular structure. Among the most important examples of this type of radiation are:

  • Infrared: radiation that is below red in the energy diagram and has a wavelength between 700 nm and 50000 nm.
  • Microwaves: are radiations produced by electronic systems through oscillators and have a higher frequency than radio waves. They are used in home to heat food and can transmit television signals or electronic communications.
  • visible light: has a frequency between 4.6 x 1014 Hz and 6.7 x 1014 Hz, with a wavelength of 450 nm to 700 nm. It is capable of sensitizing our vision.
  • Ultraviolet: radiation emitted by some atoms when they are excited, associated with the emission of light. It has a wavelength between 10 nm and 700 nm. Example: mercury vapor lamps (Hg).
  • Radio waves: are low frequency radiations, about 108 Hz, with a wavelength from 1 cm to 10000 nm. They are used for radio transmissions.


These are waves with a magnetic field and an electric field that propagate in air or in vacuum at a speed of 300,000 km/s. These radiations (gamma radiation, X-rays, ultraviolet, infrared, microwaves) are distinguished according to their wavelengths, as can be seen in the figure of the electromagnetic spectrum below:

Image of the Electromagnetic spectrum radiation.
The Electromagnetic Spectrum. What is Radiation.

Radiation Risks

Animals, plants, soil, water, and air can all be affected by radiation, each in their own way. In fact, soil, water, and air, when contaminated by radioactive substances, become carriers of radiation that is transmitted to living things.

In living things, radiation has two main effects:

  1. Genetic mutations: Exposure to radiation can alter the DNA of the cell so that a cell loses its function or performs a new function. Example: Genetic mutations can lead to the formation of new tissue, or cause a cell to perform a new function, leading to the development of a tumor.
  2. DNA breaks: Radiation can break DNA molecules and hinder the process of cell reproduction. This process can mean that cells are unable to pass on their genetic inheritance as they multiply. Cell function may be impaired, but it does not have to be.
Radiation Changes Your DNA.
Radiation Changes Your DNA.

It is worth noting that the extent of damage caused by radiation depends on two very important factors: the dose (amount of radiation that the body received) and the exposure time.

Short-term side effects

  • Nausea
  • Vomiting
  • Diarrhea
  • Fever
  • Headache
  • Burns
  • Alteration in blood production
  • Platelet breakdown
  • Decrease in immune resistance

Long-term damage

  • Skin, lung and other cancers
  • Presence of radiation in the entire food chain
  • Decreased fertility

Utilization of radiation

Regardless of the type (ionizing or non-ionizing) and origin (nuclear or non-nuclear), radiation has various uses. Among them we can highlight:

  • Sterilization of surgical material (medical or dental);
  • Sterilization of industrial food;

Note: Sterilization is performed to kill microorganisms such as fungi and bacteria.

  • Use in radiotherapy (alternative cancer treatment);
  • Medical imaging examinations (mammography, radiography and computed tomography);
  • Use in quality control in the manufacture of metal parts, mainly for aircraft;
  • Dating of fossils and historical artifacts using carbon-14;
  • Study of plant growth;
  • Study of insect behavior.

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