Radiation is often classified into two types: ionizing and non-ionizing radiation, in order to indicate the energy level and hazards of the radiation. What these hazards are and the right ways to handle them within the UT can be found here. If you are unable to find what you seek, please don't hesitate to contact the Coördinating Radiation Expert (CSD) of HR.

What is radiation? (DUTCH ONLY)

Straling is het uitzenden van energie als golven (elektromagnetische straling) of als deeltjes (deeltjesstraling, zoals alfastraling en bètastraling); volgens hedendaagse kwantummechanische opvattingen is hier overigens geen fundamenteel verschil tussen. Straling is energieoverdracht zonder dat er sprake is van direct contact.

Straling kan worden veroorzaakt door talloze natuurkundige processen, zoals radioactief verval, kernsplitsing of kernfusie, (hoge)temperatuur, of door materialen zoals gassen die kunnen gaan stralen onder invloed van elektriciteit.

Ionizing radiation

Ionizing radiation is a type of radiation which is sufficiently energetic to push an electron out of the outer shell of an atom. Because of this, the atom will in total have a positive charge instead of a neutral charge, the atom will be ionized, and becomes an ion. This type of radiation cannot be seen, heard, tasted, smelled or felt.

Ionization can occur in two ways: directly or indirectly. The direct way can only occur through charged particles, such as alpha particles or beta particles. The indirect way occurs in steps. An uncharged particle or a photon (electromagnetic radiation) starts a reaction with an atom or an atomic nucleus. Charged particles originate in this reaction, which then ionize other atoms.

The energy that a photon requires in order to ionize an atom depends on the type of atom. For example, hydrogen requires a photon with an energy of 13.6 eV (one electron volt = 1.602 10-19 joule) to be ionized, meaning radiation with a frequency of about 3.28 1015Hz, which corresponds with the frequency of ultraviolet light. Other values apply to other atoms.

Ionizing radiation exists in many different shapes, namely:

  1. particle radiation 
  2. electromagnetic radiation

Examples of particle radiation are: alpha radiation, beta radiation (of β− electrons en β+ positrons), neutrons, protons. Electromagnetic radiation consists of photons, depending on the frequency it is either X-radiation or gamma radiation.

If you are unable to find what you seek, please don't hesitate to contact the Coördinating Radiation Expert (CSD) of HR.

Non ionizing radiation

Non-ionizing radiation is a collective term for several types of radiation which are not harmful in low dosages and without long-term exposure. Non-ionizing radiation cannot cause ionization in biological systems (body cells), even at very high intensity levels. This is the major difference with ionizing radiation. However, certain effects can arise: Heating or causing electrical currents in tissues and cells.

Exposure to higher dosages or concentrations can, however, be dangerous for humans, such as radio frequency radiation of heat sealers and transmitting equipment, infrared radiation of welding arcs, hot objects and lasers (a laser pen, for example!) and UV radiation of welding processes and sterilization lamps. Even less is known about effects such as fatigue, drowsiness and carcinogenicity. Discussions are running high in this area, for example, when it concerns the safety of mobile phones, GSM masts, radars and the like.

The documents below provide more background information and a working method to manage this.

If you are unable to find what you seek, please don't hesitate to contact the Coordinating Radiation Expert (CSD) of HR.


A laser is a device that sends out a small, parallel and coherent bundle of (electromagnetic) radiation of a specific wavelength. Because of these properties, the radiation intensity in the bundle can still be high at a great distance. When living tissue is exposed to this over too long a period of time, the heat development due to the absorption of the radiation can cause damage to the tissue. A too high radiation density of the eye can inflict damage to the cornea, lens or iris. The maximum amount of acceptable radiation intensity for the skin is several orders of magnitude higher than for the eye. The required safety measures as regards the radiation risk are therefore primarily focused on the dangers for the eye.

If a staff member is or staff members are working with lasers, then the guidelines described in the 'Working with lasers' document are required to be followed. The checklist is a convenient tool to check a couple of things.
Laserclasses 3B and 4 need to registrated. Use this form for registration.

If you want work with laserclasses 3 of 4 you need to follow the E-leaning working with laser.

If you are unable to find what you seek, please don't hesitate to contact the Coordinating Radiation Expert (CSD) of HR.